Diagnostic pediatric ultrasound 9783131697417, 3131697415

Table of contents :
Diagnostic Pediatric Ultrasound
Media Center Information
Title Page
Copyright
Contents
Video Contents
Foreword
Preface
Contributors
Abbreviations
1 Examining the Child and Creating a Child-Friendly Environment
1.1 Child-Friendly Staff
1.2 Appointment
1.3 Appointment Letter
1.4 Waiting Area
1.5 Examination Room
1.6 Examination
1.7 How to Scan: Tips and Tricks
1.8 Private Room
1.9 Communicating the Results
Recommended Readings
2 Physics and Artifacts
2.1 Basic Principles of Ultrasound
2.1.1 UltrasonicWaves
2.1.2 Wave Propagation in Homogeneous Media
2.1.3 Wave Propagation in Inhomogeneous Media
2.1.4 Doppler Echo
2.2 Echoscopic Image Construction
2.2.1 Amplitude Mode
2.2.2 Brightness Mode
2.2.3 Motion Mode
2.2.4 Color Doppler
2.2.5 Power Doppler
2.3 Transducers
2.3.1 Types of Transducers
2.4 Resolution
2.4.1 Axial Resolution
2.4.2 Lateral Resolution
2.4.3 Elevational Resolution
2.5 Artifacts in Sonography
2.5.1 Artifacts in 2D Ultrasound
2.5.2 Artifacts in Doppler Ultrasound
2.6 Advances in Echoscopic Image Construction
2.6.1 Compound Imaging
2.6.2 Harmonic Imaging
2.6.3 Elastography
2.7 Biological Effects and Safety
3 Neonatal Cranial Ultrasonography
3.1 Ultrasound Anatomy of the Neonatal Brain
3.2 Maturational Changes and Distinction between Physiologic and Pathologic Echogenic Areas in the Neonatal Brain
3.2.1 White Matter
3.2.2 Deep Gray Matter
3.3 Timing of Examinations
3.4 Measurements
3.4.1 Ventricular Measurements
3.4.2 Measurements of Cerebral Structures
3.5 Preterm Infants: Pathology
3.5.1 Germinal Matrix–Intraventricular Hemorrhage
3.5.2 Post-hemorrhagic Ventricular Dilatation
3.5.3 White Matter Injury
3.5.4 Focal Infarction
3.6 Term Infants
3.6.1 Pathology
3.6.2 Congenital Abnormalities
Recommended Readings
4 Spine
4.1 Embryology
4.1.1 Ascensus Medullaris
4.2 Technique of Spinal Ultrasound
4.3 Normal Sonographic Anatomy
4.3.1 Normal Variants
4.4 Pathology
4.4.1 Non–Skin-Covered Back Masses: Open Lesions
4.4.2 Skin-Covered Back Masses: Closed Lesions
4.4.3 Occult/Closed Lesions without a Mass
4.4.4 Sacral Dimple
Recommended Readings
5 Neck
5.1 Normal Anatomy and Variants
5.2 Pathology
5.2.1 Vessels of the Neck
5.2.2 Cystic Lesions
5.2.3 Hemangiomas and Vascular Malformations
5.2.4 Pilomatrixoma
5.2.5 Solid Tumors
5.2.6 Thyroid Gland
5.2.7 Salivary Glands
5.2.8 Thymus
5.2.9 Miscellaneous Lesions
Recommended Readings
6 Mediastinum
6.1 Normal Anatomy and Variants
6.1.1 Thymus
6.1.2 Trachea
6.1.3 Esophagus
6.1.4 Heart and Great Vessels
6.2 Pathology
6.2.1 Thymus
6.2.2 Trachea
6.2.3 Esophagus
6.2.4 Congenital Vascular Anomalies
6.2.5 Mediastinal Masses
6.3 Mediastinal Ultrasound in Intensive Care: Complications Associated with Central Venous Access
Recommended Readings
7 Pleura and Thorax
7.1 Indications for Ultrasonography
7.2 Anatomy and Normal Variants
7.2.1 ThoracicWall
7.2.2 Pleura
7.2.3 Lungs
7.2.4 Breast
7.2.5 Diaphragm
7.3 Pathology
7.3.1 ChestWall
7.3.2 Pleural Space
7.3.3 Lungs
7.3.4 Breast
7.3.5 Diaphragm
Recommended Readings
8 Peritoneal Cavity and Retroperitoneal Space
8.1 Normal Anatomy
8.2 Pathology
8.2.1 Abdominal Vessels
8.2.2 Lymphadenopathy
8.2.3 Intraperitoneal Fluid Collections
8.2.4 Peritonitis
8.2.5 Pneumoperitoneum
8.2.6 Peritoneal Tumors
8.2.7 Retroperitoneal Tumors
8.2.8 Cystic Congenital Anomalies
Recommended Readings
9 Liver and Biliary System
9.1 Normal Anatomy and Variants
9.2 Normal Measurements
9.2.1 Portal Venous Flow
9.2.2 Hepatic Arterial Flow
9.2.3 Hepatic Venous Flow
9.3 Pathology
9.3.1 Congenital Anomalies
9.3.2 Infection
9.3.3 Acquired Biliary Pathology
9.3.4 Trauma
9.3.5 Tumors
9.3.6 Pneumobilia
9.3.7 Miscellaneous Conditions
Recommended Readings
10 Spleen
10.1 Normal Anatomy and Variants
10.1.1 Embryology
10.1.2 Anatomical Considerations
10.1.3 Technique and Normal Ultrasound Appearances
10.1.4 Echogenicity and Changes in Echogenicitywith Age
10.1.5 Vascularity
10.1.6 Normal Variants
10.1.7 Normal Splenic Size
10.2 Pathology
10.2.1 Abnormalities of Location and Number
10.2.2 Abnormalities of Size
10.2.3 Traumatic Injury of the Spleen
10.3 Acknowledgements
Recommended Readings
11 Pediatric Intestinal Ultrasonography
11.1 Esophagus
11.2 Gastroesophageal Junction
11.3 Stomach
11.4 Small Bowel
11.5 Appendix
11.6 Large Bowel
11.6.1 Other Causes of Colitis
11.7 Rectum
11.8 Anus
11.9 Neonatal Bowel Obstruction
11.10 Conclusion
Recommended Readings
12 Pancreas
12.1 Examination Technique
12.2 Normal Anatomy, Variants, and Pseudo-lesions
12.3 Pathology
12.3.1 Developmental Anomalies
12.3.2 Pancreatitis
12.3.3 Inherited Disorders
12.3.4 Neoplasms
12.3.5 Cystic Masses
Recommended Readings
13 Kidneys
13.1 Normal Anatomy and Variants
13.1.1 Kidneys
13.1.2 Ureters
13.1.3 Bladder
13.2 Congenital Anomalies of the Kidney and the Urinary Tract
13.2.1 Renal Hypodysplasia
13.2.2 Ureteropelvic Junction Stenosis
13.2.3 Ureterovesical Junction Stenosis
13.2.4 Ureterovesical Reflux
13.2.5 Duplicate Collecting System
13.2.6 Horseshoe Kidney
13.3 Urolithiasis and Nephrocalcinosis
13.4 Kidney Cysts and Cystic Nephropathies
13.5 Autosomal-Dominant Polycystic Kidney Disease
13.5.1 Autosomal-Recessive Polycystic Kidney Disease
13.5.2 Nephronophthisis
13.5.3 Glomerulocystic Disease
13.5.4 Medullary Sponge Kidney Disease
13.5.5 Multicystic Kidney Disease
13.5.6 Simple Cysts
13.5.7 Complicated Cysts
13.6 Renal Tumors
13.6.1 Malignant Tumors
13.6.2 Benign Tumors
13.7 Urinary Tract Infection
13.8 Renovascular Disease
13.8.1 Renal Artery Stenosis
13.8.2 Renal Vein Thrombosis
13.9 Parenchymal Nephropathy
13.9.1 Glomerular Nephropathies
13.9.2 Tubular Nephropathies
13.9.3 Interstitial Nephropathies
13.9.4 Vascular Nephropathies
13.10 Renal Trauma
13.10.1 Renal Trauma Grading
13.11 Pediatric Renal Transplantation
13.11.1 Early Postoperative Assessment
13.11.2 Differential Diagnosis of Early Graft Dysfunction
13.11.3 Differential Diagnosis of Long-Term Graft Dysfunction and Imaging Aspects
13.12 Bladder and Urethra
13.12.1 Congenital Bladder Anomalies
13.12.2 Urethral Anomalies
13.12.3 Utricle
13.12.4 Urachal Anomalies
13.12.5 Calculi
13.12.6 Infection
13.12.7 Neoplasm
13.13 Contrast-Enhanced Cystosonography
Recommended Readings
14 Adrenal Glands
14.1 Embryology of the Adrenal Glands
14.2 Normal Anatomy
14.3 Normal Sonographic Appearance
14.4 Normal Variants
14.5 Pathology
14.5.1 Neonatal Adrenal Hemorrhage
14.5.2 Adrenal Hemorrhage in the Older Child
14.5.3 Adrenal Cysts
14.5.4 Adrenal Abscesses
14.5.5 Congenital Adrenal Hyperplasia
14.5.6 Adrenal Hyperplasia in Older Patients
14.5.7 Adrenal Hypoplasia
14.5.8 Medullary Tumors: Neurogenic Tumors
14.5.9 Medullary Tumors: Pheochromocytoma
14.5.10 Adrenal Cortical Tumors
14.5.11 Other Adrenal Tumors
14.5.12 Miscellaneous Adrenal Masses
14.5.13 Wolman Disease
Recommended Readings
15 Sonography of the Female Genital Tract
15.1 Normal Anatomy and Variants
15.1.1 Normal Measurements
15.2 Pathology
15.2.1 Congenital Anomalies
15.2.2 Cloacal Malformation
15.2.3 Ovarian Tumors
15.2.4 Ovarian Torsion
15.2.5 Pelvic Inflammatory Disease
15.2.6 Amenorrhea
15.2.7 Pubertas Praecox
Recommended Readings
16 Male Genital Tract
16.1 Technique of Scrotal Ultrasound and Normal Ultrasound Anatomy
16.2 Hydrocele and Indirect Inguinal Hernia
16.2.1 Hydrocele
16.2.2 Indirect Inguinal Hernia
16.3 Scrotal Tumors
16.3.1 Testicular Tumors
16.3.2 Secondary Tumors of the Testes
16.3.3 Extratesticular Tumors and Masses
16.4 Testicular Torsion
16.4.1 Intravaginal Testicular Torsion
16.4.2 Extravaginal Testicular Torsion
16.4.3 Torsion of the Appendix Testis
16.5 Epididymitis and Epididymo-orchitis
16.6 Idiopathic Scrotal Edema
16.7 Testicular Trauma
16.8 Cystic Transformation of the Rete Testis (Tubular Ectasia)
16.9 Epididymal Cyst
16.10 Varicocele
16.11 Bilobed Testicle and Polyorchidism
16.12 Undescended Testicle and Retractile Testicle
Recommended Readings
17 Musculoskeletal Ultrasound
17.1 Pediatric Hip
17.1.1 Normal Development of the Hip
17.1.2 Ultrasound Examination for Developmental Dysplasia of the Hip
17.2 Ultrasound of the Musculoskeletal System in the Older Child
17.2.1 Arthritis
17.2.2 Soft-Tissue Masses: Lumps and Bumps
Recommended Readings
18 Ultrasound-Guided Interventional Procedures: Biopsy and Drainage
18.1 Biopsy
18.1.1 Techniques and Equipment
18.1.2 Tumor Biopsy
18.1.3 Nontumor Biopsy
18.2 Drainage Techniques and Equipment
Recommended Readings
Index

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TPS 23 x 31 - 2 | 11.05.15 - 17:20

TPS 23 x 31 - 2 | 11.05.15 - 17:20

TPS 23 x 31 - 2 | 11.05.15 - 17:20

Diagnostic Pediatric Ultrasound

Dr. Erik Beek, MD, PhD Consulting Radiologist Department of Radiology Wilhelmina Children's Hospital University Medical Center Utrecht Utrecht, The Netherlands Prof. Rick R. van Rijn, MD, PhD Professor Department of Radiology Emma Children's Hospital Academic Medical Center Amsterdam, The Netherlands Foreword by Alan Daneman, BSc, MBBCh, FRANZCR, FRCPC

2,025 illustrations

Thieme Stuttgart • New York • Delhi • Rio de Janeiro

TPS 23 x 31 - 2 | 11.05.15 - 17:20

Library of Congress Cataloging-in-Publication Data Diagnostic pediatric ultrasound / [edited by] Erik Beek, Rick R. van Rijn. p. ; cm. Includes bibliographical references and index. ISBN 978-3-13-169731-8 (hardback) – ISBN 978-3-13-169741-7 (eISBN) I. Beek, Erik, editor. II. Rijn, Rick R. van, editor. [DNLM: 1. Ultrasonography–methods. 2. Child. 3. Infant. WN 208] RJ51.U45 618.92'007543–dc23 2015006968

© 2016 by Georg Thieme Verlag KG

Important note: Medicine is an ever-changing science undergoing continual development. Research and clinical experience are continually expanding our knowledge, in particular our knowledge of proper treatment and drug therapy. Insofar as this book mentions any dosage or application, readers may rest assured that the authors, editors, and publishers have made every effort to ensure that such references are in accordance with the state of knowledge at the time of production of the book. Nevertheless, this does not involve, imply, or express any guarantee or responsibility on the part of the publishers in respect to any dosage instructions and forms of applications stated in the book. Every user is requested to examine carefully the manufacturers’ leaflets accompanying each drug and to check, if necessary in consultation with a physician or specialist, whether the dosage schedules mentioned therein or the contraindications stated by the manufacturers differ from the statements made in the present book. Such examination is particularly important with drugs that are either rarely used or have been newly released on the market. Every dosage schedule or every form of application used is entirely at the user’s own risk and responsibility. The authors and publishers request every user to report to the publishers any discrepancies or inaccuracies noticed. If errors in this work are found after publication, errata will be posted at www.thieme.com on the product description page. Some of the product names, patents, and registered designs referred to in this book are in fact registered trademarks or proprietary names even though specific reference to this fact is not always made in the text. Therefore, the appearance of a name without designation as proprietary is not to be construed as a representation by the publisher that it is in the public domain.

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| 11.05.15 - 09:43

Contents

1

Video Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

xi

Foreword. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

xv

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

xvii

Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

xix

Abbreviations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

xxi

Examining the Child and Creating a Child-Friendly Environment

...........................

2

Anne Smets 1.1

Child-Friendly Staff . . . . . . . . . . . . . . . . . . . . . . . .

2

1.6

Examination. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4

1.2

Appointment . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2

1.7

How to Scan: Tips and Tricks . . . . . . . . . . . . . .

5

1.3

Appointment Letter . . . . . . . . . . . . . . . . . . . . . . .

2

1.8

Private Room . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6

1.4

Waiting Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2

1.9

Communicating the Results . . . . . . . . . . . . . . .

6

1.5

Examination Room . . . . . . . . . . . . . . . . . . . . . . . .

3

Recommended Readings . . . . . . . . . . . . . . . . . . .

7

2

Physics and Artifacts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

10

Rob Peters 2.1

Basic Principles of Ultrasound . . . . . . . . . . . . . .

10

2.4

Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

16

2.1.1 2.1.2 2.1.3 2.1.4

Ultrasonic Waves. . . . . . . . . . . . . . . . . . . . . . . . . . . Wave Propagation in Homogeneous Media. . . . . Wave Propagation in Inhomogeneous Media . . . Doppler Echo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

10 10 10 12

2.4.1 2.4.2 2.4.3

Axial Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . Lateral Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . Elevational Resolution . . . . . . . . . . . . . . . . . . . . . .

16 16 17

2.5

Artifacts in Sonography . . . . . . . . . . . . . . . . . . .

17

2.2

Echoscopic Image Construction . . . . . . . . . . . .

13

2.2.1 2.2.2 2.2.3 2.2.4 2.2.5

Amplitude Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . Brightness Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . Motion Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Color Doppler. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Power Doppler . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

13 13 14 14 15

2.5.1 2.5.2

Artifacts in 2D Ultrasound. . . . . . . . . . . . . . . . . . . Artifacts in Doppler Ultrasound . . . . . . . . . . . . . .

17 18

2.6

Advances in Echoscopic Image Construction

19

2.3

Transducers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

15

2.6.1 2.6.2 2.6.3

Compound Imaging . . . . . . . . . . . . . . . . . . . . . . . . Harmonic Imaging . . . . . . . . . . . . . . . . . . . . . . . . . Elastography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

19 19 19

2.3.1

Types of Transducers. . . . . . . . . . . . . . . . . . . . . . . .

15

2.7

Biological Effects and Safety . . . . . . . . . . . . . . .

20

3

Neonatal Cranial Ultrasonography

.............................................................

22

Gerda Meijler, Linda de Vries, and Handan Güleryüz 3.1

Ultrasound Anatomy of the Neonatal Brain .

3.2

Maturational Changes and Distinction between Physiologic and Pathologic Echogenic Areas in the Neonatal Brain . . . . . . White Matter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Deep Gray Matter . . . . . . . . . . . . . . . . . . . . . . . . . .

3.2.1 3.2.2

3.3

Timing of Examinations . . . . . . . . . . . . . . . . . . .

31

3.4

Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . .

36

26

3.4.1 3.4.2

Ventricular Measurements . . . . . . . . . . . . . . . . . . Measurements of Cerebral Structures . . . . . . . . .

36 38

26 31

3.5

Preterm Infants: Pathology . . . . . . . . . . . . . . . .

39

22

v

| 11.05.15 - 09:43

Contents Pathology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Congenital Abnormalities . . . . . . . . . . . . . . . . . . . . Recommended Readings . . . . . . . . . . . . . . . . . . . .

70 78 94

3.6

Term Infants . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4

Spine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

98

3.5.1 3.5.2 3.5.3 3.5.4

Germinal Matrix–Intraventricular Hemorrhage Post-hemorrhagic Ventricular Dilatation . . . . . . White Matter Injury . . . . . . . . . . . . . . . . . . . . . . . . Focal Infarction . . . . . . . . . . . . . . . . . . . . . . . . . . . .

39 52 60 64 70

3.6.1 3.6.2

Samuel Stafrace and Erik Beek 4.1

Embryology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

98

4.4

Pathology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

103

4.1.1

Ascensus Medullaris. . . . . . . . . . . . . . . . . . . . . . . .

99

4.2

Technique of Spinal Ultrasound . . . . . . . . . . . .

99

4.4.1 4.4.2 4.4.3 4.4.4

4.3

Normal Sonographic Anatomy . . . . . . . . . . . . .

100

Non–Skin-Covered Back Masses: Open Lesions . . Skin-Covered Back Masses: Closed Lesions . . . . . Occult/Closed Lesions without a Mass . . . . . . . . . Sacral Dimple . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Recommended Readings . . . . . . . . . . . . . . . . . . . .

103 104 107 113 113

4.3.1

Normal Variants . . . . . . . . . . . . . . . . . . . . . . . . . . .

102

5

Neck . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

116

Erik Beek 5.1

Normal Anatomy and Variants . . . . . . . . . . . . .

116

5.2

Pathology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

119 119 120 124

5.2.4 5.2.5 5.2.6 5.2.7 5.2.8 5.2.9

5.2.1 5.2.2 5.2.3

Vessels of the Neck . . . . . . . . . . . . . . . . . . . . . . . . . Cystic Lesions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hemangiomas and Vascular Malformations . . . .

Pilomatrixoma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Solid Tumors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thyroid Gland. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Salivary Glands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thymus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Miscellaneous Lesions . . . . . . . . . . . . . . . . . . . . . . . Recommended Readings . . . . . . . . . . . . . . . . . . . .

127 127 137 138 143 145 151

6

Mediastinum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

154

Ingmar Gassner and Gisela Schweigmann 6.1

Normal Anatomy and Variants . . . . . . . . . . . . .

154

6.1.1 6.1.2 6.1.3 6.1.4

Thymus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Trachea. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Esophagus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Heart and Great Vessels . . . . . . . . . . . . . . . . . . . . .

154 157 157 157

6.2

Pathology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.2.1

Thymus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

7

Pleura and Thorax

6.2.2 6.2.3 6.2.4 6.2.5

Trachea . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Esophagus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Congenital Vascular Anomalies . . . . . . . . . . . . . . . Mediastinal Masses . . . . . . . . . . . . . . . . . . . . . . . . .

159 159 163 170

6.3

157

Mediastinal Ultrasound in Intensive Care: Complications Associated with Central Venous Access . . . . . . . . . . . . . . . . . . . . . . . . . . . .

177

157

Recommended Readings . . . . . . . . . . . . . . . . . . . .

179

................................................................................

182

Joost van Schuppen and Rick R. van Rijn

vi

7.1

Indications for Ultrasonography . . . . . . . . . . .

183

7.3

Pathology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

186

7.2

Anatomy and Normal Variants . . . . . . . . . . . . .

183

7.2.1 7.2.2 7.2.3 7.2.4 7.2.5

Thoracic Wall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pleura . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lungs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Breast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Diaphragm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

183 184 184 184 186

7.3.1 7.3.2 7.3.3 7.3.4 7.3.5

Chest Wall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pleural Space. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lungs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Breast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Diaphragm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Recommended Readings . . . . . . . . . . . . . . . . . . . .

186 200 202 202 208 211

| 11.05.15 - 09:43

Contents

8

Peritoneal Cavity and Retroperitoneal Space . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

214

Rick R. van Rijn 8.1

Normal Anatomy . . . . . . . . . . . . . . . . . . . . . . . . .

214

8.2

Pathology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

215 215 219 221

8.2.4 8.2.5 8.2.6 8.2.7 8.2.8

8.2.1 8.2.2 8.2.3

Abdominal Vessels . . . . . . . . . . . . . . . . . . . . . . . . . Lymphadenopathy . . . . . . . . . . . . . . . . . . . . . . . . . Intraperitoneal Fluid Collections . . . . . . . . . . . . .

Peritonitis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pneumoperitoneum . . . . . . . . . . . . . . . . . . . . . . . . Peritoneal Tumors. . . . . . . . . . . . . . . . . . . . . . . . . . Retroperitoneal Tumors . . . . . . . . . . . . . . . . . . . . . Cystic Congenital Anomalies. . . . . . . . . . . . . . . . . Recommended Readings . . . . . . . . . . . . . . . . . . .

225 229 229 234 238 243

9

Liver and Biliary System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

246

Rick R. van Rijn and RAJ Nievelstein 9.1

Normal Anatomy and Variants . . . . . . . . . . . . .

246

9.2

Normal Measurements . . . . . . . . . . . . . . . . . . . .

249

9.2.1 9.2.2 9.2.3

Portal Venous Flow . . . . . . . . . . . . . . . . . . . . . . . . . Hepatic Arterial Flow . . . . . . . . . . . . . . . . . . . . . . . Hepatic Venous Flow . . . . . . . . . . . . . . . . . . . . . . .

249 249 249 249

9.3.1 9.3.2 9.3.3 9.3.4 9.3.5 9.3.6 9.3.7

9.3

Pathology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Congenital Anomalies . . . . . . . . . . . . . . . . . . . . . . Infection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acquired Biliary Pathology . . . . . . . . . . . . . . . . . . Trauma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tumors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pneumobilia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Miscellaneous Conditions . . . . . . . . . . . . . . . . . . . Recommended Readings . . . . . . . . . . . . . . . . . . .

249 258 266 287 292 317 317 321

10

Spleen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

324

Samuel Stafrace 10.1

Normal Anatomy and Variants . . . . . . . . . . . . .

324

10.2

Pathology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

332

10.1.1 10.1.2 10.1.3 10.1.4 10.1.5 10.1.6 10.1.7

Embryology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Anatomical Considerations . . . . . . . . . . . . . . . . . . Technique and Normal Ultrasound Appearances Echogenicity and Changes in Echogenicity with Age Vascularity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Normal Variants. . . . . . . . . . . . . . . . . . . . . . . . . . . . Normal Splenic Size . . . . . . . . . . . . . . . . . . . . . . . .

324 324 325 325 327 327 331

10.2.1 10.2.2 10.2.3

Abnormalities of Location and Number . . . . . . . Abnormalities of Size . . . . . . . . . . . . . . . . . . . . . . . Traumatic Injury of the Spleen . . . . . . . . . . . . . . .

332 335 348

10.3

Acknowledgements. . . . . . . . . . . . . . . . . . . . . . .

354

Recommended Readings . . . . . . . . . . . . . . . . . . .

358

11

Pediatric Intestinal Ultrasonography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

360

Simon Robben 11.1

Esophagus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

360

11.6.1

Other Causes of Colitis . . . . . . . . . . . . . . . . . . . . . .

394

11.2

Gastroesophageal Junction . . . . . . . . . . . . . . . .

363

11.7

Rectum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

397

11.3

Stomach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

364

11.8

Anus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

397

11.4

Small Bowel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

367

11.9

Neonatal Bowel Obstruction. . . . . . . . . . . . . . .

403

11.5

Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

387

11.10

Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

412

11.6

Large Bowel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

393

Recommended Readings . . . . . . . . . . . . . . . . . . .

412

12

Pancreas

..........................................................................................

416

Maria Raissaki and Marina Vakaki 12.1

Examination Technique . . . . . . . . . . . . . . . . . . . .

416

12.3

Pathology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

426

12.2

Normal Anatomy, Variants, and Pseudo-lesions . . . . . . . . . . . . . . . . . . . . . . . . . . . .

417

12.3.1 12.3.2

Developmental Anomalies . . . . . . . . . . . . . . . . . . Pancreatitis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

426 428

vii

| 11.05.15 - 09:43

Contents 12.3.3 12.3.4

Inherited Disorders . . . . . . . . . . . . . . . . . . . . . . . . Neoplasms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

13

Kidneys

436 440

12.3.5

Recommended Readings . . . . . . . . . . . . . . . . . . . .

Cystic Masses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

444 449

............................................................................................

452

Maria Beatrice Damasio, Ann Nystedt, Lil-Sofie Ording Muller, and Giorgio Pioggio 13.1

Normal Anatomy and Variants . . . . . . . . . . . . .

452

13.8

Renovascular Disease . . . . . . . . . . . . . . . . . . . . . .

481

13.1.1 13.1.2 13.1.3

Kidneys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ureters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bladder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

452 455 456

13.8.1 13.8.2

Renal Artery Stenosis . . . . . . . . . . . . . . . . . . . . . . . Renal Vein Thrombosis . . . . . . . . . . . . . . . . . . . . . .

481 482

13.9

Parenchymal Nephropathy . . . . . . . . . . . . . . . . .

485

13.2

Congenital Anomalies of the Kidney and the Urinary Tract . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

456

13.2.1 13.2.2 13.2.3 13.2.4 13.2.5 13.2.6

Renal Hypodysplasia . . . . . . . . . . . . . . . . . . . . . . . Ureteropelvic Junction Stenosis . . . . . . . . . . . . . . Ureterovesical Junction Stenosis. . . . . . . . . . . . . . Ureterovesical Reflux . . . . . . . . . . . . . . . . . . . . . . . Duplicate Collecting System . . . . . . . . . . . . . . . . . Horseshoe Kidney. . . . . . . . . . . . . . . . . . . . . . . . . .

457 457 457 457 460 461

13.9.1 13.9.2 13.9.3 13.9.4

Glomerular Nephropathies. . . . . . . . . . . . . . . . . . . Tubular Nephropathies . . . . . . . . . . . . . . . . . . . . . . Interstitial Nephropathies. . . . . . . . . . . . . . . . . . . . Vascular Nephropathies . . . . . . . . . . . . . . . . . . . . .

487 487 488 489

13.10

Renal Trauma . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

490

13.10.1 Renal Trauma Grading. . . . . . . . . . . . . . . . . . . . . . .

491

13.3

Urolithiasis and Nephrocalcinosis . . . . . . . . . .

464

13.11

Pediatric Renal Transplantation . . . . . . . . . . . .

491

13.4

Kidney Cysts and Cystic Nephropathies. . . . .

467

491 491

13.5

Autosomal-Dominant Polycystic Kidney Disease . . . . . . . . . . . . . . . . . . . . . . . . . . .

469

13.11.1 Early Postoperative Assessment . . . . . . . . . . . . . . 13.11.2 Differential Diagnosis of Early Graft Dysfunction 13.11.3 Differential Diagnosis of Long-Term Graft Dysfunction and Imaging Aspects . . . . . . . .

496

13.12

Bladder and Urethra . . . . . . . . . . . . . . . . . . . . . . .

500

13.5.2 13.5.3 13.5.4 13.5.5 13.5.6 13.5.7

Autosomal-Recessive Polycystic Kidney Disease . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Nephronophthisis. . . . . . . . . . . . . . . . . . . . . . . . . . Glomerulocystic Disease . . . . . . . . . . . . . . . . . . . . Medullary Sponge Kidney Disease . . . . . . . . . . . . Multicystic Kidney Disease . . . . . . . . . . . . . . . . . . Simple Cysts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Complicated Cysts . . . . . . . . . . . . . . . . . . . . . . . . .

470 472 472 472 472 473 473

13.12.1 13.12.2 13.12.3 13.12.4 13.12.5 13.12.6 13.12.7

Congenital Bladder Anomalies . . . . . . . . . . . . . . . . Urethral Anomalies . . . . . . . . . . . . . . . . . . . . . . . . . Utricle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Urachal Anomalies . . . . . . . . . . . . . . . . . . . . . . . . . . Calculi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Infection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Neoplasm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

500 502 503 503 504 504 504

13.6

Renal Tumors. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

474

13.13

Contrast-Enhanced Cystosonography . . . . . . .

506

13.6.1 13.6.2

Malignant Tumors. . . . . . . . . . . . . . . . . . . . . . . . . . Benign Tumors . . . . . . . . . . . . . . . . . . . . . . . . . . . .

474 478

Recommended Readings . . . . . . . . . . . . . . . . . . . .

509

13.7

Urinary Tract Infection . . . . . . . . . . . . . . . . . . . .

480

14

Adrenal Glands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

512

13.5.1

Claire Gowdy and Annie Paterson

viii

14.1

Embryology of the Adrenal Glands . . . . . . . . .

512

14.2

Normal Anatomy . . . . . . . . . . . . . . . . . . . . . . . . .

512

14.3

Normal Sonographic Appearance . . . . . . . . . .

512

14.4

Normal Variants . . . . . . . . . . . . . . . . . . . . . . . . . .

513

14.5

Pathology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

514

14.5.1

Neonatal Adrenal Hemorrhage . . . . . . . . . . . . . . .

514

14.5.2

Adrenal Hemorrhage in the Older Child . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.5.3 Adrenal Cysts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.5.4 Adrenal Abscesses . . . . . . . . . . . . . . . . . . . . . . . . . . 14.5.5 Congenital Adrenal Hyperplasia . . . . . . . . . . . . . . 14.5.6 Adrenal Hyperplasia in Older Patients . . . . . . . . . 14.5.7 Adrenal Hypoplasia . . . . . . . . . . . . . . . . . . . . . . . . . 14.5.8 Medullary Tumors: Neurogenic Tumors . . . . . . . . 14.5.9 Medullary Tumors: Pheochromocytoma . . . . . . . 14.5.10 Adrenal Cortical Tumors . . . . . . . . . . . . . . . . . . . . .

514 514 517 517 518 518 519 520 520

| 11.05.15 - 09:43

Contents 14.5.11 Other Adrenal Tumors . . . . . . . . . . . . . . . . . . . . . . 14.5.12 Miscellaneous Adrenal Masses . . . . . . . . . . . . . . .

15

528 531

14.5.13 Wolman Disease . . . . . . . . . . . . . . . . . . . . . . . . . . . Recommended Readings . . . . . . . . . . . . . . . . . . .

531 534

Sonography of the Female Genital Tract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

536

Willemijn Klein 15.1

Normal Anatomy and Variants . . . . . . . . . . . . .

536

15.1.1

Normal Measurements. . . . . . . . . . . . . . . . . . . . . .

538

15.2

Pathology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

538 538 540

15.2.3 15.2.4 15.2.5 15.2.6 15.2.7

Ovarian Tumors . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ovarian Torsion . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pelvic Inflammatory Disease. . . . . . . . . . . . . . . . . Amenorrhea . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pubertas Praecox . . . . . . . . . . . . . . . . . . . . . . . . . . Recommended Readings . . . . . . . . . . . . . . . . . . .

551 560 560 560 568 568

15.2.1 15.2.2

Congenital Anomalies. . . . . . . . . . . . . . . . . . . . . . . Cloacal Malformation . . . . . . . . . . . . . . . . . . . . . . .

16

Male Genital Tract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

570

Matteo Baldisserotto 16.1

16.5

Epididymitis and Epididymo-orchitis . . . . . . .

584

16.6

Idiopathic Scrotal Edema . . . . . . . . . . . . . . . . . .

585

16.7

Testicular Trauma. . . . . . . . . . . . . . . . . . . . . . . . .

585

16.8

Cystic Transformation of the Rete Testis (Tubular Ectasia) . . . . . . . . . . . . . . . . . . . . . . . . . .

587

16.9

Epididymal Cyst . . . . . . . . . . . . . . . . . . . . . . . . . .

587

16.10

Varicocele . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

588

16.11

Bilobed Testicle and Polyorchidism . . . . . . . .

589

16.12

Undescended Testicle and Retractile Testicle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

590

Recommended Readings . . . . . . . . . . . . . . . . . . .

591

....................................................................

594

Technique of Scrotal Ultrasound and Normal Ultrasound Anatomy . . . . . . . . . . . . . . . . . . . . . .

570

16.2

Hydrocele and Indirect Inguinal Hernia . . . . .

570

16.2.1 16.2.2

Hydrocele . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Indirect Inguinal Hernia . . . . . . . . . . . . . . . . . . . . .

570 573

16.3

Scrotal Tumors. . . . . . . . . . . . . . . . . . . . . . . . . . . .

576

16.3.1 16.3.2 16.3.3

Testicular Tumors . . . . . . . . . . . . . . . . . . . . . . . . . . Secondary Tumors of the Testes . . . . . . . . . . . . . . Extratesticular Tumors and Masses . . . . . . . . . . .

576 576 578

16.4

Testicular Torsion . . . . . . . . . . . . . . . . . . . . . . . . .

580

16.4.1 16.4.2 16.4.3

Intravaginal Testicular Torsion . . . . . . . . . . . . . . . Extravaginal Testicular Torsion . . . . . . . . . . . . . . . Torsion of the Appendix Testis . . . . . . . . . . . . . . .

580 582 583

17

Musculoskeletal Ultrasound Jim Carmichael and Karen Rosendahl

Ultrasound of the Musculoskeletal System in the Older Child . . . . . . . . . . . . . . . . .

598

Arthritis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Soft-Tissue Masses: Lumps and Bumps . . . . . . . . Recommended Readings . . . . . . . . . . . . . . . . . . .

598 604 615

Ultrasound-Guided Interventional Procedures: Biopsy and Drainage . . . . . . . . . . . . . . . . . . . . . . .

618

17.1

Pediatric Hip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

594

17.1.1 17.1.2

Normal Development of the Hip . . . . . . . . . . . . . . Ultrasound Examination for Developmental Dysplasia of the Hip . . . . . . . . . . . . . . . . . . . . . . . .

594

18

594

17.2

17.2.1 17.2.2

Alex Barnacle and Derek Roebuck 18.1

Biopsy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

618

18.1.1 18.1.2 18.1.3

Techniques and Equipment . . . . . . . . . . . . . . . . . . Tumor Biopsy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Nontumor Biopsy . . . . . . . . . . . . . . . . . . . . . . . . . .

618 620 623

Index

18.2

Drainage Techniques and Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

625

Recommended Readings . . . . . . . . . . . . . . . . . . .

627

..............................................................................................

629

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Video Contents Chapter 3 Video 3.94

Doppler ultrasound shows flow in the bridging veins.

Chapter 6 Video 6.1 (1–4) Video 6.1.1a, b Video 6.1.2 Video 6.1.3 Video 6.1.4

Normal thymus. Trans-sternal transverse scan. Normal anatomy level of aortic arch. Normal esophagus.

Video 6.2

Cervical extension of normal thymus.

Video 6.4 (1–2) Video 6.4.1

Subglottic hemangioma. The hemangioma compresses the tracheal lumen to a small gap (arrowheads). Color Doppler shows the high vascularity and the involvement of the adjacent soft tissues (i.e., thyroid).

Video 6.4.2

Video 6.6 (1–2) Video 6.6.1

Video 6.6.2

Video 6.12.3

Esophageal atresia with low fistula. The suction tube (arrows) lies in the nondistended proximal pouch (arrowheads). The distal esophagus is shown behind the heart.

Left aortic arch with aberrant right subclavian artery.

Right aortic arch with aberrant left subclavian artery. Video 6.13.1a, b Right aortic arch with aberrant left subclavian artery. Video 6.13.2a, b Right aortic arch with aberrant left subclavian artery.

Video 6.13 (1–2)

Video 6.14 (1–6) Video 6.14.1 Video 6.14.2 Video 6.14.3 Video 6.14.4 Video 6.14.5 Video 6.14.6

Double aortic arch. Double aortic arch. Double aortic arch. Double aortic arch. Double aortic arch. Double aortic arch. Double aortic arch.

Video 6.15 (1–2) Video 6.15.1 Video 6.15.2

Pulmonary artery sling. Pulmonary artery sling. Pulmonary artery sling.

Video 6.7

H-type tracheoesophageal fistula.

Video 6.8

Achalasia.

Video 6.12 (1–3)

Left aortic arch with aberrant right subclavian artery. Left aortic arch with aberrant right subclavian artery. Left aortic arch with aberrant right subclavian artery.

Video 6.23 (1–3) Video 6.23.1a, b Thrombus around central venous catheter in the right atrium. Video 6.23.2 Fibrin sheath of a catheter left behind in the superior vena cava after removal of a central venous line. Video 6.23.3 Embolization of a broken catheter fragment into the pulmonary artery.

Video 7.8

Normal air containing lung.

Video 7.42b

Video 7.15

Normal movement of the diaphragm, M mode.

Follow up shows a subpleural collection with a thick wall and debris.

Video 7.42c

A 2-year-old boy with bronchopneumonia complicated by effusion. The video clearly shows motion of pleural fluid and the collapsed lung tissue during respiration.

Video 7.47a

A 2-week-old premature with on chest x-ray a persistent opacification in the left upper lung. US shows hyperechoic tissue containing vascular structures.

Video 7.47b

No air is visible in the lobe. The lung tissue resembles liver tissue.

Video 6.12.1 Video 6.12.2

Chapter 7

Video 7.17a, b

A forked rib.

Video 7.18

Prominent cartilaginous rib.

Video 7.33

Thoracic venous malformation.

Video 7.40

Pleural fluid with thick echogenic strands after liver biopsy.

Video 7.42a

Pneumonia complicated by empyema.

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Video Contents

Chapter 8 Video 8.6

Video clip shows the IVC located on the left side of the aorta.

Video 8.10

Video clip shows the hypertrophied collateral vein leading to the retroperitoneal space.

Video 8.28

Upon compression flow is seen within the purulent fluid surrounding the small bowel loops.

Video 8.31

Free air within the peritoneal cavity between the liver and the abdominal wall.

Video 8.35a

Video shows independent motion of the tumour in respect to the liver during respiration. This proves that there is no relation between these two structures.

Video 8.35b

Video shows the extent to the tumour on an axial T2 weighted MRI.

Video 8.38

Video shows the extent to the tumour on an axial T2 weighted MRI.

Video 8.42

Video shows the extent to the tumour on an axial T2 weighted MRI.

Video 8.49

During respiration there clearly is no relation between the cystic mass and the ovary.

Video 9.90

Neuroblastoma with encasement of the abdominal vessels.

Video 9.98

Tumour in the liver hilum.

Video 9.99

US shows air in the portal system.

Video 9.101

Motion of air bubbles in the portal vein branches.

Air artefact from the lung obscuring the spleen.

Video 10.32

Splenic lymphoma.

Video 11.2

Juvenile polyp in descending colon.

Video 11.13b

Normal pylorus.

Video 11.4

Patient with mesenteric Burkitt lymphoma with infiltrative invasion of the mesentery

Video 11.14

Normal anatomical position of the D3 segment of the duodenum.

Video 11.5

Esophageal atresia without a tracheoesophageal fistula.

Video 11.17

Infant with malrotation and midgut volvulus, whirlpool sign.

Video 11.9

Boy with acute abdominal distention and vomiting.

Video 11.21a, b

Crohn's disease of the terminal ileum.

Video 11.11

hypertrophic pyloric stenosis.

Video 11.24

Video 11.12

Acute lymphatic leukemia with massive nonstratified wall thickening of the stomach.

Lobulated character of the polyp and the vessels in the stalk.

Video 11.25

Food particles simulating polyps or duplication cysts.

Hypertrophic pyloric stenosis.

Video 11.26a, b

Henoch Schönlein purpura.

Video 8.16

Doppler US shows an extremely slow flow in the portal vein.

Video 8.18

Video shows flow within the metastatic mass and flow within the ascites during respiration.

Video 8.20

On respiration flow is visible within the ascites.

Video 8.24

Perforation of the gallbladder.

Video 8.26

Video clip shows flow of pus within the abscess. Note the deep extend of the abscess.

Video 8.27

Video clip shows the flow of pus within the abscess upon compression. Note the rigidity of the surrounding infiltrated fat tissue.

Chapter 9 Video 9.4

Thrombus formation in the umbilical vein.

Video 9.16

Choledochal cyst.

Video 9.21

Thick mucoid pus within the liver abscess.

Video 9.74

Mesenchymal hamartoma.

Video 9.79

Hepatoblastoma.

Video 9.85

Hepatoblastoma.

Chapter 10 Video 10.6

Chapter 11

Video 11.13a

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Video Contents Video 11.28

Meckel's diverticulum.

Video 11.48

Video 11.30

Necrotizing enterocolitis and intestinal pneumatosis.

Hydropic gangrenous appendix with a torsion at its base.

Video 11.53

Neutropenic colitis.

Video 11.31

Portal vein gas in Hirschsprung's disease.

Video 11.54

Pseudomembranouis colitis.

Video 11.32

Pneumoperitoneum in necrotising enterocolitis.

Video 11.55

Pseudomembranous colitis.

Video 11.57

Hemolytic uremic syndrome.

Video 11.33

Sloughing of the mucosa in a premature infant with transient ischemia.

Video 11.58

Juvenile polyp in the descending colon.

Video 11.35

Duplication cyst of the ileum in a newborn child.

Video 11.59

Encrusted pellets of stools in the colon.

Video 11.60

Normal appendage of the colon.

Video 11.64

A newborn with a bucket handle deformity of the anus.

Video 11.65

Jejunal atresia.

Video 11.68

Newborn with cystic fibrosis and meconium ileus.

Video 11.72

Meconium peri-orchitis.

Video 11.37

Postsurgical resolving hematoma or haemorrhagic seroma resembling a duplication cyst

Video 11.38

Benign small bowel intussusceptions.

Video 11.39

Extremely large benign small bowel intussusception.

Video 11.46

Appendicitis.

Chapter 16 Video 16.6

Communicating hydrocele.

Video 16.12c

Inguinal hernia with omentum.

Video 16.7

Non-communicating hydrocele.

Video 16.19

Benign monodermal teratoma.

Video 16.12a

Scrotal hernia containing bowel loops, the testicle in the peritoneal cavity and an encysted hydrocele.

Video 16.29

Torsioned spermatic cord.

Video 16.47

Varicocele.

Video 16.54a, b

Non-palpable testicles.

Video 16.12b

Inguinal hernia with a bowel loop.

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Foreword It is with great pleasure that I write the Foreword of this book which is dedicated to describe the role and uses of sonography in neonates, infants, and older children. For decades, sonography has played a major role in imaging protocols used in pediatric patients. The significant technical advances in sonographic equipment and the aggressive and imaginative approaches taken by many pediatric radiologists have facilitated the continuous expansion of the uses of sonography in the pediatric population. The pivotal role that sonography plays in pediatric imaging remains secure despite the advances of other imaging modalities, and its advantages have been well documented. The most significant factors are, firstly, that it does not use ionizing radiation which is extremely important in the pediatric age group and, secondly, that it is a relatively cheap modality (including equipment and running costs) compared with computed tomography and magnetic resonance imaging. Furthermore, equipment can be easily moved to the bedside where state-of-the-art examinations can be performed without moving patients who are too sick to be moved. Sonography is also ideally suited for use in pediatrics, particularly neonates and small children, in whom exquisite images can be obtained because of the small size of the patients. Performing sonographic examinations in children is a great clinical and intellectual challenge. It is more than just a simple extension of the clinical examination. It requires a broad knowledge of the disease entities encountered in the pediatric age group, an understanding of the sonographic appearances of these diseases, and an ability to perform the examination with meticulous attention to technique in order to produce the highest quality images of both normal and abnormal findings. Although one should be guided by established protocols for each type of examination, one should never be constrained by these protocols. It is essential to perform examinations with an approach that enables one to be both aggressive in the search for abnormalities and flexible in adjusting the techniques used to suit the needs of the individual patient. This requires a thorough understanding of the equipment one is using and what factors need to be altered in order to optimize the images in pursuit of the most informative examination.

There has been a relentless expansion of the uses of sonography in pediatrics over the past four decades. However, sonography has not merely expanded by becoming another layer for imaging children. It has expanded by replacing other modalities as the imaging modality of choice in many clinical situations. The modalities that have been replaced are primarily those using ionizing radiation, such as plain radiographs, fluoroscopy, computed tomography, and angiography. Furthermore, sonography has also played a major role in facilitating or guiding interventional techniques in children. This book addresses the issues related to sonographic imaging in pediatric patients extremely well. The text is very comprehensive and the images illustrating the wide variety of disease processes are of high quality. The authors have clearly made a tremendous effort to compile such an informative book. The information contained in this book is of great value not only to trainees but also to pediatric radiologists and technologists who are involved in the care of sick children, as well as pediatricians and pediatric surgeons who may require a better understanding of the role of sonography in children and who desire to become more familiar with the sonographic appearances of the diseases they are dealing with. The authors must be congratulated for the comprehensive text and high-quality images used in the book. It is a great honor to have been asked to write the Foreword of this book which is dedicated to a modality that has become so pivotal in pediatric imaging and which will definitely remain so for the foreseeable future. Alan Daneman, BSc, MBBCh, FRANZCR, FRCPC Professor of Medical Imaging Department of Medical Imaging University of Toronto Toronto, Canada Staff Pediatric Radiologist Department of Diagnostic Imaging Division of Body Imaging Hospital for Sick Children Toronto, Canada

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Preface Ultrasound is a marvelous imaging modality in pediatric radiology. Children are often lean and small and this creates favorable conditions for ultrasound. Anesthesia is not necessary and the exams can be done at the bedside. During the ultrasound examination the radiologist can not only image the patient but also obtain a clinical history, and thus be informed about the clinical situation of the patient in much more detail than any radiology request form can reveal. In 1990 a book on pediatric ultrasound by Reinhard Schulz and Ulrich Willi was published. Its chapters were composed of a short text and many images. The book inspired us to publish a new book on diagnostic pediatric ultrasound, with a limited amount of text, many images and as a tribute to modern technology: on-line video clips. Video clips capture one of the most important aspects of ultrasound imaging, the ability to see motion in real-time.

The video clips have the same number as the images in the book which illustrate a related disease. The book is intended for all health workers who perform pediatric ultrasound like pediatric-radiologists, general radiologists, radiology residents, pediatricians, and sonographers. It is the result of the efforts of many authors who describe the sonographic findings of a spectrum of diseases in their favorite organ system. This cooperation also gave the possibility to exchange images among the authors. We and the authors have enjoyed working on this book and we hope that Diagnostic Pediatric Ultrasound will increase the knowledge of the readers, who would also enjoy the illustrations and video clips. We like to thank all the authors for their contributions and Thieme for their support. Erik Beek, MD, PhD Rick R. van Rijn, MD, PhD

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Contributors Matteo Baldisserotto, MD, PhD Consultant Paediatric Radiologist Department of Radiology School of Medicine Pontificia Universidade Católica do Rio Grande do Sul Brazil Alex Barnacle, BM MRCP FRCR Consultant Paediatric Interventional Radiologist Department of Radiology Great Ormond Street Hospital for Sick Children London, United Kingdom Erik Beek, MD Consulting Radiologist Department of Radiology University Medical Center Utrecht Utrecht, The Netherlands Jim Carmichael Consultant Paediatric Radiologist Evelina London Children’s Hospital London, United Kingdom Maria Beatrice Damasio, MD Consultant Paediatric Radiologist Department of Radiology Giannina Gaslini Institute Genova, Italy

Willemijn Klein, MD, PhD Consultant Paediatric Radiologist Department of Radiology and Nuclear Medicine Radboud University Medical Center Nijmegen, The Netherlands Gerda Meijler, MD PhD Consultant Neonatologist Department of Neonatology Isala Hospital Zwolle, The Netherlands Rutger Jan Nievelstein, MD Consultant Paediatric Radiologist Department of Radiology University Medical Center Utrecht Utrecht, The Netherlands Ann Nystedt, MD Consultant Paediatric Radiologist Department of Radiology Sørlandet Hospital Arendal Arendal, Norway Lil-Sofie Ording Muller, MD PhD Consultant Paediatric Radiologist Unit for Paediatric Radiology Department of Radiology and Intervention Oslo University Hospital Oslo, Norway

Ingmar Gassner, MD Consultant Paediatric Radiologist Department of Radiology Section of Pediatric Radiology Innsbruck Medical University Innsbruck, Austria

Anne Paterson MBBS, MRCP, FRCR, FFR RCSI Consultant Paediatric Radiologist Radiology Department Royal Belfast Hospital for Sick Children Belfast, United Kingdom

Claire Gowdy MRCP, CH, FRCR Consultant Paediatric Radiologist Paediatric Radiology Royal Victoria Infirmary Newcastle upon Tyne, United Kingdom

Rob Peters, MSEE Medical Physicist Department of Physics & Medical Engineering VU Medical Center Amsterdam, The Netherlands.

Handan Güleryüz, MD Consultant Paediatric Radiologist Department of Pediatric Radiology Dokuz Eylül University Medical School Izmir, Turkey

Giorgio Piaggio, MD Consultant Paediatric Nephrologist Nephrology Unit Giannina Gaslini Institute Genoa, Italy

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Contributors

Maria Raissaki, MD, PhD Assistant Professor in Paediatric Radiology University Hospital of Heraklion Crete, Greece Prof. Rick R. van Rijn, MD, PhD Professor Department of Radiology Emma Children’s Hospital Academic Medical Center Amsterdam, The Netherlands Prof. Simon Robben, MD, PhD Consultant Paediatric Radiologist Department of Radiology Maastricht University Medical Center Maastricht, The Netherlands Derek Roebuck, MBBS, DMRD, FRCR, FRANZCR, MRCPCH Consultant Paediatric Interventional Radiologist Department of Radiology Great Ormond Street Hospital for Sick Children London, United Kingdom Anne Smets, MD Consultant Paediatric Radiologist Pediatric Radiology Unit Department of radiology Emma Children’s hospital Academic Medical Center Amsterdam, The Netherlands

xx

Joost van Schuppen, MD Consultant Paediatric Radiologist Department of Radiology Emma Children's Hospital Academic Medical Center Amsterdam, The Netherlands Gisela Schweigmann, MD Consultant Paediatric Radiologist Department of Radiology Section of Pediatric Radiology Innsbruck Medical University Innsbruck, Austria Samuel Stafrace, MD, MRCP (UK), FRCR, FRCP (Edin) Attending Physician – Radiology Sidra Medical and Research Center Doha, Qatar Previously: Consultant Radiologist Royal Aberdeen Children’s Hospital Aberdeen, Scotland, United Kingdom Marina Vakaki, MD, PhD Director of Radiology Department and Head of Ultrasonography Unit “P & A. Kyriakou” Children’s Hospital Athens, Greece Linda de Vries, MD, PhD Professor in Neonatology Department of Neonatology University Medical Center Utrecht, The Netherlands

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Abbreviations 123I-MIBG

iodine I 123 metaiodobenzylguanidine

18F-FDG-PET

fluorodeoxyglucose F 18 positron emission tomography

99mTc-MDP

technetium Tc 99m methylene diphosphonate

AAST

American Association for the Surgery of Trauma

ACTH

adrenocorticotropic hormone

ADPKD

autosomal-dominant polycystic kidney disease

AHW

anterior horn width

ALARA

as low as reasonably achievable

A-mode

amplitude mode

AP

anteroposterior.

APLS

Advanced Pediatric Life Support)

BESS

benign enlargement of the subarachnoid space

B-mode

brightness mode

CBH

cerebellar hemorrhage

CC

corpus callosum

CF

cystic fibrosis

CNS

central nervous system

CSF

cerebrospinal fluid

CSG

contrast-enhanced cystosonography

CT

computed tomography

cUS

cranial ultrasound

DDH

developmental dysplasia of the hip

DMSA

dimercaptosuccinic acid

ECMO

extracorporeal membrane oxygenation

ERCP

endoscopic retrograde cholangiopancreatography

ESPR

European Society of Paediatric Radiology

FAST

focused abdominal sonography for trauma

GCTTS

giant cell tumor of the tendon sheath

GERD

gastroesophageal reflux disease

GMH-IVH

germinal matrix–intraventricular hemorrhage

HIE

hypoxic–ischemic encephalopathy

IBD

inflammatory bowel disease

INRG

International Neuroblastoma Risk Group

INSS

International Neuroblastoma Staging System

IVC

inferior vena cava

JIA

juvenile idiopathic arthritis

LSV

lenticulostriate vasculopathy

MCE

multicystic encephalomalacia

MI

mechanical index

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Abbreviations

xxii

M-mode

motion mode

MR

magnetic resonance

MRCP

magnetic resonance cholangiopancreatography

MRKH

Mayer-Rokitansky-Küster-Hauser (syndrome)

NAFLD

nonalcoholic fatty liver disease

NICH

noninvoluting congenital hemangiomas

NPV

negative predictive value

PAIS

perinatal arterial ischemic stroke

PET

positron emission tomography

PHVD

post-hemorrhagic ventricular dilatation

PLIC

posterior limb of internal capsule

PMA

postmenstrual age

PNET

primitive neuroectodermal tumor

PPV

positive predictive value

PRF

pulse repetition frequency

PRP

pulse repetition period

PSC

Primary sclerosing cholangitis

PTLD

post-transplant lymphoproliferative disorder

PVE

periventricular echodensities

PVHI

periventricular hemorrhagic infarction

PVL

periventricular leukomalacia

PVNS

pigmented villonodular synovitis

RI

resistive index

RICH

rapidly involuting congenital hemangiomas

SD

standard deviation

SELSTOC

self-limiting sternal tumor of childhood (SELSTOC)

SMA

superior mesenteric artery

SMV

superior mesenteric vein

SPEN

solid and papillary epithelial neoplasm

SPT

solid papillary tumor

TCD

transverse cerebellar diameter

TEA

term equivalent age

TGC

time gain compensation

TI

thermal index

TOD

thalamo-occipital distance

US

ultrasound

UTI

urinary tract infection

VACTERL

(vertebral abnormalities, anal atresia, cardiac abnormalities, tracheoesophageal fistula and/or esophageal atresia, renal agenesis and dysplasia, limb defects)

VCUG

voiding cystourethrography

VI

ventricular index

VUR

vesicoureteral reflux

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Chapter 1 Examining the Child and Creating a Child-Friendly Environment

1.1 Child-Friendly Staff

2

1.2 Appointment

2

1.3 Appointment Letter

2

1.4 Waiting Area

2

1.5 Examination Room

3

1.6 Examination

4

1.7 How to Scan: Tips and Tricks

5

1.8 Private Room

6

1.9 Communicating the Results

6

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1 Examining the Child and Creating a Child-Friendly Environment Anne Smets A pediatric radiology department welcomes children between 0 and 18 years of age who are sick or wounded, accompanied by worried or anxious parents or caregivers. Their stay in the radiology department is usually of short duration, and the ultimate challenge is to collect the necessary diagnostic information while limiting the amount of pain and distress. Getting the child to cooperate will increase our chances of performing this task with success and doing it in a child-friendly way will improve the experience of the child and his/her parents or caregivers. Performing an ultrasound examination on a calm child in the presence of trusting parents or caregivers will also make life easier for the hospital staff. Moreover, it will increase our chances of building a trusting relationship and hence laying the foundations for good collaboration with the child during future examinations. Providing good preparatory information and creating a child-friendly environment in the broadest sense of the words is the basis for a successful examination.

1.1 Child-Friendly Staff Creating a child-friendly environment starts with the attitude of the staff, including the receptionist, radiology assistants, technicians, and doctors. All staff should be aware of the particular needs of pediatric patients, showing consideration and providing explanation and reassurance. They should be patient, enjoy working with children, and be comfortable with and around them. Uncertainty can be transmitted to the child and the parents, and this may very well result in inadequate examinations. The staff must be aware of the importance of building a rapport with the child and the anxious parents in order to pave the way for a good-quality examination and possible future examinations. Not everybody is capable of doing, or willing to do this; therefore, it is important to select dedicated pediatric personnel, even in a general radiology department setting. Without a committed pediatric team, child-friendly decoration and logistics are an investment of little value.

1.2 Appointment When an appointment for an ultrasound examination is scheduled, several factors should be taken into account to find the most favorable time slot. If a child is to have several tests or examinations on the same day, it is best to schedule an ultrasound scan before any invasive examination that might be upsetting because a distressed child will be much less likely to cooperate. Also, crying will increase the amount of air in the stomach and bowel, rendering an abdominal ultrasound examination more difficult, if not inconclusive. If a child needs to be fasting for an examination of the upper abdomen, the session should be planned for as early as possible in the morning. Fasting infants should be scheduled right before the next feed.

2

1.3 Appointment Letter It is often underestimated how a “benign” procedure such as an ultrasound can be perceived as a stressful event by children and their parents. It may be the child’s first visit to the radiology department, and the environment and the procedure may be unknown, which can be very intimidating. In addition, the parents and/or the child may be anxious about the findings of the examination. At best, the referring clinician will have explained what the ultrasound scan is about, including both the procedure and the possible outcome. However, supplementing this explanation with a clear information leaflet, provided with the appointment letter, which reiterates the ins and outs of the ultrasound scan, is a good practice. In our institution, we have added a section with tips from the child therapist team on how parents or caregivers can explain the procedure to a child in accordance with the age of the child. Including a contact telephone number in case there are still questions or concerns about the procedure is certainly useful. The appointment letter should state the date and time of the appointment and the scan, where the patient is due, the type of scan, and which preparation is necessary (e.g., should the child have an empty stomach or a full bladder?).

1.4 Waiting Area Examinations on children can be unpredictable and can take up more time than planned. However, keeping the waiting time for all children as short as possible should be a priority. Bored or fractious children are more difficult to examine. Annoyed parents can escalate their children’s anxiety and may direct their frustration at you, again rendering the ultrasound examination more challenging. This should be taken into account when the time slots for ultrasound scans are created. If a delay arises unexpectedly, take time to inform the parents and give them a reasonable and understandable explanation. The waiting area should be a safe, friendly, and distracting area where children of any age and their parents can wait a short while before the examination is due (▶ Fig. 1.1). In our institution, we have intentionally opted for a closed area so that parents can focus on the administrative dealings while the child can play in a safe environment where he or she is unable to run off out of sight. The administration desk has a lower part allowing children to see the person behind it, helping them to feel in control and included (▶ Fig. 1.2). There is a television showing short cartoons (▶ Fig. 1.3), as well as books and magazines, a table with paper and crayons (▶ Fig. 1.4), and lots of washable toys. Other types of distracting items can be offered. At the Royal Belfast Hospital for Sick Children, a collage has been made with medical supplies (▶ Fig. 1.5). This has proved to be very popular with the children, who try to spot things the nurses and doctors have been using.

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Examining the Child and Creating a Child-Friendly Environment

Fig. 1.1 Example of a waiting area that appeals to children. It is a closed area so that children cannot run off.

Fig. 1.2 A low administration desk allows children to participate and feel included.

Fig. 1.3 A television set showing short cartoons.

Fig. 1.4 Area where children can read, draw, or play.

It is also worth having a quiet corner for very ill or injured children and bedridden patients who are not interested in this kind of distraction.

1.5 Examination Room

Fig. 1.5 Collage made up of medical supplies. Courtesy of A. Paterson, Royal Belfast Hospital for Sick Children, Belfast, Northern Ireland.

To facilitate patient flow, it can be convenient to have two changing rooms per examination room. Having a baby changing area in the changing room will allow parents to dress and undress their infant, thus improving the patient flow (▶ Fig. 1.6). A toilet within the changing room allows for quick post-micturition scans. The examination room should also be a friendly environment. The room should be large enough to accommodate a child along with the parents, siblings, and strollers, and there should be enough room to exchange the couch for an inpatient in his or her own bed. The room temperature should be warm enough for partially undressed patients; an infrared lamp can add extra warmth for newborns, who lose heat easily when undressed. The decoration should appeal to children of all ages (▶ Fig. 1.7, ▶ Fig. 1.8, ▶ Fig. 1.9, ▶ Fig. 1.10).

3

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Examining the Child and Creating a Child-Friendly Environment

Fig. 1.7 The lights on the wall representing the positions of the moon are appreciated by all children, regardless of their age. Fig. 1.6 Encouraging parents to dress and undress their infants in the changing room will improve patient flow.

Fig. 1.8 Drawing on the wall in the digital radiography room at the Wilhelmina Children’s Hospital, Utrecht, The Netherlands. Courtesy of E. Beek.

1.6 Examination For almost all children, the presence of parents will be beneficial. Adolescents should be given the choice of having their parents present during the scan or not. It is important for the radiologist to build a good rapport with the child and parents before starting the examination. If all people involved feel at ease, the chances of a successful diagnostic examination will be good. It is usually the technician or radiology assistant who will invite the patient and parents into the room. This person will introduce himself or herself and once again explain the procedure at a level appropriate to the child’s understanding. When you walk into the scanning room and introduce yourself properly to both the child and the parents, make sure the child is feeling safe. This can be a sitting position on a parent’s lap or, if the child feels confident enough, on the couch. It is not necessary to undress the child completely; pulling up tops and loosening trousers or skirts is usually sufficient.

4

Fig. 1.9 Drawing on the wall of the fluoroscopy room at the Wilhelmina Children’s Hospital, Utrecht, The Netherlands. Courtesy of E. Beek.

Taking a few minutes to have a chat with the child and the parents will help to put everyone at ease. You should enter the room with a full knowledge of the patient’s history, the results of any previous examinations, and the clinical information delivered for this examination. It is also important in this short introduction to take a short history and ask questions about what is worrying the child and/or the parents and what has been previously discussed with the referring physician. Acknowledging their feelings about the examination and the results is important. Use this time also to tell them that you will need to concentrate during the examination but that you will inform them of the results when the scan is finished, if they wish. Some parents will prefer hearing the results and some explanation from you, whereas others may want to wait for the appointment with the referring physician if there are no urgent matters to be dealt with. Tell the child again what you will do, as a repeated explanation will help to diminish anxiety. Be honest about what will happen; an ultrasound scan is a painless test unless the region of interest is painful!

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Examining the Child and Creating a Child-Friendly Environment

Fig. 1.11 Allowing children to hold the transducer together with you will enhance their feeling of being in control and increase their cooperation.

Fig. 1.10 Detail of a wall drawing at the Wilhelmina Children’s Hospital, Utrecht, The Netherlands. Courtesy of E. Beek.

Fig. 1.13 Climbing the couch alone will make children feel in control.

Fig. 1.12 The coupling gel ought to be warm in a pediatric radiology department.

1.7 How to Scan: Tips and Tricks Sedation is almost never needed for ultrasonography, although if the child is young and too restless for the examination of a small lesion and will be sedated for another procedure, it may be convenient to use that moment to examine the child under these conditions. For abdominal examinations, an empty stomach is necessary in most cases. Babies can become very restless when hungry, making this examination difficult. If sucking on a pacifier or a parent’s finger does not help, a drop of sucrose on the pacifier or finger may do the trick. Some children will feel more secure and in control if they can hold the transducer together with the doctor (▶ Fig. 1.11).

Warming the gel will prevent a shock effect when the cold gel touches the child’s skin. This can be done in a gel warmer or small oven (▶ Fig. 1.12). Make sure to check the temperature of the gel with your fingers before starting your examination. An adjustable position in height will allow children to climb on the couch or bed by themselves, which will give them a feeling of being in control (▶ Fig. 1.13). A large couch allows flexibility in positioning, and mothers can lie down next to their infants to breast-feed them and comfort them during the examination. A parent can lie on the couch together with the child or sit next to you with the child on his or her lap (▶ Fig. 1.14 a–c). Distraction is an excellent way to help a child cope with an unfamiliar situation such as an ultrasound scan, and it will reduce stress and anxiety. It also helps the child from getting bored lying on his or her back for more than 10 minutes. It is good to have an arsenal of distracting toys at hand for the youngest, such as musical toys and books, materials for bubble blowing, and so forth. During scans on inpatients, parents may not be present; make sure you have someone (a radiology assistant or play therapist) to help you hold and entertain the child while you focus on the examination. Older children can be distracted

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Examining the Child and Creating a Child-Friendly Environment

Fig. 1.14a–c Different scanning positions can be attempted when children are too afraid to lie down on the couch by themselves. Parents can help with immobilizing their children while comforting them.

by a conversation, joke telling, singing, and other similar activities. However, distraction should not be forced upon a child who is very upset or in pain.

1.8 Private Room If there is enough space in your department, you may want to have a private room as an extension to the ultrasound scanning room. In this room, mothers can continue breast-feeding their babies after the scan in order to free the examination room for another patient. It can be used to discuss more complex or serious results in private when this discussion cannot wait, and a pediatric specialist can be called in to see the patient there immediately.

1.9 Communicating the Results The results must be reported to the referring physician as soon as possible. Parents might prefer to hear the results from you instead of waiting for the appointment with the referring physician. When the results of the test are normal, it will be easy to reassure the parents and prevent days of worrying before the appointment with the referring physician. If you need to compare the results with those of previous or other examinations,

6

tell the parents so. If your findings are worrisome and you need to make sure there is no delay in action (surgery, more tests, or referral to a specialist), tell the parents there are things you need to discuss with the referring physician while they wait in the waiting area or in a private room. Together with the referring physician, you can decide what should be said and done, when and by whom. Adolescents may not ask questions for fear of appearing stupid. Make sure they have understood what you need them to know.

Tips from the Pro ● ●

● ●

● ● ●

●

Schedule ultrasound examinations for children wisely. Provide clear information about the ultrasound scan beforehand. Make sure your department welcomes children of all ages. Time in the waiting room should be pleasant but kept as short as possible. Enter the examination room well informed and prepared. Take time to build rapport. Have distraction tools at hand and/or have someone to help you. Be prepared for how you will communicate the results.

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Recommended Readings Alexander M. Managing patient stress in pediatric radiology. Radiol Technol 2012; 83: 549–560 Goske MJ, Reid JR, Yaldoo-Poltorak D, Hewson M. RADPED: an approach to teaching communication skills to radiology residents. Pediatr Radiol 2005; 35: 381–386 Harrison D, Beggs S, Stevens B. Sucrose for procedural pain management in infants. Pediatrics 2012; 130: 918–925

Johnson AJ, Steele J, Russell GB, Moran R, Fredericks KP, Jennings SG. Decreasing pediatric patient anxiety about radiology imaging tests: prospective evaluation of an educational intervention. J Child Health Care 2009; 13: 370–382 Piira T, Sugiura T, Champion GD, Donnelly N, Cole AS. The role of parental presence in the context of children’s medical procedures: a systematic review. Child Care Health Dev 2005; 31: 233–243 Safdar N, Shet N, Bulas D, Knight N. Handoffs between radiologists and patients: threat or opportunity? J Am Coll Radiol 2011; 8: 853–857

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Chapter 2 Physics and Artifacts

2.1 Basic Principles of Ultrasound

10

2.2 Echoscopic Image Construction

13

2.3 Transducers

15

2.4 Resolution

16

2.5 Artifacts in Sonography

17

2.6 Advances in Echoscopic Image Construction

19

2.7 Biological Effects and Safety

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2 Physics and Artifacts Rob Peters Ultrasound imaging is a popular imaging technique in clinical practice. It has been used for over 6 decades. Medical ultrasound is relatively inexpensive, noninvasive, and portable; it has good spatial and temporal resolution; and it is safe. Ultrasound imaging is based on the use of the echo of a sound wave to produce an image of the insonated area. It is derived from techniques like SONAR (sound navigation ranging) and nondestructive material testing. The first clinical ultrasound image was produced by Karl and Friedrich Dussik in Vienna in 1946. They used a transmission technique, similar to the technique used in X-ray imaging. In 1949, the first pulse echo was described. After that, 2D grayscale images were produced. In 1956, Ziro Kaneko introduced the Doppler technique. In 1965, Siemens introduced the VIDOSON, the first real-time 2D gray-scale system. In 1971, the first commercially available array transducer– based systems were introduced simultaneously by Professor Klaas Bom of Erasmus University in Rotterdam, The Netherlands (the Multiscan system) and by Toshiba (the SSD-12). In 1979, Professor Bom in conjunction with Professor Wladimiroff, an obstetrician, introduced the Minivisor, the first portable ultrasound imager. After these advances, ultrasound scanners were made available by many companies. The techniques evolved into applications like life 3D and elastography, and the developments are still going fast.

¼

c ½m f

ð2:2Þ

2.1.3 Wave Propagation in Inhomogeneous Media Just like visual light, sound breaks and reflects on discontinuities in media (▶ Fig. 2.1), according to Snell’s law: sini sinr sint ¼ ¼ c1 c1 c2

ð2:3Þ

Reflection The reflection coefficient Rp describes the fraction of sound pressure that is reflected on an interface and is given by the following equation: RP ¼

Pi Z2  cosi  Z1  cost ¼ Pr Z2  cosi þ Z1  cost

ð2:4Þ

with Pi and Pr representing the incident pressure amplitude (height) and the reflected pressure amplitude, respectively. For a perpendicular incidence (α = 0°, cos α = 1), this formula simplifies as follows: Pi Z2  Z1 ¼ Pr Z2 þ Z1

2.1 Basic Principles of Ultrasound

RP ¼

2.1.1 Ultrasonic Waves

Intensity is the amount of power (energy per unit of time) per unit area. It is proportional to the square of the pressure amplitude:

Ultrasound is defined as sound having a frequency higher than 20 kHz. This is beyond the upper limit of the human audible spectrum. Frequencies used in medical ultrasound typically range from 1 to more than 20 MHz. Ultrasonic waves are longitudinal compression waves. Longitudinal means that the movement of the particles of the medium is parallel to the direction of the wave movement. This is a contrast to transverse waves, like waves on water. Here, the movement of the particles is perpendicular to the direction of the wave. In longitudinal pressure waves, the movement of the particles leads to regions of compression and expansion corresponding to high- and low-pressure areas, respectively.

2.1.2 Wave Propagation in Homogeneous Media

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The frequency (f) of the ultrasonic wave is unaffected by the propagation medium. The wavelength (λ), however, is related to the medium by the following equation:

ð2:5Þ

I / P2

ð2:6Þ

In case of a perpendicular incidence, the intensity reflection coefficient thus becomes:   I i Z 2  Z1 2 ð2:7Þ RI ¼ Ir Z2 þ Z1

Table 2.1 Acoustic properties of various materials and tissues Material/Tissue




Z [kg·m–2·s–1] (× 106)

c [ms–1]

[kg·m–3]

Air

1.2

330

0.0004

Lung

300

600

0.18

The degree of compression is related to properties of the propagation medium. These properties are characterized by the acoustic impedance, Z
Z ¼
c kg  m2  s1 ð2:1Þ

Fat

924

1,450

1.34

Water

1,000

1,480

1.45

Kidney

1,041

1,565

1.63

Blood

1,058

1,560

1.65

with ρ being the density of the medium [kg·m–3] and c being the speed of sound in the medium [ms–1]. ▶ Table 2.1 lists various properties of materials and tissues.

Liver

1,061

1,555

1.65

Muscle

1,068

1,600

1.71

Skull bone

7,500

4,080

30.6

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Fig. 2.1 Reflection and refraction on discontinuities in media.

Fig. 2.2 Reflection at critical angle.

with Ii and Ir representing the incident intensity and the reflected intensity, respectively. RI ranges between 0 and 1. At 0, no energy is reflected; no echo occurs. This is when Z1 = Z2. There is no discontinuity in the medium and no boundary to reflect on. At RI = 1, all energy in the incident wave is reflected. No energy is transmitted through the boundary. This occurs when there is a great difference between Z1 and Z2 (Z1 < < Z2 or Z1 > > Z2). As can be seen in ▶ Table 2.1, the acoustic impedance values of biomaterial are in the order of 1.3 to 1.7 × 106 kg·m–2·s–1. This leads to reflection coefficients in the order of 0.02. This means that 2% of the intensity of an incidence wave reflects on the boundary and 98% is transmitted and can produce echoes of adjacent structures. Note that without these small differences in the acoustic impedance of biomaterials, ultrasound imaging would not be possible.

Refraction As seen in ▶ Fig. 2.1, the transmitted wave is refracted. An interesting phenomenon called total reflection occurs when, given c2 > c1, the angle of incidence αi gets beyond a critical value called αc. This angle is called the critical angle (▶ Fig. 2.2). The refracted wave does not penetrate the second medium. It travels along the interface. Hence αt = 90°. We get the critical angle αc by substitution of sin αt = 1 into Eq. 2.3: sinc ¼

C1 C2

ð2:8Þ

At an interface from fat to muscle, we get sin αi = 1,450/1,600. This gives a critical angle of 65°.

Scattering A smooth boundary between two media, with the dimensions of the boundary much larger than the wavelength of the

ultrasonic wave, causes reflection, as has been explained previously. This type of reflection is called specular or smooth reflection. The roughness of an interface leads to so-called nonspecular reflection. The reflection of the incident wave is spread over a range of reflection angles. The same occurs on small objects in a tissue, about the size of the wavelength or smaller. Nonspecular reflection is also called diffuse reflection or scattering. In case of scattering, the incident wave is spread over a range of reflection angles. This means that the intensity of backscatter, the part of the scattered signal that can be detected by the ultrasound system, is quite small.

Attenuation Scattering and energy absorption in the tissue cause an attenuation of the ultrasound beam. This attenuation occurs exponentially with the distance that the ultrasound wave travels through the medium. In ▶ Fig. 2.3, the attenuation of ultrasound in liver tissue is shown for different frequencies in relation to the penetration depth. It must be taken into account that the total distance traveled by the ultrasound pulse and the echo is twice the penetration depth. The relative loss of acoustic intensity is expressed in the attenuation coefficient μ [dB/(MHz·cm)]. A decibel is not a unit, but it indicates a ratio—in this case, the ratio between the intensity of the incident wave and the transmitted wave. The relative intensity in decibels is defined as follows:   I2 Relative intensity ¼ 10log ð2:9Þ I1 An intensity ratio of 106 equals 60 dB. A ratio of 2 equals 3 dB, whereas a ratio of 0.5 equals –3 dB. The logarithmic relation compresses the values of the intensity ratio into a more manageable number range.

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Fig. 2.3 Attenuation of ultrasound in liver tissue.

Fig. 2.5 Angle of insonation.

The change in frequency due to the Doppler effect, also called the Doppler shift, is given by the following equation: Fig. 2.4 Doppler effect.

2.1.4 Doppler Echo Doppler Effect The Doppler effect is a change in the frequency of a sound due to the relative motion of the source and the receiver. This change in frequency is called the Doppler shift. In daily practice, we hear the Doppler effect when the siren of an ambulance passes by. When the vehicle is approaching, the pitch is high. As the ambulance passes by, the pitch gets lower. In ultrasound imaging, we encounter moving objects such as blood cells. The ultrasonic wave reflects on these cells. The cells thus become transmitters of sound (the echo). In ▶ Fig. 2.4, the sound source moves to the left. The wavelength on the left is smaller than the wavelength on the right. The opposite happens to the frequency. Perpendicular to the direction of movement (up and down), no change in wavelength occurs. Therefore, there is no change in frequency in these directions.

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Δf ¼ cosðÞ 

2  f send  v c

ð2:10Þ

with fsend the ultrasound frequency of the incident wave, v the speed of the reflector (cell), c the speed of sound, and α the angle of insonation, as visualized in ▶ Fig. 2.5. To calculate v, Eq. 2.10 can be rewritten as follows: v¼

Δf  c 2  f send  cosðÞ

ð2:11Þ

The Doppler shift and thus the velocity profile can be presented in a Doppler spectrogram (▶ Fig. 2.6). From typical values of fsend = 4 MHz, c = 1,480 ms–1, v = 0.5 ms–1, and α = 30°, we obtain a Doppler shift of 2,350 Hz (Eq. 2.10). This lies in the audible range. Presenting this Doppler shift through a loudspeaker can be of help for the positioning of the probe and can even help in diagnostics. During pregnancy, the blood flow in the umbilical arteries can be monitored by acoustic presentation of the Doppler shift. Pathologies give characteristic changes in Doppler shift patterns, and these can easily be revealed audibly. This simple but very effective ultrasonic device is standard equipment for a midwife.

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Physics and Artifacts frequency, the original signal can be perfectly reconstructed from the samples.

2.2 Echoscopic Image Construction

Fig. 2.6 Doppler spectrogram with maximum-velocity envelope (blue).

For a typical ultrasound Doppler measurement, fsend is known and c is assumed. The angle of insonation is set on the console of the ultrasound machine. If the angle of insonation is kept small, slight changes in positioning of the ultrasound transducer, introducing small changes in α, have little effect on the determination of v. However. If we increase the angle, a little error in α leads to an increasing error in v. Assuming α = 30° and v = 0.5 ms–1, a deviation of 3° in the real α (compared with the assumed α) gives rise to an error of up to 3% in the determination of v. The same measurement at α = 60° causes an error of up to 10% in the determination of v. Thus, for Doppler measurements, the angle of insonation should be kept as small as possible.

Continuous Wave Doppler Continuous wave Doppler transmits and receives ultrasound continuously. The velocity can easily be determined by extraction of the Doppler shift through demodulation of the ultrasound echo. Thus, there is no principal upper limit to the velocities that can be measured. However, there is no information about the period of time that the sound needed to travel back and forth, and therefore no spatial information is available.

Pulsed Wave Doppler In pulsed wave Doppler, one sample is taken from every received pulse. This results in a set of samples describing a signal that happens to have the same frequency as the Doppler shift. It is a kind of demodulation through undersampling. If no ultrasound pulse is emitted before the echo of the prior pulse has been received, spatial information is contained in the time it took for the echo to arrive. However, because of the sampling, the maximum velocity that can be measured is limited. It is related to the pulse repetition frequency according to the sampling theorem of Nyquist–Shannon. The Nyquist–Shannon theorem states that given a continuous signal with no components higher than half the sample

Image construction is basically performed by sequentially emitting a beam of small bursts of ultrasound, called pulses, followed by a period of listening to their echoes. The longer it takes for an echo to arrive, the farther away the boundary that caused this echo. With knowledge of the direction of the incident pulse, information about the spatial position of the boundary is obtained. The time between repetitive pulses determines the maximal distance from which echoes can be processed. When echoes up to a depth of 15 cm are detected, and assuming a speed of sound of 1,480 ms–1, a minimal pulse repetition period (PRP) of (2 × 0.15)/1,480 = 203 μs is needed. Thus, the maximal pulse repetition frequency (PRF) in this example is 4.9 kHz. The intensity of the echo tells something about the change in acoustic impedance at the boundary. This then provides information about the anatomical structures that form the boundary. Echoes originating from similar boundaries can differ in intensity because of attenuation of the signal. The deeper the structure, the more attenuation. This attenuation can be compensated for by using time gain compensation (TGC), usually a set of sliders on the console of the ultrasound machine. TGC enhances echoes from deeper structures. The origin of received echoes varies from specular reflection to scattering. This leads to a wide dynamic range of intensities of these echoes. In order to be able to present this information in gray notes on the screen, dynamic range compression has to be performed. This is done by so-called logarithmic compression. The logarithmic relation compresses the values of the intensity ratio into a more manageable number range. In image construction, this means that a huge range of echo intensities can be represented within the limited amount of gray notes at our disposal.

2.2.1 Amplitude Mode In amplitude mode (A-mode), one line of ultrasound pulses is used. Along this scan line, the A-line, echoes are generated by tissue boundaries. The amplitudes of these echoes are plotted against the distance from the probe. The A-mode (▶ Fig. 2.7) is currently used in ophthalmology applications for precise distance measurements of the eye.

2.2.2 Brightness Mode In brightness mode (B-mode; ▶ Fig. 2.8), a 2D image is built out of multiple scan lines. The intensity of the echo is represented in gray levels. The B-mode image is the image type commonly used in ultrasound imaging. It presents a real-time 2D slice through the insonated object and is used for examination of anatomy and function.

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Fig. 2.7 Amplitude mode.

Fig. 2.8 Brightness mode.

Fig. 2.9 Motion mode of the inferior vena cava.

2.2.3 Motion Mode In motion mode (M-mode) ultrasound, one scan line in the Bmode image is selected. This scan line passes through a moving anatomical structure (▶ Fig. 2.9). The changes in intensity of this one scan line are plotted in relation to time. M-mode can provide excellent temporal resolution of motion patterns. In cardiology, it is used in the evaluation of heart valves and other heart anatomy.

2.2.4 Color Doppler

Fig. 2.10 Color Doppler.

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In color Doppler, velocity information is merged with the B-mode image. The velocity is represented in color scale. Color Doppler images are widely used (▶ Fig. 2.10). In vascular examinations, it adds information about blood flow. Also, it can visualize perfusion and detect a stenosis.

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Fig. 2.11 Power Doppler.

Fig. 2.12 Piezoelectric effect.

electric signal when it is deformed. On the other hand, when an electric signal is applied, the crystal deforms. Thus, the crystal can be used for both generating and receiving signals. The ultrasonic pulse is generated when echoes exit the crystal. Then, the crystal is switched to receiving mode for incoming echoes. After a certain time, the pulse repetition time, when no echoes are expected to be received anymore, the next pulse is generated, and so on. Fig. 2.13 Linear array transducer.

2.2.5 Power Doppler In duplex mode, velocities can be derived by pulsed wave Doppler. The colors overlying the B-mode image represent velocity values at that particular spot. The underlying calculations are time-consuming. In power Doppler, just the total strength of the Doppler signal (power) is used for color representation. Directional information is ignored. This dramatically improves sensitivity. The shorter computing time can be translated into a higher temporal resolution and/or a higher spatial resolution. Power Doppler procedures are little affected by the angle of insonation (▶ Fig. 2.11). It is superior in its visualization of small vasculature and is used to visualize perfusion.

2.3 Transducers The ultrasonic pulse is generated by exciting the crystal with an electric pulse (▶ Fig. 2.12). A piezoelectric crystal generates an

2.3.1 Types of Transducers There are two basic forms of ultrasound transducers or probes: linear/curvilinear array and phased array transducers. They are identified by the way in which the ultrasound beam is produced, and by the field-of-view coverage.

Linear Array The linear array transducer consists of an array of crystals. Sequentially, a group of adjacent crystals are fired, resulting in an active transducer area. Thus, a single scan line is created. Then, the group of crystals are shifted one or more elements and another scan is performed, generating the next line of echo information. Thus, the ultrasound beam sequentially sweeps across the region of interest. The number of scan lines is approximately equal to the number of crystals (▶ Fig. 2.13). Mounting the array of crystals on a flat transducer surface produces a rectangular image. The width of the image and number of scan lines are the same at all tissue levels. Mounting the array of crystals on a curved transducer surface produces a trapezoidal image. This type of transducer is known as a curved array transducer. The density of the scan lines

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Physics and Artifacts Phased array transducers are used in cases with a small entrance window, such as in neonatal brain imaging, in which the width of the neonatal fontanel can be a limiting factor.

2.4 Resolution In echoscopic imaging, the spatial resolution is not uniform throughout the image. It depends on the beam-forming process.

2.4.1 Axial Resolution Fig. 2.14 Phased array transducer.

decreases with increasing distance from the transducer. The linear array transducer has the advantage of a wide field of view.

Phased Array The crystals of a phased array transducer are typically tightly grouped together, forming a small footprint (▶ Fig. 2.14). In a phased array transducer, unlike in a linear array transducer, all crystals are simultaneously used to generate an ultrasound beam. The angle of individual scan lines is manipulated by tuning the delay in firing of individual crystals. This is called electronic beam steering (▶ Fig. 2.15). The same technique is also used in electronic focusing (▶ Fig. 2.16).

Axial resolution or longitudinal resolution is the minimum distance that can be discerned between two reflectors located in the direction of the ultrasound beam. Axial resolution depends on the wavelength of the ultrasound pulse and is better with a short wavelength. So, the higher the frequency, the shorter the wavelength and thus the higher the axial resolution. Focusing has no influence on the axial resolution.

2.4.2 Lateral Resolution Lateral resolution is the minimum distance that can be discerned between two reflectors located perpendicular to the beam direction. Lateral resolution is related to the width of the ultrasound beam. When the width of the ultrasound beam is narrow, the lateral resolution is high. With focusing, the lateral resolution is highest in the focal zone.

Fig. 2.15 Beam steering.

Fig. 2.16 Electronic focusing.

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Fig. 2.18 Posterior shadowing (arrowheads) behind gallstones (arrow). Fig. 2.17 Ultrasound imaging resolutions.

2.5.1 Artifacts in 2D Ultrasound A main reason for these artifacts is the fact that in echoscopic image construction, a set of basic assumptions is made. Some important assumptions are the following: ● The width of the sound bundle is infinite. ● Sound travels in a straight line. ● Sound travels with a constant velocity. ● Pressure wave reflects only once. ● A received reflection is coming from the last emitted pulse. Failure to comply with these assumptions leads to artifacts such as those discussed in the next sections.

Shadowing

Fig. 2.19 Enhancement artifact behind the urinary bladder.

Shadowing (▶ Fig. 2.18) occurs when no echo is received from a region distal to an object or an interface (tissue dropout) because of high attenuation, reflection, or refraction of the incident beam. It occurs with bone or stones. Shadowing can be distinguished by slightly tilting or rocking the transducer. The hypoechogenic area will follow the movement of the transducer.

Enhancement

2.4.3 Elevational Resolution Elevational resolution or slice thickness is the thickness of the ultrasound beam. It is perpendicular to the image plane. Slice thickness is related to the height of the crystals, in much the same way as lateral resolution is related to the width of the ultrasound beam (▶ Fig. 2.17). A fixed focal length lens is used to optimize slice thickness at a fixed focal distance.

Enhancement is somewhat related to shadowing (▶ Fig. 2.19). It occurs distal to objects with low attenuation. Because of the low attenuation, the echoes of distal structures have a relatively high intensity. Enhancement occurs distal to fluid-filled cavities such as the gallbladder or cysts. It can also be seen deep to very homogeneous tissue. Again, slightly tilting or rocking the transducer reveals the artifact.

Reverberation

2.5 Artifacts in Sonography An artifact is defined as an incorrect display of anatomy. There are many distinguishable types of artifacts in ultrasound imaging. A set of commonly occurring artifacts is discussed here.

Reverberation artifact is also known as the comet tail artifact (▶ Fig. 2.20). It arises when an ultrasound pulse is trapped between two closely spaced, highly reflective boundaries. Part of the pulse is reflected between the boundaries, thus causing it to move back and forth.

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Fig. 2.20 Reverberation artifact at the diaphragm (arrow). Fig. 2.21 Mirror artifact of the liver above the diaphragm.

Fig. 2.22 Aliasing in the Doppler spectrogram. The peaks of the spectrum are shown below at –40 cm/s. Fig. 2.23 Aliasing in color Doppler imaging of the aorta and superior mesenteric artery. The velocity scale, –13 to + 13 cm/s, is too low.

On every reflection, a small part of the intensity is transmitted through the boundary and received by the transducer. The delay of these echoes is related to the number of times that the pulse was reflected in its trap. It takes these echoes longer to reach the transducer. Thus, they are displayed as a series of echoes at an increasingly greater depth. Again, slightly tilting or rocking the transducer reveals the artifact.

Mirror Artifacts When a highly reflective surface is distal to an object, ghosts of the object are displayed distal to the highly reflective surface. The ghost is generated by multiple reflections caused by the same phenomenon as described with the reverberation artifact. The mirror artifact typically arises at, for instance, the diaphragm, where an erroneous image of the liver is displayed in the thorax (▶ Fig. 2.21).

18

2.5.2 Artifacts in Doppler Ultrasound Aliasing Aliasing is a common artifact in pulsed wave Doppler. It is due to undersampling. The ultrasound echo is sampled at the PRF. According to the Nyquist–Shannon criterion, the PRF must be larger than twice the maximum Doppler shift. If the Nyquist–Shannon criterion is not followed, frequencies cannot uniquely be distinguished. Higher frequencies fold back into the spectrum (▶ Fig. 2.22). In the Doppler spectrogram, aliasing appears as in ▶ Fig. 2.22. Aliasing in a color Doppler image is shown in ▶ Fig. 2.23. In color Doppler imaging, aliasing and turbulence look quite similar. However, in turbulence, the gradient from positive to negative velocities always passes a region of zero velocity. This means there is always a black line between red and blue colors. In a case of aliasing, no black line is present.

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Fig. 2.25 Ultrasound elastography: applying external pressure.

Fig. 2.24 Flash artifact.

Flash Artifact All movements, including unintended movements, result in a Doppler shift. A characteristic flash artifact occurs in liver echoscopy (▶ Fig. 2.24). When the patient coughs, the organ moves, and this movement shows in a span of color in the color or power Doppler image. In Chapter 17, examples and tips are provided in the section 17.2.2, regarding the application of technical factors in ultrasound.

2.6 Advances in Echoscopic Image Construction Progress in technology has made it possible to improve image quality and has opened up new sources of information within the ultrasound echo. As examples of this progress, compound imaging, harmonic imaging, and elastography are discussed.

2.6.1 Compound Imaging In compound imaging, beam steering is used to produce a set of echoscopic images with a different (lateral) angle for each image. The images are summed into one combined image. The combined image has a better quality because image noise is reduced. Furthermore, curved and irregular structures are better visualized.

2.6.2 Harmonic Imaging The speed of sound is slightly pressure-dependent. The higher the pressure, the higher the speed of sound. Thus, as it propagates through tissue, the ultrasound wave, consisting of areas of higher and lower acoustic pressure, deforms. In parts at higher acoustical pressure, the ultrasound wave moves faster than in parts at lower acoustic pressure. In signal theory, this deformation means that higher harmonics are introduced. The higher harmonics, called tissue harmonics, can be used for ultrasound image construction, which results in images with higher resolution. Because the harmonics are generated inside the tissue and not emitted by the transducer, their propagation path through the tissue is relatively

short. Echoscopic images produced with higher harmonics have better resolution at greater depths than do images made only with the fundamental frequency. Harmonic imaging has its roots in contrast ultrasound. In contrast ultrasound, an (air) bubble within the ultrasound bundle is deformed because of the variable acoustic pressure of the pressure pulse. At low pressure variations, deformation is linear. At high pressure variations, deformation becomes alinear. Alinearity introduces harmonics in the echo of the bubble. The intensity of these harmonics is high in contrast to that of tissue harmonics. Imaging only the high-intensity harmonics in contrast ultrasound enables the visualization of perfusion.

2.6.3 Elastography Ultrasound elastography reveals functional information by monitoring tissue deformation. It is kind of palpation using ultrasound. Information about the stiffness of tissue is obtained.

Axial Deformation By manipulating the transducer (compression), the underlying tissue can be deformed. Areas of low stiffness are deformed more than areas of high stiffness. The degree of deformation reveals information about the stiffness of the tissue. In ▶ Fig. 2.25, an echo transducer is placed on an object containing a soft and a hard area. Repeatedly pushing the transducer causes the object to deform, with relatively more deformation in the soft area. The variations in the echo image during deformation then are represented in an elastographic image of the object. This is a color Doppler-like image that can be colorcoded (soft, medium, hard) and merged into a B-mode image. Thus, the relative stiffness of tissues can be determined.

Lateral Deformation Quantitative measurement of tissue stiffness is possible with so-called shear wave elastography. The ultrasound pulses invoke a shear wave that travels perpendicular to the ultrasound wave, parallel to the surface. The frequency of the shear wave is orders less than the frequency of the ultrasound wave (▶ Fig. 2.26). Through imaging with an extremely high frame rate (100– 200 times faster than in conventional systems), the shear wave is monitored as it travels through the tissue. Thus, the speed of sound in the tissue can be measured. The stiffness of tissue is

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Fig. 2.26 Ultrasound elastography: shear waves.

Fig. 2.27 Safe use of ultrasound.

directly related to the speed of sound. Shear wave elastography depicts tissue stiffness in real time. It is a user-independent method. Shear wave elastography is used in assessing liver fibrosis. Other fields of application are in the evaluation of breast and prostate cancers and in the evaluation of nodules.

2.7 Biological Effects and Safety Diagnostic ultrasound has an outstanding safety record. Significant harmful bioeffects on either patients or operators of diagnostic ultrasound imaging equipment have never been reported. However, high-intensity ultrasound can cause

20

biological effects by thermal and mechanical mechanisms. These effects are used in high-intensity, focused ultrasound for the treatment of tumors. The acoustic energy is absorbed in the tissue and converted into heat and motion. The ability of the tissue to drain thermal energy is characterized by the thermal index (TI). Absorption increases with ultrasound frequency and varies with tissue types. Related to high attenuation, acoustic energy is absorbed much more in bone than in soft tissue. This can cause significant heat deposition at the bone–tissue interface. Mechanically, ultrasound can evoke particle movement. When high energy is applied over a short period, implosion and cavitation can occur. However, the intensities used in echoscopic imaging are limited by the manufacturers and are far below the threshold at which deleterious cavitation effects, such as implosions, might occur. The mechanical index (MI) is an estimation for the induction of cavitation. Taking into account intensity and exposure time, ▶ Fig. 2.27 gives an indication of the safe use of ultrasound. No biological effects have been shown at intensity levels under 100 mW/cm2, shown by the dashed line in ▶ Fig. 2.27. For intensities above 100 mW/cm2, exposure to acoustic energy should be applied prudently, with the principle of as low as reasonably achievable (ALARA) in mind. Food and Drug Administration regulations require TI and MI to be displayed. The TI implemented is that of cranial bone. The display of TI and MI gives the operator feedback about the power dissipation within the patient. Guidelines, such as those composed by the safety group of the British Medical Ultrasound Society, give the operator recommended scan times related to TI and MI settings. If there is a clinical need to exceed these guidelines, the ALARA principle should be followed.

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Chapter 3

3.1 Ultrasound Anatomy of the Neonatal Brain

22

Neonatal Cranial Ultrasonography

3.2 Maturational Changes and Distinction between Physiologic and Pathologic Echogenic Areas in the Neonatal Brain

26

3.3 Timing of Examinations

31

3.4 Measurements

36

3.5 Preterm Infants: Pathology

39

3.6 Term Infants

70

3

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3 Neonatal Cranial Ultrasonography Gerda Meijler,1 Linda de Vries,1 and Handan Güleryüz2 The neonatal skull is easily accessible by ultrasound because of its small size and multiple acoustic windows. In sick or preterm neonates, serial brain imaging is indicated to follow brain development and injuries. As minimal handling is recommended, ultrasonography, which can be performed at the bedside, is the preferred tool to visualize the brain of both preterm and high-risk full-term neonates. For a successful neonatal cranial ultrasound (cUS) examination, the experience of the sonographer and the use of a modern, portable ultrasound machine with appropriate transducers and presets are required. In addition, the examiner should take the necessary precautions to prevent hypothermia, infection, and disturbance of the infant. Besides bedside imaging, there are other major advantages of cUS compared with other imaging modalities, including that it is safe, does not involve ionizing radiation, and is relatively cheap. cUS can reliably diagnose most congenital anomalies, hemorrhagic lesions, calcifications, and many forms of hypoxic–ischemic injury. It is, however, less reliable than magnetic resonance imaging (MRI) for subtle lesions and does not depict myelination. In this chapter, we will discuss ultrasound anatomy of the neonatal brain, how to differentiate normal findings from (subtle) abnormalities, the optimal timing of ultrasound examinations, and the most frequently occurring brain lesions of the preterm infant.

3.1 Ultrasound Anatomy of the Neonatal Brain

presets and well-fitting, appropriate transducers are used. The scan frequency for a standard examination is set at 7.5 to 8 MHz. The examination includes assessing anatomy, maturation, and the presence of abnormalities by: ● Systematically scanning the whole brain in the coronal (from frontal to occipital) and sagittal (from right to left) planes, recording images in at least six standard coronal and five standard sagittal planes. ● Additionally recording images of (suspected) abnormalities in two planes. Examples of the standard coronal planes, showing the anatomical structures in both the very preterm and the full term infant’s brain, are presented in ▶ Fig. 3.1, ▶ Fig. 3.2, ▶ Fig. 3.3, ▶ Fig. 3.4, ▶ Fig. 3.5, ▶ Fig. 3.6, ▶ Fig. 3.7, ▶ Fig. 3.8, ▶ Fig. 3.9. For details on the anatomical structures seen in these planes, we refer to recent literature. Scanning through the anterior fontanel generally allows an accurate assessment of most supratentorial structures. The posterior parts of the brain, the infratentorial structures, and the brainstem are further away from the transducer, especially in larger preterm and full-term neonates. These structures can therefore only be reliably assessed if the supplemental acoustic windows (posterior fontanel, mastoid fontanels, and temporal windows) are additionally used. For detailed descriptions on how to use the supplemental windows for cUS and on the anatomical structures visualized while scanning through these windows, we refer to recent literature.

For a routine ultrasound examination of the neonatal brain, the anterior fontanel is used as the acoustic window. Appropriate

Fig. 3.1a,b First coronal plane through the frontal lobes. a Preterm neonate, GA 26 weeks. b Term neonate.

1Sections 2Section

22

3.1 to 3.5 are contributed by Dr. Gerda Meijler and Dr. Linda de Vries. 3.6 is contributed by Dr. Handan Güleryüz.

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Neonatal Cranial Ultrasonography

Fig. 3.2a,b Second coronal plane through the frontal horns of the lateral ventricles. a Preterm neonate, GA 26 weeks. b Term neonate.

Fig. 3.3a,b Third coronal plane through the third ventricle (arrows). a Preterm neonate, GA 26 weeks. b Term neonate.

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Neonatal Cranial Ultrasonography

Fig. 3.4a,b Fourth coronal plane through the bodies of the lateral ventricles. a Preterm neonate, GA 26 weeks. b Term neonate.

Fig. 3.5a,b Fifth coronal plane through the trigone of the lateral ventricles. a Preterm neonate, GA 26 weeks, scanned at postmenstrual age 29 weeks. b Term neonate.

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Fig. 3.6a,b Sixth coronal plane through the bodies of the lateral ventricles. a Preterm neonate, GA 26 weeks, scanned at postmenstrual age 29 weeks. b Term neonate.

Fig. 3.7a,b Midsagittal plane through corpus callosum, third and fourth ventricles. a Preterm neonate, GA 26 weeks. b Term neonate.

Fig. 3.8a,b Parasagittal plane through lateral ventricle. a Preterm neonate, GA 26 weeks. b Term neonate.

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Neonatal Cranial Ultrasonography

Fig. 3.9a,b Parasagittal plane through insula. a Preterm neonate, GA 30 weeks. b Term neonate.

Fig. 3.10a,b Physiologic frontal echodensities (arrow) in preterm neonate, GA 26 weeks. a Coronal plane. b Parasagittal plane.

3.2 Maturational Changes and Distinction between Physiologic and Pathologic Echogenic Areas in the Neonatal Brain Areas of echogenicity are often seen in the neonatal brain. Some of these are normal and related to maturational changes, whereas others may reflect (serious) injury. The distinction is not always easy.

26

3.2.1 White Matter The immature white matter is characterized by its very high water content, almost complete absence of myelin, and, in cases of very preterm birth, additionally by migrating glial cells. So-called frontal echodensities (subtle, homogeneous, symmetric echogenic zones in the frontal white matter and bilateral echogenic lines around/below the lateral ventricles on anterior coronal cUS scans) are related to this glial cell migration and seen in preterm neonates before term equivalent age (TEA; ▶ Fig. 3.10 and ▶ Fig. 3.11). Frontal echodensities should be

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Neonatal Cranial Ultrasonography

Fig. 3.13 Physiologic “flag-shaped” echogenicity in the parietal white matter (arrow). Full-term neonate, GA 38 weeks. Fig. 3.11 Physiologic echogenic lines (arrow) around the frontal horns of the lateral ventricle in very preterm neonate, GA 26 weeks.

Fig. 3.12a,b Nonphysiologic PVE in a preterm neonate, GA 30 weeks. a Coronal plane showing the frontal, inhomogeneous, asymmetric PVE (arrow). b Right parasagittal plane showing patchy, inhomogeneous PVE in the frontal, parietal, and temporal white matter (arrows).

distinguished from nonphysiologic periventricular echodensities (PVE) that may indicate white matter injury. These are more echogenic, less homogeneous, and less symmetric (▶ Fig. 3.12). “Flag-shaped” echogenicities in the parietal white matter on parasagittal scans, subtle echogenic blushes superolaterally from the lateral ventricles, and linear echogenicities running parallel to the trigone of the lateral ventricles on coronal scans are all

considered physiologic phenomena in both preterm and fullterm neonates (▶ Fig. 3.13, ▶ Fig. 3.14, ▶ Fig. 3.15). These echogenicities are symmetric and homogeneous, and they tend to fade with age. The latter are thought to represent the optic radiation. These normal echogenicities should be distinguished from pathologic PVE in the parietal white matter, which are likely to represent white matter injury (▶ Fig. 3.16).

27

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Neonatal Cranial Ultrasonography

Fig. 3.14a,b Physiologic echogenic blush in the parietal white matter (arrows). Preterm neonate, GA 27 weeks. a Coronal plane. b Parasagittal plane. Also note frontal echodensity (arrowhead), a physiologic finding at this age.

Fig. 3.15a,b Physiologic echodensities parallel to the trigone of the lateral ventricles (arrows) in the coronal plane. a Preterm neonate, GA 26 weeks. b Full-term neonate.

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Neonatal Cranial Ultrasonography

Fig. 3.16a-d Coronal (a) and parasagittal (b) cranial ultrasound images: nonphysiologic echodensities in the parietal white matter (arrows). c T1weighted transverse MRI showing multiple punctate white matter lesions in the frontal white matter (arrowheads), also showing small right-sided GMH. d Diffusion-weighted MRI showing extensive diffusion restriction throughout the parietal and occipital white matter (arrows). Preterm neonate, GA 34 weeks. MRI performed 3 days after birth. (continued)

29

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Neonatal Cranial Ultrasonography

Fig. 3.16e-h (continued) e (coronal) and f (parasagittal) cUS images: 2 weeks later cystic lesions have developed in the parietal white matter, still surrounded by abnormal PVE. g T1-weighted transverse MR image at high ventricular level, showing irregular dilatation of the ventricular system and deep sulci due to severe white matter loss, nearly abutting the ventricular wall, indicating white matter loss (arrows). h T2-weighted transverse MR image at mid-ventricular level, showing the abnormally shaped lateral ventricles and abnormal signal intensity in the frontal white matter (arrow heads). Also note the small right-sided IVH. MRI performed around TEA.

30

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Neonatal Cranial Ultrasonography

Fig. 3.17a,b Physiologic echogenicity of the basal ganglia (arrows) in preterm neonates. a Coronal plane, preterm neonate, GA 26 weeks. b Parasagittal plane, preterm neonate, GA 29 weeks.

3.2.2 Deep Gray Matter The immature deep gray matter has a higher cell and tissue density than the immature white matter and therefore appears relatively echogenic compared with the surrounding white matter on ultrasound scans performed in preterm infants before TEA. Especially the caudate nucleus and globus pallidus may look strikingly echogenic. The echogenicity is symmetric and homogeneous and tends to fade with age (▶ Fig. 3.17). Echogenicity in the deep gray matter should, however, never be considered a normal phenomenon in (near)-term neonates or in preterm neonates beyond TEA. In this age group, it most likely represents hypoxic–ischemic injury, which is associated with serious consequences for outcome. The echogenicity may also be subtle and symmetric and often includes the thalami. A zone of low echogenicity can sometimes be seen between the basal ganglia and thalami, representing the internal capsule. This may cause a so-called onion peel appearance, whereby the echogenic basal ganglia and thalami are seen as separate echogenic structures and are interspersed by the low echogenicity of the internal capsule (▶ Fig. 3.18). Other echodensities in the deep gray matter, resulting from infarction or hemorrhage, are more echogenic, asymmetric, focal, and easily distinguishable from physiologic echodensities (▶ Fig. 3.19). Lenticulostriate vasculopathy is characterized by linear or punctate hyperechoic areas in the basal ganglia and thalami. It is probably caused by a benign vasculitis of the lenticulostriate vessels and suggestive of mineralization of the arterial wall. It is seen in healthy preterm neonates, but also in association with various abnormal conditions such as central nervous system infections, metabolic disorders, and chromosomal abnormalities. It can easily be distinguished from the aforementioned physiologic deep gray matter echogenicity in preterm infants as it is linear or punctate and follows a typical vascular pattern (▶ Fig. 3.20).

Tips from the Pro In summary, white matter echogenicities are likely to be physiologic if they have the following characteristics: ● The echogenicity does not exceed that of the choroid plexus; ● The echogenicity is homogeneous and symmetric; ● The echogenicity fades with age.

Echogenicity in the deep gray matter is likely physiologic if it is seen in the preterm period, fades with age, and does not persist beyond TEA. It is subtle, homogeneous, and symmetric. The internal capsule should not be visible as a separate entity.

3.3 Timing of Examinations The optimal timing and frequency of examinations is of great importance. In the preterm infant, cUS performed on the first day of life will first of all diagnose an antenatally or perinatally acquired lesion (see ▶ Fig. 3.16; ▶ Fig. 3.21 and ▶ Fig. 3.22) or congenital anomaly (▶ Fig. 3.23). Secondly, it enables the detection of (new) lesions within hours or days after the onset. Most of these lesions are clinically silent. Once the diagnosis is made, the evolution of the lesion over time should be assessed. In infants with germinal matrix–intraventricular hemorrhage (GMH-IVH), this enables timely recognition of post-hemorrhagic ventricular dilatation (PHVD), a potentially serious condition that may need intervention. Another serious complication of GMH-IVH is periventricular hemorrhagic infarction (PVHI). This lesion and its evolution can be diagnosed and followed if serial cUS scans are performed on a regular basis. In preterm infants with nonphysiologic PVE, sequential imaging will show whether the echogenicity will resolve without cystic evolution or whether cystic changes occur. Small cystic lesions develop only 3 to 6 weeks after the abnormal echogenicity is

31

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Neonatal Cranial Ultrasonography

Fig. 3.18a–d Abnormal echogenicity in the basal ganglia (arrow) and thalami (open arrow) in two full-term neonates with hypoxic-ischemic deep gray matter injury following acute perinatal asphyxia. (a, c) Coronal planes. (b, d) Parasagittal planes, also showing a zone of low echogenicity representing the internal capsule (arrowheads).

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Neonatal Cranial Ultrasonography

Fig. 3.19a,b Focal echogenic lesion in the left thalamic area (arrows) representing infarction. Near-term neonate, GA 36 weeks. a Coronal plane. b Parasagittal plane.

Fig. 3.20a,b Lenticulostriate vasculopathy (arrowheads) in a near-term neonate with viral meningoencephalitis. a Coronal plane. b Parasagittal plane.

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Neonatal Cranial Ultrasonography

Fig. 3.21a–d Preterm neonate, GA 30 weeks, 5 days. Large left-sided subdural hemorrhage. a, b Coronal, resp. parasagittal cUS showing the large extra-axial hemorrhage in the temporal region. Also showing increased echogenicity in the temporal lobe (arrows) and compression of the left lateral ventricle. c, d Coronal, resp. transverse T2-weighted MRI showing, besides the extra-axial hemorrhage, abnormal signal intensity in the left temporal lobe adjacent to the extra-axial hemorrhage (open arrows) due to multiple small hemorrhages and tissue compression. The remainder of the brain parenchyma has a normal aspect for this age. MRI performed on day 6 after birth.

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Neonatal Cranial Ultrasonography

Fig. 3.22a–d Full-term neonate, traumatic delivery. a, b Coronal, resp. parasagittal cUS images showing increased echogenicity in the frontoparietal white matter (arrows) consistent with swelling or ischemia. Also showing increased echogenicity in the basal ganglia and thalami (open arrows), again related to edema or ischemia. Furthermore, there is a small hemorrhage in the thalamocaudate notch (arrowhead). c, d Coronal, resp. transverse (supraventricular level) T2-weighted MRI showing a left parietal epidural hematoma with some mass effect upon the adjacent frontal and parietal lobe. Areas of abnormal signal intensity in the white matter (open arrowheads). MR imaging performed 1 month after birth. The epidural hemorrhage was missed with cUS because of its high and peripheral location, being outside the scope of cUS.

35

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Neonatal Cranial Ultrasonography

Fig. 3.23a,b Preterm neonate, GA 34 weeks. a Midsagittal cUS showing retrocerebellar fluid collection (arrow). The cerebellar vermis and other midline structures have a normal appearance. b Midsagittal T2-weighted MRI confirming a retrocerebellar cerebrospinal fluid collection without mass and with a normally developed cerebellar vermis, probably representing a small arachnoid cyst.

first seen and tend to resolve within several weeks. They may thus not be visible around TEA. In most infants, some degree of ventriculomegaly, resulting from white matter loss, will then be recognized. Not only cystic periventricular leukomalacia (PVL) but also nonphysiologic PVE of longer duration without cystic evolution (noncystic PVL) is associated with suboptimal neurodevelopmental outcome. Therefore, it is important to know the total duration of abnormal echogenicity. Although GMH-IVH generally develops within the first few days after birth and is thus diagnosed on cUS scans performed during the first week of life, white matter injury may develop at any time during the neonatal period. Late-onset cystic PVL may occur following sepsis, viral infections, necrotizing enterocolitis, surgery, or recurrent apneic spells (▶ Fig. 3.24). It is therefore important to perform serial cUS scans from the day of birth until TEA and to increase the number and intensity of cUS examinations following any acute deterioration (▶ Table 3.1).

In the preterm neonate, serial cUS scans from birth until TEA are needed to detect and follow brain injury. ▶ Table 3.1 shows an example of a scan protocol used in our hospitals. The frequency of cUS examinations should be increased when injury is seen and following any clinical deterioration or recurrent apneic spells. For other useful scan protocols, we refer to recent literature.

Table 3.1 Cranial ultrasound scan protocol for preterm infants

3.4 Measurements

GA at birth (weeks) Postnatal age

23–26

27–32

33–37

3.4.1 Ventricular Measurements

Day 3a

In preterm neonates with progressive ventricular dilatation, mostly due to PHVD, it is recommended to perform serial measurements of the ventricular system. The decision to treat ventricular dilatation depends largely on these measurements. In order to prevent any further increase in ventricular size and raised intracranial pressure and thereby white matter injury, treatment of PHVD should be considered when ventricular dilatation is rapidly progressive. In this paragraph, we will demonstrate how ventricular measurements are performed and will refer to reference values. The most frequently used measurement of the lateral ventricles is the so-called ventricular index (VI), introduced by Levene in 1981. It is defined as the distance between the falx and the lateral wall of the anterior

Days 1, 2, 3,a 7a

Days 1, 3,a 7a

2 weeks

2 weeks

Weekly to PMA 31 weeks

Weekly to PMA 31 weeks

Alternating weeks to PMA 35 weeks

At PMA 32 weeks or before discharge

TEA

TEA

Before discharge

Abbreviations: GA, gestational age; PMA, postmenstrual age; TEA, term equivalent age. Note: aInclude scanning through posterior fontanel and mastoid fontanel.

36

A cUS examination around TEA is recommended in every very preterm neonate (GA < 32 weeks). It enables the detection/ evaluation of the following: 1. Late-onset cystic PVL; 2. Focal infarction; 3. The later stages of cystic PVL and PVHI; 4. Ventriculomegaly resulting from white matter loss in infants with diffuse, noncystic white matter injury; 5. Ventricular dilatation and white matter injury due to PHVD. 6. In the preterm neonate, serial cUS scans from birth until TEA are needed to detect and follow brain injury.

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Neonatal Cranial Ultrasonography

Fig. 3.24a–d Preterm neonate, GA 34 weeks. a, b Coronal, resp. parasagittal cUS images on the first day of life showing PVE in the frontal and parietal white matter, physiologic at this age. c, d Coronal, resp. parasagittal cUS images performed 1 month later, after the child had developed necrotizing enterocolitis. Now showing cystic lesions in the parietal white matter. In addition, there is mild dilatation of the lateral ventricle and echogenic ventricular lining (arrow), the first related to white matter loss, the latter to a small IVH.

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Neonatal Cranial Ultrasonography

Fig. 3.25 Coronal cUS image at the level of the third ventricle in a preterm neonate with PHVD. The VI is measured on both sides.

Fig. 3.26 Coronal cUS image at the level of the third ventricle in the same preterm neonate with PHVD. The AHW is measured on both sides.

the lateral ventricles, but a change in ventricular shape with rounding of the frontal horns, so-called ballooning. This phenomenon results in an increase of the width of the anterior horns. The anterior horn width (AHW) is defined as the diagonal width of the anterior horn of the lateral ventricle, measured at its widest point in the coronal plane (▶ Fig. 3.26). The AHW remains constant with age. In the majority of neonates, the AHW is less than 3 mm. Values above 6 mm are associated with ballooning, and intervention should be considered. In extremely preterm infants, dilatation of the occipital horns often occurs before an increase in frontal horn size. The occipital horns are usually more dilated than the frontal horns and may even be the only site of ventricular dilatation. The thalamo-occipital distance (TOD) is defined as the distance between the outermost point of the thalamus at its junction with the choroid plexus and the outermost part of the occipital horn. It is measured in the parasagittal plane (▶ Fig. 3.27). The TOD remains rather constant with age. The VI graph of Levene has an age range between 27 and 40 weeks. New reference values for the VI, AHW, and TOD were recently published by Brouwer et al, with an age range between 24 and 42 weeks. A summary is presented in ▶ Table 3.2. Fig. 3.27 Parasagittal cUS image through the left lateral ventricle in the same preterm neonate with PHVD. The TOD is measured. Note the blood clot continuous with the choroid plexus.

horns in the coronal plane. The VI is measured in the third coronal plane (at the level of the interventricular foramina of Monro) at the largest width of both lateral ventricles (▶ Fig. 3.25). The VI increases with age. Values above the 97th percentile indicate ventricular dilatation. The first sign of an increase in intracranial pressure is, however, not dilatation of

38

3.4.2 Measurements of Cerebral Structures Preterm infants have lower volumes of supratentorial white and gray matter on MRI performed at TEA compared with fullterm infants. The corpus callosum (CC) is thinner and the cerebellar volume reduced. The CC is the main white matter commissure connecting the cerebral hemispheres. It is essential for cognitive development and function. In a normal fetus, the CC grows rapidly, with an almost linear increase in length between 20 and 40 weeks of gestation, while the height remains rather constant during the

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Neonatal Cranial Ultrasonography Table 3.2 Cross-sectional reference values (i.e., estimated means + 95% reference intervals, in millimeters) for the ventricular index (VI), anterior horn width (AHW), and thalamo-occipital distance (TOD) of 625 neonates from 24 to 42 weeks’ gestational age (GA) (P, percentile; n = 625) (Brouwer et al, see reference) GA (weeks)

VI (mm)

AHW (mm)

TOD (mm)

P 2.5

Estimated mean

P 97.5

P 2.5

Estimated mean

P 97.5

P 2.5

Estimated mean

P 97.5

24 + 0

6.8

8.0

9.4

1.1

1.5

2.8

11.2

14.5

18.7

25 + 0

7.0

8.3

9.7

1.1

1.5

2.8

11.4

14.7

19.0

26 + 0

7.2

8.5

10.1

1.1

1.5

2.8

11.6

15.0

19.3

27 + 0

7.4

8.8

10.3

1.1

1.5

2.8

11.8

15.2

19.6

28 + 0

7.6

9.0

10.6

1.1

1.5

2.8

11.9

15.4

19.8

29 + 0

7.8

9.3

10.9

1.1

1.5

2.8

12.0

15.5

20.0

30 + 0

8.0

9.5

11.2

1.1

1.5

2.8

12.1

15.6

20.2

31 + 0

8.2

9.7

11.5

1.1

1.5

2.8

12.2

15.8

20.3

32 + 0

8.4

10.0

11.8

1.1

1.5

2.8

12.3

15.9

20.5

33 + 0

8.6

10.2

12.0

1.1

1.5

2.8

12.3

15.9

20.5

34 + 0

8.8

10.4

12.3

1.1

1.5

2.8

12.4

16.0

20.6

35 + 0

9.0

10.6

12.5

1.1

1.5

2.8

12.4

16.0

20.6

36 + 0

9.2

10.8

12.8

1.1

1.5

2.8

12.4

16.0

20.6

37 + 0

9.4

11.1

13.1

1.1

1.5

2.8

12.4

16.0

20.6

38 + 0

9.5

11.3

13.3

1.1

1.5

2.8

12.3

15.9

20.6

39 + 0

9.7

11.5

13.5

1.1

1.5

2.8

12.3

15.9

20.5

40 + 0

9.9

11.7

13.8

1.1

1.5

2.8

12.2

15.8

20.4

41 + 0

10.0

11.9

14.0

1.1

1.5

2.8

12.1

15.7

20.2

42 + 0

10.2

12.0

14.2

1.1

1.5

2.8

12.0

15.5

20.0

same period. The cerebellum has important connections with supratentorial brain structures and the spinal cord. It plays an important role not only in motor control but also in language processing, auditory and visual memory, cognition, and social development and behavior. During the fetal period, growth and development of the cerebellum are rapid and critical. In the human fetus, the CC and cerebellum are markers for brain development. This is related to the rapid growth of both structures and the fact that they are easily visualized by ultrasonography. There can be partial or complete agenesis of the CC. This may be an isolated finding but is also seen in association with other (more serious) central nervous system abnormalities and syndromes. The cerebellar vermis is abnormal in the fetus with a Dandy– Walker malformation or variant and, again, in association with other central nervous system malformations and syndromes. The transverse cerebellar diameter (TCD) serves as a predictor of gestational age in the fetus. It is also used to assess cerebellar growth and to diagnose cerebellar hypoplasia when the gestational age is known. In preterm infants, abnormal growth of the CC is associated with delayed cognitive and motor development. Injury to the cerebellum, a frequent complication in very preterm neonates, may severely disrupt its normal growth and development and is associated with abnormal motor and cognitive outcome and behavioral problems. Measurement of cerebral structures in the brain of the preterm neonate can be of clinical importance to diagnose and quantify brain abnormalities and altered development. The length and height of the CC and the width (maximum anterior–posterior diameter) and height of the vermis are

measured in the midsagittal plane during scanning through the anterior fontanel (▶ Fig. 3.28). The TCD (widest diameter of the cerebellum) is measured in the coronal plane through the fourth ventricle, with the mastoid fontanel used as an acoustic window (▶ Fig. 3.29).

3.5 Preterm Infants: Pathology 3.5.1 Germinal Matrix–Intraventricular Hemorrhage GMH-IVH remains a common neurologic complication of preterm birth, occurring in about 10 to 20% of preterm infants with a GA below 30 weeks. A large IVH and especially a hemorrhage with PVHI are often associated with an adverse neurologic outcome. The risk to develop PHVD increases when GMH-IVH is more severe. About 30 to 50% of infants with a large GMH-IVH will develop PHVD, and around 20 to 40% of infants with a severe GMH-IVH will consequently need a permanent ventriculoperitoneal shunt. The presence of associated white matter injury due to a unilateral PVHI or the presence of more diffuse, bilateral white matter damage as well as the development of PHVD further increases the risk for an adverse neurodevelopmental outcome. The classification system suggested by Volpe is suitable to describe early and late ultrasound appearances (▶ Table 3.3). It is better to avoid the use of grade 4 and instead provide a separate description of the size, site, and appearance of a parenchymal lesion. Making a distinction between a small hemorrhage

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Fig. 3.28 Midsagittal cUS, preterm neonate, GA 32 weeks. The vermis height (D1) and width (D2) and callosal length (D3) are measured. Fig. 3.29 Coronal cUS, with the mastoid fontanel used as an acoustic window. Preterm neonate, GA 27 weeks; postmenstrual age at scanning, 36 weeks. The TCD is measured.

Table 3.3 Grading of germinal matrix–intraventricular hemorrhage Description

Generic term

Grade 1: GMH

GMH-IVH

Grade 2: GMH and small IVH without ventricular dilatation

GMH-IVH

Grade 3: GMH and large IVH with ventricular dilatation (clot fills > 50% of ventricle)

GMH-IVH and ventriculomegaly

restricted to the germinal matrix or a GMH with some blood ruptured through the ependyma into the ventricular lumen is not always possible. The use of the posterior fontanel as an alternative acoustic window has been advocated, showing improvement in the diagnosis of a small GMH-IVH (▶ Fig. 3.30). Using the posterior fontanel is also helpful for looking at the degree of dilatation/ballooning of the occipital horn in infants with PHVD (▶ Fig. 3.31). A GMH at a site other than the head of the caudate nucleus, like the roof of the temporal horn, often remains undiagnosed and will be diagnosed only when MR imaging is also performed. A large GMH-IVH, grade 3, is diagnosed based on presence of a large clot in the ventricle, filling the ventricle more than 50%, as well as acute dilatation of the ventricle involved. A grade 3 IVH may lead to PHVD over a period of 1 to 3 weeks. The diagnosis of a grade 3 IVH cannot be made on a single examination performed during the second or third week, when ventricular dilatation is not acute but has occurred because of PHVD (▶ Fig. 3.32). The maximal extent of the hemorrhage may take a few days. Many centers therefore perform a first scan at the end of the first week. The evolution of a small GMH-IVH to a large hemorrhage would then be missed (▶ Fig. 3.33). Blood can sometimes be seen in the cavum septum pellucidum. This is not an isolated finding but tends to occur in

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combination with a GMH-IVH (▶ Fig. 3.34). Blood can also extend into the corpus callosum as a consequence of involvement of the septal vein (Dudink et al; ▶ Fig. 3.35). A PVHI is usually unilateral, either globular in shape and communicating with the ventricle containing a moderate to large ipsilateral GMH-IVH, or triangular in shape, with the apex at the outer border of the lateral ventricle and not or partly communicating with the ipsilateral ventricle (▶ Fig. 3.36). In the past, PVHI was considered to be due to direct extension of the hemorrhage into the periventricular white matter, but this is no longer considered to be the most likely explanation for this type of parenchymal lesion. Most would now agree that this type of lesion is due to the presence of a GMH-IVH, which can lead to impaired venous drainage and subsequent venous infarction of the medullary veins of the white matter. This sequence of events can sometimes be followed with sequential ultrasound examinations, with change from a normal image to a stage of simple GMH-IVH and PVHI on the following day (▶ Fig. 3.37). Whereas the globular type of PVHI tends to evolve into a porencephalic cyst (▶ Fig. 3.38, ▶ Fig. 3.39, ▶ Fig. 3.40), the triangular type of lesion is more likely to evolve into multiple cysts, which are partly or even not at all communicating with the lateral ventricle and are therefore sometimes wrongly diagnosed as cystic PVL (▶ Fig. 3.41). This is especially likely to happen when sequential scans are not available and the initial GMH-IVH has been missed. A PVHI may also resolve with cystic evolution, with eventual ex vacuo dilatation on the affected side (▶ Fig. 3.42). The PVHI is most often seen in the parietal lobe but can also develop in the frontal or temporal lobe, depending on the veins involved (see ▶ Fig. 3.42; ▶ Fig. 3.43). The site of the lesion in relation to the area of the trigone of the lateral ventricle is important for outcome prediction. If the lesion is anterior to the trigone (frontal or temporal lobe), the development of a

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Fig. 3.30a,b a Preterm infant, GA 26 weeks. The coronal view, angling backwards, shows a small clot in the left ventricle (arrowhead). b The image taken through the posterior fontanel confirms the presence of an IVH (arrowhead).

Fig. 3.31a,b Parasagittal views of another infant, taken through the posterior fontanel, showing dilatation of the right occipital horn, posterior to the calcarine fissure (arrowhead, a). A large clot is seen in the left occipital horn (b). Enlargement of the occipital horns is present bilaterally.

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Fig. 3.32a,b Preterm infant, GA 26 weeks. A large GMH-IVH is present on the left. While there is a clot filling more than 50% of the ventricle, there is also PHVD. The TOD is measured in the parasagittal view. The white matter does not appear to be involved.

Fig. 3.33a,b Preterm infant, GA 26 weeks. A bilateral GMH-IVH is seen on the day of birth. On day 3, a large GMH-IVH is now present on the left, with acute dilatation of the left ventricle. Also note the pressure effect on the cavum septum pellucidum (arrow).

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Fig. 3.34a–c Preterm infant, GA 33 weeks. A GMH-IVH is seen on the left, associated with blood in the cavum septum pellucidum, seen in (a) coronal and (b) parasagittal views. Following punctures from a reservoir, the PHVD stabilized and the ventricular size normalized (c).

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Fig. 3.35a–c Two preterm infants (a, c) with blood within the corpus callosum (arrows), the first one with an early MRI correlate (b). This is most likely due to involvement of the septal vein.

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Fig. 3.36a,b Two preterm infants with a PVHI. a A globular lesion, where there appears to be continuity between the ventricle and PVHI. A porencephalic cyst would be expected to evolve. b A GMH-IVH on the left, with a triangular PVHI. There appears to be no continuity between the ventricle and PVHI, and cystic lesions are expected to develop in the white matter.

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Fig. 3.37a–d Preterm infant, GA 27 weeks. Perinatal asphyxia and pneumothorax between days 4 and 5. Normal scan on day 1 (a), small bilateral IVH on day 4 (b), evolving into a large grade 3 IVH on the right on day 5 with a right-sided PVHI (c). Porencephalic cyst on the affected side at TEA (d).

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Fig. 3.38a–d Preterm infant, GA 30 weeks, showing a large PVHI communicating with the ventricle. There is a large resolving clot in the ventricle seen on the coronal (a) and parasagittal (b) views. At TEA, a porencephalic cyst is present (c, d). Also note the atrophy of the affected hemisphere, best seen on the coronal view.

Fig. 3.39a,b Same patient as in ▶ Fig. 3.38. MRI, performed at 2 weeks of age (a, T2SE) and at TEA (b, T1). There is good agreement with the ultrasound scans, but more detail is seen on the early T2SE, and asymmetry of myelination of the internal capsule (arrow) is seen at TEA b.

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Fig. 3.40a–d Preterm infant, GA 25 weeks. a Coronal image obtained on day 3 shows a PVHI. b Ten days later, the hemorrhage is resolving, and this is associated with mild PVHD. At TEA, a small porencephalic cyst is seen (c, d), which is smaller than expected based on the initial images.

Fig. 3.41a,b Girl, GA 30 weeks. A large, triangular PVHI is seen on the right with a large ipsilateral IVH (a). At TEA, a single large cyst is seen (b), which has remained separate from the lateral ventricle.

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Fig. 3.42a–c Preterm infant, GA 34 weeks. A discrete triangular lesion (arrow) is seen lateral to the IVH (a), virtually unchanged after 1 week (arrow, b). No cystic evolution was seen, just ex vacuo dilatation, seen at TEA (c).

unilateral spastic cerebral palsy is unlikely (see ▶ Fig. 3.42 and ▶ Fig. 3.43). The location is more important than the size of the lesion for outcome prediction. The scoring system of Bassan et al uses size, midline shift, and the presence of bilateral involvement as predictors of outcome. It is sometimes possible to see wallerian degeneration when a scan is performed through the temporal bone in a child at term or near-term age (▶ Fig. 3.44). MR imaging at TEA is highly recommended to look for asymmetry of myelination of the posterior limb of the internal capsule (PLIC), as well as atrophy of the affected cerebral peduncle (▶ Fig. 3.45). Both abnormalities (abnormal myelination of the internal capsule and wallerian degeneration) are highly predictive of abnormal motor outcome. GMH-IVH can be associated with a cerebellar hemorrhage (CBH). This is probably explained by the comparable etiology of the two lesions; GMH-IVH originates from the germinal matrix in the supratentorial ventricular wall, whereas CBH originates from the germinal matrix in the fourth ventricle and/or the

extensive granular layer covering the cerebellar surface. CBH can also occur following extension of supratentorial IVH into the fourth ventricle and cerebellum. CBH affects the smallest and sickest preterm neonates, and large CBHs are associated with adverse neurodevelopmental outcome. This is probably related to the fact that a large CBH may permanently disrupt further development of the cerebellum, which undergoes critical and rapid growth and development during the late fetal period and, in case of preterm birth, the preterm period. Recent studies have shown that when the mastoid fontanel is used as an additional acoustic window, most large (> 4 mm) CBHs and clots in the fourth ventricle will be visualized (▶ Fig. 3.46, ▶ Fig. 3.47, ▶ Fig. 3.48, ▶ Fig. 3.49, ▶ Fig. 3.50). The small and punctate CBHs (▶ Fig. 3.51) will still be missed, but these are not related to an abnormal outcome, at least during the preschool period. Many centers have now included the mastoid fontanel approach to their routine cUS examinations (see ▶ Fig. 3.4). CBHs generally develop within the first few days

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Fig. 3.43a–d Two preterm infants. Coronal (a) and parasagittal (b) views of a PVHI in the frontal lobe of the first infant. Acute (c) and late (d) parasagittal views of a PVHI in the temporal lobe of the second infant.

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Fig. 3.44a–c Preterm infant, GA 25 weeks. Cranial ultrasound performed at 10 weeks. Large, left-sided periventricular hemorrhagic infarction with resolving clot and formation of a porencephalic cyst on coronal (a) and parasagittal (b) views. The scan taken through the right temporal bone shows atrophy of the left cerebral peduncle (arrow, c).

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Neonatal Cranial Ultrasonography after birth, around the onset of GMH-IVH. We recommend the addition of mastoid fontanel imaging to the routine anterior fontanel cUS procedure at least once in the first week of life and at least twice (with an interval of 4 to 7 days) in preterm neonates with a GMH-IVH.

Tip from the Pro Use imaging through the mastoid fontanel at least once in the first week of life and at least twice in preterm neonates with a GMH-IVH.

We also recommend scanning through the mastoid fontanel when dilatation of the ventricular system occurs that is insufficiently explained by a supratentorial hemorrhage (no or only small GMH-IVH), as in some infants this ventricular dilatation is due to an isolated hemorrhage in the cerebellum and/or the fourth ventricle.

3.5.2 Post-hemorrhagic Ventricular Dilatation

Fig. 3.45 T1-weighted MRI of the same child, performed at TEA, mild motion artifact, showing the porencephalic cyst and lack of myelination of the left PLIC.

There is a significant risk of PHVD, especially following development of a grade 3 hemorrhage. As PHVD tends to develop between 7 and 14 days after the onset of the hemorrhage, sequential imaging should be performed comparing measurements with the graphs mentioned above (see ▶ Fig. 3.5). An echogenic lining of the ventricular wall can also be seen around this time and can help to confirm the presence of an IVH (▶ Fig. 3.52 and ▶ Fig. 3.53). The third ventricle, which can normally barely be seen on a coronal view, is now also visible, and the massa intermedia will be seen on a parasagittal view (▶ Fig. 3.54). There is a lot of discussion about the optimal

Fig. 3.46a,b Preterm infant, GA 25 weeks. Cranial ultrasound performed on the first day of life. a Coronal view (anterior fontanel). b Axial view (mastoid fontanel). There is a small bilateral IVH (a); the cerebellum is normal (a and b).

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Fig. 3.47a–c Same preterm infant as in ▶ Fig. 3.46. cUS performed 1 day later. a, b Coronal, resp. parasagittal views (anterior fontanel). c Coronal view (left mastoid fontanel). Small bilateral IVH are seen in (a) and (b). In addition, there is an echogenic lesion in the cerebellar vermis and left hemisphere, suspect for hemorrhage (arrow). The mastoid fontanel view confirms a large hemorrhage in the cerebellar vermis and left hemisphere (arrow) and also shows a smaller hemorrhage in the right cerebellar hemisphere.

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Fig. 3.48a–c Same preterm infant as in ▶ Fig. 3.46 and ▶ Fig. 3.47. cUS performed 5 weeks later. a, b Coronal, resp. parasagittal views (anterior fontanel). c Axial view (right mastoid fontanel). In (a) and (b), the normal architecture of the cerebellum is lacking. The disruption of the normal cerebellar growth and development is also clearly shown in (c). Compare with ▶ Fig. 3.49, showing a normally developed cerebellum in a very preterm neonate, scanned before discharge.

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Fig. 3.49a–d Preterm neonate, GA 28 weeks. cUS performed at postmenstrual age 36 weeks. a–c Coronal, midsagittal, and parasagittal views (anterior fontanel). d Axial view (left mastoid fontanel). Normal architecture and development of the cerebellum are shown on all images.

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Fig. 3.50a–e Preterm neonate, GA 31 weeks. a, b Coronal, resp. parasagittal views (anterior fontanel) show small bilateral IVH (a). No abnormalities are seen in the posterior fossa. c, d Coronal, resp. axial views (left mastoid fontanel) showing a small echogenic lesion (arrows), suggestive of a CBH at the convexity of the right cerebellar hemisphere. This is an example of the smallest CBH that can be detected by cranial ultrasound when the mastoid fontanel is used as acoustic window. e T2weighted transverse MRI, performed around TEA in the same infant, confirming the CBH.

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Fig. 3.51a,b T2-weighted transverse MRI of two preterm neonates scanned around a A punctate CBH is seen in the left cerebellar hemisphere (arrow). b Multiple punctate CBHs in both cerebellar hemispheres. These punctate hemorrhages are undetectable with cUS but do not cause destruction of the cerebellar parenchyma and are associated with a favorable short-term outcome.

Fig. 3.52a,b Preterm infant delivered by cesarean section because of progressive ventricular dilatation following an antenatal hemorrhage. a A large resolving clot is seen in the right ventricle and the third ventricle. Also note the enlarged temporal horn and the echogenic ventricular lining. b The blood cast is especially clear on the sagittal image.

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Fig. 3.53a,b MRI (T2-weighted transverse images), performed the day the child was born, confirmed the cUS findings and additionally showed blood in the dilated fourth ventricle (arrow) with reduced cerebellar volume and vermian hypoplasia, most likely due to hemorrhage in and around the fourth ventricle. Reduced cortical folding posteriorly and increased signal intensity in the occipital white matter are also additional findings compared with the ultrasound images.

Fig. 3.54a,b Preterm infant, GA 34 weeks. First cranial ultrasound was performed at the onset of clinical symptoms, including sunsetting and splaying of the sutures. Severe PVHD resulting from old IVH.

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Fig. 3.55a–c Preterm infant, GA 26 weeks, developed PVHD following a IVH grade 3. Large clots are seen in the ventricles, the right more than the left. a Coronal view, also showing dilated third ventricle. b Parasagittal view before punctures from a reservoir. Stabilization occurred following punctures from the reservoir with normalization of ventricular size (c).

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Fig. 3.56a-d Preterm neonate, GA 36 weeks. Antenatal hydrocephalus due to IVH. a, b Extensive strands and debris, seen in both ventricles 3 days following insertion of a ventriculoperitoneal shunt, due to an infection with a Gram-negative organism. c, d Six weeks later, there is marked discrepancy between the two ventricles due to occlusion of the left foramen of Monro. The tubing of the reservoir is located in the right ventricle. The septum pellucidum was fenestrated to reestablish communication.

timing of intervention and how best to intervene. An example of early intervention, with lumbar punctures followed by punctures from a reservoir and subsequent stabilization, is shown in ▶ Fig. 3.55. Complications may occur following the insertion of a reservoir or shunt. The shunt is not always in the right position or may be inserted too far into the brain, or the device may become infected (▶ Fig. 3.56).

3.5.3 White Matter Injury Changes within the white matter are variable and more difficult to diagnose than GMH-IVH. Many start to call changes in the white matter abnormal when they are as echogenic as or more echogenic than the choroid plexus. Although this is usually helpful, cystic changes in the white matter sometimes occur

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Table 3.4 Grading of periventricular echogenicity Description

Generic term

PVE persisting for > 7 days

Grade 1A

Inhomogeneous or “patchy” periventricular echogenicity persisting for > 7 days

Grade 1B

PVE evolving into small, localized, frontoparietal cystic lesions

Grade 2

PVE evolving into extensive periventricular cystic lesions

Grade 3

PVE extending into the deep white matter, evolving into extensive subcortical cysts

Grade 4/MCE

Abbreviations: MCE, multicystic encephalomalacia; PVE, transient periventricular echogenicities.

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Fig. 3.57a–d Preterm infant, GA 31 weeks. cUS (a) and MRI (b) on day 10 showing inhomogeneous echogenicity in the white matter and punctate lesions of increased signal intensity on T1-weighted image. (c) A second cUS TEA shows more linear punctate echogenicity and good correlation with MRI at TEA. (d) T1-weighted image.

following echogenicity in the white matter that does not meet these criteria. Inhomogeneous or so-called patchy changes in the white matter are more often indicative of pathology, and abnormal echogenicity that persists for more than a week should also be followed carefully (▶ Table 3.4). Inhomogeneous echogenicity may suggest the presence of punctate white matter lesions on MR imaging (▶ Fig. 3.57) and can be seen early as well as around TEA. It has now been shown repeatedly that sequential cUS during the neonatal period detects severely abnormal white matter in very preterm infants but is less reliable for mildly or moderately abnormal white matter. MR imaging around TEA is needed to reliably detect white matter

injury in very preterm infants. Once periventricular echogenicity has been diagnosed, ultrasound examinations should be repeated on a weekly basis for at least 4 weeks, at discharge, and preferably also at TEA (see ▶ Table 3.1). The evolution from abnormal echogenicity into cystic lesions varies from 10 to 14 days for those with extensive cysts (grade 3) to 4 to 5 weeks for those with focal cystic lesions (grade 2; ▶ Fig. 3.58, ▶ Fig. 3.59, ▶ Fig. 3.60). The cysts vary in diameter from a few millimeters to over a centimeter and usually do not communicate with the ventricles. Injury to the white matter may occur following a late-onset sepsis, necrotizing enterocolitis, or a viral illness, such as with rotavirus or

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Fig. 3.58a,b Preterm infant, GA 24 weeks. Late-onset PVL following necrotizing enterocolitis. a Cysts were first seen when the infant was 6 weeks old. b The cysts were confirmed with MRI, T1-weighted sequence.

Fig. 3.59a–c Preterm infant, GA 29 weeks. Perinatal asphyxia and hypocarbia. Coronal cUS images on day 1 (a) and day 14 (b), and at term equivalent age TEA (c). The initial cUS did not show abnormal echogenicity. Cysts were first seen on day 14, more marked on the right. At TEA, cysts were seen mainly on the right side.

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Fig. 3.60a–d Same infant as in ▶ Fig. 3.59. (a, b) The parasagittal views at TEA show extensive cysts throughout the periventricular white matter on the right, also seen on the T2-weighted MR parasagittal image (d). The left ventricle already shows ex vacuo dilatation (c).

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Fig. 3.61a–d Preterm infant, GA 34 weeks, who developed a rotavirus infection. a Bilateral PVE and bilateral GMH were seen following the illness. b, c Extensive cystic evolution occurred 2 weeks later. The cysts were most extensive in the frontal lobes, also on the TEA MRI, which did not show any myelination of the internal capsule (d).

enterovirus, and is then referred to as late-onset PVL (see ▶ Fig. 3.58; ▶ Fig. 3.61). The large and extensive cysts remain visible for several weeks but tend to become smaller and are usually no longer visible on ultrasound examination once the infant is 2 to 3 months old. The localized and smaller cysts are visible for only a few weeks and are no longer visible at TEA in about half of the cases, but by then, ex vacuo dilatation may be seen instead, and the shape of the lateral ventricle may be irregular (▶ Fig. 3.62). One should take care to make a distinction between cysts within the PVL spectrum and subependymal pseudocysts, also referred to as connatal cysts, which are located at or just below the superolateral angles of the frontal horns or bodies of the lateral ventricles and are mainly anterior to the foramina of Monro (▶ Fig. 3.63). Cysts within the cystic PVL spectrum should be considered when they are above this angle. Subependymal pseudocysts as an isolated finding tend to be associated with a good outcome, but they may also be a marker of an underlying problem, such as a congenital infection, metabolic disorder, or chromosomal abnormality.

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Multicystic encephalomalacia (MCE), sometimes referred to as subcortical leukomalacia, is rare and may be due to a variety of underlying problems. An example is shown of a survivor of a twin-to-twin transfusion syndrome (▶ Fig. 3.64), but MCE can also be seen in metabolic disorders—for example, molybdenum cofactor deficiency.

3.5.4 Focal Infarction Perinatal arterial ischemic stroke (PAIS) is usually reported in full-term infants but can also be diagnosed with cUS in preterm infants. As in full-term infants, the middle cerebral artery is most commonly involved, but in contrast to what occurs in fullterm infants, the main branch is less often affected than the lenticulostriate arteries (▶ Fig. 3.65, ▶ Fig. 3.66, ▶ Fig. 3.67, ▶ Fig. 3.68, ▶ Fig. 3.69). PAIS is diagnosed in preterm infants primarily with routine neuroimaging because they do not often present with clinical symptoms. As in full-term infants, PAIS

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Fig. 3.62a–c Preterm infant, GA 27 weeks, who developed localized grade 2 cystic PVL. a Only a few cysts were seen at 4 weeks of age in the parietal white matter (arrow). b These were no longer present at TEA, when irregular ventricular enlargement was seen at the site where the cysts were initially noted (arrow). c The TEA T1-weighted image shows the same irregularity of the lateral ventricle.

Fig. 3.63a,b Preterm infant with a large subependymal cyst on the left in coronal (a) and parasagittal (b) views.

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Fig. 3.64a–c Preterm infant, born at 29 weeks as the survivor of a twin-to-twin transfusion syndrome. a, b cUS performed 3 weeks after birth shows MCA. There is a discrepancy with the T2-weighted MRI performed on the same day (c), which shows no brain tissue except in the cerebellum, whereas there appears to be some tissue left on cUS. Also note the increased echogenicity in the thalami on cUS (arrowhead, a).

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Fig. 3.65a,b Lenticulostriate infarct with onset after surgery for a ventricular septal defect at 44 weeks’ postmenstrual age. Note the elliptical lesion close to the midline, best seen on the coronal view (a).

Fig. 3.66a,b Preterm infant, GA 30 weeks. Lenticulostriate infarct seen following surgery for duodenal atresia. Note the wedge-shaped hyperechoic lesion extending from the caudate nucleus into the basal ganglia.

Fig. 3.67a,b Preterm infant, GA 36 weeks. Lenticulostriate infarct (arrow, a) first seen following surgery for congenital hydronephrosis. The T2weighted MRI obtained at TEA (b) shows a small cyst, which does not appear to cross the internal capsule.

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Fig. 3.68a–d Preterm infant, GA 30 weeks, who developed a small PVHI on the left during the first week. Six weeks later, a large, wedge-shaped lenticulostriate infarct (arrowheads, b and c) was first seen (arrow shows PVHI). The infarct crossed the PLIC, as is best seen on the MRI performed at 2 years of age (d). Also note the ipsilateral atrophy of the basal ganglia. A small area of low signal intensity is also seen at the site of the PVHI (arrowhead).

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Fig. 3.69a–c Preterm infant, GA 27 weeks, developed a large bilateral IVH and PVHI on the left during the first 48 hours after birth (a). A wedgeshaped lenticulostriate infarct (arrowheads) was first seen 3 weeks later, both on cUS (b) and on early T2-weighted MRI (c).

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Neonatal Cranial Ultrasonography will become visible only several days after the onset of the infarct, but in preterm infants the onset may be several weeks after birth. PAIS can sometimes follow a surgical procedure (see ▶ Fig. 3.65, ▶ Fig. 3.66, ▶ Fig. 3.67), whereas in other infants it may be a chance finding on a routine second scan (see ▶ Fig. 3.68 and ▶ Fig. 3.69). Involvement of the PLIC will help to predict motor outcome, and this will be easier to see with MR imaging than with cUS (see ▶ Fig. 3.67 and ▶ Fig. 3.68).

3.6 Term Infants cUS of full-term infants will give invaluable information about the anatomy and maturation of the brain and about possible injury or congenital abnormalities. The head of a full-term infant is larger than that of a preterm infant, and brain structures are farther away from the probe. This causes a slightly more difficult cUS examination of the term infant than of the preterm infant’s brain. In term-born infants, hypoxic–ischemic encephalopathy (HIE) and stroke are the major causes of, respectively, diffuse and focal brain injury and neurologic morbidity. Areas of the brain that are prone to hypoxic–ischemic or hemorrhagic injury are mostly located at the brain’s convexity and/or in the central region, and these areas are less easy to access than the ventricular and periventricular areas. In addition, mineralization of the skull is more advanced in full-term infants than in preterm infants, and the fontanels may be small, making the brain less accessible for ultrasound imaging. Agitation in unsedated fullterm infants often makes the cUS more challenging than it is in preterm infants. The standard acoustic window used for imaging the neonatal brain is the anterior fontanel. Scanning through the posterior fontanel (junction of the lambdoid and sagittal sutures) and mastoid fontanel (junction of the posterior parietal, temporal, and occipital bones) can help to detect lesions and structural malformations in these areas. Imaging through the temporal window allows good views of the mesencephalon and brainstem. The transducer frequency should be selected to maximize resolution and depth of penetration. A 5-MHz real-time sector or vector transducer is usually adequate for most neonatal brains. A lower-frequency transducer (3 MHz) may be needed in older, larger infants with closing fontanels. Higher-frequency probes (7, 5, or 10 MHz) are helpful to image superficial structures in the near field, such as the extracerebral spaces or cortex.

Tips from the Pro It is recommended that at least one cUS be routinely performed in sick full-term infants. Serial examinations are necessary in infants with (suspected) injury and/or neurologic symptoms.

intracranial bleeding compared with delivery by cesarean section. Acquired and congenital coagulopathies, such as neonatal isoimmune thrombocytopenia and vitamin K deficiency and those caused by anticoagulant therapy and sepsis, may also present with intracranial bleeding. Hemorrhages caused by coagulation disorders are often large and centered in the deep white matter, basal ganglia, and cerebellum. The ultrasound appearance changes with the evolution of the hematoma. With time, the lesions may be cystic in appearance or of intermediate echogenicity compared with normal brain. Large hemorrhages at the brain’s convexity (subdural and subarachnoid hemorrhages) are rare, and smaller hemorrhages may not be well detected with ultrasound. Although moderate to large hematomas in the convexity can be identified, small subdural hematomas can be difficult to recognize by ultrasound because of the inability to angle the probe sufficiently to image the curved surface of the brain. If there is no evidence of significant birth trauma or coagulopathy, in infants with deep parenchymal hemorrhages the possibility of an underlying arteriovenous malformation should be kept in mind. It can be quite difficult to image the malformation with Doppler techniques because of initial vascular spasm. MR imaging or a computed tomographiy (CT) examination after the initial phase can be helpful for a specific diagnosis. Rarely, arterial hypertension associated with critical coarctation of the aorta results in intracranial hemorrhage in the newborn period. The final cause is diffuse hypoxic–ischemic injury; a common location of secondary bleeding is in the subcortical u fibers that interconnect adjacent gyri. On ultrasound, u-shaped, brightly echogenic lesions are present adjacent to the gray matter strip.

Intraventricular Hemorrhage This type of hemorrhage is less common in full-term than in preterm infants. It mostly originates from the choroid plexus but may also arise from the residual germinal matrix. Although choroid plexus hemorrhages are generally rare, they are more frequent in term infants. In choroid plexus hemorrhage, the sonographic findings are nodularity, enlargement, and asymmetry of the choroid plexus (▶ Fig. 3.70).

Intraparenchymal Hemorrhage Primary parenchymal hematomas are rare. These hemorrhages occur mostly in combination with intraventricular hemorrhage and have the same risk factors. On cUS, these hemorrhages can be recognized as rather circumscribed echogenic lesions. They are seen mainly in the temporal lobe after traumatic deliveries but may also occur in other lobes and, rarely, the cerebellum (▶ Fig. 3.71). Intraparenchymal, periventricular calcifications may mimic parenchymal hemorrhages. A scattered appearance is more common in calcifications (▶ Fig. 3.72 and ▶ Fig. 3.73).

Tips from the Pro

3.6.1 Pathology Hemorrhage In the term infant, the most common cause of intracranial hemorrhage is birth trauma. Vaginal delivery is a major reason for

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The sonographic differentiation between a primary parenchymal hemorrhage and nonhemorrhagic infarction can be very difficult because both entities may be equally echogenic.

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Fig. 3.70a–c Term infant with neonatal sepsis. Coronal (a, b) and sagittal (c) view images show that the right choroid plexus is enlarged due to hematoma (arrows). (Courtesy Dr. Zeynep Yazici, Uludag University Medical School, Bursa, Turkey)

Infarction: Hypoxic–Ischemic Encephalopathy in Term Infants As the infant matures, the regions of the brain most susceptible to ischemic damage change. Mild to moderate hypotension results in injury to the cerebral cortex, particularly in the intervascular boundary zones (watershed areas), which lie in the regions between the anterior and middle cerebral arteries and between the middle and posterior cerebral arteries (▶ Fig. 3.74). This distribution is termed parasagittal, the same

as watershed zones. In term neonates, different patterns of brain injury result from severe versus mild to moderate (partial) asphyxia. Severe asphyxial events such as profound hypotension or cardiocirculatory arrest in term neonates result in a primarily central pattern of injury involving the deep gray matter (putamina, ventrolateral thalami, hippocampi, dorsal brainstem, and lateral geniculate nuclei) and occasionally the perirolandic cortex. These areas of the brain are actively undergoing myelination (an energy-intensive process) or contain the

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Fig. 3.71a-d (a) Full-term infant with bilateral IVH and unilateral thalamic hemorrhage on US (b, c) and MRI (d). Venous sinus thrombosis was excluded with MR venography. (Images courtesy of LS de Vries, UMC Utrecht, Utrecht, The Netherlands)

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Fig. 3.72a–d Term infant with a congenital cardiac defect. Sagittal (a) and coronal (b) cranial US images show periventricular and basal ganglia petechial echogenicities (arrow). Gradient echo T2-weighted (c) and T1-weighted (d) MRI demonstrate punctuate calcifications (arrow) as low signal on T2 and high signal on T1 series at a higher, paraventricular level.

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Fig. 3.73a,b Full-term infant with direct hyperbilirubinemia and thrombocytopenia. Cranial ultrasound (a) helped to make a diagnosis of congenital CMV infection. There is extensive bilateral calcification in the thalami and basal ganglia (arrow) as well as germinolytic cysts (arrowhead). These abnormalities are not seen on the T1-weighted MRI (b). (Images courtesy of LS de Vries, UMC Utrecht, Utrecht, The Netherlands)

Fig. 3.74 Drawings on a paracoronal cranial US image of a normal newborn infant show the intervascular boundary zones (watershed areas) which lie in the region between the anterior and middle cerebral arteries (blue triangles), and between the middle and posterior cerebral arteries (red triangles).

highest concentrations of N-methyl-d-aspartate receptors at term, and they are therefore the most susceptible to neonatal HIE. As the remainder of the cerebral cortex is generally less metabolically active in the immediate perinatal period, it is generally spared or shows mild insults. If the insult is prolonged, the remaining cortex will become involved, which generally indicates a worse neurologic outcome.

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cUS in term-born infants with suspected HIE has several roles. It helps to time the onset of lesions—that is, whether the injury was imposed antenatally, perinatally, or after birth. In addition, cUS can assist in distinguishing hypoxic–ischemic injury from other causes of neonatal encephalopathy, such as metabolic disease. The initial scanning result is clearly important for early diagnosis and management. The evolution of intrapartum injury can be monitored, which is, apart from clinical implications, very important in medicolegal issues. The imaging characteristics of HIE in term neonates can be subdivided based on the severity of injury (severe versus mild to moderate [partial] asphyxia). Features of both severe and partial asphyxia may be seen in any given patient. Transfontanelle cUS is usually the first neuroimaging study to be performed in neonates with suspected HIE. A negative study should not be interpreted as definitive evidence that no injury has occurred. If clinical suspicion for HIE remains, MR imaging should be performed to evaluate the presence and severity of injury. Predominant injury to the deep gray matter is seen as a gradual increase in echogenicity in the basal ganglia or thalami, mostly first present hours to days after the severe hypoxic– ischemic event and becoming more prominent over time (▶ Fig. 3.75). Early detection may be facilitated by additional scanning with a low transducer frequency of 5 MHz. MR imaging should be performed to determine the exact site and extent of injury and involvement of the PLIC, which is of major importance for the neurologic prognosis. Predominant injury to the cortex and subcortical white matter (“watershed pattern”) occurs not only after an acute, severe hypoxic–ischemic event but also after longer-lasting or repetitive hypoxic periods, in a pattern with or without basal ganglia or thalamic involvement. It is not easy to detect this injury with cUS examination because of its localization at the brain’s convexity. Broadening of the hypoechogenic cortical rim and relative enhancement of the echogenic fissures, which is called “tramline”–like cerebral cortex, is often seen in many cases combined with increased echogenicity of the subcortical white

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Fig. 3.75a–d Term infant with HIE, consecutive coronal (a, b) and sagittal (c, d) cranial US images show bilateral increased basal ganglia and thalamic echogenicity (arrows). (continued)

matter. MR imaging is performed to see the extent of the injury. Neurologic outcome depends on the size of injury and whether basal ganglia/thalamic injury coexists. In case of global brain injury, the whole brain is affected. The injury affects the deep and cortical gray matter and white matter, and in some cases, the cerebellum may also be affected. Diffuse brain swelling with diffusely increased echogenicity, loss of sulci, and narrowing of the lateral ventricles are seen on cUS (▶ Fig. 3.76). Although the MR imaging findings will be limited, as they will only confirm the cUS findings, MR imaging confirmation may help the clinician to make important decisions about intensive treatment. It is not easy to detect arterial infarction with cUS. Initially, a slight asymmetry in the appearance of the hemispheres, an

abnormal sylvian fissure, or a focal region of echogenicity in the territory of a main artery may be detected with ultrasound. The abnormalities mostly become more prominent over the subsequent days (▶ Fig. 3.77 and ▶ Fig. 3.78).

Tips from the Pro It is important to keep in mind that the histologic and biochemical features of injured tissue evolve over time, so that the results of a study performed hours after an anoxic episode can differ significantly from those of a study performed several days later.

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Fig 3.75e-h (continued) T2- and T1-weighted axial MRI (e, f) demonstrate increased T2 and T1 signal in the bilateral basal ganglia and thalami as well as increased signal of the cerebral cortex on a coronal FLAIR image (g), which is not very subtle on the other sequences and on US examination. ADC map (h) clearly shows restricted diffusion in both basal ganglia, thalami, and cortex (arrows) due to ischemic injury causing cytotoxic edema.

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Fig. 3.76a-d Global brain injury: Coronal (initial, a, 3 days later, b) and sagittal (c) US images show diffuse brain swelling with diffusely increased echogenicity, loss of sulci, and narrowing of the lateral ventricles (b). Follow-up brain CT (5 days old) (d) shows diffuse decreased cerebral parenchymal density.

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Fig. 3.77a,b Full-term infant with a large right sided middle cerebral artery infarct. Note the linear demarcation line (arrow) as well as involvement of the right thalamus (arrowhead, a). The sylvian fissure is no longer distinguished (b). (Images courtesy of LS de Vries, UMC Utrecht, Utrecht, The Netherlands)

3.6.2 Congenital Abnormalities The classification of congenital abnormalities of the central nervous system is complex; they can be classified into three groups, related to primary errors of development or from destructive injuries in utero. Although MR imaging has become the gold standard for imaging congenital central nervous system malformations, ultrasound can provide useful information on structural brain abnormalities, too. In this section, the sonographic appearances of some of the more common and more important malformations are discussed.

Posterior Fossa Anomalies cUS is a valuable tool for imaging congenital posterior fossa anomalies, such as mega cisterna magna, arachnoid cyst, cerebellar vermis agenesis or hypoplasia, cerebellar hypoplasia, and Dandy–Walker malformation or variants.

Dandy–Walker Complex Included in this group is the true Dandy–Walker malformation, which is associated with a large posterior fossa and ballooned fourth ventricle and with inferior vermian and cerebellar hypoplasia. The Dandy–Walker malformation is commonly diagnosed in utero by the demonstration of a large posterior fossa cyst associated with dilatation of the lateral ventricles. The characteristic sonographic features of the Dandy–Walker malformation are best demonstrated on the midline sagittal image and posterior occipital–mastoid ultrasound view (▶ Fig. 3.79). Retrocerebellar fluid collections appear as an anechoic space located behind the inferior vermis and extending to the posterior lip of the foramen magnum. The tentorium cerebelli is elevated and the posterior fossa is enlarged. The

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Dandy–Walker variant represents a lesser degree of vermian hypoplasia and fourth ventricular dilatation. A mega cisterna magna and Blake pouch cyst come into the syndrome complex. There are reported associations with other anomalies, including encephaloceles, agenesis of the CC, and malformations of cortical development. cUS of the Dandy–Walker variant shows vermian hypoplasia and fourth ventricular dilatation with an enlarged retrocerebellar cerebrospinal fluid space, but the tentorium does not appear elevated as in classic Dandy–Walker malformation (▶ Fig. 3.80). A retrocerebellar enlarged cerebrospinal fluid space may be due to mega cisterna magna or Blake pouch cyst, both of which are part of the Dandy–Walker complex, or to an unrelated arachnoid cyst. In the latter, there is no communication between the fluid collection and the fourth ventricle. In practice, differentiation of these entities is rarely possible on cUS and is of little value if the patient is asymptomatic and without other associated abnormalities. However, the finding of an enlarged cisterna magna should prompt detailed examination of the brain for other features of the Dandy– Walker complex.

Chiari Malformation The Chiari malformation of the brain is a complex anomaly that is associated with cerebellar dysplasia, spinal dysraphism, and an encephalocele or myelomeningocele. Infratentorial cUS findings of the Chiari II malformation include downward displacement of the cerebellum into the cervical spinal canal, loss of visualization of the cisterna magna, a small or absent fourth ventricle, and a small posterior fossa (▶ Fig. 3.81 and ▶ Fig. 3.82). Supratentorial abnormalities include an enlarged massa intermedia partially or totally filling the third ventricle and ventriculomegaly.

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Fig. 3.78a-c a A 2-week-old girl was operated for a hypoplastic left heart syndrome. US shows a hyperechoic lesion (arrow) in the right basal nuclei. b At 6 weeks the infarct (arrow) has decreased in size. MR at 8 months c shows an old infarct (arrow) in the basal nuclei. (Images courtesy of E Beek, UMC Utrecht, Utrecht, The Netherlands)

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Fig. 3.79a–d Dandy–Walker malformation. Mastoid view (a) and coronal (b) US demonstrate ballooned dilatation of the fourth ventricle (arrows), and enlargement of the posterior fossa and agenesis of the cerebellar vermis. Hydrocephalus is seen as well. Cranial CT axial (c) and sagittal reformatted (d) images confirm the diagnosis.

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Fig. 3.80a–d Dandy–Walker variant. Sagittal (a) and mastoidal (b) images show hypoplasia of the cerebellar vermis (arrow) and lesser degree of cystic dilatation of the fourth ventricle. This is confirmed on transverse (c) and sagittal (d) MRI. (Courtesy G. Meijler, Isala hospital, Zwolle, The Netherlands)

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Fig. 3.81a–e Chiari II malformation. Sagittal (a), mastoid view (b), paraxial (c), and coronal (d) cranial US demonstrate loss of visualization of the cisterna magna, a small or absent fourth ventricle, and a small posterior fossa (arrows). Noncommunicating hydrocephalus is seen on a paraxial view (c). Septum pellucidum agenesis is seen as well (arrow on d). Sagittal posterior fossa and spinal MRI (e) confirms the Chiari II malformation diagnosis (e).

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Fig. 3.82a-e Full-term infant with spina bifida. The frontal horns are slightly enlarged (a). There is beaking of the mesenencephalon (b, arrow). The fourth ventricle is not visible. The occipital horns are enlarged, colpocephaly. The detail of the T2-weighted MRI shows the downward displacement of the vermis (arrowhead) and the beaking of the mesencephalon in the Chiari II malformation. (Images courtesy of LS de Vries, UMC Utrecht, Utrecht, The Netherlands)

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Dysgenesis of the Corpus Callosum The CC is the major midline commissural tissue that connects the two cerebral hemispheres. It forms during the first 8 to 12 weeks of fetal life. The anterior part develops before the posterior part. An insult before the 12th gestational week results in callosal agenesis. Destructive insults, such as infection or ischemic injury, occurring after formation of the CC lead to secondary callosal dysgenesis and varying degrees of partial absence. The fibers do not cross the midline but become oriented posteroanteriorly as the bundles of Probst, lying along the superomedial aspect of the lateral ventricles. The sonographic findings in callosal agenesis include complete absence of the CC, separated lateral ventricles, ventriculomegaly, and dorsal extension of the third ventricle between the lateral ventricles. The varying degree of dysgenesis is reflected by the ultrasound appearance, with variable displacement of the third ventricle (▶ Fig. 3.83 and ▶ Fig. 3.84). The occipital horns of the parallel-oriented lateral ventricles are larger than the frontal horns, a condition that is called colpocephaly. Callosal dysgenesis may be isolated, or it may be associated with other cerebral abnormalities, including the Chiari II malformation, encephaloceles, the Dandy–Walker malformation, interhemispheric arachnoid cysts, and intracranial lipomas. Lipomas of the CC are found in about half of cases of callosal dysgenesis. The lipomatous mass usually occurs in the ventral portion of the CC (▶ Fig. 3.85).

Phakomatoses Skin and central nervous system abnormalities together with visceral abnormalities are called phakomatoses. These include tuberous sclerosis, Sturge–Weber syndrome, and neurofibromatosis. Intracranial findings of tuberous sclerosis may occur in neonates and infants; therefore, cUS examination can be used as a diagnostic tool.

Holoprosencephaly

Tuberous Sclerosis

When there is failure of the cleavage of the prosencephalon into the telencephalon and diencephalon, the ensuing congenital brain anomaly is called holoprosencephaly. It results in varying degrees of fusion of the cerebral hemispheres, thalami, and olfactory tracts. Holoprosencephaly is a spectrum of abnormalities, ranging from a large single midline ventricle with a dorsal cyst (alobar), to partial division of the cerebral hemispheres but fused thalami (semilobar), to minimal failure of separation of the frontal lobes accompanied by absence of the septum pellucidum (lobar). cUS demonstrates a single, dilated ventricle with fused thalami and a variable thickness of cerebral tissue in the alobar and semilobar types (▶ Fig. 3.86). Lobar holoprosencephaly is the least severe type, with absence of the septum pellucidum producing squaring of the frontal horns. The anatomy of the cerebellum and midbrain is normal in all types. Isolated absence of the septum pellucidum is rare but can be as an incidental finding on cUS. Careful evaluation of the rest of the brain is required to exclude associated abnormalities. An absent septum pellucidum has overlaps with lobar holoprosencephaly. When absence of the septum pellucidum is an incidental finding on cUS, clinical review is advisable, and an MR imaging examination should be considered.

Subependymal brain nodules and cortical tubers are the most common nervous system lesions, occurring in about 95% of patients with tuberous sclerosis. cUS demonstrates the subependymal nodules as echogenic nodules protruding from the lateral walls of the lateral ventricles (▶ Fig. 3.89). They can mimic GMH and calcification. Cortical tubers are not shown as easily as subependymal nodules on cUS because they can be isoechogenic with cerebral parenchyma. When they are more echogenic than normal, cerebral tissue tubers can mimic focal infarction or hemorrhage.

Disorders of Sulcation and Migration Cerebral cortical neuronal migration occurs between the second and sixth months of gestation. Abnormalities of the process of neuroblast formation and migration to the cerebral cortex result in a spectrum of disorders, which include lissencephaly, focal or diffuse cortical dysplasias (▶ Fig. 3.87), schizencephaly,

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and gray matter heterotopias. In lissencephaly, the cerebral sulci and gyri fail to develop fully, and a thick, smooth, fourcell-layered cortex resembling an hourglass is seen in the coronal plane. Two types are encountered. In type I lissencephaly (Miller–Dieker syndrome, Norman–Roberts syndrome), microcephaly, facial dysmorphism, and severe mental disability are the rule. On ultrasound, and particularly on MR imaging, the cerebral cortex resembles that of a 24-week fetus, with no cerebral sulci and wide sylvian fissures. Type II lissencephaly (characterized by the Walker–Warburg syndrome) typically presents with macrocephaly secondary to obstructive hydrocephalus. Ultrasound can help to identify the agyric cortex despite severe ventricular dilatation, which can be difficult to identify on CT scans (▶ Fig. 3.88). A focal abnormality or area of damage to the radially migrating neuroblasts results in schizencephaly. It can present in two types as closed (fused) or open-lipped transcerebral clefts lined by dysplastic, most often polymicrogyric, cortex.

Tips from the Pro Ultrasound is often the first imaging used when a congenital abnormality is suspected based on fetal ultrasound, fetal MR imaging, or clinical features. Although ultrasound can make the diagnosis, a more complete evaluation requires MR imaging in most of the congenital anomalies.

Tumors Congenital brain tumors, within the first 60 days of life, are rare, representing only about 0.5 to 1.9% of all childhood brain tumors. The majority of brain tumors in children younger than 1 year of age is supratentorial, and cUS remains a useful tool for identifying and characterizing intracranial masses (▶ Fig. 3.90 and ▶ Fig. 3.91). It can also be used intraoperatively to identify the site of a tumor and monitor the progress of the procedure. Congenital teratomas, primitive neuroectodermal tumors,

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Fig. 3.83a–d Dysgenesis of the corpus callosum. Sagittal (a) and coronal (b) US demonstrates no prominent corpus callosum, separated lateral ventricles and mild displacement of the third ventricle (a, arrow). Cranial axial and sagittal MRI (c, d) reveal separated lateral ventricles and dysgenetic corpus callosum (arrow).

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Fig. 3.84a–d Agenesis of the corpus callosum with an interhemispheric lipoma: Coronal (a) cranial US image shows an echogenic nodular lipoma and agenesis of the corpus callosum. Anterior cerebral arteries are shown on color Doppler coronal (b) cranial US image (arrow). Sagittal T2-weighted (c) and axial T1-weighted MRI (d) demonstrate separated, parallel-oriented lateral ventricles and a ventral placed, T1 high signal intensity lipoma with chemical shift artifact on T2-weighted sagittal image (arrow). (Courtesy Dr. Zeynep Yazici, Uludag University Medical School, Bursa, Turkey.)

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Fig. 3.85a,b Another example of agenesis of the corpus callosum in a 3-month-old girl in coronal (a) and sagittal (b) planes. (Images courtesy of RR van Rijn, AMC, Amsterdam, The Netherlands).

Fig. 3.86a,b a Semilobar holoprosencephaly. Coronal US image shows monoventricle and fused thalami. b Cranial MRI demonstrates the fusion of the frontal lobes with a frontal monoventricle and partially developed occipital and temporal horns. (Courtesy Dr. Zeynep Yazici, Uludag University Medical School, Bursa, Turkey.)

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Fig. 3.87a–c Cortical dysplasia. Coronal US image obtained with a linear high frequency tranducer (a) shows bilateral intraventricular germinolytic cysts (arrow) in a patient with Zellweger syndrome. MR images shows the cysts (b) and cortical dysplasia /polymicrogyria (c) (arrows). The sonographic diagnosis of cortical dysplasia is not easy.

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Fig. 3.88a–d Full-term infant with lissencephaly. Note lack of cortical folding and sylvian fissure on coronal view (a) and dilation of the ventricle, especially posteriorly (b). The corpus callosum is not well seen on the midsagittal view (c). T2-weighted MRI for comparison (d). (Images courtesy of LS de Vries, UMC Utrecht, Utrecht, The Netherlands.)

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Fig. 3.89a–d Tuberous sclerosis. Cranial US image (a) demonstrates the subependymal nodules as echogenic foci (arrows) protruding from the lateral walls of the lateral ventricles. US image with a high-frequency linear probe (b) shows cortical tubers as hyperechogenic areas (arrows) compared to cerebral parenchyma. T2-weighted axial (c) and T1-weighted sagittal (d) images reveal both subependymal nodules and cortical tubers.

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Fig. 3.90a–d Hypothalamic hamartoma (proven at surgery). Coronal (a) and sagittal (b) images show a space-occupying mass (arrows) in the sellar region (arrow in c). The suprasellar cisterns and vascular structures are obscured by the mass. T2-weighted axial image demonstrates the mass lesion in the sellar region and contrast-enhanced T1-weighted sagittal view shows no enhancement of the lesion which is typical for a hypothalamic hamartoma (arrow in d). (Images courtesy of Dr. Zeynep Yazici, Uludag University Medical School, Bursa, Turkey)

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Fig. 3.91a–d Eight-month-old girl with a hypothalamic glioma, seen on ultrasound as an echogenic mass (a, b, c). Ventricular dilatation is present. The tumor is well seen on a T1-weighted MR image (d). (Images courtesy of RR van Rijn, AMC, Amsterdam, The Netherlands)

atypical teratoid rhabdoid tumors, astrocytomas, ependymomas, and choroid plexus tumors are the most common histologic types. Almost all are large at presentation and of heterogeneously increased echogenicity. Cystic foci and highly reflective punctate or craggy calcifications may also be encountered. Depending on their location, the tumors may produce hydrocephalus, and patients usually present with a rapidly expanding head. Although ultrasound is usually able to detect and in some cases characterize these lesions, definitive investigation of the entire neuraxis, to define the tumor accurately, plan surgery, and demonstrate distant spread, is now almost entirely the province of MR imaging.

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Benign Enlargement of the Subarachnoid Space Benign enlargement of the subarachnoid space (BESS) is a relatively common normal variant in which children present with macrocephaly or, less often, frontal bossing. There are no good studies of the incidence of BESS, but in a normal pediatric radiology practice, this is not an uncommon finding. There is a male predominance, and in many cases there is a family history of macrocephaly. Children with BESS will be “discovered” on routine clinical screening, and in order to rule out underlying pathology, radiologic imaging is mandatory.

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Fig. 3.92a,b a Four-month-old boy with macrocephaly. Cranial ultrasound shows enlargement of the subarachnoid space (asterisk). b With the use of a linear high-frequency probe, the subarachnoid space is better visualized. The subarachnoid space measures respectively 1.6 and 1.2 cm, well above normal for his age.

Table 3.5 Subarachnoid space in mL (95th percentile) Age (weeks)

CCW

SCW

IHW

0

2.4 (7.2)

2.2 (5.2)

2.9 (6.6)

4

3.2 (8.0)

2.7 (5.7)

3.4 (7.0)

8

3.8 (8.6)

3.1 (6.1)

3.8 (7.4)

12

4.3 (9.2)

3.4 (6.4)

4.1 (7.8)

16

4.8 (9.5)

3.6 (6.7)

4.4 (8.0)

20

5.1 (9.8)

3.8 (6.8)

4.6 (8.2)

24

5.2 (10.0)

3.9 (6.9)

4.7 (8.4)

28

5.3 (10.1)

3.9 (7.0)

4.8 (8.4)

32

5.2 (10.0)

3.9 (6.9)

4.8 (8.5)

36

5.1 (9.8)

3.8 (6.8)

4.8 (8.4)

40

4.8 (9.6)

3.6 (6.6)

4.6 (8.3)

44

4.4 (9.2)

3.3 (6.4)

4.5 (8.2)

48

3.8 (8.8)

3.0 (6.1)

4.2 (7.9)

Abbreviations: CCW, craniocortical width; IHW, interhemispheric width; SCW, sinocortical width. Source: Table created from data in Lam WW, Ai VH, Wong V, Leong LL. Ultrasonographic measurement of subarachnoid space in normal infants and children. Pediatr Neurol 2001;25:380–384, with permission from Elsevier.

The first-line imaging should be cUS, CT and MR imaging should play no role in the initial work-up of these children. On cUS, children with BESS will show an enlarged subarachnoid space in the frontal or frontoparietal areas and a widened interhemispheric fissure (▶ Fig. 3.92 and ▶ Table 3.5). If it is not clear that the enlargement is due to BESS or a subdural hematoma, color Doppler can be applied. The presence of bridging veins confirms the diagnosis BESS (▶ Fig. 3.93). In contrast, the ventricles will have a normal size. Only if on follow-up clinical examination the head circumference deviates from the growth

Fig. 3.93 Eight-month-old boy with benign enlargement of the subarachnoid space and an incidental finding of a bilateral subdural hematoma (arrows). Work-up showed no evidence of abusive head trauma, and this case was ruled idiopathic.

curve or neurologic symptoms develop would follow-up imaging, including MR imaging, be indicated. Occasionally, children with BESS present with a subdural hematoma, which can cause a discussion about the origin of this finding (▶ Fig. 3.94). In a study by McKeag et al, only 4 in a cohort of 210 children with BESS developed a subdural hematoma (incidence, 1.9%; 95% CI, 0.04–3.8%). Of these four children, one had abusive head trauma. This implies that an incidental finding of a subdural hematoma in BESS does warrant a full work-up for potential abusive head trauma.

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Fig. 3.94 The same patient as in ▶ Fig. 3.92 (

Video 3.94).

The subarachnoid space was assessed in 278 full-term healthy Chinese infants (see ▶ Table 3.5). Measurements were taken in the coronal plane at the level of the foramen of Monro. The mean values in the table were calculated from the equations given in the article, and the 95% confidence levels were derived from the graphs in the article.

Recommended Readings Abels L, Lequin M, Govaert P. Sonographic templates of newborn perforator stroke. Pediatr Radiol 2006; 36: 663–669 Adams-Chapman I, Hansen NI, Stoll BJ, Higgins R NICHD Research Network. Neurodevelopmental outcome of extremely low birth weight infants with posthemorrhagic hydrocephalus requiring shunt insertion. Pediatrics 2008; 121: e1167–e1177 Anderson NG, Laurent I, Woodward LJ, Inder TE. Detection of impaired growth of the corpus callosum in premature infants. Pediatrics 2006; 118: 951–960 André P, Thébaud B, Delavaucoupet J et al. Late-onset cystic periventricular leukomalacia in premature infants: a threat until term. Am J Perinatol 2001; 18: 79–86 Barkovich AJ, Raybaud CA. Congenital malformations of the brain and skull. In: Barkovich AJ, Raybaud CA, eds. Pediatric Neuroimaging. 5th ed. Philadelphia, PA: Wolters Kluwer; 2012:367–569 Bassan H, Benson CB, Limperopoulos C et al. Ultrasonographic features and severity scoring of periventricular hemorrhagic infarction in relation to risk factors and outcome. Pediatrics 2006; 117: 2111–2118 Benders MJ, Groenendaal F, Uiterwaal CS et al. Maternal and infant characteristics associated with perinatal arterial stroke in the preterm infant. Stroke 2007; 38: 1759–1765 Boxma A, Lequin M, Ramenghi LA, Kros M, Govaert P. Sonographic detection of the optic radiation. Acta Paediatr 2005; 94: 1455–1461 Brouwer MJ, de Vries LS, Groenendaal F et al. New reference values for the neonatal cerebral ventricles. Radiology 2012; 262: 224–233 Buetow PC, Smirniotopoulos JG, Done S. Congenital brain tumors: a review of 45 cases. AJNR Am J Neuroradiol 1990; 11: 793–799 Chen CY, Chou TY, Zimmerman RA, Lee CC, Chen FH, Faro SH. Pericerebral fluid collection: differentiation of enlarged subarachnoid spaces from subdural collections with color Doppler US. Radiology 1996; 201: 389–392 Correa F, Enríquez G, Rosselló J et al. Posterior fontanelle sonography: an acoustic window into the neonatal brain. AJNR Am J Neuroradiol 2004; 25: 1274–1282 Cowan F, Mercuri E, Groenendaal F et al. Does cranial ultrasound imaging identify arterial cerebral infarction in term neonates? Arch Dis Child Fetal Neonatal Ed 2005; 90: F252–F256 Pierrat V, Duquennoy C, van Haastert IC, Ernst M, Guilley N, de Vries LS. Ultrasound diagnosis and neurodevelopmental outcome of localised and extensive cystic periventricular leucomalacia. Arch Dis Child Fetal Neonatal Ed 2001; 84: F151– F156

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Davies MW, Swaminathan M, Betheras FR. Measurement of the transverse cerebellar diameter in preterm neonates and its use in assessment of gestational age. Australas Radiol 2001; 45: 309–312 Davies MW, Swaminathan M, Chuang SL, Betheras FR. Reference ranges for the linear dimensions of the intracranial ventricles in preterm neonates. Arch Dis Child Fetal Neonatal Ed 2000; 82: F218–F223 de Vries LS, Groenendaal F, Eken P, van Haastert IC, Rademaker KJ, Meiners LC. Infarcts in the vascular distribution of the middle cerebral artery in preterm and fullterm infants. Neuropediatrics 1997; 28: 88–96 de Vries LS, Gunardi H, Barth PG, Bok LA, Verboon-Maciolek MA, Groenendaal F. The spectrum of cranial ultrasound and magnetic resonance imaging abnormalities in congenital cytomegalovirus infection. Neuropediatrics 2004; 35: 113– 119 De Vries LS, Van Haastert IL, Rademaker KJ, Koopman C, Groenendaal F. Ultrasound abnormalities preceding cerebral palsy in high-risk preterm infants. J Pediatr 2004; 144: 815–820 Dodelson de Kremer R, Grosso C. Maternal mutation 677C > T in the methylenetetrahydrofolate reductase gene associated with severe brain injury in offspring. Clin Genet 2005; 67: 69–80 Dudink J, Lequin M, Weisglas-Kuperus N, Conneman N, van Goudoever JB, Govaert P. Venous subtypes of preterm periventricular haemorrhagic infarction. Arch Dis Child Fetal Neonatal Ed 2008; 93: F201–F206 Epelman M, Daneman A, Blaser SI et al. Differential diagnosis of intracranial cystic lesions at head US: correlation with CT and MR imaging. Radiographics 2006; 26: 173–196 Epelman M, Daneman A, Chauvin N, Hirsch W. Head Ultrasound and MR imaging in the evaluation of neonatal encephalopathy: competitive or complementary imaging studies? Magn Reson Imaging Clin N Am 2012; 20: 93–115 Epelman M, Daneman A, Kellenberger CJ et al. Neonatal encephalopathy: a prospective comparison of head US and MRI. Pediatr Radiol 2010; 40: 1640–1650 Govaert P, de Vries LS. An Atlas of Neonatal Brain Sonography. 2nd ed. London, United Kingdom: Mac Keith Press; 2010 Gupta SN, Kechli AM, Kanamalla US. Intracranial hemorrhage in term newborns: management and outcomes. Pediatr Neurol 2009; 40: 1–12 Harris DL, Bloomfield FH, Teele RL, Harding JE Australian and New Zealand Neonatal Network. Variable interpretation of ultrasonograms may contribute to variation in the reported incidence of white matter damage between newborn intensive care units in New Zealand. Arch Dis Child Fetal Neonatal Ed 2006; 91: F11–F16 Huang BY, Castillo M. Hypoxic-ischemic brain injury: imaging findings from birth to adulthood. ;():–439 Kutschera J, Tomaselli J, Maurer U, Pichler G, Schwantzer G, Urlesberger B. Minor neurological dysfunction, cognitive development and somatic development at the age of 3 to 11 years in very-low-birthweight infants with transient periventricular echodensities. Acta Paediatr 2006; 95: 1577–1581 Leijser LM, de Vries LS, Cowan FM. Using cerebral ultrasound effectively in the newborn infant. Early Hum Dev 2006; 82: 827–835 Leijser LM, de Vries LS, Rutherford MA et al. Cranial ultrasound in metabolic disorders presenting in the neonatal period: characteristic features and comparison with MR imaging. AJNR Am J Neuroradiol 2007; 28: 1223–1231 Leijser LM, de Bruïne FT, van der Grond J, Steggerda SJ, Walther FJ, van Wezel-Meijler G. Is sequential cranial ultrasound reliable for detection of white matter injury in very preterm infants? Neuroradiology 2010; 52: 397–406 Leijser LM, de Vries LS, Cowan FM. Using cerebral ultrasound effectively in the newborn infant. Early Hum Dev 2006; 82: 827–835 Leijser LM, Klein RH, Veen S, Liauw L, Van Wezel-Meijler G. Hyperechogenicity of the thalamus and basal ganglia in very preterm infants: radiological findings and short-term neurological outcome. Neuropediatrics 2004; 35: 283–289 Leijser LM, Srinivasan L, Rutherford MA, Counsell SJ, Allsop JM, Cowan FM. Structural linear measurements in the newborn brain: accuracy of cranial ultrasound compared to MRI. Pediatr Radiol 2007; 37: 640–648 Leijser LM, Srinivasan L, Rutherford MA et al. Frequently encountered cranial ultrasound features in the white matter of preterm infants: correlation with MRI. Eur J Paediatr Neurol 2009; 13: 317–326 Limperopoulos C, Bassan H, Gauvreau K et al. Does cerebellar injury in premature infants contribute to the high prevalence of long-term cognitive, learning, and behavioral disability in survivors? Pediatrics 2007; 120: 584–593 Limperopoulos C, Soul JS, Gauvreau K et al. Late gestation cerebellar growth is rapid and impeded by premature birth. Pediatrics 2005; 115: 688–695 McKeag H, Christian CW, Rubin D, Daymont C, Pollock AN, Wood J. Subdural hemorrhage in pediatric patients with enlargement of the subarachnoid spaces. J Neurosurg Pediatr 2013; 11: 438–444

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Neonatal Cranial Ultrasonography Meijler G. Neonatal Cranial Ultrasonography. 2nd ed. Heidelberg, Germany: Springer; 2012 Pierrat V, Duquennoy C, van Haastert IC, Ernst M, Guilley N, de Vries LS. Ultrasound diagnosis and neurodevelopmental outcome of localised and extensive cystic periventricular leucomalacia. Arch Dis Child Fetal Neonatal Ed 2001; 84: F151–F156 Sandow BA, Dory CE, Aguiar MA, Abuhamad AZ. Best cases from the AFIP: congenital intracranial teratoma. Radiographics 2004; 24: 1165–1170 Steggerda SJ, de Bruïne FT, Smits-Wintjens VE, Walther FJ, van Wezel-Meijler G. Ultrasound detection of posterior fossa abnormalities in full-term neonates. Early Hum Dev 2012; 88: 233–239 Steggerda SJ, De Bruïne FT, van den Berg-Huysmans AA et al. Small cerebellar hemorrhage in preterm infants: perinatal and postnatal factors and outcome. Cerebellum 2013; 12: 794–801 Steggerda SJ, Leijser LM, Walther FJ, van Wezel-Meijler G. Neonatal cranial ultrasonography: how to optimize its performance. Early Hum Dev 2009; 85: 93–99 Steggerda SJ, Leijser LM, Wiggers-de Bruïne FT, van der Grond J, Walther FJ, van Wezel-Meijler G. Cerebellar injury in preterm infants: incidence and findings on US and MR images. Radiology 2009; 252: 190–199 Trawber R, Rao S, Srinivasjois R et al. Outcomes of preterm neonates with frontal horn cysts: a retrospective study. J Child Neurol 2010; 25: 1377–1381 van Wezel-Meijler G, De Bruïne FT, Steggerda SJ et al. Ultrasound detection of white matter injury in very preterm neonates: practical implications. Dev Med Child Neurol 2011; 53 Suppl 4: 29–34 Van Wezel-Meijler G, de Vries LS. Cranial ultrasound-optimizing utility in the NICU. Curr Pediatr Rev 2013 van Wezel-Meijler G, Leijser LM, Wiggers-de Bruïne FT, Steggerda SJ, van der Grond J, Walther FJ. Diffuse hyperechogenicity of basal ganglia and thalami in preterm neonates: a physiologic finding? Radiology 2011; 258: 944–950

van Wezel-Meijler G, Steggerda SJ, Leijser LM. Cranial ultrasonography in neonates: role and limitations. Semin Perinatol 2010; 34: 28–38 van Wezel-Meijler G, van der Knaap MS, Sie LT et al. Magnetic resonance imaging of the brain in premature infants during the neonatal period. Normal phenomena and reflection of mild ultrasound abnormalities. Neuropediatrics 1998; 29: 89–96 Volpe JJ. Intracranial hemorrhage: germinal matrix-intraventricular hemorrhage of the premature infant. In: Volpe JJ, ed. Neurology of the Newborn. 5th ed. Vol 3. Philadelphia, PA: Saunders Elsevier; 2008:517–589 Volpe JJ. Neuronal proliferation, migration, organization and myelination. In: Volpe JJ, ed. Neurology of the Newborn. 5th ed. Vol 3. Philadelphia, PA: Saunders Elsevier; 2008:51–118 Volpe JJ. Cerebellum of the premature infant: rapidly developing, vulnerable, clinically important. J Child Neurol 2009; 24: 1085–1104 Volpe JJ. Neonatal Neurology. 5th ed. Philadelphia, PA: Saunders Elsevier; 2008 de Vries LS, Cowan FM. Evolving understanding of hypoxic-ischemic encephalopathy in the term infant. Semin Pediatr Neurol 2009; 16: 216–225 Whitelaw A. Periventricular hemorrhage: a problem still today. Early Hum Dev 2012; 88: 965–969 Yikilmaz A, Taylor GA. Cranial sonography in term and near-term infants. Pediatr Radiol 2008; 38: 605–616, 718–719 Zahl SM, Egge A, Helseth E, Wester K. Benign external hydrocephalus: a review, with emphasis on management. Neurosurg Rev 2011; 34: 417–432 Zalel Y, Seidman DS, Brand N, Lipitz S, Achiron R. The development of the fetal vermis: an in-utero sonographic evaluation. Ultrasound Obstet Gynecol 2002; 19: 136–139

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Chapter 4 Spine

4.1 Embryology

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4.2 Technique of Spinal Ultrasound

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4.3 Normal Sonographic Anatomy

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4.4 Pathology

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4 Spine Samuel Stafrace and Erik Beek The use of ultrasound for imaging of the spinal canal in newborns and infants has been described in the literature since the beginning of 1980s. The spinal structures are superficially located in infants, and the dorsal structures of the vertebral column are mostly cartilaginous. This provides an acoustic window through which ultrasound can exquisitely demonstrate the spinal structures, especially with the use of a high-frequency (5- to 15-mHz) linear array probe. In children past the age of 6 months, progressive ossification of these dorsal structures obstructs the ultrasonic beam, and imaging becomes difficult or impossible. However, an impression of the position of the conus medullaris can be obtained in older children with a lower-frequency probe in the transverse plane. Spinal dysraphism is defined as incomplete or absent fusion of midline neural, mesenchymal, and cutaneous structures. This leads to a wide spectrum of congenital spinal anomalies, ranging from a fatty-infiltrated filum terminale to a more extensive myelomeningocele. Some patients are completely asymptomatic, whereas others have bladder and bowel dysfunction, motor and sensory deficits, scoliosis, and secondary foot deformities. These deficits are often progressive. Some authors believe that operative correction of a tethered cord can prevent the occurrence of neurologic deficit or halt further deterioration, whereas others are doubtful about the indication for untethering the conus medullaris in asymptomatic patients. Notwithstanding these differences of opinion, early detection of a tethered cord is worthwhile, and knowledge of its presence can help to plan future management. The main role of ultrasound is as a screening examination for occult spinal dysraphism. If ultrasound shows a normal position of the conus medullaris and an absence of lower intraspinal anomalies, then magnetic resonance (MR) imaging is not indicated. If ultrasound does show anomalies, an MR imaging examination will generally be done to confirm the diagnosis, and also to obtain baseline images for future comparison once ultrasound is no longer possible because of progressive ossification of the vertebrae. MR imaging is also indicated when a discrepancy exists between the clinical signs and symptoms and the results of ultrasound examination. The main indications for spinal ultrasound can be divided in two categories: 1. Screening the vertebral column for anomalies in infants with other congenital anomalies that are associated with occult spinal dysraphism, like anorectal and cloacal malformations; 2. Examining the spine of infants with a back mass or cutaneous markers, the latter of which include skin hemangiomas, sinuses, dimples, and abnormal hairy patches. Perhaps ultrasound of the vertebral column is most frequently requested for the infant with a sacrococcygeal dimple. If the dimple is over the distal coccyx, then intraspinal pathology is extremely rare. If the dimple is higher up, and especially if it is combined with skin anomalies or an abnormal gluteal cleft, intraspinal anomalies are much more likely to be present. Spinal ultrasound is also described for other indications, including ultrasound-guided lumbar puncture, intraoperative

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ultrasound, and ultrasound in diagnosing traumatic lesions of the spinal cord. The anomalies of the vertebral column can be divided into three categories: 1. Non–skin-covered (open) back masses (e.g., myelocele and myelomeningocele); 2. Skin-covered (closed) back masses (e.g., meningocele, lipomyelocele, lipomyelomeningocele, and myelocystocele); 3. Occult spinal dysraphism (e.g., intradural lipoma, dorsal dermal sinus, syringohydromyelia, diastematomyelia, caudal regression syndrome, anterior sacral meningocele, and tight filum terminale). In non–skin-covered back masses, ultrasound plays no clinical role. The diagnosis is obvious, and an ultrasound examination could lead to infection of the exposed neural tissue. In skin-covered back masses, ultrasound can be useful as a quick orientation, but MR imaging will still need to be performed. The ultrasound will help the clinician decide if there is involvement of neural tissue, as in a myelocystocele or lipomyelomeningocele, as opposed to a simple meningocele. MR imaging and ultrasound provide summative information in this setting. It is in the third category, suspected occult spinal dysraphism, that ultrasound can be most useful. Ultrasound can often make a proper diagnosis and help the clinician to decide on the timing of an additional MR imaging examination, if required. Motion-mode (M-mode) ultrasound can help add further information. It can quantify the anteroposterior oscillation of the spinal cord and cauda equina with the cardiac cycle.

4.1 Embryology In this section, the embryologic development of the spinal canal is briefly described. The notochord forms between the 18th and 20th day of embryologic development. During primary neurulation, the notochord induces the formation of a neural plate from the dorsal ectoderm, which then forms the neural groove (▶ Fig. 4.1a). This groove deepens, folds in, and forms the neural tube (which is an ectodermal structure; ▶ Fig. 4.1b). Subsequently during disjunction, the neural tube separates from the cutaneous ectoderm when a layer of mesenchymal cells is interposed between the neural tube and the cutaneous ectoderm. Closure of the neural tube starts at the 22nd day at the level of the future junction of the brain and spinal cord. From here, the tube proceeds in closing in both rostral and caudal directions. Secondary neurulation is a process that starts at the caudal end in the 22-day embryo. A mass of mesodermal cells, the caudal cell mass, is formed. This then expands to form the distal part of the notochord and the spinal cord, forming the neural cord. The lumen of the primary neural tube invaginates into this neural cord, forming the primitive spinal cord. At the terminal end of the spinal cord, the central canal subsequently widens to form the terminal ventricle. Around the 50th day of embryologic development, through a process called retrogressive

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Spine meningocele. Excessive retrogressive differentiation causes caudal regression syndrome with underdevelopment of the distal spinal column, malformation of the distal conus medullaris, and associated abnormalities of the distal colon and urogenital tract.

4.1.1 Ascensus Medullaris During embryologic development, the conus medullaris ascends from the distal vertebral column to its normal position at the level of the first to second lumbar vertebrae. This is probably caused by a disproportionate growth between the vertebral column and the neural tube. The nerve roots of the lower spinal cord segments emerge from the spinal canal at the foramina of the corresponding vertebrae. This results in the formation of the cauda equine, which is a bundle of nerve roots distal to the conus medullaris in the subarachnoid space. Between 13 and 18 weeks of gestation, the conus medullaris is situated at the level of the L4 vertebra, or more caudally, in 100% of fetuses. At 27 weeks, the conus medullaris is on average at the L2–L3 level. At term, the conus medullaris is often at its “adult” position at the L1–L2 level, but the position is considered normal up to the L2–3 disk level.

4.2 Technique of Spinal Ultrasound

Fig. 4.1a–c Schematic drawings of the embryologic development of the spine and spinal cord. a The notochord (arrow) induces in-folding of the neural plate (arrowhead). b The neural groove deepens further (arrow). c The neural groove has developed into a neural tube (arrow), which has separated from the cutaneous ectoderm.

differentiation, the caudal cell mass diminishes in size and the distal spinal cord involutes. Secondary neurulation leads to the formation of the conus medullaris and the more caudal spinal canal, including the filum terminale. A deficient primary neurulation with nonclosure or reopening of the distal neural tube will cause a myelocele or myelomeningocele. Premature disjunction of the cutaneous and neural ectoderm will cause mesenchymal cells to come into contact with the nonneurulated neural plate. The mesenchymal cells differentiate into fat cells, which adhere to the neural plate, forming a lipomyelomeningocele or an intradural lipoma. Disorders of secondary neurulation lead to a variety of congenital malformations. Lipomas of the filum terminale and a tight filum terminale are caused by disorders of retrogressive differentiation. Malformation of the terminal ventricle can produce a cystic dilatation of the distal cord or a distal myelocystocele. Malformation of the sacrum can lead to an anterior sacral

Spinal ultrasound is easy and quick to perform. Unrest and lack of cooperation on the part of the patient, although increasing the challenge, will hardly ever cause an unsuccessful examination. The infant can be positioned in the prone or in the lateral decubitus position. The latter is favored because it is easier to immobilize the infant. In a prone position, older children tend to arch the back, hindering good contact between the probe and the skin. If a small posterior meningocele is suspected, the infant can be examined in an upright position, which can distend the meningocele with fluid. Sagittal images provide a nice view of the spinal cord and the distal nerve roots. A panoramic view (when this option is available) will provide an extended overview and facilitate the determination of the position of the conus medullaris (▶ Fig. 4.2). Transverse images are favored to show the nerve roots and assess the filum terminale for thickening. Most other anomalies are also easier to diagnose on transverse images than on sagittal images. The first cardinal question to answer when scanning is to identify with certainty the location of the conus medullaris, the lower, slightly bulbous end of the spinal cord. There are several methods to assess this position. With some practice, the lumbosacral junction (the transition from the lumbar vertebrae to the sacrum) can be reliably located by identifying the change in angulation of the spine at this level. Counting the vertebral bodies upward from the lumbosacral junction will then allow correct localization of the level of the conus medullaris (see ▶ Fig. 4.2). A complementary method is to locate the last rib (presumed 12th rib) and through this the T12 vertebral body. This is done by positioning the probe in a parasagittal plane to identify the

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Fig. 4.2 Panoramic view of the spinal canal. The lumbosacral junction is marked with an arrow.

Fig. 4.3 Longitudinal paramedian image showing the echogenic appearance of the 12th rib (arrow) with posterior acoustic shadowing. This is used to help identify the T12 vertebral body.

echogenic short last rib superficial to the kidney. The rib is then followed medially to the T12 vertebral body (▶ Fig. 4.3). As a method of last resort, one can sonographically locate the iliac crest, which should be anatomically located at the level of the fifth lumbar vertebra. All the above techniques should come to the same conclusion and position the conus medullaris at the same vertebral level. Anatomical variants and anatomical anomalies (e.g., 11 or 13 ribs, increased/decreased numbers of lumbar vertebrae, and segmentation anomalies in the lower spine) can complicate the above assessments, resulting in conflicting results. If the above methods are unsuccessful or give indeterminate/ conflicting results, the sonographer can count upward from the lowest ossified sacral or coccygeal vertebral body, place a radiopaque marker at the level of the conus medullaris, and obtain a lateral plain film of the vertebral column. In this way, the position of the conus medullaris can be determined. It is important to appreciate that ultrasound is very sensitive for bony structures and can detect tiny ossification centers that are not well appreciated on plain films. The sizes of the ossification centers seen on plain film and ultrasound should, however, more or less correspond. After the location of the conus has been assessed, attention should shift to the morphology and integrity of the cord. When the scan is being performed for a sacral dimple, only the lumbar cord needs assessment. If a more complex abnormality is being assessed, then it would be best examine the entire cord up the cervical region. Following this, the subarachnoid space and the distal nerve roots should be assessed. One should confirm the presence of normal pulsatile movements in the distal nerve roots and cauda equina. If the child is in a decubitus position, the nerve roots can gravitate to the dependent side (▶ Fig. 4.4). The filum terminale needs to be assessed separately in transverse and sagittal planes. The lower vertebral column and the posterior elements should be carefully reviewed, with special attention paid to the presence and anatomy of the sacrum and the coccyx. M-mode sonography is described in the literature as a useful tool to assess the free pulsatile movement of the cord and nerve

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roots. However, in many normal infants, M-mode may show no movement at all. Additional information that can be provided by M-mode sonography includes quantification of the anteroposterior oscillation of the spinal cord and cauda equina. An oscillation amplitude of less than 0.3 mm in a symptomatic patient should alert the clinician to cord abnormalities and/or tethering. With color Doppler, the venous epidural plexus can be seen, and sometimes the spinal arteries are also visualized.

Tips from the Pro Always use a linear probe with the highest frequency available. If you detect any abnormality, extend the examination along all the visible spinal cord, and also review the kidneys in the same study.

4.3 Normal Sonographic Anatomy When examined in the sagittal plane, the spinal cord is depicted as a hypoechoic to anechoic tapering structure with a central echo complex. This linear echogenic appearance is probably secondary to reflection from the central canal. Another possible explanation is that this increased central echogenicity is caused by the central end of the fissura mediana anterior. With current techniques, differentiation between gray and white matter is not yet possible. The margins of the spinal cord appear echogenic, and the cord is surrounded by echogenic spinal nerve roots. The distal conus medullaris is thicker than the more proximal thoracic cord (▶ Fig. 4.5). The tip of the conus medullaris is usually located at the L1–L2 level, but a position down to the L2–3 disk space is considered normal. On transverse images, the conus medullaris is oval, with its transverse diameter larger than its anteroposterior depth (▶ Fig. 4.6). Thin, echogenic strands of the arachnoid can be seen, and larger echogenic dots representing the nerve roots

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Fig. 4.4a,b Images of a 1-month-old boy showing nerve roots gravitating to the dependent side. a The patient is in a right decubitus position. b The patient is in a left decubitus position. The arrowhead is at the dependent side.

Fig. 4.5a,b Normal sagittal ultrasound appearances. a Sagittal image at the level of the thoracic spine. Note the echogenic anterior and posterior walls of the cord (arrows) and the echogenic central canal (arrowhead). b Sagittal image at the level of the conus medullaris. It is surrounded by nerve roots (arrowhead) and cerebrospinal fluid (open arrow).

Fig. 4.6a,b Transverse ultrasound appearances of the spinal canal. a At the level of the thoracic cord. b At the level of the conus medullaris. Note the oval appearances of the cord, which is surrounded by the exiting nerve roots.

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Fig. 4.8a,b Sagittal (a) and transverse (b) images of the normal filum terminale (arrows), lying centrally within the distal nerve roots.

Fig. 4.7a,b Normal appearances of the cauda equina. a Sagittal view. b Transverse view.

are well identified laterally at this level. At the more proximal thoracic level, the dentate ligaments can also be visualized as echogenic lines at the lateral margins of the cord. These ligaments are not as well identified at the level of the conus medullaris. Below the conus medullaris, the grouped nerve roots constitute the cauda equina (▶ Fig. 4.7). The number of nerve roots diminishes caudally as two ventral and two dorsal nerve roots exit at every vertebral level. The dural sac ends at the level of the second sacral vertebra. The filum terminale is in continuity with the tip of the conus medullaris and is depicted as a centrally located, slightly echogenic structure (▶ Fig. 4.8). It can be followed to the caudal end of the dural sac. It attaches to the coccyx, but below the dural sac the filum terminale is not visible as a separate structure. This structure should be less than 2 mm in axial diameter. Its echogenicity needs to be carefully assessed to exclude fatty contents within it.

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The bony structures and vertebral bodies are visualized as echogenic structures. The intervertebral disks appear hypoechoic. The cartilaginous, unossified parts of the vertebra, especially the spinous processes, are hypoechoic or anechoic, increasing in echogenicity with age. The first coccygeal vertebra can be ossified in the young infant. The distal coccyx is composed of anechoic to hypoechoic cartilage. The coccyx generally has the same continuous sacral kyphotic curve as in adults, although it is occasionally straight. The tip of the coccyx can even have a lordotic curvature (upturned toward the skin/probe) and present as a small, palpable “distal mass” (▶ Fig. 4.9).

4.3.1 Normal Variants A slight widening of the central echo complex can be seen in normal infants. No upper limits of normal are available (▶ Fig. 4.10).

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Fig. 4.10 Sagittal image of the spine in a neonate showing mild dilatation of the central canal (white arrow). This is normal and referred to as transient dilatation of the central canal.

Sometimes, a more local dilatation of the distal central canal in the conus medullaris is seen. This is called the ventriculus terminalis. It is considered a normal variant if it is anechoic, not septate, and not associated with any other findings. It should measure less than 4 mm in diameter (▶ Fig. 4.11). A filar cyst is a small, cystic, midline anechoic structure that can be seen in the proximal filum terminale. This has no clinical significance (▶ Fig. 4.12). A pseudosinus tract is a residual cordlike structure occasionally seen extending from the tip of the coccyx to an adjacent deep end of a sacral dimple (▶ Fig. 4.13). A dermal sinus is located more proximally. Acceptable variety in the contour of the coccyx has been described in the preceding section.

4.4 Pathology Fig. 4.9a–c Normal sagittal ultrasound appearance of the distal sacrum and coccyx. b, c Sagittal ultrasound images demonstrating dysmorphic appearances of the coccyx. A straight coccyx (b). A slightly upturned tip (c). The latter may be palpable and present as a “mass.”

Fig. 4.11 Sagittal image showing dilatation of the central canal (open arrow) within the distal spinal canal and no other findings, in keeping with a ventriculus terminalis.

4.4.1 Non–Skin-Covered Back Masses: Open Lesions Myelocele/Myelomeningocele In simple terms, a myelomeningocele develops during the stage of primary neurulation when the neural plate fails to fold and close, resulting in an abnormal superficial placode of neural tissue. This exposed neural tissue should have been inside the closed neural tube. In a myelocele, this placode is flat with the skin. Drops of cerebrospinal fluid (CSF) can leak externally from the lesion. In a myelomeningocele, a mass is present with a wall consisting of neural, arachnoid, and connective tissue. The sac is filled with CSF. The spinal cord is tethered as it blends into the dysraphic neural tissue, which is attached to the skin. On a bony level, there is absence of the spinous processes and lamina at the level of the myelomeningocele. The pedicles are splayed, and the spinal canal is widened. Ultrasound is not indicated before surgical repair. The diagnosis is obvious, and the therapeutic strategy depends on the severity of the neurologic deficit and the extent of associated abnormalities. It will not be influenced by a sonographic examination of the mass, a study that itself could lead to infection. After surgical closure, ultrasound reveals a thin spinal cord with

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Fig. 4.13 Lateral sagittal image at the level of the coccyx with a deep sacral dimple related to this (arrow). This appearance may be misinterpreted as a sinus tract.

Fig. 4.12a,b Two examples of a filar cyst, a normal variant (arrows). Sagittal images showing a cystic longitudinal area within the proximal filum terminale.

a stretched appearance. The rim of the cord is more echogenic than in a normal spinal cord (▶ Fig. 4.14). The roots exit laterally from the cord, and a cauda equina is absent. Ultrasound can demonstrate additional abnormalities like diastematomyelia and hydromyelia.

4.4.2 Skin-Covered Back Masses: Closed Lesions Meningocele A meningocele is a protruding mass in which a sac consisting of meninges filled with CSF herniates through a defect of the vertebral column. The defect can occur posteriorly through a bifid vertebral arch (posterior meningocele), anteriorly through a partially absent sacrum (anterior sacral meningocele), laterally through an enlarged vertebral foramen (lateral meningocele, mostly at the thoracic level), or distally into the sacrum (intrasacral meningocele). The posterior meningocele is the most common and is a skincovered back mass. When it occurs in isolation, only one or two vertebrae are dysraphic. The wall of the sac consists of dura and arachnoid. Generally, no neural tissue is present in the sac, although a spinal nerve root can adhere to it. Posterior meningoceles are most frequently seen at the lumbosacral level, but they can also occur at other levels. An anterior sacral meningocele is a protrusion of dura and arachnoid through an anterior sacral defect. It can present as an isolated anomaly, but it is frequently seen as part of a Currarino

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Fig. 4.14a,b A 6-week-old boy with a low spina bifida. a On a sagittal image, the cord extends to the sacral level. The lining of the cord is very echogenic. b A transverse view shows a relatively small cord, and the cauda equina is absent.

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Fig. 4.16a,b a Drawing of a myelocystocele. A dilated central canal (arrow) forms a herniating skin-covered back mass. The surrounding subarachnoid space is herniating, as well (arrowheads). b Sagittal image of a terminal myelocystocele. There is a low-lying cord, with the distal spinal canal dilated and ending in an extraspinal cystic expansion. Image courtesy of Dr. K. A. Duncan, Royal Aberdeen Children’s Hospital, Aberdeen, Scotland.

distend the sac. Meningoceles can be seen to decrease in size with mild compression by the probe (▶ Fig. 4.15).

Fig. 4.15a,b a Ultrasound appearance of a simple meningocele (arrow). b With slight compression the meningocele disappears, which may occasionally be seen.

triad. This is a combination of a partial sacral agenesis, an anorectal anomaly, and a presacral tumor, which can be an anterior sacral meningocele, a rectal duplication, or a teratoma. The contents of a meningocele can appear anechoic, or alternatively, the meningocele can contain multiple septa and stranding. A small posterior meningocele can be better visualized with the patient in an upright position, which helps

Myelocystocele A myelocystocele is a skin-covered back mass in which the contents of the herniating sac are connected to and sometimes include cystic dilatation of the central canal. The mass protrudes through dysraphic, deficient vertebral arches. It occurs most frequently in the lumbosacral region, and when it involves the distal end, this abnormality is referred to as a terminal myelocystocele (▶ Fig. 4.16). More proximally, it is called a nonterminal myelocystocele. In the latter form, a complex cystic mass on ultrasound can be seen connecting to the central canal through a bony defect. There is often dilatation of the central canal where this connection occurs, and associated distortion of the spinal cord can be seen.

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Fig. 4.18a–c A 2-year-old boy, recently adopted. He had a lump on the lower back. Ultrasound was used to quickly assess the nature of the mass. Although difficult at this age, ultrasound (a) showed a lowending spinal cord with a hydromyelia (arrowhead) terminating in an echogenic mass (arrow), presumably a lipomyelomeningocele. The findings were confirmed and much more easily visible on (b) T1weighted and (c) T2-weighted magnetic resonance images.

Fig. 4.17a–c Lipomyelocele in a neonate. Sagittal T1 (a) and T2 (b) magnetic resonance images with the interface between subcutaneous fat and placode in the spinal canal. Associated tethered cord, dilated distal central canal, and absence of the coccyx. c Sagittal ultrasound image demonstrating the intraspinal appearances in another, similar case.

Lipomyelomeningocele/Lipomyelocele Lipomyelomeningocele and lipomyelocele (the latter is also known as a lipomyeloschisis) are characterized by abnormal fatty subcutaneous soft-tissue masses that are in turn directly connected to a terminal placode of neural tissue through a bony defect in the spinal canal. When the placode–lipoma interface occurs within the spinal canal, this is referred to as a lipomyelocele or lipomyeloschisis (▶ Fig. 4.17). When the interface occurs

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outside the spinal canal, the abnormality is referred to as a lipomyelomeningocele (▶ Fig. 4.18). This latter type is often associated with widening of the CSF space, with a meningocele component adjacent to the placode–fat interface outside the canal. These defects are probably caused by a premature disjunction of the cutaneous ectoderm from the neural ectoderm. Ultrasound can be used to make a quick and likely diagnosis and is able to differentiate the above lesions quite specifically.

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Fig. 4.19a,b Newborn boy with esophageal atresia, a cardiac defect, and vertebral anomalies. a Ultrasound of the spinal canal shows a spinal cord ending at L3–L4, a thickened filum, and a distal intradural lipoma (arrow). b The same is seen on a T1-weighted magnetic resonance image.

The abnormal fat appears echogenic, and the spinal cord can be followed down to the interface with the fatty mass. The spinal cord can have the same thin, stretched appearance as it does in patients after closure of a myelomeningocele. The cord blends into an echogenic mass of fat, in which the spinal cord is sometimes well defined. The meningocele component is easily identified in a lipomyelomeningocele. The cord should be scanned more proximally to exclude associated dilatation of the central canal.

4.4.3 Occult/Closed Lesions without a Mass Intradural Lipoma Intradural lipomas are juxtamedullary lipomas within a complete dural sac. They are probably caused by a premature disjunction of the cutaneous ectoderm from the neural ectoderm. Mesenchymal cells come into contact with neural tissue of the not yet completely closed dorsal side of the neural plate and differentiate into fat cells. This lesion is often associated with other abnormalities. On ultrasound, an echogenic mass is demonstrated (▶ Fig. 4.19). The fatty nature of the mass will be confirmed with additional MR imaging examination.

Dorsal Dermal Sinus A dorsal dermal sinus is an epithelium-lined canal extending from the back for varying lengths. This can extend into the subcutaneous tissues or more deeply into the spinal canal and/or into the spinal cord. The cord can be low-ending. If the dermal sinus enters the spinal canal, an associated dermoid or epidermoid lesion is present in around half of the patients. Vertebral anomalies are uncommon in this scenario. The majority of children presents with skin abnormalities or infection/meningitis because of the open communication of the spinal contents with the skin whereby the dermal sinus acts as an entry point for infections. Excision of the sinus tract should prevent this complication. On ultrasound, the subcutaneous tract is seen as a hypoechoic band with posterior acoustic shadowing traveling caudally from the skin into the deeper structures (▶ Fig. 4.20). The intradural extension is difficult to image. Although spinal ultrasound generally provides better images than MR imaging in the neonate, this is one condition in which MR imaging has additional value.

Syringohydromyelia Hydromyelia is an abnormal dilatation of the central canal in the spinal cord. It can be difficult to distinguish from syringomyelia, which is a fluid-filled cavity within the cord. The term syringohydromyelia combines both entities. Syringohydromyelia in newborns is mostly seen in conjunction with a congenital spinal anomaly, such as a myelomeningocele, but it can occur after trauma. Other locations where it is seen include distal to spinal tumors and distal to obstructing lesions at the foramen magnum. On ultrasound, a syringohydromyelia appears as an anechoic longitudinal lesion within the spinal cord (▶ Fig. 4.21). If the cord is very expanded, it can be difficult to determine whether the mass is actually within the cord. At the proximal and distal ends of the lesion, the syringohydromyelia is smaller, and is it easier to determine that cystic expansion indeed lies within the cord. If on ultrasound the cord shows some movement, the syringohydromyelia should be seen to move with it.

Diastematomyelia Diastematomyelia is an abnormal partial or complete clefting of the spinal cord along the sagittal plane. It can be associated with a bony or cartilaginous intraspinal spur, in which case the arachnoid and dura are also duplicated. The spur is located at the caudal end of the split in the cord. Diplomyelia is characterized by two complete parallel cords, each with a complete set of ventral and dorsal nerve roots. In diastematomyelia, the cords have only one set of ventral and dorsal nerve roots. The term split cord malformation is used to encompass both conditions. Cutaneous markers are common. Concomitant hydromyelia, lipomas of the terminal filum, and intradural lipomas are also frequent. An embryologic theory is that an accessory neurenteric canal occurs at the end of the third gestational week. It splits the notochord and the neural plate and is invested with mesenchyme, which causes an endomesenchymal tract. During neurulation, two hemicords are formed, and the endomesenchymal tract can persist as a fibrous midline septum or as an osteocartilaginous spur. The accessory canal can persist as a dorsal enteric fistula, which is a communication between the bowel and the dorsal skin through a split cord. Alternatively, the accessory canal can close at the ventral, dorsal, or both sides. If the dorsal canal persists, a dorsal dermal sinus results. If the ventral canal persists,

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Fig. 4.20a–c A 4-day-old boy with a dorsal dermal sinus at the lumbosacral level. a Sagittal ultrasound demonstrates an echogenic tract (arrow) traveling in a cranial direction through the soft tissues. b The conus medullaris (arrow) was at the L3–L4 level. c The findings were confirmed at magnetic resonance imaging. Arrow indicates sinus tract.

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Fig. 4.21a–d A 4-month-old boy with a cutaneous discoloration in the lumbosacral region. a A dermal sinus (arrow) is present at the level of S2. The conus medullaris is at L3. b, c In the distal spinal cord, a syringohydromyelia (arrows) is visible on sagittal and transverse images. d This is also shown on a T2-weighted magnetic resonance image, acquired 4 months later.

an associated enteric cyst is formed. If the ventral and dorsal ends close and a septum persists, a diastematomyelia is formed. On ultrasound, two spinal cords are seen. This abnormality is best appreciated in the transverse plane. The spinal cords are usually side by side and often of unequal size. At the lower end of the split, the spur can be seen as an echogenic structure with posterior acoustic shadowing (▶ Fig. 4.22).

Caudal Regression Syndrome Caudal regression syndrome is the combination of agenesis of the distal spinal column, abnormalities of the cord, and often associated urologic abnormalities and malformations of the

anus and external genitalia. There is a large clinical spectrum ranging from asymptomatic minimal involvement of the coccyx to extensive missing lower aspects of the spine with cord anomalies and significant clinical impact. Caudal regression syndrome is classified into two groups. The more severe form is referred to as type 1 caudal regression syndrome. In this case, the cord often ends above the first lumbar vertebra, and the end appears wedge-shaped (▶ Fig. 4.23). Type II caudal regression syndrome refers to lesser degrees of abnormality. In this case, the bony regression involves the sacrum and below. In type II abnormality, the cord does not appear truncated but is often low-lying, with tethering generally present (▶ Fig. 4.24).

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Fig. 4.22a–c Diastematomyelia. a Transverse ultrasound in a neonate at the level of the lower thoracic spine demonstrates two hemicords. (Images courtesy of Dr. K. A. Duncan, Royal Aberdeen Children’s Hospital, Aberdeen, Scotland.) b Transverse image in another neonate with diastematomyelia associated with a bony spur (arrow). c Transverse T2 magnetic resonance imaging appearance of the same neonate as in (b). Note the presence of an associated meningocele (arrow).

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Fig. 4.24a,b Spectrum of appearances in caudal regression syndrome type II. a Sagittal image demonstrates partial sacral agenesis with an abrupt end of the sacrum below S3. b Sagittal image of the lumbar area in the same child shows a tethered, low-lying cord with an intradural lipoma (white arrow) and an associated dilated distal segment of the spinal canal (arrowhead).

suggest the minor forms of this condition when absence of the distal vertebral levels is identified. Fig. 4.23a,b Caudal regression syndrome type I in a newborn with multiple congenital anomalies. a Ultrasound demonstrates a truncated conus medullaris. The dorsal and ventral nerve roots are strikingly well visible (arrows). b Sagittal T2-weighted magnetic resonance image shows a wedge-shaped cord terminus at T12. Note the distal sacral agenesis.

This syndrome is seen in combination with a variety of abnormalities, such as a thickened filum terminale, intradural lipomas, myelocystoceles, VACTERL (vertebral abnormalities, anal atresia, cardiac abnormalities, tracheoesophageal fistula and/or esophageal atresia, renal agenesis and dysplasia, limb defects) association, and Currarino triad. With ultrasound, the identification of a wedge-shaped cord end is less easy than with MR imaging. It should be suspected when the conus is abnormally blunt. The associated spectrum of abnormalities and the absence of the coccyx and sacrum are, however, easily demonstrated on ultrasound, which often is the first investigation to

Tip from the Pro A more extensive search for associated anomalies is needed if the ultrasound suggests caudal regression.

Tight Filum Terminale A tight filum terminale is one of the causes of a tethered cord syndrome. In this case, the filum is thickened by fat or fibrous tissue. In infants, the filum is considered too thick if it exceeds 2 mm axially. An associated low position of the conus medullaris is generally seen (▶ Fig. 4.25), although the tethered cord syndrome has been described in patients with a normal position of the conus. On ultrasound, the thickened filum is easily seen, especially in the transverse plane (▶ Fig. 4.26). It may be displaced posteriorly and is often hyperechoic secondary to fatty infiltration.

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Fig. 4.25a,b A 1-week-old boy with an anorectal malformation and vertebral anomalies was screened for a possible spinal malformation. a A thickened filum is visible, and a small filar cyst (arrow). b A “panoramic view” shows that the conus terminalis is situated at L3–L4 (arrow, L5–S1).

Fig. 4.26a,b Sagittal (a) and transverse (b) images demonstrating appearances of abnormally thickened and echogenic filum terminale (arrows) in different neonates.

Fig. 4.27a,b a A 2-month-old boy with a sacral dimple (arrow) over the coccyx. No connection is visible between the dimple and the spinal canal. b The conus terminalis (arrowhead) is at the L1–L2 level.

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Fig. 4.28a–c A 6-week-old boy with a sacral dimple over the coccyx. a The dimple is at the tip of the coccyx (arrow). b The coccyx and sacrum are normal. c The conus medullaris (arrowhead) is at L2.

When tethered, the conus medullaris can be positioned as low as the proximal sacrum.

Tips from the Pro Examination in the transverse plane is more reliable than in the sagittal plane to identify a thickened filum terminale.

4.4.4 Sacral Dimple Many children are referred for spinal ultrasound because of a sacral dimple. In the authors’ experience, this is the most common reason for referral. A midline simple pit over the end of the coccyx located less than 2.5 cm from the anus is not associated with intraspinal pathology (▶ Fig. 4.27 and ▶ Fig. 4.28). Indications for scanning include location of a dimple to one side, size larger than 5 mm, position of a dimple more than 2.5 cm from the anus, and the presence of associated other skin

lesions like hairy tufts, hemangiomas, and lipomas. A patients with dimple that appears to leak CSF will need assessment of the spine by MR imaging.

Recommended Readings ACR-AIUM-SPR-SRU practice guideline for the performance of an ultrasound examination of the neonatal spine. Accessed 15 February 2014 Barkovich AJ, Edwards Ms, Cogen PH. MR evaluation of spinal dermal sinus tracts in children. AJNR Am J Neuroradiol 1991; 12: 123–129 Barkovich AJ, Raghavan N, Chuang S, Peck WW. The wedge-shaped cord terminus: a radiographic sign of caudal regression. AJNR Am J Neuroradiol 1989; 10: 1223– 1231 Beek FJA, de Vries LS, Gerards LJ, Mali WP. Sonographic determination of the position of the conus medullaris in premature and term infants. Neuroradiology 1996; 38 Suppl 1: S174–S177 Beek FJA, van Leeuwen MS, Bax NM, Dillon EH, Witkamp TD, van Gils AP. A method for sonographic counting of the lower vertebral bodies in newborns and infants. AJNR Am J Neuroradiol 1994; 15: 445–449 Ben-Sira L, Ponger P, Miller E, Beni-Adani L, Constantini S. Low-risk lumbar skin stigmata in infants: the role of ultrasound screening. J Pediatr 2009; 155: 864–869 Byrd SE, Darling CF, McLone DG. Developmental disorders of the pediatric spine. Radiol Clin North Am 1991; 29: 711–752

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Spine Byrne RW, Hayes EA, George TM, McLone DG. Operative resection of 100 spinal lipomas in infants less than 1 year of age. Pediatr Neurosurg 1995; 23: 182–186, discussion 186–187 Coley BD, Shiels WE, II, Hogan MJ. Diagnostic and interventional ultrasonography in neonatal and infant lumbar puncture. Pediatr Radiol 2001; 31: 399–402 Currarino G, Coln D, Votteler T. Triad of anorectal, sacral, and presacral anomalies. AJR Am J Roentgenol 1981; 137: 395–398 de Vries E, Robben SG, van den Anker JN. Radiologic imaging of severe cervical spinal cord birth trauma. Eur J Pediatr 1995; 154: 230–232 Hughes JA, De Bruyn R, Patel K, Thompson D. Evaluation of spinal ultrasound in spinal dysraphism. Clin Radiol 2003; 58: 227–233 Kriss VM, Kriss TC, Coleman RC. Sonographic appearance of the ventriculus terminalis cyst in the neonatal spinal cord. J Ultrasound Med 2000; 19: 207–209 Lam WW, Ai V, Wong V, Lui WM, Chan FL, Leong L. Ultrasound measurement of lumbosacral spine in children. Pediatr Neurol 2004; 30: 115–121 Lam WW, Ai V, Wong V, Lui WM, Chan FL, Leong L. Ultrasound measurement of lumbosacral spine in children. Pediatr Neurol 2004; 30: 115–121 Lew SM, Kothbauer KF. Tethered cord syndrome: an updated review. Pediatr Neurosurg 2007; 43: 236–248 Lin KL, Wang HS, Chou ML, Lui TN. Sonography for detection of spinal dermal sinus tracts. J Ultrasound Med 2002; 21: 903–907 Lowe LH, Johanek AJ, Moore CW. Sonography of the neonatal spine: part 1, Normal anatomy, imaging pitfalls, and variations that may simulate disorders. AJR Am J Roentgenol 2007; 188: 733–738

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Naidich TP, McLone DG, Shkolnik A, Fernbach SK. Sonographic evaluation of caudal spine anomalies in children. AJNR Am J Neuroradiol 1983; 4: 661–664 Nelson MD, Jr, Sedler JA, Gilles FH. Spinal cord central echo complex: histoanatomic correlation. Radiology 1989; 170: 479–481 Ogiwara H, Lyszczarz A, Alden TD, Bowman RM, McLone DG, Tomita T. Retethering of transected fatty filum terminales. J Neurosurg Pediatr 2011; 7: 42–46 Pang D, Dias MS, Ahab-Barmada M. Split cord malformation: Part I: A unified theory of embryogenesis for double spinal cord malformations. Neurosurgery 1992; 31: 451–480 Pierre-Kahn A, Zerah M, Renier D et al. Congenital lumbosacral lipomas. Childs Nerv Syst 1997; 13: 298–334, discussion 335 Scheible W, James HE, Leopold GR, Hilton SV. Occult spinal dysraphism in infants: screening with high-resolution real-time ultrasound. Radiology 1983; 146: 743– 746 Schenk JP, Herweh C, Günther P, Rohrschneider W, Zieger B, Tröger J. Imaging of congenital anomalies and variations of the caudal spine and back in neonates and small infants. Eur J Radiol 2006; 58: 3–14 Yundt KD, Park TS, Kaufman BA. Normal diameter of filum terminale in children: in vivo measurement. Pediatr Neurosurg 1997; 27: 257–259 Zalel Y, Lehavi O, Aizenstein O, Achiron R. Development of the fetal spinal cord: time of ascendance of the normal conus medullaris as detected by sonography. J Ultrasound Med 2006; 25: 1397–1401, quiz 1402–1403

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Chapter 5

5.1 Normal Anatomy and Variants

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5 Neck Erik Beek The structures of the neck are superficially located and easily examined with ultrasound. The retropharyngeal region is an exception because of the interposed air-filled pharynx. The deep lobe of the parotid gland is hidden behind the bony ramus of the mandible. A high-frequency linear array transducer (15.5 MHz) can exquisitely show the structures of the neck. However, a successful examination depends for a great part on the cooperation of the patient. Patience is required. The use of warm coupling gel can be advantageous. A small pillow under the shoulders improves access to the neck but can be perceived as threatening. Its use can be postponed until a later stage of the examination. The most common reason why an ultrasound examination is requested in our hospital is to assess the patency of the jugular and subclavian veins before the insertion of a central line. The technique is described below. The second most common reason is to evaluate a swelling. Ultrasound can in the vast majority of patients differentiate cystic from solid lesions. If considered in combination with the location of a swelling, the patient’s age,

signs, and symptoms, and the laboratory data, ultrasound can often provide a straightforward diagnosis, such as a second branchial cleft cyst or fibromatosis colli. Another common question is whether inflammation of neck structures has progressed to abscess formation. The following paragraphs will describe the most common anomalies of the neck that are examined with ultrasound.

5.1 Normal Anatomy and Variants The structures of the neck are easily imaged. A complete study should include the following: The echogenic parotid gland over the ramus of the mandible (▶ Fig. 5.1, ▶ Fig. 5.2, ▶ Fig. 5.3); The more hypoechoic and coarse submandibular gland at the tip of the parotid gland, medial to the mandibular angle (▶ Fig. 5.4 and ▶ Fig. 5.5); The sublingual gland in the floor of the mouth (▶ Fig. 5.6 and ▶ Fig. 5.7);

Fig. 5.2 Normal parotid gland in an 8-year-old boy.

Fig. 5.1 Normal parotid gland (arrow) in a 2-month-old boy.

Fig. 5.3 Normal parotid gland in a 6-year-old girl. Often, small islands of lymphoid tissue (arrows) are seen. Fig. 5.4 Normal submandibular gland (arrow) in a 2-month-old boy.

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Fig. 5.5a,b Normal submandibular gland in a 5-year-old girl (arrow, a) and in a 13-year-old girl (arrows, b).

Fig. 5.6 Normal sublingual glands (arrows) in an 8-year-old boy.

Fig. 5.7 Normal sublingual glands (arrows) in a 13-year-old girl. Note the mylohyoid muscle (arrowheads).

The homogeneous echogenic thyroid gland in the midline in the lower neck (▶ Fig. 5.8, ▶ Fig. 5.9); The more hypoechoic thymus in the suprasternal notch (▶ Fig. 5.10, ▶ Fig. 5.11); The carotid and subclavian arteries and the jugular and subclavian veins (▶ Fig. 5.12, ▶ Fig. 5.13, ▶ Fig. 5.14, ▶ Fig. 5.15, ▶ Fig. 5.16). In healthy children, lymph nodes are almost invariably present. A large node is located laterally under the floor of the mouth, just behind the meeting point of the parotid and submandibular glands. See the section on lymphadenopathy.

Tips from the Pro ●

Fig. 5.8 Normal thyroid gland (arrows) in a 2-month-old boy.

Use the highest-frequency linear array transducer that still shows enough of the deeper structures.

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Fig. 5.9a,b Normal thyroid gland (arrows) in a 13-year-old girl. Transverse (a) and sagittal (b) views.

Fig. 5.10 Normal thymus (arrow) in a term neonate.

Fig. 5.11 Normal thymus in a 2-month-old boy (arrowheads).

Fig. 5.12 Transverse view of the right subclavian artery (arrow) and vein (arrowhead).

Fig. 5.13 Transverse view of the left jugular vein (arrow) and common carotid artery (arrowhead) in a 2-month-old boy.

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Fig. 5.15 Six-year-old girl. Longitudinal view of the subclavian artery (arrow). Fig. 5.14 Six-year-old girl. Transverse view of the subclavian artery (arrow) and vein (arrowhead).

Fig. 5.16 Six-year-old girl. Longitudinal view of the subclavian vein (arrow). The vein will show changes in diameter with respiration, unlike the subclavian artery.

5.2 Pathology 5.2.1 Vessels of the Neck One of the most common reasons why ultrasound of the neck is requested is to demonstrate patency of the jugular, subclavian, and brachiocephalic veins before the insertion of a central venous line. The examination is generally easy to perform, although restlessness of the child can pose a problem, especially if combined with crying, which hampers Doppler measurements. The internal jugular vein is easily seen lateral to the common carotid artery. The right jugular vein is usually larger than the left jugular vein. The distal subclavian vein can be picked up in the sagittal plane below the collar bone, superficial and caudal to the subclavian artery. After redirection of the transducer along the length of the vein, Doppler measurements can be done. More

Fig. 5.17 Seventeen-year-old boy with recurrence of leukemia. This color Doppler image shows a calcified thrombus (arrow) at the transition from the right subclavian vein to the brachiocephalic vein.

medially, the subclavian vein can be seen from a window above the collar bone, and its confluence with the jugular vein. The left brachiocephalic vein is seen when the neck of the child is extended or a pillow is placed under the shoulder blades. The superior caval vein can be seen in infants through the thymus, but in older children, it is often hidden behind the lung. Normal veins vary in caliber with the respiratory cycle. Thrombosed veins do not collapse and cannot be compressed. A thrombus is echogenic (▶ Fig. 5.17), although fresh thrombus can be almost anechoic (▶ Fig. 5.18, ▶ Fig. 5.19, ▶ Fig. 5.20). In thrombosis, collaterals can be present, but a collateral vein can be mistaken for the normal vein. Look for the presence of superficial veins in a patient as a sign of collateral circulation. A thrombosis can be clinically occult. Sometimes, a large swelling can be seen laterally in the lower neck when a child is crying or pushing. Ultrasound can demonstrate an enlarged, ectatic external jugular vein.

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Fig. 5.18a,b a Thrombosed right subclavian vein (arrow) in a 12-year-old boy with a peripherally inserted central catheter (PICC line). The axillary and basilic veins were also thrombosed. Some echogenic material is visible in the vein. b Flow is absent on color Doppler.

Tips from the Pro ●

●

If you are requested to look for a thrombus at the tip of a central venous line, study a plain chest film to locate the tip before you start your sonographic examination. Know the location of normal veins, and do not mistake a collateral vein for a patent normal vein.

5.2.2 Cystic Lesions Thyroglossal Duct Cyst A thyroglossal duct cyst is a remnant of the thyroid gland that is detached during the descent of the gland from the base of the tongue to the lower neck. The cyst is located within 2 cm of the midline. Most are exactly in the midline between the thyroid gland and the hyoid bone, but they can occur above the level of the hyoid bone. The contents can be clear or cloudy, especially after being infected (▶ Fig. 5.21, ▶ Fig. 5.22, ▶ Fig. 5.23, ▶ Fig. 5.24). The cyst should move upward during swallowing. The differential diagnosis of a thyroglossal duct cyst is epidermoid or dermoid cyst.

Fig. 5.19 Seven-year-old girl with a Hickmann catheter in the right subclavian vein. A large thrombus in the superior caval vein (arrow) is seen. Blood flows around the thrombus on color Doppler.

Fig. 5.20a–c Twelve-year-old girl with a peripherally inserted central catheter (PICC line) via the left arm. a A large thrombus (arrow) is seen in the left subclavian vein, extending into the left brachiocephalic vein. b The left jugular vein is open, but no flow is detected on Doppler examination. c Flow is detected in the right jugular vein.

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Fig. 5.21a,b Two-year-old girl with a midline swelling. a An intermediate echogenic structure slightly right of the midline at the level of the hyoid bone is seen on a transverse image (arrow). b A normal thyroid gland is present (arrowheads). Pathology was concordant with a thyroglossal duct cyst.

Fig. 5.22 Three-year-old girl with a small midline tumor. Between the hyoid bone and the thyroid gland, a small hypoechoic cyst is demonstrated (arrow). It was resected with a central part of the hyoid bone (Sistrunk procedure). Pathologic examination showed a thyroglossal duct cyst.

Fig. 5.23 Three-year-old girl with a swelling in the anterior neck for a few weeks. A hypoechoic, smooth tumor is seen. This could be a thyroglossal duct cyst or a dermoid cyst. Pathologic examination showed a dermoid cyst.

Fig. 5.24a,b Thirteen-year-old girl with a fluctuating mass in the neck for 3 years. Ultrasound showed (a) a small cyst (arrow) to the right of the midline at the level of the hyoid bone and (b) a larger cyst (arrow) slightly lower on the left. No communication was seen. Also on magnetic resonance imaging, no connection between the cysts was observed. Pathology was concordant with a thyroglossal duct cyst.

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Neck In postoperative patients, imaging is more difficult. Sometimes, a cystic lesion is visible, but on other occasions an unclear clump of tissue with variable echogenicity is seen (▶ Fig. 5.25). Always image the thyroid gland itself because anecdotal stories tell of patients whose only ectopic thyroid tissue was located in the cyst itself. If a normal thyroid gland is demonstrated with ultrasound, then confirmation with radionuclear imaging is not necessary. Cysts are treated surgically with a Sistrunk procedure, which entails excision of the cyst and its track along with the central part of the hyoid bone. Fig. 5.25 Five-year-old boy, operated on three times for a thyroglossal duct cyst. A swelling and redness appeared in the middle of the scar. Ultrasound shows an irregular hypoechoic structure extending into the deeper tissue. The lesion moved with swallowing. The ultrasound findings are consistent with inflammation and possibly a small abscess. The boy underwent surgery again. On pathology, scar tissue was found and a small remnant of a cyst wall.

Branchial Cleft Cyst Branchial cleft cysts develop from remnants of the branchial apparatus. Most common are cysts of the second branchial arch and pouch. These lesions usually present in teenagers as a slowly growing mass in the lateral neck or, when infected, as a painful swelling where no tumor was noted before. The location of the cyst is anteromedial to the sternocleidomastoid muscle and anterolateral to the carotid artery and jugular vein (▶ Fig. 5.26). Although a cyst, it usually contains debris (▶ Fig. 5.27). It is sharply demarcated with a thin wall.

Fig. 5.26a,b Six-year-old girl with a swelling in the lateral neck for 9 months. a A branchial cleft cyst is seen anteromedial to the sternocleidomastoid muscle (M SCM) and anterolateral to the common carotid artery (ACC). VJ, jugular vein. b The cyst is in close contact with the submandibular gland.

Fig. 5.27a–c a Typical image of a branchial cleft cyst in a 9-month-old boy. The cyst is filled with debris, which swirls when the child is moving. b A branchial cleft cyst in a 12-year-old boy. c A more atypical cyst in a 12-year-old girl. She had a fluctuating mass in the right neck for 3 months. On ultrasound, a rather solid-looking mass is seen without vascularity. Differential diagnosis: lymph node abscess or inflamed branchial cleft cyst. At operation, pus was seen. On pathology, a branchial cleft cyst was identified.

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Fig. 5.29 Four-year-old boy with a sinus (arrow) in the right lateral neck. Beneath it, a cystic structure is visible, compatible with a branchial cleft cyst, which extends cranially.

Fig. 5.28 Four-month-old boy with a small pit in the right neck. Underneath it, a cystic structure (arrow) is visible that could not be traced into the deeper structures.

Fig. 5.30a–c Five-year-old boy with a fistula in the right neck. a Ultrasound shows a tract (arrow) coursing deep to the sternocleidomastoid muscle. On magnetic resonance imaging, no abnormalities were seen. A fistulogram (b, c) demonstrates a connection (arrows) to the right tonsillar fossa.

Ultrasound can be helpful during treatment with sclerosing agents. If the cyst is infected, the wall thickens, with increased flow seen on color Doppler. Debris will be present. Cysts from the first, third, and fourth arches are less frequent. Sinus and fistulas can be present (▶ Fig. 5.28, ▶ Fig. 5.29, ▶ Fig. 5.30). Ultrasound can demonstrate accompanying cysts, but in producing fistulas, a contrast fistulogram is indicated to demonstrate the tract and a possible connection to the pharynx. This diagnosis is very difficult with ultrasound.

Dermoid Cyst A dermoid cyst is a cystic teratoma that contains developmentally mature skin and adnexa of the skin, such as sweat glands, hair follicles, hair, and sebaceous glands. Dermoid cysts are

benign. An epidermoid cyst is lined by epithelium and contains keratin. Calcifications are absent. In the head and neck region, two types of dermoid cyst occur: orbital cysts and cysts in the subcutaneous tissue, often in the floor of the mouth or suprasternal notch. The most common site for an orbital dermoid cyst is at the lateral eyebrow, where it develops around the zygomaticofrontal suture. The cyst can also present at the medial orbit or on the skull. On ultrasound, the lesion is sharply demarcated, oval, and hypoechoic (see ▶ Fig. 5.30). Where the tumor abuts the skull, a depression of the bone is often visible. A very hyperechoic inner border of the cyst does not necessarily mean that the bone is intact. The dura is also very echogenic. If the cyst is near the midline and one is unsure whether it has eroded through the skull, additional computed tomography (CT) or magnetic

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Fig. 5.31 One-year-old girl with a swelling at the lateral eyebrow. An oval tumor (arrow) with hypoechoic content is present. The underlying bone is flattened but intact. Typical orbital dermoid cyst.

Fig. 5.32 Five-year-old girl with a swelling in the suprasternal notch. A sagittal image shows a well demarcated oval tumor (arrow) with almost homogeneous echogenicity. Pathologic examination showed a dermoid cyst.

resonance (MR) imaging is indicated. These imaging methods can also demonstrate an encephalocele. Dermoid cysts (▶ Fig. 5.31, ▶ Fig. 5.32, ▶ Fig. 5.33, ▶ Fig. 5.34, ▶ Fig. 5.35, ▶ Fig. 5.36, ▶ Fig. 5.37) in the neck region are usually in the midline. The tumor is smooth and oval or round, and its contents can be of any echogenicity. It can be homogeneous or mixed because of its contents, which may be fat, hair, blood, keratin, or something else. If a dermoid cyst is found between the hyoid bone and the thyroid gland, differentiation from a thyroglossal duct cyst is difficult. CT or MR imaging can show fatty content in a dermoid cyst; fat is not present in thyroglossal duct cysts.

Fig. 5.33 Two-year-old boy with a submental tumor located in the midline. Well delineated lesion with a thick wall. It is cystic with a large solid nodule. It was close to the hyoid bone. The patient was too young to follow instructions such as to stick out his tongue. The nodule is not compatible with a thyroglossal duct cyst. Pathologic examination showed a dermoid cyst.

5.2.3 Hemangiomas and Vascular Malformations Hemangiomas and vascular malformations are both endothelial malformations. Today, the classification of Mulliken is used. He described a division into hemangiomas and vascular malformations. The latter can be further divided into capillary, venous, arteriovenous, lymphatic, and mixed malformations and fistulas. In the case of vascular malformations, a separation into

Fig. 5.34a,b Four-year-old girl with a small swelling just left of the midline. On (a) transverse and (b) sagittal images, ultrasound shows an almost round tumor anterior to the left lobe of the thyroid gland (arrows). It was believed to be a thyroglossal duct cyst, but on microscopic examination, it was compatible with a dermoid cyst.

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Fig. 5.35a,b Sagittal (a) and transverse (b) views of a swelling (arrow) in the suprasternal notch of a 4-year-old girl, present for 2 weeks. It was free from the skin and underlying tissue. It did not move when the patient stuck out her tongue. On pathologic examination, a dermoid cyst was found.

Fig. 5.36 One-year-old boy presenting with a firm smooth tumor at the suprasternal notch. Sagittal ultrasound image shows an anechoic cyst with some wall thickening just above the sternal manubrium. Pathologic examination showed an epidermoid cyst.

Fig. 5.37 Fourteen-year-old boy with a swelling on the right cheek. There was a bluish discoloration over the bump. Clinically, it was a vascular tumor. Ultrasound showed an oval tumor with homogeneous echogenicity and a hypoechoic rim. Color flow was absent. On pathology, an infected sebaceous cyst was found.

Fig. 5.38a,b Ten-week-old girl with a hemangioma at the right lateral neck. a A well demarcated echogenic tumor (arrowheads) is visible in the subcutis. No extension into the deeper layers is present. b On color Doppler, the lesion is richly perfused.

high-flow lesions and low-flow lesions is even more important. High-flow lesions have an arterial component. Low-flow lesions do not have an arterial component. Hemangiomas are often called infantile hemangiomas because of the age at which they appear. They are small or absent at birth. They increase in size during the first year of life. Thereafter, they slowly decrease in size and can disappear, often

leaving a fibrofatty scar. If they occur in places where their increasing size poses clinical problems, such as around the orbit or near the airway, treatment is necessary. For the past few years, β-blockers have been the first line of treatment. On ultrasound, infantile hemangiomas in the infant are richly perfused tumors (▶ Fig. 5.38 and ▶ Fig. 5.39). Ultrasound can show their extent into deeper tissues. If there is any doubt

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Fig. 5.39a–c Four-month-old boy with a progressive swelling anterior to the left ear. On palpation, a mass was felt. a Ultrasound shows a lesion that involves almost the entire parotid gland. b The lesion shows abundant perfusion on color Doppler. c Magnetic resonance imaging demonstrates extension toward the parapharyngeal space. Note the large vessels (arrow).

about this, MR imaging is indicated. On color Doppler, the involution of a hemangioma is signaled by decreased perfusion of the mass. Vascular malformations are present at birth and grow proportionally with the child. They can be asymptomatic or cause symptoms, sometimes at an older age. Ultrasound can show the extent of a lesion, but if this is unclear, MR imaging should be employed (▶ Fig. 5.40 and ▶ Fig. 5.41). Doppler ultrasound can demonstrate the presence of arterial Doppler signals and direct further imaging. If Doppler ultrasound shows arterial waveforms suggesting a high-flow lesion, angiography should be done to determine if transarterial embolization is feasible. If Doppler ultrasound shows a low-flow lesion, direct puncture under ultrasound can be done, followed by phlebography and, if possible, sclerosis. Excision is another therapeutic option. Vascular malformations, especially those with predominantly venous components, can be difficult to depict because they are

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easily compressed. Use a lot of gel and just touch the lesion lightly. Lesions with mostly lymphatic components, also called lymphangiomas, cannot be easily compressed (▶ Fig. 5.42, ▶ Fig. 5.43, ▶ Fig. 5.44, ▶ Fig. 5.45). In infancy, a multicystic form occurs, composed of innumerable small cysts. This lesion is often apparent at birth as a gross swelling of the neck and is also known as hygroma colli. In older children, lymphangiomas appear mostly in the posterior neck and consist of one or more larger cysts. Lymphangiomas can extend much farther than ultrasound shows. If there is any doubt about the extent of a tumor, additional MR imaging is indicated. Surgery is the primary treatment for hygroma colli, but the operation can be difficult because the tumor has a tendency to infiltrate the deeper tissues (see ▶ Fig. 5.42). The form with larger cysts can be surgically removed, but aspiration and

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Fig. 5.40a,b Seventeen-year-old girl with a vascular malformation of the left masseter muscle, discovered at the age of 3 weeks. It was a lesion with high flow on ultrasound. No therapy was given. She returned after 10 years because of ridicule at school due to the swelling of her face. a Ultrasound shows an echogenic lesion in the lateral part of the masseter muscle (arrow). The normal right side (arrowhead) is shown for comparison. b T2weighted coronal magnetic resonance imaging of the same lesion (arrow).

injection with a sclerosing agent is also done (see ▶ Fig. 5.43, ▶ Fig. 5.44, ▶ Fig. 5.45).

5.2.4 Pilomatrixoma A pilomatrixoma (calcifying epithelioma of Malherbe) is a benign tumor of the subcutaneous tissue. The center contains cells loaded with keratin, and calcifications are common. Approximately half of the lesions occur in the head and neck region. Most of the patients come to medical attention between 5 and 10 years of age. Multiple tumors can occur. Pilomatrixoma is not infrequent but is rarely imaged; consequently, the imaging characteristics are not well-known by radiologists. On ultrasound, the lesion is superficially located. It is mostly oval and heterogeneously hyperechoic with posterior acoustic shadowing. A hypoechoic rim is present in the majority of lesions. In approximately half of the lesions, the peritumoral tissue is hyperechoic (▶ Fig. 5.46, ▶ Fig. 5.47, ▶ Fig. 5.48, ▶ Fig. 5.49). The differential diagnosis includes calcified lymph node, ossifying hematoma, and hemangioma with phleboliths.

Tips from the Pro ●

If you detect a superficial lesion that is oval and heterogeneously hyperechoic with posterior acoustic shadowing and a hypoechoic rim, think of pilomatrixoma.

5.2.5 Solid Tumors Fibromatosis Colli Fibromatosis colli appears in infants in the first weeks of life. It is probably caused by ischemia of the muscle. Although many believe it to be a hemorrhage into the muscle, this is not confirmed by pathologic examination or MR imaging studies. Infants present with either a swelling in the neck or a torticollis. A large percentage of affected infants are born in breech. The clinical course is mostly benign, and a wait-and-see policy is appropriate. The administration of active exercise with head

movements by the parents of patients with torticollis is often sufficient therapy. Surgical cleavage of the affected muscle is seldom necessary. Fibromatosis colli causes thickening of the sternocleidomastoid muscle. This can affect the sternal head, the clavicular head, or both heads of the muscle. The lesion can be hypo-, iso-, or hyperechoic. The thickening of the muscle can be focal or diffuse. If the distal ends of both heads of the muscle are affected, ultrasound shows two tumors (▶ Fig. 5.50, ▶ Fig. 5.51, ▶ Fig. 5.52).

Lymphadenopathy Lymph Node Levels The necks of healthy children are full of lymph nodes, and they are seen even in babies. A normal lymph node is oval and mildly echogenic, with a more echogenic hilum. With color Doppler, vessels can be demonstrated in the hilum (▶ Fig. 5.53 and ▶ Fig. 5.54). A commonly used classification for the location of lymph nodes is shown in ▶ Fig. 5.55. The nodes are classified according to their location in seven levels, as proposed by Greene et al. Level 1 includes the submental and submandibular nodes, found at the floor of the mouth. The nodes in levels 2, 3, and 4 are situated along the internal jugular vein. Level 2 extends from the hyoid bone upward. The jugulodigastric node (see below) is included in level 2. Level 3 reaches from the hyoid bone to the cricoid cartilage. Level 4 extends from the cricoid cartilage to the clavicles. Level 5 is the posterior triangle, which is posterior to the sternocleidomastoid muscle and above the clavicles. Level 6 nodes are anterior to the thyroid gland. Level 7 nodes are in the upper mediastinum. With ultrasound, the classification is more difficult than with CT and MR imaging, especially in uncooperative children.

Sonographic and Clinical Features Large nodes are often found in asymptomatic children. Nodes larger than 1 cm are considered as pathologic. Below the angle of the mandible, slightly behind the meeting point of the

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Fig. 5.41a–d One-month-old girl with a swelling in the floor of the mouth, under the tongue. Ultrasound (a) did not show the extension of the vascular malformation into the parapharyngeal space (arrow, b) and mediastinum (arrowheads, c, d) seen on magnetic resonance imaging.

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Fig. 5.42a,b Two-year-old boy with a swelling in the right neck. Ultrasound (a) shows a multicystic vascular malformation. No perfusion was seen on color Doppler. The mass was treated with a sclerosing agent (arrow: needle tip) (b). (Courtesy of R. R. van Rijn, Academic Medical Center, Amsterdam, The Netherlands.)

Fig. 5.43a,b Seven-month-old girl with a swelling in the right neck, deep to the sternocleidomastoid muscle, consistent with a vascular malformation (arrow). b One week after OK-432 injection, the lesion has increased in size. One year later, the lesion had decreased slightly in size.

Fig. 5.44a,b Two-year-old girl with a swelling in the right lower neck. a A multicystic tumor was detected with ultrasound. b On magnetic resonance imaging (proton density fat-suppressed sequence), extension into the parapharyngeal space (arrowhead) and into the floor of the mouth was visible. Sclerotherapy of the lesion with OK-432 had limited success.

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Fig. 5.45 One-year-old girl with a swelling in the right lower neck. A multicystic tumor (arrow) extends behind the larynx (arrowhead) to the left. After sclerotherapy with OK-432, the lesion involuted. Two years later, a recurrence was seen in the supraclavicular region. Unfortunately, no magnetic resonance imaging was done before the sclerotherapy.

Fig. 5.46 Four-year-old boy with a preauricular bluish tumor. A well demarcated superficial lesion (arrow) is seen at the tip of the parotid gland, with mixed echogenicity and a hypoechoic rim. No posterior shadowing. Pathology showed a pilomatrixoma.

Fig. 5.47 Two-year-old girl with a tumor (arrow) at the medial right eyebrow. The tumor has mixed echogenicity and a hypoechoic rim, consistent with a pilomatrixoma.

Fig. 5.48a,b Ten-year-old boy with a tumor at the right upper arm. a The tumor is located in the subcutis, is well demarcated, and has mixed echogenicity and a hypoechoic rim. Also, some posterior acoustic shadowing is present. b Power Doppler shows some vascularization of the wall.

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Fig. 5.50 Three-week-old girl. Transverse view of the normal distal left sternocleidomastoid muscle. The sternal head (arrow) and clavicular head (arrowhead) are well seen. Fig. 5.49 Three-year-old boy with a preauricular swelling. Again, a tumor with mixed echogenicity and a hypoechoic rim is demonstrated. Also, some posterior acoustic shadowing is present in this pilomatrixoma.

Fig. 5.51a–c Seven-week-old boy with a swelling in the right neck since the age of 2 weeks. He was delivered via cesarean section. a A mass of mixed echogenicity (arrows) is visible in the right sternocleidomastoid muscle on a sagittal image, compatible with fibromatosis colli. b On a transverse image, both heads of the muscle are affected (arrows). c The left muscle (arrow) is normal.

Fig. 5.52a–c Three-week-old boy, born in breech, with a swelling in the left neck. The sternocleidomastoid muscle was swollen. a A transverse view through the distal muscle shows swelling of the sternal (S) and clavicular (C) heads. b Another patient with a swollen right muscle (arrow) and a normal left muscle (arrowhead) on sagittal views.

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Fig. 5.53 Normal lymph node next to the jugular vein in a 4-day-old boy (arrow).

Fig. 5.54 Normal lymph node next to the jugular vein in a 4-year-old boy (arrow).

Fig. 5.56 Normal lymph node at the left mandibular angle in a 6-yearold boy (arrow). It measures 2 cm. It abuts the edge of the submandibular gland (arrowhead).

Fig. 5.55 Drawing of the cervical lymph node levels. For the description, see the text. The solid line through the hyoid cartilage separates levels 2 and 3. The dashed line through the cricoid cartilage separates levels 3 and 4.

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parotid and submandibular glands, the jugulodigastric node can be as large as 2 cm in normal children (▶ Fig. 5.56). Reactive lymph nodes are enlarged but generally retain a morphology with an echogenic hilum. In upper airway infections and infections of the head and neck, many of these reactive nodes are visible. On imaging alone, a specific pathology can be suggested, but a combination of sonographic findings and clinical signs and symptoms is better for making a useful limited differential diagnosis. Sometimes biopsy is necessary. In banal lymphadenitis, enlarged nodes are present. The infection will often regress with antibiotic therapy (▶ Fig. 5.57). In some infections, such as those caused by Bartonella henselae (▶ Fig. 5.58, ▶ Fig. 5.59, ▶ Fig. 5.60, ▶ Fig. 5.61), and malignancies the nodes are hypoechoic with loss of the hilum, enlarged, and almost round. These features should alert the sonographer that serious pathology can be present. In atypical mycobacterial infection, the child is often remarkably free of symptoms, although grossly swollen nodes can be seen (▶ Fig. 5.62 and ▶ Fig. 5.63). The infection can persist for months, and abscess formation can slowly progress in the nodes. Calcifications can be seen in a later stage. The floor of

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Fig. 5.57 Four-year-old boy with slight fever and a swelling in the left neck. Ultrasound depicts several enlarged hypoechoic lymph nodes (arrows). The boy recovered quickly with antibiotic therapy.

Fig. 5.58 Fifteen-year-old girl with a nontender swelling in the left neck for 2 weeks. Several enlarged, hypoechoic, almost round lymph nodes were seen, possibly malignant lymphoma. The final diagnosis was a Bartonella henselae infection (cat-scratch disease).

Fig. 5.59a,b Six-year-old girl with swollen lymph glands bilaterally in the neck on physical examination. Ultrasound demonstrated large confluent masses, partly perfused (a), partly nonperfused (b). The mass on the left side was drained surgically. The final diagnosis was Bartonella henselae infection.

Fig. 5.60 Eighteen-month-old girl presenting with a nontender swelling in the right neck and overlying redness of the skin. Ultrasound shows a rather well demarcated echogenic mass (arrows). After 2 weeks, the ultrasound appearance was unchanged. A biopsy confirmed a Bartonella henselae infection.

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Fig. 5.61a,b Six-year-old girl with a painful swelling in the submental region. a Several enlarged lymph nodes were visible. b On color Doppler, no avascular areas were seen, thus no abscess formation. The child was treated with antibiotics directed at Bartonella henselae. The mass liquefied and was aspirated. Polymerase chain reaction of the pus was positive for Bartonella henselae.

Fig. 5.62a–c Three-year-old girl with a progressive swelling in the left neck at level 5. a Several swollen lymph nodes are seen. b One month later, small abscesses (arrow) are present. c Computed tomography confirms the abscess formation and demonstrates extension into the parapharyngeal space (arrows). The final diagnosis was an atypical mycobacterial infection.

Fig. 5.63a–c Two-year-old girl with a painless progressive swelling in the left neck. a A 4-cm lymph node is seen with a small anechoic area. There were several other enlarged nodes. b Three months later, abscess formation is present. It caused a gross swelling of the neck with purple–red overlying skin. The abscess was drained. c After another 2 months, the abscess had slowly diminished. A neighboring node shows beginning calcification (arrow).

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Fig. 5.64a,b One-and-a-half-year-old boy with a progressive swelling of the submandibular area, resembling Ludwig angina. a A diffuse swelling of the floor of the mouth is seen. Some enlarged lymph nodes were present. b One week later, a small abscess (arrow) is present. This was drained, and the boy had an uncomplicated recovery.

Fig. 5.65 Four-year-old boy. He had had an ear infection, followed by fever and a swollen neck. His condition improved on a 7-day course of antibiotic therapy, but then the swelling reappeared. Ultrasound shows a mass with a hypoechoic center. Moving debris was seen in this area. Fifteen milliliters of pus was aspirated, but the abscess filled after 2 days and was surgically drained. No microorganisms were cultivated.

the mouth is a common site of infection. In early stages, a diffuse edematous swelling is seen that can progress to abscess formation (▶ Fig. 5.64). Inflamed lymph nodes can become necrotic and form abscesses (▶ Fig. 5.65 and ▶ Fig. 5.66). A large abscess with debris swirling in its center is easy to diagnose, but the diagnosis of a small abscess can be demanding. Color Doppler can show absence of flow in the lymph node. Sometimes a conglomerate of nodes is seen, with some areas of abscess formation. Malignant lymph nodes, as seen in Hodgkin lymphoma, nonHodgkin lymphoma, and leukemia, are mostly enlarged and hypoechoic with loss of the echogenic hilum. The sonographic features alone often do not allow a differentiation from infectious causes (▶ Fig. 5.67, ▶ Fig. 5.68, ▶ Fig. 5.69, ▶ Fig. 5.70). Supraclavicular lymph nodes are considered malignant until proven otherwise.

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Fig. 5.66a,b Eighteen-year-old boy with a very firm swelling in the lateral neck. a Ultrasound shows a lymph node with a length of almost 3 cm. Because of the firmness of the lymph node, an excision biopsy was done. No malignancy was found on pathologic examination. The biopsy was complicated by inflammation with abscess formation. b On ultrasound, echogenic fluid was moving in the superficial part of the collection (arrows).

Fig. 5.67 Fourteen-year-old boy presenting with a rapidly progressive swelling of the left neck, extending to the supraclavicular area. Several hypoechoic, well demarcated supraclavicular lymph nodes are visible (arrows). Pathology showed a large-cell anaplastic lymphoma.

Fig. 5.69 Seven-year-old boy with a progressive swelling in the left neck for 5 months. Ultrasound demonstrates an enlarged lymph node with a maximum diameter of 4 cm. It is slightly hypoechoic and homogeneous, and it lacks an echogenic center. On pathology, a paragranuloma, a mild form of Hodgkin disease, was identified.

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Fig. 5.68 Fourteen-year-old girl with a slowly growing tumor in the left neck. Ultrasound showed a hypoechoic enlarged lymph node medial to the lower tip of the parotid gland. The normal echogenic hilum is not visible. Excision biopsy showed Hodgkin disease.

Fig. 5.70 Eighteen-year-old girl with multiple endocrine neoplasia type 2 syndrome. A thyroidectomy was performed for a medullary carcinoma. Elevated calcitonin levels was noted during follow-up. A slightly enlarged lymph node with some microcalcifications is seen (arrow). More enlarged nodes were present in the neck. Pathology after a neck dissection showed metastatic lymph nodes.

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Fig. 5.71a,b Three-year-old girl with a slowly growing mass high in the right neck for 4 months. a No thyroid tissue was seen in the normal location. b The mass in the right neck at the level of the hyoid bone is of mixed echogenicity (arrow). Cytology showed thyroid tissue, thus an ectopic thyroid gland.

Fig. 5.73 Fifteen-year-girl girl with fatigue. Ultrasound shows a coarse, inhomogeneous thyroid gland with some small nodules. Imaging, clinical, and laboratory findings were compatible with Hashimoto thyroiditis.

▶ Fig. 5.10). The bridge between the two lobes is the isthmus. A pyramidal lobe can be present at the isthmus. On color Doppler, a rich perfusion of the gland is seen.

Ectopic Thyroid Gland Fig. 5.72 Neonate with an abnormal neonatal screening test for thyroid function. A radionuclide scan was indeterminate, possibly a lingual thyroid. Ultrasound shows a rather echogenic mass between the hyoid bone and the base of the tongue (arrow).

5.2.6 Thyroid Gland The thyroid develops from the floor of the primitive pharynx, at the base of the tongue, and descends to the lower neck. Along its path of descent is the thyroglossal duct, which normally obliterates. Remnants of this duct give rise to thyroglossal duct cysts. Remnants of thyroid tissue can persist in this tract, or all of the thyroid tissue can be arrested somewhere along it. The normal thyroid consists of two lobes with an echogenicity comparable with that of the spleen (see ▶ Fig. 5.8, ▶ Fig. 5.9,

Patients with an ectopic thyroid often have hypothyroidism. The most common ectopic location of a thyroid gland is at the base of the tongue. If no thyroid gland is visible in its normal location anterior to the thyroid cartilage, one should image up to the floor of the mouth (▶ Fig. 5.71 and ▶ Fig. 5.72). Radionuclide scanning can be of considerable help.

Thyroiditis The most common form of thyroiditis in childhood is Hashimoto thyroiditis, an autoimmune disorder (▶ Fig. 5.73). On ultrasound, the gland is enlarged with a coarse pattern. On color Doppler, perfusion is normal, differentiating it from Graves disease, in which the flow is increased (▶ Fig. 5.74). The ultrasound appearance of Graves disease cannot be distinguished from that of Hashimoto thyroiditis; the organ is enlarged with a coarse echo pattern. On color Doppler, the increased vascularity is imaged as a “thyroid inferno.”

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Fig. 5.74a,b Thirteen-year-old girl with hyperthyroidism. a The thyroid gland is inhomogeneous and enlarged. b On color Doppler, it is hypervascular. Graves disease was the final diagnosis.

Fig. 5.75 Small cyst in the left thyroid lobe in a 12-year-old girl. Fig. 5.76 Seventeen-year-old girl with a slowly growing tumor just left of the midline. On ultrasound, a cyst with an irregular wall was seen. Aspirated cyst fluid and cytologic aspiration of the cyst wall did not demonstrate malignant cells.

Thyroid Nodules Tumors in the thyroid gland are well imaged by ultrasound. Cysts are easily diagnosed as echolucent lesions with sharp walls and posterior acoustic enhancement (▶ Fig. 5.75 and ▶ Fig. 5.76). Solid nodules can be single (▶ Fig. 5.77 and ▶ Fig. 5.78) or multiple, also called a struma (▶ Fig. 5.79). Malignant tumors of the thyroid gland are uncommon. Papillary carcinoma is more frequent than medullary carcinoma (▶ Fig. 5.80). The latter disorder is associated with multiple endocrine neoplasia syndrome (▶ Fig. 5.81).

5.2.7 Salivary Glands

Fig. 5.77 Solitary thyroid nodule in a 16-year-old girl, panoramic view. Cytologic aspiration demonstrated only benign cells.

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The parotid and submandibular glands are well visualized by ultrasound (see ▶ Fig. 5.1, ▶ Fig. 5.2, ▶ Fig. 5.3, ▶ Fig. 5.4, ▶ Fig. 5.5). The sublingual gland is more hidden in the floor of the mouth (see ▶ Fig. 5.6 and ▶ Fig. 5.7). A 17.5-MHz linear array probe provides excellent images. The superficial lobe of the parotid gland is located at the ramus mandibulae. Posteriorly, the parotid gland wraps around

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Fig. 5.78 Solitary homogeneous thyroid nodule (arrow) in a 13-yearold boy. Cytologic aspiration was compatible with an adenoma. (Courtesy of R. R. van Rijn, Academic Medical Center, Amsterdam, The Netherlands.)

Fig. 5.79a,b Sixteen-year-old girl with a swelling in the lower neck, clinically a struma. a On ultrasound, multiple nodules were present in both lobes of the thyroid gland, consistent with a multinodular struma. b The nodules are richly vascularized.

Fig. 5.80a,b Sixteen-year-old girl with an enlarged thyroid gland. In the right lobe, a 2-cm nodule was seen, and in both lobes, hypoechoic lesions with punctate hyperintensities (arrows) were present. a Transverse view of the right lobe. b Sagittal view of the left lobe. Aspiration cytology showed malignant cells. Examination after thyroidectomy demonstrated papillary carcinoma in both lobes.

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Fig. 5.81 Twelve-year-old boy with multiple endocrine neoplasia type 2. Bilateral hypoechoic lesions were seen. A total thyroidectomy was done. The anomaly on the right was a microinvasive medullary carcinoma. The lesion on the left showed hyperplasia.

Fig. 5.82 Four-year-old boy with progressive swelling and redness of the left check. Ultrasound shows swollen lymph glands (arrows) within the left parotid gland. The lesion was aspirated twice under ultrasonic guidance. The second time, polymerase chain reaction for Bartonella henselae was positive. After a month of antibiotic therapy, there was no improvement. The left parotid gland was drained, after which the swelling and redness quickly disappeared.

Fig. 5.83 Two-year-old boy with a swollen left cheek for several weeks. On ultrasound, the left parotid gland was very inhomogeneous and contained multiple hypoechoic masses, probably lymph nodes. The boy was treated with oral antibiotics, after which the swelling disappeared. The final diagnosis was a bacterial parotitis.

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the mandible. The deep lobe is at the inner side of the mandible and thus largely hidden from view. The parotid gland is homogeneously echogenic. In older children, hypoechoic islands of lymphoid tissue can be present. The submandibular gland is located below the floor of the mouth. Its posterior portion wraps around the free edge of the mylohyoid muscle. It is less echogenic than the parotid gland. The sublingual gland can be seen in the floor of the mouth contained by the mandible and the mylohyoid, genioglossus, and geniohyoideus muscles. The parotid gland is more frequently affected by disease than the other glands. Infection, autoimmune disease, and tumors can involve the parotid gland (▶ Fig. 5.82 and ▶ Fig. 5.83). A common pattern is a gland with numerous small hypoechoic lesions. This is, for instance, seen in HIV infection and Sjögren disease (▶ Fig. 5.84, ▶ Fig. 5.85, ▶ Fig. 5.86). The parotid gland is a favorite location of infantile hemangioma (see ▶ Fig. 5.39). An obstruction of the duct of a sublingual gland can cause a cystic dilatation of the duct, called a ranula. It appears with a

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Fig. 5.84a,b Eleven-year-old girl, known to have Sjögren disease. For a month, she experienced increasing tenderness of the left cheek. Ultrasound shows subtle hypoechoic lesions in both parotid glands, more (a) left sided than (b) right sided, compatible with Sjögren disease.

Fig. 5.85a,b Seventeen-year-old girl with Sjögren disease. Small hypoechoic lesions were visible in the (a) left parotid gland and (b) left submandibular gland. On the right side, the salivary glands were normal.

Fig. 5.86 Ten-year-old boy with bilateral swelling of the cheeks. On ultrasound, both parotid glands showed multiple small hypoechoic lesions. After a few weeks, the swellings disappeared. No final clinical diagnosis was made.

swelling under the tongue. Most ranulas herniate through a defect in the mylohyoid muscle into the submandibular space, in which case they are called plunging ranulas. Ultrasound of the floor of the mouth can demonstrate these lesions (▶ Fig. 5.87). Sialoliths are rare in children. More than 80% occur in the submandibular gland. Ultrasound can demonstrate the stones with posterior shadowing and a dilated duct (▶ Fig. 5.88). The gland can be enlarged. Tumors of the salivary glands are rare in children. The most common benign tumors are pleomorphic adenoma (▶ Fig. 5.89) and hemangioma (see ▶ Fig. 5.39). Most tumors are located in the parotid gland. Approximately one-third of salivary gland tumors in the pediatric age group are malignant. Again, the parotid gland is most frequently affected, and mucoepidermoid carcinoma is the most common type. In patients with excessive drooling (sialorrhea), ultrasoundguided injection of botulinum toxin A (Botox A) into the parotid and submandibular salivary glands can diminish drooling and improve patient care (▶ Fig. 5.90). We inject 1 mL containing 25 units in each gland, but there is a wide variation in volume and

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Fig. 5.87 Thirteen-year-old boy with a swelling in the floor of the mouth. A cystic lesion (arrowhead) of the left sublingual gland is seen, compatible with a ranula. Note the curved mylohyoid muscle (arrows).

Fig. 5.88a,b Twelve-year-old boy with pain in the left floor of the mouth for more than a year. The duct of the submandibular gland is dilated (arrow, a), and a sialolith (arrow, b) with posterior shadowing is seen. (Courtesy of R. R. van Rijn, Academic Medical Center, Amsterdam, The Netherlands.)

Fig. 5.89a,b Twelve-year-old girl with a swelling in the left side of the floor of the mouth. a A hypoechoic mass is seen in the submandibular gland. b There is some perfusion in the lesion. Pathology: pleomorphic adenoma. (Courtesy of R. R. van Rijn, Academic Medical Center, Amsterdam, The Netherlands.)

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Fig. 5.90 Botox injection into the submandibular gland. The needle (arrow) is visible under ultrasound guidance.

Fig. 5.91 Thymus (arrow) in a 26-week-old premature infant.

Fig. 5.92a,b Thymus (arrows) in a term neonate on (a) transverse and (b) sagittal views.

dose between institutions. Always aspirate before injection to prevent intravascular deposition.

5.2.8 Thymus The thymus can be imaged through the suprasternal notch in infants. The thymus provides an acoustic window to the deeper mediastinal structures, especially the large vessels. The older the child, the more limited the sonographic access because of the more advanced ossification of the cartilaginous parts of the sternum and ribs and relative shrinkage of the thymus. In infants, the thymus is hypoechoic with echogenic standing. With advancing age, the echogenicity of the thymus becomes more punctate (▶ Fig. 5.91, ▶ Fig. 5.92, ▶ Fig. 5.93, ▶ Fig. 5.94).

The thymus can be involved in lymphatic malignancies, but in these patients imaging is primarily by CT or MR imaging. Ultrasound can be useful in neonates and infants with a wide upper mediastinum on plain films in whom doubt persists regarding the nature of the widening. With ultrasound, the presence of a normal large thymus is easily demonstrated (▶ Fig. 5.95).

Ectopic Thymic Tissue The thymus descends during fetal life from the upper neck to its retrosternal location. Remnants of thymic tissue, or an entire thymic lobe, can be found along this course of

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Fig. 5.93 Thymus (arrow) in a 6-year-old girl has punctate echogenicity.

Fig. 5.94a–c Transverse (a) and sagittal (b) images of the thymus (arrows) in a 9-year-old boy. The thymus shows a coarse echogenicity. c Very coarse, punctate thymus (arrows) in a 12-year-old boy.

Fig. 5.95a–c Five-month-old boy presenting with fever for 5 days and an elevated white cell count. a A plain chest film shows a mass in the left apex (arrow). The clinicians suspected a tumor. b A computed tomographic scan depicts a mass compatible with a large thymus (arrow). c Additional ultrasound convinced the clinicians that the mass was indeed a large thymus (arrow).

descent. These can be cystic or solid tumors. The first are also named thymopharyngeal duct cysts. There can be a connection to the piriform sinus. These remnants are more frequently an incidental finding as a consequence of the increased use of ultrasound. The lesions are mostly small and clinically silent. In a retrospective study of more than 25,000 patients treated for head and neck lesions, only three cases of cervical ectopic thymus presenting as a mass were

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found. Thymic remnants in the thyroid gland have been described as being observed quite frequently with modern ultrasound probes. The sonographic appearance depends on the age of the child, as the echogenicity and coarseness of the thymus increase with advancing age. Knowledge of the sonographic patterns of the aging thymus enable a diagnosis of cervical thymic rests (▶ Fig. 5.96 and ▶ Fig. 5.97).

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Fig. 5.96a–c a Incidental finding of a mass in the left neck on magnetic resonance imaging in an 8-month-old boy (arrow). It followed the signal intensities of thymic tissue (arrowhead) in all pulse sequences. b Ultrasound confirms ectopic thymic tissue (arrow), which has the same sonographic characteristics as the orthotopic thymus (arrowhead).

Fig. 5.97a,b Two-year-old boy presenting with a swelling in the right neck. a Ultrasound demonstrates a mass with a coarse echotexture, compatible with thymic tissue. b Comparison of the echotextures of the ectopic thymus (arrow, left) and the orthotopic thymus (arrowhead, right).

5.2.9 Miscellaneous Lesions

Fig. 5.98 Eighteen-year-old boy with a soft swelling in the dorsal neck for a few weeks, clinically and sonographically a lipoma. The lesion is of mixed echogenicity and well demarcated.

In addition to the anomalies described in the previous pages, other, rarer lesions can occur. Some are mentioned in this section. Lipomas (▶ Fig. 5.98) are not that rare but are infrequently imaged with ultrasound. The nature of the mass is often clear on clinical grounds. The clinician may want to know if the lesion is confined to the subcutaneous tissue or infiltrates deeper structures, like muscle. If the lesion is well demarcated, ultrasound alone is sufficient. It will show a mass that resembles subcutaneous fat. If there is doubt about the borders of the lipoma and deeper infiltration cannot be excluded, MR imaging should be done if excision is contemplated.

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Fig. 5.99a,b Six-year-old girl presenting, according to the mother, with a slowly progressive firm mass in the right neck. a Ultrasound shows an echogenic lesion (arrow) with acoustic shadowing and a hypoechoic rim, probably cartilage. b A plain film of the thoracic inlet demonstrates bilateral cervical ribs (arrows), the right side larger than the left.

Fig. 5.100a,b Eighteen-year-old boy aware of a swelling in the right neck for 1½ years. On palpation, a firm swelling was felt deep to the sternocleidomastoid muscle. a Ultrasound shows a well delineated solid mass beneath the sternocleidomastoid muscle. b The lesion is well perfused but not abundant. Pathologic examination of an excision biopsy showed a paraganglioma.

A cervical rib can present as a hard supraclavicular mass. Ultrasound can reveal the nature of the mass. This is an echogenic structure that can have a hypoechoic cartilaginous covering (▶ Fig. 5.99). It disappears in the deeper structures of the neck. A plain film of the thoracic inlet can confirm the presence of a cervical rib. Paragangliomas are rare tumors that can occur sporadically or in hereditary forms with multiple endocrine neoplasia type 2 syndrome, von Hippel–Lindau disease, and or neurofibromatosis type 2. In the familial form, paragangliomas are often multiple. They can present as a neck mass located at the bifurcation of the carotid artery (▶ Fig. 5.100). They are mildly echogenic and well perfused.

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Midline tumors of the skull should be suspected to be of neurogenic origin. Although many will turn out to be epidermoid cysts, a small meningocele or meningoencephalocele can occur (▶ Fig. 5.101). A cephalohematoma is a subperiosteal hematoma most commonly presenting over the parietal bone, sometimes bilaterally. It is a clinical diagnosis, but parents can be worried because a cephalohematoma can take long to resolve or to be remodeled into the skull. Ultrasound shows a fluid collection with variable amounts of clotted blood (▶ Fig. 5.102). The superficial periosteum starts to calcify within a few weeks (▶ Fig. 5.103). Noticeable is that the hematoma often produces a mirror-image

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Fig. 5.101 Three-month-old boy with cheilognathopalatoschisis and a swelling in the midline of the skull. Ultrasound shows a superficial well demarcated oval lesion (arrow) with an intracranial extension. Magnetic resonance imaging was compatible with a small meningocele.

Fig. 5.102 Eighteen-day-old boy with a parietal swelling that developed 1 day after a normal delivery. Ultrasound shows an organizing hematoma, consistent with a cephalohematoma. Notice the start of calcification in the uplifted periosteum (arrowhead). Also notice the mirror-image artifact, which could be mistaken for an epidural hematoma (arrows).

Fig. 5.103a,b Two-month-old boy with a very firm swelling in the parietal region since birth. Ultrasound (a) shows an anechoic collection with a very echogenic wall. A plain film (b) confirms the presence of a calcifying cephalohematoma.

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Neck artifact, which should not be mistaken for an intracranial fluid collection like an epidural hematoma. As an oddity, images are shown of an osteal location of acute myeloid leukemia, called a chloroma (▶ Fig. 5.104). Notice the spiculated appearance of the periosteal reaction. A large variety of tumors can occur in the head and neck region in children. To mention some: teratoma (▶ Fig. 5.105), benign fibrous histiocytoma, myofibroma (▶ Fig. 5.106), esthesioneuroblastoma, Ewing sarcoma, fibrosarcoma, giant cell granuloma, Langerhans cell histiocytosis, neuroblastoma (▶ Fig. 5.107), neurofibroma, osteochondroma, and rhabdomyosarcoma. All are rare and seldom diagnosed with ultrasound alone.

Tips from the Pro ●

A cephalohematoma often produces a mirror-image artifact, which should not be mistaken for an epidural hematoma.

Fig. 5.104 One-year-old boy treated 2 months ago for acute myeloid leukemia, which manifested with swellings on the back of the head that proved to be chloromas. Now, his mother has noticed a mass on the left cheek. Ultrasound shows a hypoechoic lesion originating from the left side of the mandible (arrows). It has echogenic lines perpendicular to the mandible, suggesting periosteal reaction. Pathologic examination showed a new chloroma.

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Fig. 5.105a,b Newborn boy with a large mass in the neck. a Ultrasound shows a mass with solid tissue and cysts. b This is confirmed on a coronal T2weighted magnetic resonance image. The diagnosis was an immature teratoma. The tumor was successfully resected. (Courtesy of R. R. van Rijn, Academic Medical Center, Amsterdam, The Netherlands.)

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Fig. 5.106a,b A newborn boy with a firm erythematous mass on the right cheek. a Ultrasound shows a mass with mixed echogenicity. b On color Doppler, hardly any flow is detected. The sonographic differential diagnosis included a dermoid cyst and atheroma, but pathology was compatible with a myofibroma. Later, multiple hepatic myofibromas were found. The patient received chemotherapy.

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Fig. 5.107a–d One-year-old boy with a slowly progressive swelling in the neck for 2 months. Ultrasound (a, b) shows a well demarcated, moderately perfused mass of mixed echogenicity. Magnetic resonance imaging (c, d) depicts an inhomogeneous mass compressing the pharynx. Final diagnosis: neuroblastoma. (Courtesy of R. R. van Rijn, Academic Medical Center (AMC), Amsterdam, The Netherlands.)

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Recommended Readings Agarwal RP, Handler SD, Matthews MR, Carpentieri D. Pilomatrixoma of the head and neck in children. Otolaryngol Head Neck Surg 2001; 125: 510–515 Avula S, Daneman A, Navarro OM, Moineddin R, Urbach S, Daneman D. Incidental thyroid abnormalities identified on neck US for non-thyroid disorders. Pediatr Radiol 2010; 40: 1774–1780 Bedi DG, John SD, Swischuk LE. Fibromatosis colli of infancy: variability of sonographic appearance. J Clin Ultrasound 1998; 26: 345–348 Cakmakci H, Gulcu A, Zenger MN. Mirror-image artifact mimicking epidural hematoma: usefulness of power Doppler sonography. J Clin Ultrasound 2003; 31: 437– 439 Chang YW, Hong HS, Choi DL. Sonography of the pediatric thyroid: a pictorial essay. J Clin Ultrasound 2009; 37: 149–157 Donnelly LF, Adams DM, Bisset GS, III. Vascular malformations and hemangiomas: a practical approach in a multidisciplinary clinic. AJR Am J Roentgenol 2000; 174: 597–608 Ellies M, Rohrbach-Volland S, Arglebe C, Wilken B, Laskawi R, Hanefeld F. Successful management of drooling with botulinum toxin A in neurologically disabled children. Neuropediatrics 2002; 33: 327–330 García CJ, Flores PA, Arce JD, Chuaqui B, Schwartz DS. Ultrasonography in the study of salivary gland lesions in children. Pediatr Radiol 1998; 28: 418–425 Greene FL, Page DL, Fleming ID, et al, eds. AJCC Cancer Staging Manual. 6th ed. New York, NY: Springer; 2002:19 Imhof H, Czerny C, Hörmann M, Krestan C. Tumors and tumor-like lesions of the neck: from childhood to adult. Eur Radiol 2004; 14 Suppl 4: L155–L165

Jain P, Jain R, Morton RP, Ahmad Z. Plunging ranulas: high-resolution ultrasound for diagnosis and surgical management. Eur Radiol 2010; 20: 1442–1449 Kim MG, Kim SG, Lee JH, Eun YG, Yeo SG. The therapeutic effect of OK-432 (picibanil) sclerotherapy for benign neck cysts. Laryngoscope 2008; 118: 2177–2181 La’porte SJ, Juttla JK, Lingam RK. Imaging the floor of the mouth and the sublingual space. Radiographics 2011; 31: 1215–1230 Lim HW, Im SA, Lim GY et al. Pilomatricomas in children: imaging characteristics with pathologic correlation. Pediatr Radiol 2007; 37: 549–555 Lindeboom JA, Smets AM, Kuijper EJ, van Rijn RR, Prins JM. The sonographic characteristics of nontuberculous mycobacterial cervicofacial lymphadenitis in children. Pediatr Radiol 2006; 36: 1063–1067 Meuwly JY, Lepori D, Theumann N et al. Multimodality imaging evaluation of the pediatric neck: techniques and spectrum of findings. Radiographics 2005; 25: 931–948 Mulliken JB, Glowacki J. Hemangiomas and vascular malformations in infants and children: a classification based on endothelial characteristics. Plast Reconstr Surg 1982; 69: 412–422 Restrepo R, Oneto J, Lopez K, Kukreja K. Head and neck lymph nodes in children: the spectrum from normal to abnormal. Pediatr Radiol 2009; 39: 836–846 Sidell DR, Shapiro NL. Diagnostic accuracy of ultrasonography for midline neck masses in children. Otolaryngol Head Neck Surg 2011; 144: 431–434 Wang J, Fu H, Yang H, Wang L, He Y. Clinical management of cervical ectopic thymus in children. J Pediatr Surg 2011; 46: e33–e36 Wong KT, Lee YY, King AD, Ahuja AT. Imaging of cystic or cyst-like neck masses. Clin Radiol 2008; 63: 613–622

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Chapter 6 Mediastinum

6.1 Normal Anatomy and Variants

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6.2 Pathology

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6.3 Mediastinal Ultrasound in Intensive Care: Complications Associated with Central Venous Access

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6 Mediastinum Ingmar Gassner and Gisela Schweigmann Ultrasound of the mediastinum is particularly useful to delineate anomalies of the mediastinum and great vessels, evaluate masses in children with mediastinal widening, search for lymph nodes, and assess malposition and complications of central vein catheters. It can also be used to perform biopsies. Ultrasound is quickly implemented in the remote intensive care situation in which patients can be examined in any given position and location, thus minimizing the need to move or transfer persons who are on life support devices. To correlate findings, it is always recommended to review the patient’s most recent chest radiograph before the ultrasound examination. The ultrasound examination of the pediatric mediastinum is facilitated by the nonossified sternum and thymus, especially in newborns and infants. To analyze mediastinal structures, a supraclavicular, suprasternal, trans-sternal, parasternal, subcostal, or subxiphoidal approach is used. In neonates and small infants, the sternum is predominantly cartilaginous and allows a trans-sternal approach. A supraclavicular or suprasternal approach is best performed with the patient’s shoulders lifted by a helping hand or by a pillow or rolled-up towel placed under the patient’s shoulders to extend the neck. Turning the patient’s head to the opposite side gives also free access to the region. The transducer is placed above the sternum or clavicle and tilted posteriorly. This position offers a high degree of flexibility for documenting mediastinal structures in different planes. Axial and sagittal parasternal views are acquired with the transducer positioned next to the sternum as the patient lies in the supine position. For subcostal or subxiphoidal ultrasound access, the transducer position is immediately below the xiphoid process and along the lower border of the thoracic cage. Transverse, coronal, and sagittal scans image intrathoracic pathology along with the spine, inferior vena cava, and aorta and determine the situs.

Transducers are selected according to the size of the patient and the position of the lesion being evaluated. High-frequency linear and sector transducers are used for examining preterm infants, newborns, and small infants, and for evaluating the sonographic patterns of mediastinal masses. Small transducers are valuable to insonate from the supraclavicular or suprasternal notch. Changing the patient’s position will delineate the position dependency of a lesion and can help to move intestinal air out of sight. It may be helpful to give the patient something to drink during the examination to delineate the esophagus, and to fill the stomach with fluid, which then provides an excellent acoustic window. The following paragraphs will describe how to reliably document normal vascular anatomy and will illustrate the most common mediastinal pathologies accessible to ultrasound.

6.1 Normal Anatomy and Variants 6.1.1 Thymus The thymus (▶ Fig. 6.1a) is located in the anterior superior mediastinum and changes in size, configuration, and position with the patient’s age (▶ Table 6.1). In newborns and infants, the normal thymus is visible in trans-sternal, parasternal, and suprasternal views. It is bilobed with smooth margins and has a homogeneous, fine, granular echotexture with some regular linear and punctate echogenicities that most likely represent connective tissue. On Doppler imaging, it has scant vascularity. It is an easily deformable organ that, even when large, does not compress or displace neighboring vascular structures. The thymus gland responds to acute physiologic stress with rapid and severe involution. After cessation of the stress, it takes weeks to months to regenerate and may then be enlarged because of “rebound growth.”

Table 6.1 Thymic size from 0 to 2 years of age Thymic dimensions, cm (SD) Age (months)

No. of cases

Transverse

AP right

AP left

Length

Premature

20

2.9 (0.3)

1.5 (0.4)

1.5 (0.4)

3.1 (0.4)

0–1

25

3.3 (0.3)

1.6 (0.3)

1.8 (0.3)

3.6 (0.3)

1–2

21

3.6 (0.6)

1.9 (0.3)

2.0 (0.3)

3.9 (0.4)

2–3

11

3.7 (0.5)

1.9 (0.3)

2.1 (0.3)

3.8 (0.3)

3–4

15

3.8 (0.4)

1.9 (0.5)

2.2 (0.6)

4.0 (0.4)

4–5

7

4.0 (0.6)

2.0 (0.6)

2.2 (0.4)

4.1 (0.3)

5–6

8

3.9 (0.2)

1.9 (0.4)

2.3 (0.3)

4.0 (0.2)

6–8

8

3.6 (0.5)

1.8 (0.4)

1.9 (0.5)

3.6 (0.6)

8–10

14

3.7 (0.5)

1.7 (0.5)

1.9 (0.5)

3.7 (0.4)

10–12

5

3.7 (0.5)

1.9 (0.6)

1.8 (0.5)

3.6 (0.2)

12–18

7

2.8 (0.5)

1.2 (0.5)

1.4 (0.4)

3.2 (0.9)

18–24

10

3.3 (0.4)

1.2 (0.4)

1.2 (0.3)

3.4 (0.7)

Abbreviations: AP, anteroposterior; SD, standard deviation. Source: Reproduced with permission of American Institute of Ultrasound in Medicine (AIUM) from Yekeler E, Tambag A, Tunaci A, et al. Analysis of the thymus in 151 healthy infants from 0 to 2 years of age. J Ultrasound Med 2004;23(10):1321–1326; permission conveyed through Copyright Clearance Center, Inc. Note: Mediastinal ultrasound was performed in 151 children (79 boys and 72 girls). All children were healthy and had no stress factors affecting thymic size. The maximum transverse diameter, right lobe AP length, and left lobe AP length were assessed. Perpendicular to the transverse plane, the longest craniocaudal length was assessed.

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Fig. 6.1a–d Normal ultrasound appearance of the mediastinum. a Normal thymus. Trans-sternal transverse scan shows the normal echo pattern with multiple linear echogenic lines and foci and the border of the two thymic lobes (arrows). b Suprasternal longitudinal scan shows the trachea with echopoor cartilages (arrowheads). AAo, ascending aorta. c Trans-sternal longitudinal scan demonstrates the esophagus (arrowheads) with echogenic mucosa and submucosa, sonolucent muscle, and intraluminal air. AA, aortic arch; BV, brachiocephalic vein. dNormal left aortic arch. (Schematic diagram, Theresa Geley.) RS, LS, right, left subclavian arteries; RC, LC, right, left common carotid arteries; PT, pulmonary trunk; RP, LP, right, left pulmonary arteries. (continued)

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Fig. 6.1e-j (continued) Normal ultrasound appearance of the mediastinum. e Normal left aortic arch. Oblique parasagittal supraclavicular scan demonstrates ascending aorta (AAo), aortic arch with origin of the brachiocephalic vessels (IA, innominate artery; LC, left carotid artery; LS, left subclavian artery), and descending aorta (DAo). The right pulmonary artery (RP) is seen in cross-section. f–h Trans-sternal transverse scans at subsequent levels: f At the level of the manubrioclavicular junction, the large innominate artery (IA), the left common carotid artery (LC), and the left subclavian artery (LS) are seen in cross-section. M, manubrium; BV, left brachiocephalic vein; SVC, superior vena cava. g At a lower level, the aortic arch (AA) passes anterolateral to the trachea (open arrowhead) and esophagus (arrowhead). SVC, superior vena cava. h With only slight anticlockwise rotation of the transducer, the pulmonary artery bifurcation as a whole can be imaged. AAo, ascending aorta; PT, pulmonary trunk; RP, LP, right, left pulmonary arteries; SVC, superior vena cava; TH, thymus. i A plane from the suprasternal notch directed toward the right shoulder visualizes the innominate artery (IA) and its bifurcation into the right subclavian artery (RS) and right common carotid artery (RC). AA, aortic arch. j A coronal scan from the suprasternal notch visualizes the brachiocephalic vein (BV) entering the superior vena cava (SVC), the right pulmonary artery (RP) branching Video 6.1 (1–4). into right upper lobe (ROL) and lower lobe (RLL) arteries in longitudinal section, and the aortic arch (AA) in cross-section.

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6.1.2 Trachea The trachea (▶ Fig. 6.1b) runs together with the esophagus in the midline, and both can be used to determine the midline of the mediastinum. In longitudinal section, the wall of the trachea has the appearance of a necklace because of its hypoechoic cartilages.

6.1.3 Esophagus The esophagus (▶ Fig. 6.1c) is a muscular tube consisting of an echogenic mucosa and submucosa and a hypoechoic muscle wall. The movement of air and fluid in its lumen can be visualized by ultrasound imaging, and delineation of the esophagus can be improved when the patient swallows fluid.

Tips from the Pro ●

The trachea and esophagus are important in locating the midline of the mediastinum. On a longitudinal scan, at least one of these two structures has to be identified to determine the side of the aortic arch. Failure to identify the trachea or esophagus may cause a misinterpretation of the position of the aortic arch in cases with midline shift to one side of the chest (e.g., hypoplasia or agenesis of a lung, atelectasis of lung parenchyma on the side of the shift, a contralateral mass).

6.2 Pathology 6.1.4 Heart and Great Vessels The aortic arch (▶ Fig. 6.1d) is scanned from a suprasternal, supraclavicular, or high parasternal transducer position (▶ Fig. 6.1e). A high transverse scan at the level of the manubrioclavicular junction demonstrates the aortic arch branches in cross-section: the larger innominate artery and the smaller left common carotid artery and left subclavian artery. The left brachiocephalic vein runs directly anterior (▶ Fig. 6.1f). Shifting the transducer to a lower level reveals the left-sided aortic arch passing from right to left anterolateral to the trachea and esophagus (▶ Fig. 6.1g). A transverse scan more caudally visualizes the right superior vena cava, ascending aorta, main pulmonary artery, and right pulmonary artery. As the left pulmonary artery runs more cephalad than the right, a slight anticlockwise rotation of the transducer is needed to image the pulmonary artery bifurcation as a whole (▶ Fig. 6.1h). On a coronal scan from the suprasternal fossa, the left innominate vein, which joins the superior vena cava, runs above the aortic arch, which is cut in cross-section (▶ Fig. 6.1j). The right pulmonary artery runs beneath the aortic arch and behind the superior vena cava (▶ Fig. 6.1e, h). In a sagittal oblique plane, the ascending aorta, the aortic arch with its usually three brachiocephalic vessels, and the proximal descending aorta are shown in a single image. The right pulmonary artery is seen in cross-section below the arch (▶ Fig. 6.1e). To reliably determine the side of the aortic arch, the trachea or esophagus must be identified as a midline marker. Also, visualization of a right or left innominate artery makes it possible to determine the side of the aortic arch. A right innominate artery implies a left aortic, arch and vice versa. A plane directed from the suprasternal notch toward the right shoulder visualizes the innominate artery and its bifurcation into the right subclavian and carotid arteries (▶ Fig. 6.1i). In the sagittal right parasternal scan, the superior vena cava and azygos vein entering the posterior aspect of the superior vena cava are visualized. Subcostal transverse and sagittal planes serve to image the inferior vena cava, the entire thoracic aorta, and the spine. If present, azygos continuation of the inferior vena cava can be shown.

6.2.1 Thymus Aberrant or Ectopic Thymus Congenital anomalies of the position of the thymus are classified as aberrant or ectopic. The normal pathway of embryonic thymic descent is from the angle of the mandible to the superior mediastinum. Aberrant thymus is due to incomplete or missing descent, leading to remnants of thymic tissue positioned in any location along the normal pathway of descent. Most often, there is an incidental finding of a mass in the lateral neck or in the suprasternal area without signs of airway obstruction or compression of adjacent vessels. As in persons with a normal thymus, multiple linear echoes and discrete echogenic foci are found (▶ Fig. 6.2a, b). By contrast, an ectopic thymus can be found in any position except the normal pathway of embryologic descent of the gland (i.e., pharynx, trachea, posterior neck or mediastinum, or esophagus). There is often continuity with the normally positioned thymus. When an ectopic thymus is located in the posterior mediastinum or within the trachea or pharynx, its visualization during an ultrasound examination can be obscured by overlying ribs or air. Awareness of this uncommon entity and knowledge of its variable presentation are essential to avoid unnecessary surgery.

Thymic Aplasia The thymus is responsible for the development of T-cell immunity. Thymic aplasia or hypoplasia is associated with T cell– related immunodeficiencies such as 22q11.2 deletion syndrome (cardiovascular [especially aortic arch] anomalies, abnormal facial features, thymic hypoplasia, cleft palate, hypocalcemia), ataxia telangiectasia, and severe combined immune deficiency syndrome (SCID). SCID syndrome is characterized by the absence of normal thymic tissue in all cases. Mediastinal ultrasound will document agenesis or hypoplasia of the thymus and associated cardiac and aortic arch anomalies (▶ Fig. 6.3a–c).

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Fig. 6.2a,b Cervical extension of a normal thymus in (a) a 4½ -year-old boy and (b) a 6½ -year old boy. a Transverse scans at the level of the supraclavicular notch: the thymic tissue (arrowheads) extends into the lower neck between the right (RC) and left (LC) common carotid arteries. b Longitudinal scan just below the level of the left lobe of the thyroid gland. The thymus (arrowheads) is adjacent to the thyroid gland (arrows). Video 6.2. Open arrowheads, esophagus.

Fig. 6.3a–c Thymic hypoplasia in immunologic deficiency syndrome in a 4-month-old girl. a Note the narrow superior mediastinum (arrowheads) and the reticulonodular infiltrates due to pulmonary infection. Axial (b) and longitudinal (c) scans of the superior mediastinum. The thymus (arrowheads) is very small with slightly increased echogenicity. LBC, left brachiocephalic vein; IA, innominate artery; LC, left common carotid artery; AAo, ascending aorta.

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Tips from the Pro ●

Absence of the thymus can be an important feature in an infant presenting with recurrent or severe infections during the first months of life. The radiologist may be the first to suggest the diagnosis of an immunodeficiency syndrome (▶ Fig. 6.3a).

6.2.2 Trachea Subglottic Hemangioma Infantile hemangioma is the most common vascular tumor of infancy. This benign neoplasm is characterized by a rapid endothelial proliferation stage followed by a slower involution stage. The lesions can be isolated or multiple anywhere in the body, most frequently in the skin and subcutaneous tissue. Localization within the epithelial lining of the trachea is rare but may result in tracheal stenosis presenting with biphasic stridor. Symptoms develop frequently before 6 months of age. Progressive airway obstruction during the proliferative phase has the potential to be life-threatening. When large, the hemangioma infiltrates the soft tissue around the trachea or the thyroid gland. An association between the presence of cutaneous hemangioma in the beard distribution and airway involvement due to derivation from the same embryologic structures is known. Ultrasound documents the characteristic features of hemangioma. There is a well circumscribed solid mass with variable echogenicity (▶ Fig. 6.4a, b). Draining and feeding vessels may be identified. Blood flow, documented with color Doppler, varies between exuberant and barely detectable (▶ Fig. 6.4c).

Tracheobronchial Calcification Calcification of the cartilaginous rings of the trachea and bronchi (▶ Fig. 6.5a, b) is part of the natural process of aging. In children, it is rare and often associated with laryngeal calcification. It has been described in patients with chondrodysplasia punctata, Keutel syndrome, warfarin embryopathy, adrenogenital syndrome, or diastrophic dysplasia and (as in our patient) after long-term warfarin therapy.

6.2.3 Esophagus Esophageal Atresia and Tracheoesophageal Fistula

Fig. 6.4a–c Subglottic hemangioma in a 2-month-old girl with stridor. a Subglottic transverse scan at the age of 2 months reveals narrowing of the tracheal lumen by a polypoid anterior intratracheal mass (arrows). Tracheostomy was performed. b Six months later, the size of the hemangioma has dramatically increased, and it compresses the tracheal lumen to a small gap (arrowheads). c Color Doppler shows the intense vascularity and involvement of the adjacent soft tissues (i.e., thyroid). Video 6.4.

Esophageal atresia (▶ Fig. 6.6a–d) and tracheoesophageal fistula are the most common congenital malformations of the esophagus. The prognosis is influenced by the frequent associated anomalies such as congenital heart disease, gastrointestinal anomalies, and the VA(C)TER(L) complex (vertebral defects, anal atresia, tracheoesophageal fistula, radial aplasia, renal dysplasia, and cardiac and limb anomalies). In the majority of patients, the atresia is between the proximal and middle thirds of the esophagus and is associated with a distal fistula (Vogt type IIIb). Because the patients can swallow, isolated tracheoesophageal fistula may not be detected early.

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Fig. 6.5a,b Tracheobronchial calcification after mitral valve replacement and warfarin sodium therapy in a 9½ -year-old girl with asplenia syndrome. Chest radiograph showed faintly visible tracheobronchial calcification. Transverse scan of the cricoid cartilage (a) and longitudinal scan of the trachea (b) show central calcification of the cricoid cartilage (arrows) and tracheal rings (arrowheads).

Fig. 6.6a–d Esophageal atresia. a–c A 1-day-old boy with type III b esophageal atresia. a Suprasternal longitudinal scan shows the nondistended proximal pouch (arrowheads) ending at the level of the aortic arch (AA). b, c After it has been filled with saline solution, suprasternal longitudinal (b) and transverse (c) scans clearly demonstrate the distended esophageal pouch (arrowheads). d A 1-day-old girl who has type III esophageal atresia with two proximal fistulas and without a distal tracheoesophageal fistula. Suprasternal transverse scan shows moving air bubbles (open arrows) between the trachea (open arrowheads) and esophagus (arrowheads), indicating a proximal tracheoesophageal fistula. See also ▶ Fig. 6.7b and Video 6.6 (1–2).

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Mediastinum Ultrasound technique allows a clear documentation of the length and condition of the wall of the proximal pouch and its relation to surrounding structures (i.e., aortic arch; ▶ Fig. 6.6a). Visualization may be enhanced by the instillation of saline solution into the pouch (▶ Fig. 6.6b, c). An isolated tracheoesophageal fistula as well as one or rarely multiple fistulas from the proximal pouch in esophageal atresia may be recognized by the presence of tiny air bubbles that move in the soft tissue between the trachea and the esophagus (▶ Fig. 6.6d, ▶ Fig. 6.7a–c).

Tips from the Pro ●

A determination of the side of the aortic arch by ultrasound is important before surgery, as thoracotomy will be on the opposite side of the aortic arch.

Esophageal Achalasia This esophageal motility disorder is characterized by failure of the lower esophageal sphincter to relax normally as a consequence of the absence or destruction of the ganglion cells of the myenteric plexus. Absence of primary peristalsis and uncoordinated contractions are associated with progressive dilatation of the esophagus. Frequent aspiration may result in pneumonia and bronchiectasis. In advanced cases, upright chest radiographs show esophageal dilatation with an air–fluid level and a gasless stomach. Ultrasound demonstrates the characteristic dilatation of the esophagus and failure of relaxation of the lower esophageal sphincter (▶ Fig. 6.8a, b). In contrast studies, the classic tapered, beaklike deformity of the lower end of the esophagus may be seen (▶ Fig. 6.8c).

Tips from the Pro ●

Achalasia is very rare in children younger than 4 years of age, and in cases of early-presenting achalasia, congenital esophageal stenosis should be kept in mind.

Esophageal Foreign Body

Fig. 6.7a–c H-type tracheoesophageal fistula in a 3-week-old girl. a Suprasternal transverse view. The trachea (open arrowhead) and proximal esophagus (arrowhead) lie side by side. b Suprasternal transverse view. Moving air bubbles (open arrows) between the trachea (open arrowhead) and esophagus (arrowheads) indicate a tracheoesophageal fistula. The wall of the fistula (arrows) is also clearly visible. c Photograph taken at the time of surgery shows the fistula (F), esophagus (O), and trachea (T). (Images courtesy of of Dr. Murat Sanal, Video 6.7. Innsbruck, Austria.)

Because of their tendency to examine things, infants and children put many types of foreign bodies into their mouth and swallow them accidentally. Coins are the objects most commonly swallowed by children younger than 5 years. Foreign bodies that do not pass the esophagus usually become impacted at sites of physiologic narrowing: at the thoracic inlet below the level of the cricopharyngeus muscle, at the level of the aortic arch and carina, or just proximal to the esophagogastric junction. A foreign body coming to rest at any other site should suggest an underlying esophageal anomaly (webs, strictures, extrinsic masses). The imaging approach to finding radiopaque foreign bodies is plain film of chest and abdomen (from mouth to anus), with an additional lateral view of the neck. Foreign bodies that are radiolucent or of low radiodensity may be revealed in contrast

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Fig. 6.8a–c Five-year-old boy with triple A syndrome (achalasia, ACTH insensitivity, alacrima). Ultrasonography of the esophagus. Transverse scan at the cervical level (a) and longitudinal scan at the distal end (b) show a distended esophagus (open arrowheads). Arrowhead, trachea. c Esophagram shows moderate dilatation of the esophagus with beaklike deformity of its very distal end. The stomach is contracted without gas bubbles. Video 6.8.

studies, whereas small radiolucent or minimally opaque foreign bodies may remain undiscovered. Both radiopaque and radiolucent foreign bodies lodged at the level of the cricopharyngeal muscle or thoracic inlet or just proximal to the gastroesophageal sphincter may also be detected by ultrasound (▶ Fig. 6.9a, b).

Tips from the Pro ●

The orientation of a coin or other flat object gives a clue to its position. If located in the esophagus, it lies in the coronal plane. If oriented in the sagittal plane, it is located in the trachea.

produce a deep liquefaction necrosis that involves all layers of the esophagus. The middle and lower portions of the esophagus are more likely to be affected. The acute necrotic phase is followed by an ulcerative granulation phase and finally by the phase of cicatrization and stricture formation. These pathologic changes correspond with the development of mucosal irregularity, esophageal dysmotility, ulceration, a stenotic rigid tube, and finally esophageal stricture in contrast esophagography. The advantage of endoscopy is in the assessment of the extent and severity of the esophageal injury. The risk for esophageal perforation, however, requires a very cautious approach, and it should be kept in mind that radiologic studies may also provide valuable information during both the acute and chronic stages of the disease. In the acute phase, ultrasound can demonstrate an increased thickness of the pharynx wall, the proximal esophagus, and the cardia (▶ Fig. 6.10a, b).

Corrosive Esophagitis The ingestion of household cleaning products (alkalis, acids, bleaches) or burns (microwave-overheated baby food) may lead to this condition. Acid compounds produce a coagulative necrosis that is usually limited to the mucosa, whereas alkalis

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Tips from the Pro ●

The absence of mouth lesions due to a short time of contact does not exclude injury of the esophagus.

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6.2.4 Congenital Vascular Anomalies Vascular rings (complete encirclement of the trachea and the esophagus) and slings (incomplete encirclement) may present as respiratory distress in the neonate or as stridor and/or dysphagia in the older child. However, some vascular anomalies may remain clinically silent, being discovered only incidentally. A wide variety of vascular rings and slings can occur, but the two groups of greatest clinical significance are those involving the aortic arch and the pulmonary artery. Chest radiography as a first-line imaging modality reveals the position of the aortic arch and any anomalies of the airways and secondary airway obstruction that may be present. Imaging of the esophagus in strictly frontal and lateral views when it is filled with contrast agent demonstrates characteristic impressions. The presence or absence of a vascular ring or sling that is frequently associated with stridor may also be shown by ultrasound. Computed tomography (CT) or magnetic resonance (MR) imaging with the need for patient sedation should be used only to further delineate an existing anomaly.

Aortic Arch Anomalies Most malformations of the aortic arch can be explained by the hypothetical double aortic arch postulated by Edwards (▶ Fig. 6.11). This double aortic arch encircles the esophagus and trachea and has a ductus arteriosus on each side. The aorta descends in the midline. Each aortic arch gives rise to its own common carotid and subclavian arteries. The normal, left-sided aortic arch results from regression of the right aortic arch distal to the origin of the right subclavian artery. Aortic arch anomalies result from failure of this regression, or regression in an abnormal site. Fig. 6.9a,b Esophageal foreign body. a Chest radiograph demonstrates a coin lodged in the esophagus at the level of the thoracic inlet. The coin, like other flat objects, typically lies in the coronal plane. b Axial sonogram shows the coin (open arrowheads) in the esophagus on the left of the trachea (T). C, left carotid artery.

Fig. 6.10a,b Corrosive esophagitis secondary to ingestion of sodium hydroxide by a 3-year-old girl. Ultrasonography was performed 24 hours after ingestion. Transverse (a) and longitudinal (b) scans at the cervical level. The esophageal mucosa is markedly swollen (asterisks) and tightly surrounds the nasogastric tube (arrowheads). Arrows, esophagus; T, trachea.

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Mediastinum RC 2

RS

Left Aortic Arch with Aberrant Right Subclavian Artery (Arteria Lusoria)

LC 3

DA

LS DA

1

4

AAO PT

LP

RP RDA

LDA

Fig. 6.11 Hypothetical double aortic arch postulated by J. Edwards. (Schematic representation, G. Schweigmann after R. M. Freedom.) This double aortic arch encircles the esophagus and trachea with a ductus arteriosus (DA) on each side. The aorta descends in the midline. AAO, ascending aorta; RDA, right descending aorta; LDA, left descending aorta. Each aortic arch gives rise to its own common carotid (RC, LC) and subclavian (RS, LS) arteries. A normal, left-sided aortic arch results from regression of the right aortic arch distal to the origin of the right subclavian artery (1). Aortic arch anomalies result from failure of this regression (double aortic arch) or regression in an abnormal site. 2, Left aortic arch with aberrant right subclavian artery; 3, right aortic arch with aberrant left subclavian artery; 4, right aortic arch with mirror-image branching.

This common anomaly of the aortic arch results from regression of the right aortic arch between the right common carotid artery and the right subclavian artery. The aberrant right subclavian artery always runs as the last branch of the aortic arch behind the esophagus to the right arm (▶ Fig. 6.12a). As it constitutes an incomplete vascular ring, it seldom causes symptoms. Contrast imaging of the esophagus demonstrates an oblique indentation of the esophagus from the lower left to the upper right in the frontal view and a small posterior indentation in the lateral view. The first aortic arch branch is small, without branching (▶ Fig. 6.12b, c). The aberrant subclavian artery arises from the descending aorta and can be seen in cross-section behind the esophagus (▶ Fig. 6.12d, e).

Right Aortic Arch with Aberrant Left Subclavian Artery This anomaly can be explained as interruption of the left aortic arch between the left common carotid artery and the left subclavian artery. As a consequence, a right aortic arch is present together with a right descending aorta. The aberrant left subclavian artery arises as the last branch from a usually large Kommerell diverticulum in the descending aorta. The left-sided ductus arteriosus extends from this diverticulum to the left pulmonary artery, forming a complete vascular ring that may cause tracheoesophageal compression (▶ Fig. 6.13a). This aortic arch

Fig. 6.12a,b a Left aortic arch with aberrant right subclavian artery (RS) in a 5-week-old girl as an incidental finding. LS, left subclavian artery. (Schematic diagram, Theresa Geley.) b Trans-sternal transverse scans. The first aortic arch branch (RC) is small and shows an absence of normal branching (see also ▶ Fig. 6.1f, i). Open arrowhead, trachea; arrowhead, esophagus. (continued)

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Fig. 6.12c-e (continued) c Trans-sternal transverse scans. The first aortic arch branch (RC) is small and shows an absence of normal branching (see also ▶ Fig. 6.1f, i). Open arrowhead, trachea; arrowhead, esophagus. d Trans-sternal oblique scan slightly angulated toward the right shoulder. The aberrant right subclavian artery (arrowhead) arises from the distal aortic arch (AA). e Longitudinal scan. The aberrant right subclavian artery (open arrowhead) is seen in cross-section behind the esophagus. AAo, ascending aorta; RC, LC, right, left common carotid arteries; LS, left subclavian artery; RS, aberrant right subclavian artery; RP, right pulmonary artery; BV, brachiocephalic vein. Video 6.12 (1–3).

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Fig. 6.13a,b Right aortic arch with aberrant left subclavian artery (ALSA) in a five-day-old girl. a Diagrammatic representation (Theresa Geley). Transsternal axial scan at the level of the pulmonary artery (b) and axial scan the level of the aortic arch. (continued)

anomaly is usually not associated with congenital heart disease, in contrast to a right aortic arch with mirror-image branching. A chest radiograph shows the right aortic arch and right descending aorta. The trachea is indented on the right side and deviated to the left. On contrast imaging, indentation of the esophagus on the right side and also a large posterior indentation due to the Kommerell diverticulum are seen. Ultrasound shows the right aortic arch, no branching of the first vessel arising from the aorta (left common carotid artery), and a large Kommerell diverticulum behind the esophagus giving rise to the aberrant left subclavian artery (▶ Fig. 6.13b–e).

Double Aortic Arch Double aortic arch results from the persistence of both arches. This complete vascular ring tightly encircles the trachea and esophagus. Each arch gives rise to only two main vessels, the ipsilateral common carotid artery and subclavian artery (▶ Fig. 6.14a). The right aortic arch is usually a little larger in diameter and slightly higher in position than the left. Occasionally, a portion of the left arch is atretic. The two arches fuse into a single descending aorta, which descends on the left or less often remains on the right. On a chest radiograph in the anteroposterior projection, the trachea is fixed in the midline between both arches and poorly

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delineated because of compression. Contrast imaging of the esophagus in the anteroposterior projection displays bilateral indentation, with the indentation on the right slightly higher than that on the left side. The esophagus also has a large posterior indentation as the right arch crosses posterior to the esophagus to join the left arch. Ultrasound demonstrates both arches and their common carotid and subclavian arteries on suprasternal nearly sagittal views. With slight clockwise rotation of the transducer, the left arch is imaged on the left side of the esophagus. Rotation of the transducer in the other direction will reveal the right arch on the right side of the esophagus. A clue to the diagnosis is that each arch gives rise to only two main vessels (▶ Fig. 6.14b, c). On a transverse scan, one will notice that the carotid and subclavian arteries are symmetrically arranged (▶ Fig. 6.14d). The complete vascular ring is displayed on a trans-sternal axial view (▶ Fig. 6.14e). In a suprasternal coronal plane, both arches are imaged in cross-section. (▶ Fig. 6.14f).

Anomalies of the Pulmonary Arteries: Pulmonary Artery Sling In pulmonary artery sling or aberrant left pulmonary artery, the left pulmonary artery arises from the right pulmonary artery. To reach the left lung, it hooks around the carina and

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Mediastinum crosses behind the trachea and in front of the esophagus (▶ Fig. 6.15a). This anomaly is frequently associated with tracheobronchial malformations (long segmental tracheal and left main bronchial stenosis with absence of the membranous part and complete cartilage rings). Contrast imaging of the esophagus on lateral view shows an anterior pulsating indentation of the esophagus. Parasternal transverse ultrasound scan reveals absence of the normal origin of the left pulmonary artery and displays the origin of the left pulmonary artery from the dorsal aspect of the right pulmonary artery (▶ Fig. 6.15b, e). A suprasternal scan in the plane of the aortic arch shows both the right and aberrant left pulmonary arteries in cross-section beneath the aortic arch. The slightly larger right pulmonary artery is found ventral to the smaller left pulmonary artery (▶ Fig. 6.15c–e). MR imaging and CT show the vascular anomaly together with the associated tracheobronchial anomalies.

Tips from the Pro The following three facts have to be proved to document normal anatomy of the mediastinal vessels and to exclude vascular rings or a vascular sling: ● A left-sided aortic arch (i.e., left of the trachea and esophagus) that gives rise to three main vessels excludes a right aortic arch and a double aortic arch. (▶ Fig. 6.1e). ● A normal pulmonary artery bifurcation excludes a pulmonary artery sling and anomalies of the proximal pulmonary arteries (▶ Fig. 6.1h). ● Normal branching of the right innominate artery or three main vessels leaving the aortic arch with the first being the largest exclude an aberrant subclavian artery (▶ Fig. 6.1f, i).

Pulmonary sling is the only vascular anomaly that causes an anterior indentation of the esophagus.

Anomalies of the Pulmonary Veins: Total Anomalous Pulmonary Venous Return

Fig. 6. 13c-e (continued) Right aortic arch with aberrant left subclavian artery (ALSA) in a five-day-old girl. (c) show a right aortic arch and right descending aorta (DAo) and a large Kommerell diverticulum (D). d A slightly oblique trans-sternal section demonstrates the aberrant left subclavian artery (ALSA) arising from the diverticulum (D) and passing behind the trachea and esophagus (arrowhead). e Suprasternal parasagittal scan shows the diverticulum (D) in cross-section with posterior indentation of the esophagus (arrowheads). The apex of the aortic arch lies in the supraclavicular fossa above the manubrium (M). This represents a cervical aortic arch. AAo, ascending aorta; LC, RC, left, right common carotid arteries; RS, right subclavian artery; PT, pulmonary trunk; LDL, left ductus ligament; RP, right pulmonary artery. Video 6.13 (1–2).

Because of abnormal development of the common pulmonary vein in total anomalous pulmonary venous return, the pulmonary veins unite posterior to the heart and form a single vessel, which drains to the right-sided circulation. According to the drainage, four types of lesion are described: type I (supracardiac connection), in which the common pulmonary vein joins the persistent left superior vena cava on the left or the azygos vein on the right; type II (cardiac connection), in which the common pulmonary vein drains into the right atrium; type III (infracardiac connection), in which the common pulmonary vein inserts into a systemic abdominal vein, most frequently into the portal vein; and type IV, which is a mixture of the first three types. Types I and III have characteristic radiologic features that guide the pediatric radiologist through subsequent ultrasound analyses. In type I, the lineup of venous connections (common vein, persistent left superior vena cava, innominate vein, superior vena cava) forms an inverted U-shaped vessel that can be demonstrated on ultrasound. The unusual enlargement of left

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Fig. 6.14a–f Double aortic arch in a 6-month-oldgirl. a Schematic diagram (Theresa Geley). b Suprasternal right parasagittal scan demonstrating the right (b) aortic arch, common carotid and subclavian arteries.

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Fig. 6.15a–e Pulmonary artery sling in a 6-month-old boy. a Diagrammatic representation (Theresa Geley). b Trans-sternal axial scan. The anomalous left pulmonary artery (arrowheads) arises from the proximal right pulmonary artery (asterisk) and passes between trachea (open arrowhead) and esophagus (arrow) to the left lung. The proximal right pulmonary artery and ascending aorta have almost equal diameters. c Scan in the plane of the aortic arch documents the aortic arch and both pulmonary arteries in cross-section underneath the aortic arch. The right pulmonary artery is larger than the left. d Diagrammatic representation of the scan plane in c (Theresa Geley). (continued)

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Mediastinum Table 6.2 Common pediatric mediastinal masses Anterior mediastinum

Malignant lymphoma Thymus (benign enlargement) Thymoma Teratoma Dermoid Cystic hygroma

Middle mediastinum

Lymphadenopathy (inflammatory, neoplastic) Bronchopulmonary foregut malformations (bronchogenic cyst, esophageal duplication cyst, neurenteric cyst)

Posterior mediastinum

Ganglion cell tumors (neuroblastoma, ganglioneuroma, ganglioneuroblastoma) Peripheral nerve tumors (neurofibroma, schwannoma)

Fig. 6.15 (continued) e Schematic diagram of ultrasound scans: normal anatomy (a, b) in comparison with the findings in pulmonary artery sling (a1, b1). AAo, ascending aorta; DAo, descending aorta; PT, pulmonary trunk; RP, right pulmonary artery; LP, anomalous left pulmonary artery; TR, trachea; OE, esophagus. Video 6.15 (1–2).

brachiocephalic vein draining into the right-sided superior vena cava can also be seen (▶ Fig. 6.16a–c). Type III is frequently associated with life-threatening clinical symptoms related to interstitial pulmonary edema caused by pulmonary venous obstruction. Abdominal ultrasound will demonstrate the large infradiaphragmatic connection of the common pulmonary vein into the portal venous system (▶ Fig. 6.17a–d).

Tips from the Pro ●

When pulmonary edema is present on a neonatal chest radiograph, abdominal ultrasound should be performed to rule out total anomalous pulmonary venous return type III anomaly.

6.2.5 Mediastinal Masses Usually, mediastinal masses are initially detected by chest radiography. CT and MR imaging are performed to evaluate the localization and extent of a lesion, as well as its internal structure and vascularity. Ultrasound has a screening role in the evaluation of mediastinal masses. The supra- and parasternal approach enables the evaluation of internal structure, localizes a possible site for biopsy, and is also suited for therapeutic follow-up. Compartmentalization of the mediastinum is useful in generating a likely differential diagnosis. ▶ Table 6.2 displays the most common pediatric mediastinal masses according to the compartment in which they typically arise. Benign thymic enlargement, malignant lymphoma, teratomas, foregut cysts, and neurogenic tumors account for 80% of mediastinal masses in children.

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Lymphadenopathy and Inflammation Lymphadenopathy accounts for the most common middle mediastinal mass in children. Inflammatory lymphadenopathy is more frequent than neoplastic disease. Bilateral hilar lymphadenopathy is usually caused by viral lower respiratory infection. Other common causes are fungal, mycoplasmal, or tuberculous infections. Noninfectious bilateral lymphadenopathy occurs with sarcoidosis, Langerhans cell histiocytosis, Wegener granulomatosis, or metastatic disease. Unilateral lymphadenopathy is commonly associated with primary tuberculosis and is found frequently in mycoplasmal or fungal infections. Occasionally, it appears in bacterial pneumonia and is rarely associated with viral infections. Necrotic areas in lymph nodes are common in patients with tuberculosis, fungal infections, and neoplasms such as ovarian carcinoma, seminoma, and rhabdomyosarcoma. They can also be seen in patients with lymphoma before or after treatment. Calcifications of lymph nodes in the mediastinum or hilum reflect prior granulomatous infections such as tuberculosis and histoplasmosis and occur as well in sarcoidosis, amyloidosis, and Pneumocystis carinii infection. Calcified lymph nodes can also be seen in certain malignancies, such as osteosarcoma, mucinous ovarian carcinoma, and papillary carcinoma of the thyroid. In patients with Hodgkin lymphoma, they are commonly seen after radiation therapy and also rarely in untreated cases. Chest radiography is the first-line imaging modality, and chest CT is the gold standard for the detection of lymphadenopathy. Mediastinal sonography has also proved to be a valuable tool in demonstrating mediastinal lymph node enlargement in children. Solitary or multiple enlarged lymph nodes or a solid mass representing the coalescence of multiple nodes may be found. (▶ Fig. 6.18a, b and ▶ Fig. 6.19a, b).

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Fig. 6.16a-c Total anomalous pulmonary venous connection to the left innominate vein via the left vertical vein in a 3-month- old boy. a Frontal view demonstrates markedly enlarged heart and increased pulmonary arterial vasculature. Enlargement of the left vertical vein (open arrowheads) and right superior vena cava (arrowheads) results in the typical figure-of-8 appearance (“snowman heart”). b, c Suprasternal coronal views (c color Doppler). All of the pulmonary veins (arrows) drain into the common pulmonary vein (CPV). The vertical vein (V) enters a dilated left brachiocephalic vein (BV), which in turn joins the right-sided superior vena cava (VC). These connections form an inverted U-shaped vessel (open arrowheads). Within the encircling venous structures, the aortic arch (Ao) and main pulmonary artery (PA) are seen in cross-section. RP, right pulmonary artery.

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Fig. 6.17a–d Infracardiac (infradiaphragmatic) total anomalous pulmonary venous connection to the portal vein in a 4-hour-old girl. a Anteroposterior chest radiograph shows small cardiac size. Both lung fields show diffuse reticular vascularity, characteristic of passive vascular engorgement. Haziness results from associated pulmonary interstitial edema. Note the fluid in the minor fissure (arrowhead). Longitudinal (b) and axial (c) scans through the upper abdomen show the large common pulmonary vein (arrows) crossing the diaphragm and draining directly into the portal vein (open arrows). The common pulmonary vein is narrowed from extrinsic compression where it passes through the diaphragm (open arrowhead), and it is obstructed from intrinsic stenosis where it connects to the portal vein (arrowhead). Ao, aorta. d Sagittal oblique scan through the upper abdomen demonstrates the drainage via the large ductus venosus (open arrowheads) to the left hepatic vein (arrowheads) and inferior vena cava (IVC). Arrows, umbilical vein; UR, umbilical recess; RA, right atrium.

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Fig. 6.19a,b Sarcoidosis in a 4½-year-old girl. a Suprasternal oblique parasagittal scan reveals enlarged lymph nodes in the aortopulmonary window (arrowheads), AA, aortic arch; RPA, right pulmonary artery. b The right parasternal axial scan shows the lymph node enlargement in the right paratracheal region (arrows) and in the aortopulmonary window (arrowheads). AAo, ascending aorta; SVC, superior vena cava.

Fig. 6.18a,b Tuberculosis in a 5-month-old boy. a Chest radiograph shows a dense consolidation of the left upper lobe and extrinsic compression of the left bronchus (arrowhead). b Parasternal transverse scan demonstrates the consolidated lung (black arrows), as well as large hilar lymph nodes (arrowheads) adjacent to the left pulmonary artery (LP), left main bronchus (asterisks), and descending aorta (DA).

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Fig. 6.20a–c Mediastinal B-cell lymphoma in a 14-year-old boy. a Chest radiograph shows a large mediastinal mass (arrowheads) causing deviation of the trachea (open arrowhead) to the left. b Right parasternal transverse ultrasound scan shows the lobulated anterior mediastinal mass displacing the ascending aorta (AAo) and pulmonary artery (PA). c Contrast-enhanced computed tomography reveals the full extension of the lymphoma (arrowheads). AAo, ascending aorta; PA, pulmonary artery.

Tips from the Pro ●

Mediastinal lymph nodes are best detected with small transducers from the supraclavicular or suprasternal approach.

Lymphoma In children and adolescents, lymphoma is the most common malignant tumor in the mediastinum. Hodgkin lymphoma is more frequent in children older than 5 years and rare in younger children. Often, the initial presentation is asymptomatic cervical or axillary lymphadenopathy. The spread of disease is

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contiguous with neck adenopathy. Mediastinal nodal involvement is seen in 85% of cases and hilar adenopathy in 25%. Discrete nodular masses or confluent homogeneous or heterogeneous masses of tumor occur. Areas of necrosis are common. Calcification is rare before therapy. Pleural and pericardial effusions are infrequent findings. Non-Hodgkin lymphoma is more common in children younger than 5 years. Mediastinal masses are found in more than onethird of cases (▶ Fig. 6.20a). Frequently, involvement of hilar, subcarinal, posterior mediastinal, and paracardiac nodes is shown. Respiratory symptoms, airway obstruction, and superior vena cava syndrome often appear. Large pleural effusions are seen. Hematogenous spread and noncontiguous abdominal tumors (kidneys, liver, spleen) or bone marrow involvement is common.

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Fig. 6.21a,b Cystic lymphangioma of the neck with large extension into the mediastinum in a 2¼-year-old boy. a Left parasternal transverse scan shows the multicystic nature of the mediastinal lesion. b T2-weighted magnetic resonance imaging in the coronal plane demonstrates the extension of the lymphangioma into the mediastinum and both axillae.

The two types of lymphoma have similarities in appearance on imaging. On ultrasound, discrete nodes, conglomerate masses of lymph node enlargement, or diffuse thymic infiltration may be seen. The affected lymph nodes tend to be hypoechoic and relatively avascular compared with those affected by inflammatory processes and other neoplasms. The infiltrated thymus appears heterogeneous, with convex or lobulated borders, and it displaces and deforms adjacent structures (▶ Fig. 6.20b, c).

Tips from the Pro ●

In patients with Hodgkin or non-Hodgkin lymphoma or enlarged cervical lymph nodes (especially on one side), it is recommended to extend the ultrasound investigation to the mediastinum and abdomen (to detect spleen, abdominal lymph node, liver, and kidney involvement).

Cystic Lymphatic Malformations Lymphangiomas are congenital hamartomatous malformations of the lymphatic system. Most often, they arise in the head and neck. Occurrence in the upper anterior mediastinum is almost always as an extension of a cervical hygroma. Primary mediastinal lymphangioma is extremely rare. Lymphangiomas can also be found in the axilla, mesentery, retroperitoneum, and lower limbs. They are classified as benign but can behave very aggressively. Encasement of mediastinal structures and infiltration of adjacent soft tissues are seen. Displacement of the trachea and esophagus and the compression of adjacent structures occur. Sudden increase in size due to hemorrhage or infection may lead to a mass effect that can be life-threatening. However, spontaneous shrinkage can occur. Cystic lymphatic malformations are subdivided into macrocystic, microcystic, and mixed types. On ultrasound, macrocystic lymphangiomas are multiloculate or septate masses that sometimes contain fluid–fluid levels (▶ Fig. 6.21a). Doppler

ultrasound reveals flow only within the septa. After hemorrhage, the lesions appear as uniformly echogenic masses or multiple cysts containing echogenic debris. Microcystic lymphangiomas appear hyperechoic without any lesional flow on Doppler. MR imaging is most accurate for evaluating the extent of a lesion (▶ Fig. 6.21b).

Neuroblastoma–Ganglioneuroblastoma– Ganglioneuroma Complex Neuroblastoma, ganglioneuroblastoma, and ganglioneuroma are tumors of the sympathetic nervous system. Among these, neuroblastoma is the least differentiated and most malignant, preferentially affecting young children. Ganglioneuroblastoma is more well differentiated and of intermediate malignancy. Ganglioneuroma consists of mature ganglion cells and is a benign lesion that usually occurs in older children. Ten percent to 15% of neuroblastomas are located in the posterior mediastinum. Neuroblastomas are frequently apparent on plain radiographs (▶ Fig. 6.22a). Ultrasound may show a fusiform, paraspinal mass from the thoracic inlet to the diaphragm. It is isoechoic or hyperechoic relative to thymus or muscle. Anechoic areas within the tumor correspond to hemorrhage or necrosis. Calcifications are common and appear as focal echogenic areas or very fine calcifications with diffusely increased echogenicity (▶ Fig. 6.22a, b). Ultrasound may help to identify tumor extension through neuroforamina (“dumbbell” lesion) and subsequent dural cord compression. MR imaging is the modality of choice to evaluate the full extent of a mass, especially extradural intraspinal involvement (▶ Fig. 6.22c).

Tips from the Pro ●

Intraspinal extension must be detected preoperatively. Think of ultrasound of the spinal cord in newborns with neuroblastoma!

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Fig. 6.22a–c Neuroblastoma in the posterior mediastinum in a 3-week-old boy. a Chest radiograph. In addition to bilateral widening of the mediastinum by the thymus (arrowheads), a posterior mediastinal mass (arrow) displaces the trachea (ventilation tube) and esophagus (feeding tube) to the left (open arrowhead). b Suprasternal transverse scan demonstrates a mass (arrows) that is immediately adjacent to the spine (SP). The central echogenic area and punctate echogenic foci (open arrowheads) represent calcifications. c Magnetic resonance imaging (TIRM [turbo inversion recovery measurement] sequence) in the coronal plane shows the large tumor in the posterior mediastinum (arrows) causing deviation of the trachea (open arrowhead).

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Fig. 6.23 a,b Complications associated with central venous access. a Five-week-old girl. Trans-sternal axial scan shows thrombus (arrowheads) in the left brachiocephalic vein (LBV) around a central venous catheter. b Three-year-old boy. Subxiphoidal sagittal scan shows thrombus (arrowheads) around the central venous catheter in the superior vena cava (arrows) and right atrium (RA). (continued)

6.3 Mediastinal Ultrasound in Intensive Care: Complications Associated with Central Venous Access The insertion of a venous catheter is associated with both immediate and long-term complications. The immediate complications include catheter malposition, extraluminal placement with infusate extravasation, pneumothorax, and hemothorax, usually secondary to the insertion procedure. Late complications are occlusion, thrombosis, sepsis, and catheter tip migration. Catheter tip migration may lead to pericardial effusion, cardiac tamponade, or hydrothorax (▶ Fig. 6.23d, e). Malfunction of the central line may be caused by a wrong catheter position, clot formation around the catheter, or thrombosis of the central vein. Thrombosis of the superior vena cava may lead to lymphatic duct blockage and subsequently chylothorax.

Ultrasound may visualize a catheter tip too close to the vessel wall, an echogenic clot at the end of the catheter, or an echogenic clot within the vein and lack of a normal response of the vein to respiratory movements (▶ Fig. 6.23a, b). A fibrin sheet around the catheter is frequently seen but does not necessarily cause malfunction of the catheter. Ultrasound evaluation after catheter removal may show the left-behind fibrin sheath mimicking a catheter fragment (▶ Fig. 6.23c). Doppler ultrasound can be used to demonstrate the lack of jet flow in an obstructed catheter and the lack of blood flow in an obstructed vessel.

Tips from the Pro ●

Any chest X-ray that reveals an unusual catheter position should be further analyzed by ultrasound to exclude catheter migration or misplacement of a venous catheter into an artery. Furthermore, any catheter should be viewed with suspicion if an acute pleural collection is seen on the same side as the catheter.

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Fig. 6.23c–e (continued) c Ten-day-old boy. Right parasternal longitudinal scan shows remaining fibrin sheath (arrowheads) of a catheter in the superior vena cava (arrows) after removal of a central venous line. Open arrowheads, azygos vein entering the superior vena cava; TH, thymus. d, e Three-day-old girl. Trans-sternal high (d) and low (e) axial scans show a significant amount of echo-free pericardial effusion (asterisks) related to catheter tip migration in the right atrium with subsequent fluid leakage. AAo, ascending aorta; MPA, main pulmonary artery; SVC, superior vena cava; Video 6.23 (1–3). LV, left ventricle; RV, right ventricle; RA, right atrium.

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Recommended Readings Abramson SJ, Price AP. Imaging of pediatric lymphomas. Radiol Clin North Am 2008; 46: 313–338, ix Berdon WE. Rings, slings, and other things: vascular compression of the infant trachea updated from the midcentury to the millennium—the legacy of Robert E. Gross, MD, and Edward B. D. Neuhauser, MD. Radiology 2000; 216: 624–632 Bergami GL, Fruhwirth R, Di Mario M, Fasanelli S. Contribution of ultrasonography in the diagnosis of achalasia. J Pediatr Gastroenterol Nutr 1992; 14: 92–96 Bosch-Marcet J, Serres-Créixams X, Borrás-Pérez V, Coll-Sibina MT, Guitet-Juliá M, Coll-Rosell E. Value of sonography for follow-up of mediastinal lymphadenopathy in children with tuberculosis. J Clin Ultrasound 2007; 35: 118–124 Burrill J, Williams CJ, Bain G, Conder G, Hine AL, Misra RR. Tuberculosis: a radiologic review. Radiographics 2007; 27: 1255–1273 Cartwright DW. Central venous lines in neonates: a study of 2186 catheters. Arch Dis Child Fetal Neonatal Ed 2004; 89: F504–F508 Dillman JR, Yarram SG, Hernandez RJ. Imaging of pulmonary venous developmental anomalies. AJR Am J Roentgenol 2009; 192: 1272–1285 Elshabrawi M, A-Kader HH. Caustic ingestion in children. Expert Rev Gastroenterol Hepatol 2011; 5: 637–645 Enriquez G, Aso C, Serres X. Chest Ultrasound. In: Javier L, Strife J, eds. Pediatric Chest Imaging, Berlin, Germany: Springer; 2007:1–36 Franco A, Mody NS, Meza MP. Imaging evaluation of pediatric mediastinal masses. Radiol Clin North Am 2005; 43: 325–353 Gassner I, Geley TE. Sonographic evaluation of oesophageal atresia and tracheooesophageal fistula. Pediatr Radiol 2005; 35: 159–164 Harris MA, Valmorida JN. Neonates with congenital heart disease, Part IV: Total anomalous pulmonary venous return. Neonatal Netw 1997; 16: 63–66 Hernanz-Schulman M. Vascular rings: a practical approach to imaging diagnosis. Pediatr Radiol 2005; 35: 961–979 Hogan MJ. Neonatal vascular catheters and their complications. Radiol Clin North Am 1999; 37: 1109–1125 Keesling CA, Frush DP, O’Hara SM, Fordham LA. Clinical and imaging manifestations of pediatric sarcoidosis. Acad Radiol 1998; 5: 122–132 Kidney DD, Nguyen DT, Deutsch LS. Radiologic evaluation and management of malfunctioning long-term central vein catheters. AJR Am J Roentgenol 1998; 171: 1251–1257 Kim OH, Kim WS, Kim MJ, Jung JY, Suh JH. US in the diagnosis of pediatric chest diseases. Radiographics 2000; 20: 653–671 Koumanidou C, Vakaki M, Theophanopoulou M et al. Aberrant thymus in infants: sonographic evaluation. Pediatr Radiol 1998; 28: 987–989

Lonergan GJ, Schwab CM, Suarez ES, Carlson CL. Neuroblastoma, ganglioneuroblastoma, and ganglioneuroma: radiologic-pathologic correlation. Radiographics 2002; 22: 911–934 McGahren ED. Esophageal foreign bodies. Pediatr Rev 1999; 20: 129–133 Merten DF. Diagnostic imaging of mediastinal masses in children. AJR Am J Roentgenol 1992; 158: 825–832 Moncada RM, Venta LA, Venta ER, Fareed J, Walenga JM, Messmore HL. Tracheal and bronchial cartilaginous rings: warfarin sodium-induced calcification. Radiology 1992; 184: 437–439 Mong A, Epelman M, Darge K. Ultrasound of the pediatric chest. Pediatr Radiol 2012; 42: 1287–1297 Navarro OM. Soft tissue masses in children. Radiol Clin North Am 2011; 49: 1235– 1259, vi–vii Newman B. Thoracic neoplasms in children. Radiol Clin North Am 2011; 49: 633– 664, v Nishino M, Ashiku SK, Kocher ON, Thurer RL, Boiselle PM, Hatabu H. The thymus: a comprehensive review. Radiographics 2006; 26: 335–348 Piñeiro-Carrero VM, Sullivan CA, Rogers PL. Etiology and treatment of achalasia in the pediatric age group. Gastrointest Endosc Clin N Am 2001; 11: 387–408, viii Rahbar R, Nicollas R, Roger G et al. The biology and management of subglottic hemangioma: past, present, future. Laryngoscope 2004; 114: 1880–1891 Restrepo R, Palani R, Cervantes LF, Duarte AM, Amjad I, Altman NR. Hemangiomas revisited: the useful, the unusual and the new. Part 1: overview and clinical and imaging characteristics. Pediatr Radiol 2011; 41: 895–904 Restrepo R, Palani R, Cervantes LF, Duarte AM, Amjad I, Altman NR. Hemangiomas revisited: the useful, the unusual and the new. Part 2: endangering hemangiomas and treatment. Pediatr Radiol 2011; 41: 905–915 Rovin JD, Rodgers BM. Pediatric foreign body aspiration. Pediatr Rev 2000; 21: 86–90 Sridhar S, Thomas N, Kumar ST, Jana AK. Neonatal hydrothorax following migration of a central venous catheter. Indian J Pediatr 2005; 72: 795–796 Taybi H, Capitanio MA. Tracheobronchial calcification: an observation in three children after mitral valve replacement and warfarin sodium therapy. Radiology 1990; 176: 728–730 Wells TR, Gwinn JL, Landing BH, Stanley P. Reconsideration of the anatomy of sling left pulmonary artery: the association of one form with bridging bronchus and imperforate anus. Anatomic and diagnostic aspects. J Pediatr Surg 1988; 23: 892– 898 Williams HJ, Alton HM. Imaging of paediatric mediastinal abnormalities. Paediatr Respir Rev 2003; 4: 55–66 Yonehara Y, Nakatsuka T, Ichioka S, Sasaki N, Kobayashi T. CATCH 22 Syndrome. J Craniofac Surg 2002; 13: 623–626

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Chapter 7 Pleura and Thorax

7.1 Indications for Ultrasonography

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7.2 Anatomy and Normal Variants

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7.3 Pathology

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7 Pleura and Thorax Joost van Schuppen and Rick R. van Rijn The use of ultrasonography of the thorax is limited by the presence of bone, air-containing structures (e.g., lungs, esophagus), and sometimes free air (e.g., subcutaneous emphysema, pneumothorax). Imaging of the chest with ultrasound is therefore confined to those structures that are not obscured by interposed aerated lung tissue or bony structures. Intrathoracic vascular structures such as the aorta, pulmonary arteries, and veins can be only superficially examined. For ultrasonography of the chest, a 15- to 17-MHz linear probe is used for the evaluation of superficial structures and pleural effusions. A 5to 8-MHz curved probe can be used to analyze the mediastinum, intrathoracic structures, and pleural fluids. B-mode ultrasound is mostly used, in gray-scale and Doppler imaging. However, M-mode can be used to quantify motion of the diaphragm or to diagnose a pneumothorax.

The approach is either via a cervical, suprasternal/supraclavicular, intercostal/parasternal route or via a transdiaphragmatic view through the abdomen (▶ Fig. 7.1, ▶ Fig. 7.2, ▶ Fig. 7.3). The advantage of using ultrasound in thorax imaging is its accessibility and bedside capabilities, which makes it a patientfriendly technique that can readily be used in emergency situations without the need for moving patients from the ward or emergency department. Furthermore, it allows direct intervention such as biopsy or pleural drainage (▶ Fig. 7.4; see also Chapter 18). Since the general practice is that cardiac ultrasonography is performed by cardiologists rather than radiologists, imaging of the heart is not discussed in this chapter. Ultrasound of the mediastinum is discussed in Chapter 6.

Fig. 7.1 Probe position for a subdiaphragmatic view of the chest.

Fig. 7.3 Probe position for a parasternal view of the chest.

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Fig. 7.2 Probe position for an intercostal view of the chest.

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Fig. 7.4 Ultrasound-guided 16G histologic biopsy of a pleural lesion of unknown origin. Note the guidelines for the biopsy procedure (dotted lines).

Fig. 7.5 A 13-year-old boy presented with an asymmetric chest wall. Ultrasound shows an asymmetric aspect of the cartilage at the costosternal junction without any signs of pathology. This is regularly seen in early puberty and can last for months to years. Additional imaging is not indicated.

7.1 Indications for Ultrasonography

7.2 Anatomy and Normal Variants

Ultrasonography of the chest can be indicated for an evaluation of pathology seen on a chest radiograph, in which case it allows a differentiation between pulmonary, pleural, and chest wall disease. A more common indication is to assess a superficial lesion that is palpable or visible on physical examination. In these cases, the findings at physical examination can be correlated with the ultrasonographic findings. Ultrasound is an easily accessible imaging technique for making an initial assessment of the lesion in question.

Subcutaneous fat, muscle, and unossified costochondral and sternal cartilage are easily accessible for ultrasonography. Muscle appears hypoechoic, with hyperechoic muscle fibers and tendons. Fat is hypoechoic, with connective tissue septa visible as hyperechoic strands. Unossified cartilage is hypoechoic, with variation in shape and size. Ossified bone is only superficially accessible, as only the cortex can be assessed. Ultrasound can also be used to discriminate between pathology and normal variants, as in patients with asymmetric development of the chest wall and cartilage (▶ Fig. 7.5 and ▶ Fig. 7.6) or a prominent xiphoid (▶ Fig. 7.7).

Tips from the Pro

7.2.1 Thoracic Wall

Sometimes, respiratory movement can make ultrasonography difficult. Challenging a small child to hold his or her breath as if swimming under water can be helpful. “I bet you can hold your breath longer than I can.”

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Fig. 7.6 Four-year-old girl with an asymmetric chest. Ultrasound shows asymmetrically developed below rib cartilage.

Fig. 7.7 A 6-year-old boy presenting with a painless swelling below the sternum. Ultrasound shows the swelling to be based on a prominent xiphoid (open arrowhead).

Tips from the Pro Changes in shape of the chest wall can be hard to visualize. The use of dual-screen imaging in which both sides can be visualized side by side can be helpful. Panoramic views can be helpful, as well.

7.2.2 Pleura The pleura itself under normal conditions is not visible on ultrasonograms. Ultrasound can, however, depict pleural thickening, pleural fluid, and a pneumothorax. Under normal circumstances, the pleural cavity may contain a small amount of fluid. Whereas chest radiographs will miss small amounts of fluid of up to 200 mL, ultrasound can easily detect them. Small amounts of fluid can best be visualized with the patient in a sitting position with the back toward the sonographer.

7.2.3 Lungs Normal, air-containing lung parenchyma is not accessible to ultrasound. The presence of air will cause a hyperechoic reflective surface with reverberation and comet tail artifacts (▶ Fig. 7.8a,b; Video 7.8). One can appreciate the movement of lung and visceral pleura along the parietal pleura on inspiration, the “gliding sign.” On M-mode, this will produce a typical

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Fig. 7.8a,b Normal, air-containing lung with a hyperechoic reflective surface and comet tail artifact (open arrowhead). During normal breathing, this will move (“gliding sign”) ( Video 7.8).

pattern known as “seashore sign” (▶ Fig. 7.9), which if present excludes a pneumothorax. In case of pulmonary consolidation or atelectasis, the lung parenchyma can be visualized.

7.2.4 Breast For imaging of the breast in children, ultrasound is the method of choice. With high-frequency probes, excellent detailed imaging can be obtained. Mammography does not play a significant role in the imaging of pediatric breast lesions because of the denseness of the mammary glands and the use of radiation. After birth, breasts can be enlarged in both boys and girls up to the age of 12 months under the influence of maternal hormones. On ultrasound, flaring of glandular tissue is typical

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Fig. 7.10 Normal breast development in a 1-year-old girl, Tanner stage 1. Fig. 7.9 M-mode imaging shows the “seashore sign.”

Fig. 7.11 Normal breast development in a 15-year-old girl, Tanner stage 3.

Fig. 7.12 Normal breast development in a 16-year-old girl, Tanner stage 4.

Fig. 7.13 One-year-old girl with asymmetric swelling of the breast. Ultrasound shows asymmetric development of normal mammary gland tissue.

(▶ Fig. 7.10). In prepubertal children, the breast is a collection of simple, branched, epithelium-lined ducts surrounded by connective tissue. Physiologic breast development in girls occurs between 9 and 13 years of age under hormonal stimulation. Development can be divided in five Tanner stages ranging from subtle hypere-

choic retroareolar tissue to fully developed breast tissue with echogenic fibroglandular tissue, hypoechoic ducts, Cooper ligaments, and hypoechoic fat (see ▶ Fig. 7.11 and ▶ Fig. 7.12). Changes in hormonal levels can lead to asymmetric breast development. Ultrasound is often used to exclude pathology (▶ Fig. 7.13).

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Fig. 7.15 Normal movement of the diaphragm is shown on M-mode ( Video 7.15). Fig. 7.14 The normal diaphragm is seen as a hyperreflective line (open arrowhead).

7.2.5 Diaphragm

7.3 Pathology

The diaphragm is visible as a thick echogenic line. This is best appreciated via the subxiphoid view in the parasagittal or coronal plane (▶ Fig. 7.14). Ultrasound can be used for both anatomical and functional analysis. Contour abnormalities (e.g., eventration and hernias) are visible on ultrasound. The most common anatomical variant is the diaphragmatic slip. This is characterized by a slip or fold of muscle of the diaphragm, which can cause a smooth indentation of the liver or spleen. Also, nodular crura and hypertrophy of the medial and lateral arcuate ligaments can be seen. The movement of the diaphragm can be analyzed with M-mode (▶ Fig. 7.15; Video 7.15). It can visualize the direction of motion and the amplitude excursion of the diaphragm. For this technique two acoustic windows are used, oblique transverse subxiphoidal and intercostal. On inspiration the diaphragm moves toward the transducer, and on expiration movement is cephalad, away from the probe. This should be correlated with the phase of the respiratory cycle to determine normal or paradoxical movement. The amplitude is measured in the vertical axis. Movement should be reported as either normal, absent, or paradoxical. Normal movement of the diaphragm is over 4 mm on M-mode, and there should be less than a 50% difference in excursion between the two hemidiaphragms.

7.3.1 Chest Wall

Tips from the Pro With the use of M-mode, a reproducible quantification can be easily shown. Also, for the clinician, this is readily interpretable information.

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Poland Syndrome Poland syndrome (OMIM %173800) is hypoplasia of one side of the thorax. Features include hypoplasia of the breast, nipples, and subcutaneous tissue; lack of the pectoralis major muscle and minor musculature; and aplasia or deformity of the costal cartilages of ribs 2 through 4 or ribs 3 through 5. In addition, part of the syndrome can be alopecia of the axillary and mammary region in combination with ipsilateral brachysyndactyly. A possible cause of this syndrome may be developmental abnormality due to hypoplasia of the subclavian artery. The genetics of this disorder are not yet understood. The clinical manifestations can range from aplasia of the pectoral muscles alone to the complete spectrum of features. On ultrasound, an asymmetry of the chest due to hypoplasia or aplasia of the musculature should raise the possible diagnosis of of Poland syndrome (▶ Fig. 7.16).

Rib Anomalies Asymptomatic swelling and asymmetry of the chest will often be due to an abnormal development of ribs, especially of the costal cartilage. In these patients, chest radiographs will often be requested by the referring physicians. However, since the asymmetry is most often located in the cartilaginous part of the rib cage, thoracic ultrasound should be the imaging method of first choice. With the help of ultrasound, it is possible to exclude underlying pathology in most patients. Thoracic ultrasound can show developmental abnormalities of the cartilage and ribs such as forked ribs (▶ Fig. 7.17; Video 7.17a,b), fusion of ribs (▶ Fig. 7.18; Video 7.18), and cervical ribs.

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Pleura and Thorax Infectious processes of the chest wall, like other soft-tissue infections, can appear as a complex mass with or without abscess formation. A heterogeneous mass with hypervascularity can be seen on Doppler ultrasound with infiltration of the surrounding fat. Also, destruction of ribs can be seen on ultrasound. In case of a chest wall abscess, ultrasound will show an encapsulated, hypoechoic, sometimes heterogeneous mass. The mass can have posterior acoustic enhancement. Doppler can show peripheral flow surrounding the lesion. Abscess formation can also occur around surgically implanted materials such as a Nuss bar (▶ Fig. 7.23 and ▶ Fig. 7.24). Magnetic resonance (MR) imaging or computed tomography (CT) is helpful when there is suspicion of expansion into more deeply positioned structures or intrathoracic involvement. In cases of osteomyelitis, there is no role for ultrasound. Only in complications such as abscess formation ultrasound can play a role .

Self-Limiting Sternal Tumor of Childhood

Fig. 7.16a,b Two-year-old girl with an asymmetric thorax. a Ultrasound shows absence of the pectoralis major muscle on the left (compare a with b). Her left hand was normally developed. Genetic analysis showed a Poland sequence. Her mother had an underdeveloped left hand (third and fourth distal phalanges) as an apparent carrier of the gene. b Normal developed right side.

Trauma Although not the imaging method of choice, ultrasound can be used to visualize fractures of the ribs and sternum. In the acute phase, a fracture will produce a cortical disruption, sometimes surrounded by a hematoma (▶ Fig. 7.19). In a later phase, callus formation can be seen (▶ Fig. 7.20 and ▶ Fig. 7.21). Hematoma can cause a broad spectrum of nonspecific sonographic features (▶ Fig. 7.22). Moreover, hematomas are usually clinically evident. Therefore, they are not discussed here.

Infectious Lesions Chest wall infection in children is uncommon. Spread is either hematogenous or via direct infection from surrounding tissue (e.g., after chest surgery). Infectious agents include Staphylococcus aureus, Mycobacterium tuberculosis, Actinomyces, Nocardia, Aspergillus, and Candida. Fungal infections usually occur in immunocompromised patients (e.g., during chemotherapy).

In young children presenting with a fast-growing tumor over the sternum, a self-limiting sternal tumor of childhood (SELSTOC) should be considered in the differential diagnosis. Children can present with or without signs of infection. In the latter case, the main concern will be the presence of a tumor. In the majority of children, the presenting symptom is pain, and discoloration is visible in 50% of reported patients. Generally, laboratory examinations are normal, and microbiologic cultures are negative in all reported cases. Ultrasound shows a well defined, dumbbell-shaped, hypoechoic, heterogeneous, poorly vascularized lesion (▶ Fig. 7.25). The lesion has no contact with the skin and does not infiltrate bone or muscle. As a result of the dumbbell shape and involvement of the sternal cartilage, the distance between the sternal ossification centers can be increased. When ultrasound imaging is typical of SELSTOC, a wait-and-see policy can be implemented. Follow-up via ultrasonography is not necessary but can be reassuring for the parents, who can be afraid of malignancy, and treating physicians, who may not be aware of this entity.

Lymphadenopathy Lymphadenopathy can be seen in reaction to all kinds of (superficial) infections (e.g., in cat-scratch disease). The differentiation between reactive lymphadenopathy and malignant lymph nodes is based mainly on the presence of a fat center and an oval shape in reactive lymphadenopathy (▶ Fig. 7.26, ▶ Fig. 7.27, ▶ Fig. 7.28). In the course of infectious disease, abscess formation in lymph nodes is possible. This will present as lymph nodes with central liquefaction and surrounding hyperemia.

Tips from the Pro If there is concern about fluctuation during ultrasonography, try to keep the ultrasound probe stable while gently compressing the collection with your free hand.

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Fig. 7.17a–c Six-year-old girl with a bump on the thorax, caused by a forked rib on the left. Laterally, a wide cartilaginous rib is present (a). When followed medially, this rib splits into two (b). c Asymmetry due to the cartilaginous malformation in the forked ribs ( Video 7.17).

Fig. 7.18 Eight-year-old girl with asymmetry of the chest. Ultrasound shows a prominent cartilage rib with focal fusion of two ribs (open arrowhead) ( Video 7.18).

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Fig. 7.19 Thirteen-year-old girl who fell from a horse. Ultrasound shows cortical disruption with displacement of the rib (open arrowhead). No hematoma was evident.

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Fig. 7.20a,b One-month-old girl with a bump on the chest. No known trauma. a Ultrasound of the bump shows a fracture at the costochondral junction. The cortex is irregular, and echogenic callus has formed around the fracture (open arrowhead). The fracture produces an impression on the pleura (closed arrowhead). b Chest radiography shows swelling of the chest wall (open arrow).

Fig. 7.21a,b Fifteen-year-old boy with a swelling of the chest wall. a Conventional imaging shows a possible old fracture (lead markings). b Ultrasound shows an irregular rib without signs of pathology (open arrowhead).

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Fig. 7.22 Thirteen-year-old boy with blunt thoracic trauma and pain in the chest wall. Imaging shows a cortical disruption of the sternum in two places with hematoma (open arrowheads).

Fig. 7.23 Fourteen-year-old boy after placement of a Nuss bar (open arrowheads) in pectus excavatum. The scar was red, painful, and swollen. Ultrasound shows extensive infiltration of the fat surrounding the bar (open arrows). No collections were seen.

Fig. 7.24a,b Four-year-old boy after sternotomy closed by cerclage wires. The patient presented 2 months postoperatively with a red swelling of the scar and fever. Ultrasound shows a fluid collection (open arrows) that communicates with the sternotomy (open arrowhead). The abscess was surgically drained.

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Fig. 7.25a–c Ten-month-old girl with an acute, reddish blue painless swelling on the sternum. No history of trauma. Two weeks earlier, she had a short period of high fever. No symptoms at the moment. Ultrasound shows a presternal mass and infiltration with a dumbbell shape in the subcutis. There is a central hypoechoic part, which can be interpreted as an abscess. There seems to be connection with the underlying cartilaginous sternum (open arrow). After diagnosis a self-limiting sternal tumor of childhood (SELSTOC), a wait-and-see strategy was chosen. Follow-up showed resorption of the lesion.

Fig. 7.26 Fifteen-year-old boy with a subcutaneous swelling next to the areola. Ultrasound shows a reactive lymph node.

Fig. 7.27a,b Ten-year-old girl presenting with fever and weight loss. Physical examination showed enlarged supraclavicular lymph nodes. On ultrasound, the parotid gland had hypoechoic foci. a Ultrasound shows an enlarged lymph node with a fatty center. b A hilar vessel with arterial flow on Doppler interrogation. A lymph node was extirpated. This proved to be sarcoidosis.

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Pleura and Thorax Table 7.1 Miscellaneous soft-tissue tumors of the chest wall Type

Presentation

Imaging characteristics

Lipoblastoma

Benign tumor of the chest wall with aggressive growth

Contains fat on ultrasound

Neurogenic tumors, e.g., Neuroblastoma and ganglioneuroblastoma

Arising from intercostal and sympathetic ganglia. Can cause direct growth in chest wall

Paraspinal mass, with splaying of ribs and extension in neuroforamina

Congenital fibrosarcoma

Most common in axilla and upper extremity

Hypervascular soft-tissue mass on Doppler; often primarily diagnosed as vascular malformation

Fig. 7.28 Ten-year-old girl treated for anaplastic lymphoma located mainly in the chest. At follow-up, she presented with a swelling of the lateral right chest wall. Ultrasound shows a lymph node with cortical thickening up to 9 mm. Doppler shows extensive flow. The surrounding fatty tissue is hyperechoic, caused by infiltration. Pathology showed recurrent anaplastic lymphoma.

Tumors of the Chest Wall

Lymphoma

Tumors of the chest wall are rare, and in contrast to those in adults, chest wall tumors in children are mainly primary tumors. Most chest wall tumors are malignant. In most cases, ultrasound will be the initial imaging technique. Often, the imaging characteristics will be nonspecific, but a combination of the patient’s history and age, location of the tumor, and imaging characteristics can be helpful for making a differential diagnosis. A practical diagnostic approach is to categorize the tumors based on their origin as either soft-tissue tumors or bone tumors.

Lymphoma is usually a mediastinal tumor, but sometimes it can extend directly into the chest wall or present as a solitary mass (▶ Fig. 7.30). Extension into the chest wall can be seen parasternally and can be combined with the destruction of osseous structures. A solitary mass presents on ultrasound as a homogeneous hypoechogenic mass near or within the pectoralis musculature. MR imaging and CT are used to determine the extent of the disease. Other, miscellaneous soft tumors of the chest wall are summarized in ▶ Table 7.1.

Soft-Tissue Tumors of the Chest Wall Rhabdomyosarcoma Rhabdomyosarcoma is the most common soft-tissue sarcoma in children and, after Ewing sarcoma, the most common chest wall malignancy in childhood. The prognosis and survival of a patient with rhabdomyosarcoma depend on the site of origin and histology. Chest wall rhabdomyosarcoma tends to have a poor prognosis. The initial presentation is often a soft-tissue swelling, and the clinical symptoms depend mainly on the structures involved. Ultrasound will show a lesion without specific characteristics, usually heterogeneous and poorly defined with flow in the periphery. Biopsy is necessary for diagnosis. In all cases, additional MR imaging will be mandatory to assess the extent of the tumor and its relation to surrounding anatomical structures such as nerves and vessels (▶ Fig. 7.29).

Askin Tumor and Extraosseous Ewing Sarcoma Primitive neuroectodermal (Askin) tumors and extraosseous Ewing sarcomas are part of the Ewing sarcoma group. The tumors of this group are the most common malignancies of the chest wall. (See the later section of this chapter on bone tumors of the chest.)

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Vascular Lesions In the imaging of vascular lesions, ultrasound plays an important role. Both high-frequency gray-scale imaging and Doppler imaging are important. MR imaging can be useful to determine the exact extent of the lesion. According to the classification of Mulliken and Glowacki, vascular anomalies can be divided into vascular tumors and vascular malformations, based on their underlying biology. Vascular tumors in children include mostly hemangiomas. Vascular malformations can be divided in slow-flow and fast-flow malformations, based on the presence of arterial flow in the malformation. Fast-flow malformations include arteriovenous malformations and arteriovenous fistulas, or combined complex lesions. Low-flow malformations include venous malformations, capillary malformations, and lymphatic malformations. ▶ Table 7.2 gives an overview of the imaging characteristic of the different vascular lesions.

Hemangiomas Hemangiomas can be divided into infantile hemangiomas, rapidly involuting congenital hemangiomas (RICH), and noninvoluting congenital hemangiomas (NICH).

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Fig. 7.29a–d Four-year-old boy, with swelling on his right chest. a, b US shows a heterogeneous hypoechoic lesion in the pectoral muscle, well circumscribed with vessels running through it. No invasion of the chest wall or pleural space was seen. c, d MR confirms the same lesion. PA proved to be a small blue round cell tumour, rhabdomyosarcoma.

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Fig. 7.30a,b Twelve-year -old girl presenting with a fast progressive swelling of the right thoracic wall. No other symptoms were present. Physical exam showed a swelling in the right pectoral muscle, under the clavicle. a, b US showed a heterogeneous mass, rather well circumscribed, probably originating in the minor pectoral muscle. Flow on Doppler. Tight relationship with the vessels. c No growth in the thorax was seen. (continued)

Table 7.2 Imaging characteristics of different vascular lesions

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Type

Presentation

Imaging characteristics

Hemangioma

Bluish soft-tissue swelling; can be present at birth or appear in first weeks; fast-growing period followed by regression

Hypoechoic well defined lesion, usually confined to subcutis; possible central scar; sometimes heterogeneous, with dilated vessels; hypervascular on Doppler with venous and arterial waveform

Arteriovenous malformation

Present at birth, sometimes discovered later because of symptoms; can cause right–left shunting with cardiac failure

Tangle of vessels without soft-tissue component; arterial waveform on Doppler

Venous malformation

Present at birth, sometimes discovered later because of symptoms (e.g., growth and pain after clot formation)

Sharply defined lesion without solid component; no wall thickening or mural nodes; can be small and superficial, but may also extend into deep structures; varies in appearance from focal dilatation of one or multiple veins to cystic, with fluid–fluid levels; 30% will show phleboliths, which are virtually pathognomonic; Doppler can show low-flow venous patterns, but as well may show no flow at all; thrombosis can lead to the appearance of a solid lesion; lesion can change with compression, breathing, or Valsalva

Lymphatic malformation

Typically present at birth; grows as patient grows; soft, painless, slowly growing lesion; hemorrhage can cause sudden growth or symptoms

Macrocystic: anechoic mass with thick or thin septa; no solid parts; flow signal can be seen on Doppler in septa; no flow seen in lesion Microcystic: more hyperechoic lesion, can appear solid; after bleeding, lesion can contain hematoma and debris, mimicking a solid lesion; no change at compression, breathing, or Valsalva

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Fig. 7.30(c–e) (continued) MR confirmed the lobulated lesion, with a narrow relationship with the subclavian vessels (arrowhead), without growth in the thorax. MR also shows contralateral lymphadenopathy. The latter pointed towards lymphoma, differential diagnosis was rhabdomyosarcoma and non-osseous Ewing sarcoma. This was PA proven to be a Hodgkin lymphoma.

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Fig. 7.31a,b One-year-old boy with a superficial soft bump on the chest that has a slightly bluish color. a Ultrasound shows a well-circumscribed hypoechoic lesion in the subcutis. b Doppler shows flow in the lesion, confirming the diagnosis of a hemangioma.

Fig. 7.32a–c Four-month-old girl with a swelling on the right scapula. Ultrasound shows a hyperechoic well-circumscribed lesion with flow on Doppler (a, b), confirming the diagnosis of a hemangioma (c).

Infantile Hemangiomas Infantile hemangiomas are the most common neoplasm in children. Hemangiomas can arise in all kinds of tissue, but they are mostly located in the subcutaneous soft-tissue, most commonly in the head and neck, chest wall, and extremities. They consist of abnormally proliferated endothelial cells. These can be present at birth, but they can also appear in the first weeks of life. Usually, the lesions grow fast in the first months of life, sometimes up to 12 months of age, and then regress after this period. Up to 90% of the lesions disappear completely by the

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age of 3 to 5 years, sometimes leaving a fibrous scar. The appearance of a hemangioma after 3 to 5 years of age is atypical, and another diagnosis should be considered. Most hemangiomas are diagnosed clinically as a bluish swelling, but in larger lesions with extension into deeper structures, imaging can help in the analysis. When lesions are large, MR imaging can be indicated. Ultrasound will show a hypoechoic well defined lesion (▶ Fig. 7.31), usually confined to the subcutis. This can also be slightly hyperechoic (▶ Fig. 7.32). On ultrasound, these lesions can have a central scar, causing a

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Fig. 7.33a–d A nearly 3-year-old boy with a painless growing mass on his right shoulder. a Ultrasound shows an iso- to hypoechoic multilobular lesion, with fluctuation on palpation. The lesion is partially solid. b Doppler shows flow in the periphery of the lesion, which is partially intramuscular. c Magnetic resonance imaging shows a partially cystic lesion with rim enhancement on gadolinium-enhanced T1 and the impression of a solid part caudally (open arrowhead, d). Ultrasound-guided biopsy proved the presence of a venous malformation. The swelling was most likely due to clot formation ( Video 7.33).

hypoechoic center. Larger lesions can be more heterogeneous, with dilated vessels. On Doppler imaging, they are hypervascular, with venous and arterial waveforms. Vascular shunting can be present.

RICH and NICH These hemangiomas are larger at birth because the rapid growth phase takes place in utero, whereas infantile hemangiomas grow after birth. Imaging will show larger, prominent feeding vessels. The lesions, RICH more than NICH, show a central hypoechoic focus due to central necrosis. This is sometimes described as a cystic center. NICH resembles infantile hemangioma. A distinction between congenital hemangiomas and infantile hemangiomas cannot be made on US. Although a RICH will involute, a NICH will grow as the patient grows.

Fast-Flow (Arteriovenous) Malformations Arteriovenous malformations contain abnormal connections between arteries and veins. Usually, these lesions are present at birth, although they can be discovered at a later age because of lack of symptoms. When large enough, the lesions can cause a left-to-right shunt with cardiac failure. On imaging, a tangle of vessels is seen, usually without a soft-tissue component. Arterial feeding vessels will show an arterial waveform on Doppler.

Venous Malformations Venous malformations are congenital malformations of the venous system. Lesions can be small and superficial but also can be large with extension into deep structures, soft-tissue, and bone. The lesion consists of tortuous dilated venous vessels (▶ Fig. 7.33). Venous malformations are present at birth but can become apparent at a later age. Sometimes, the initial presentation is the result of an increase of volume (e.g., after clot formation in the lesion). Imaging characteristics depend on the location and type of venous malformation. The malformation can appear as only a focal dilatation of one or multiple veins, sometimes referred to as phlebectasia. Lesions can also appear more cystic, with fluid–fluid levels, known as the cavitary spongiform type. Lesions are sharply defined and should not contain solid tissue, especially no wall thickening or mural nodes because then a neoplasm would be suspected. Phleboliths can be recognized as echogenic foci with posterior shadowing. Only 30% of venous malformations will show phleboliths on conventional imaging, but when present on conventional X-ray or CT, they are virtually pathognomonic for this diagnosis. Doppler can show low-flow venous patterns but may also show no flow at all. Valsalva or changes in position can cause the channels to fill with blood. Arterial flow patterns can be detected in septa or surrounding tissue. The lesion is compressible with a probe. This will show movement of internal sludge.

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Fig. 7.34a–d Five-month-old boy presenting with a soft swelling under the left axilla. a Ultrasound shows multiple fluid collections with clearly perceptible walls. b No flow was detected in the collections, only in the walls. No solid process was identified. The process reached from the clavicle to the diaphragm, around the pectoral muscles, and into the subscapular region. c, d Magnetic resonance imaging confirmed the diagnosis of a lymphatic malformation, with high signal on STIR (short T1 inversion recovery), low signal on T1, and some wall enhancement, without solid parts (arrowhead, d).

Thrombosis in the lesion can cause sudden growth or symptoms like pain and redness. This can raise concerns on the part of both parents and clinicians. Imaging will show complete or partial filling of a lesion with clot. Sometimes, this can be indistinguishable from a solid lesion, and histology will be required. The spongiform type of malformations can cause inflammation with atypical imaging features on ultrasound, MR imaging, and CT.

Tips from the Pro The presence of phleboliths is virtually pathognomonic for a venous malformation. In case of doubt, conventional imaging can confirm their presence.

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Lymphatic Malformations Lymphatic malformations are the result of a congenitally abnormal formation of the lymphatic system. Lesions consist of an abnormal number of dilated lymphatic channels surrounded by endothelium (▶ Fig. 7.34 and ▶ Fig. 7.35). Lymphatic malformations can be classified as macrocystic, microcystic, or a combination of both. Lymphatic malformations are most commonly encountered in the axilla, chest, and neck. Malformations are often present at birth and up to 90% are discovered at the age of 2 years. These lesions grow as the patient grows. Patients usually present with a soft, painless, slowly growing swelling. However, hemorrhage in a lymphatic malformation

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Fig. 7.35a–c Eight-year-old girl with an acute swelling on her right scapula. a, b Ultrasound shows a multicystic lesion with internal debris, moving on pressure. c No flow is seen on Doppler. The diagnosis is lymphatic malformation. The internal debris reflects recent bleeding, which caused the swelling.

can cause an acute expansion of the lesion. When the lesion is confined to superficial dermal layers, ultrasound can depict the lesion very well. With extension into deep layers or into the thorax, MR imaging is indicated for analysis of the spread. A high-frequency probe will show anechoic masses with septa. Septa can be thick or thin, but no solid parts will be seen in the macrocystic variant. Flow signal can be seen on Doppler in the septa or surrounding the lesion. No flow will be seen in the lesion. The microcystic variant will appear as a more hyperechoic mass, which can look solid. After bleeding, the lesion can contain hematoma and debris, mimicking a solid lesion. The differentiation between a lymphatic malformation and a venous malformation without flow can be difficult. Ultrasound

can also be used to guide intervention (e.g., diagnostic biopsy) and also treatment with the injection of therapeutic agents.

Bone Tumors of the Chest Bone tumors of the chest are rare. The most common types are discussed here. ▶ Table 7.3 summarizes other bone tumors of the chest.

Ewing Sarcoma Ewing sarcomas comprise three types of tumor, including primitive neuroectodermal tumors (Askin tumor), osseous Ewing

Table 7.3 Miscellaneous osseous tumors of the chest wall Type

Presentation

Imaging characteristics

Langerhans cell histiocytosis

Can appear in all osseous structures of chest wall

Soft-tissue around a lesion expanding from bone with a punched out defect in bone; conventional imaging indicated

Primary osteosarcoma

Extremely rare in chest

Diagnosis usually made on X-ray showing destruction of osseous structures, with osteoid matrix; ultrasound, computed tomography, magnetic resonance imaging show large, heterogeneous soft-tissue mass expanding from destroyed bone

Chondrosarcoma

Most common in mandible and ribs

Ultrasound shows large soft-tissue swelling extending from rib, with central calcifications and chondroid matrix

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Fig. 7.37 Two-year-old girl with a painless swelling on the sixth rib on the left side. Ultrasound shows the typical image of an osteochondroma, with a small hypoechoic cartilage cap (open arrowhead).

presence of metastasis before the start of therapy. During therapy, the tumor can show partial necrosis and cyst formation. Fig. 7.36 Three-year-old girl with a painless swelling on a right rib. The image is typical of an osteochondroma, with outgrowth of bone and a small cartilage cap (open arrowhead).

Fig. 7.38 Two-year-old girl with reactive pleural fluid in posttraumatic intrathoracic pancreatic pseudocyst.

sarcoma, and extraosseous Ewing sarcoma. All types contain small blue round cells expressing the MIC2 gene, based on translocation of the same gene. The clinical presentation is usually a painful swelling of the chest in combination with pulmonary discomfort. In general, chest radiography will be the first imaging modality, showing a mass with erosion of the ribs or other bony structures. Ultrasound will show a heterogeneous mass with Doppler flow. Intrathoracic extrapleural extension is possible, with the presence of a pleural effusion. The imaging findings on ultrasound are in general nonspecific. CT and MR imaging will be mandatory in all cases for analysis of the extent of tumor, involvement of other structures, and the

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Osteochondroma Osteochondroma, more commonly referred to as exostosis, is the most common benign bone tumor. These tumors are bony outgrowths composed of epiphysial growth plate, cortical bone, and medullary bone with a hyaline cartilage cap. They can occur in any osseous structure of the chest wall and in the chest are most commonly located in the ribs. They tend to grow inward. They can be solitary; however, in multiple hereditary exostosis, multiple tumors are found in a single patient. Usually no symptoms are present, but symptoms can occur as a result of physical stress caused by the compression of muscles, nerves, or vascular structures. Ultrasound will show a bony outgrowth with a hypoechoic cartilaginous cap (▶ Fig. 7.36 and ▶ Fig. 7.37). Malignant transformation into chondrosarcoma is rare, occurring in fewer than 1% of solitary osteochondromas. In cases of multiple osteochondromas, the risk for malignant degeneration is up to 25%. Usually, malignant degeneration presents with symptoms of pain and ongoing growth of the osteochondroma after skeletal maturation. MR imaging can give information about the growth of the osteochondroma and its influence on surrounding tissue. In adults, a cartilage cap thickness of 2 cm or more is a strong indicator of malignant degeneration. In children, however, the thickness of the cartilaginous cap has not proved to be such a useful indicator of malignancy.

7.3.2 Pleural Space Pleural Fluid Collection Pleural fluid is excellently depicted on ultrasound, its sensitivity is higher than that of conventional radiography. Fluids can differ in appearance, depending on their contents. Simple fluids can appear completely anechoic (▶ Fig. 7.38), whereas complicated fluids such as hematoma or empyema (▶ Fig. 7.39 and ▶ Fig. 7.40; Video 7.40) will contain hyperechoic reflections and may contain septa or fibrin (▶ Fig. 7.41 and ▶ Fig. 7.42; Video 7.42a, b, c). Based on ultrasound alone, a differentiation between an exudate and transudate cannot be made.

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Fig. 7.39 Six-year-old boy with long-standing pneumonia. Chest X-ray shows opacification of the right hemithorax with a partially aerated lung. Ultrasound shows pleural fluid with internal echoes moving on inspiration. The partially aerated lung lies centrally in the thorax (open arrowhead). Fig. 7.40 One-year-old boy with difficulty breathing after liver biopsy. Ultrasound shows pleural fluid with thick echogenic strands (open arrowhead). This was a hematoma as a complication after puncture ( Video 7.40).

Fig. 7.41a–c Eighteen-month-old boy with pneumonia complicated by empyema. a Ultrasound at first shows a pleural collection with multiple septa, internal fluid that moves with heartbeat, and transgression through the chest wall. Follow-up shows resolving pleural collections after drainage, but still a subpleural collection with a thick wall and debris (b, c). This was drained via thoracotomy.

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Pleura and Thorax in cases of inflammation and infection, and also in cases of malignancy.

Pleural Mass Pleural mass usually is detected on conventional imaging or CT (▶ Fig. 7.43). If a pleural mass is diagnosed with other modalities, ultrasound can be helpful in guiding a percutaneous biopsy.

7.3.3 Lungs Consolidation

Fig. 7.42 Fourteen-year-old boy with severe Staphylococcus aureus pneumonia complicated by pleural empyema. On ultrasound, complicated pleural fluid is seen, with heterogeneity of the fluid and septa (open arrow). Consolidation of the lungs is seen, with an air bronchogram (open arrowhead) ( Video 7.42a,b,c).

During respiration, fluid and lung will show motion, but in loculate collections, this will be less evident ( Video 7.42a, b, c). Simple fluids will be present in the dependent parts of the thorax, whereas complex/loculate collections will also be present in the nondependent parts, including the anterior and lateral pleural spaces. When a fluid collection organizes, septa and fibrin bands appear. Septa and fibrin strands are better appreciated on ultrasound than on CT; therefore, ultrasound should be the first imaging method of choice after the initial chest radiograph. During breathing, fibrin bands and septa can show motion ( Video 7.42a, b, c). The presence of septa and fibrin strands is important for the choice of an appropriate therapy. Ultrasound can distinguish between a subpulmonal fluid collection and an elevated hemidiaphragm. It can also detect an accompanying pulmonary or pleural tumor.

Pneumothorax Ultrasound is excellent for the detection of small pneumothoraces that would remain undiscovered on chest radiographs. In pneumothorax, the normal reflective surface and movement of the pleura and pulmonary parenchyma are not seen. Especially in neonatal care and in the setting of trauma, this can be of importance. Ultrasound shows, on the nondependent side of the thorax, a static acoustic shadow. There is no movement of the pleura and lung. Artifacts such as reverberation and the comet tail sign will not be seen.

Pleural Thickening Pleural thickening is an anomaly caused by scarring, calcification, and/or thickening of the pleura itself. One of the most important causes of pleural thickening worldwide is asbestos exposure, but this occurs significantly less often in children than in adults. In children, pleural thickening can be seen

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When lung parenchyma is consolidated, air is replaced by fluid, mucus, or cells, This produces an acoustic window for ultrasound. Consolidation in a lung can mimic liver parenchyma, socalled hepatization. Sonographic air bronchograms can appear as hyperechoic linear branches (▶ Fig. 7.44). As mentioned, the bronchi can also contain mucus and fluid. They will appear as hypoechoic linear branches with perceptible thin walls with or without air bubbles, called sonographic fluid bronchograms. Normal vascularization can be seen on color Doppler sonography. With ultrasound, a differentiation between consolidation and atelectasis can be made by the presence of moving air in air bronchograms, indicating a consolidation (▶ Fig. 7.45). However, in some cases atelectasis can also contain air bronchograms, so that this sign is not 100% sensitive. Furthermore, necrosis of parenchyma, causing hypoechoic foci and collections, can be seen in consolidation due to infection.

Atelectasis Atelectasis is the collapse of lung tissue as a result of absent aeration. Unlike in consolidation, the alveoli are deflated. On ultrasound, this can resemble liver tissue (▶ Fig. 7.46 and ▶ Fig. 7.47). Volume loss of the lung will cause crowding of vessels. Sometimes central air bronchograms are seen.

7.3.4 Breast Congenital Anomalies Premature Thelarche The early development of breast tissue in girls (before 7 or 8 years of age) can be seen from the age of 1 to 3 years. This can be an isolated event but also a part of precocious puberty. Ultrasound will show normal, although premature, development of glandular breast tissue, without signs of focal pathology (▶ Fig. 7.48).

Gynecomastia As a consequence of physiologic changes in hormonal levels, the development of breast tissue in boys can occur. This can be unilateral or bilateral and is seen in up to 75% of boys at the age of 13 to 14 years. It is self-limiting and usually resolves in 2 years’ time. Gynecomastia can be idiopathic but has a close relation to obesity. In obesity, there is an increased conversion of testosterone to estradiol in the adipose tissue mass that can

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Fig. 7.43a–d Twelve-year-old boy presenting with symptoms of pneumonia. After 14 days of treatment, there was no improvement. Chest X-ray showed a consolidation. After computed tomography (CT) of the chest, he was referred to our hospital. a, b Ultrasound shows a solid lesion of the pleura without signal on Doppler. A hyperechoic focus is also seen, possibly calcification (open arrowheads). c CT shows a lesion of the pleura without osseous destruction. No differentiation could be made between a solid tumor and an infectious condition, so a biopsy was done. d Pathology proved it to be an infectious process. This lesion resolved without intervention.

Fig. 7.44a,b Three-year-old girl with a pneumonia complicated by empyema. Ultrasound shows consolidation of the parenchyma with linear hyperechoic branches as air bronchograms (a) and with flow on Doppler (b).

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Pleura and Thorax lead to reduced luteinizing hormone and testosterone levels. Secondary gynecomastia can be caused by hormone-producing tumors, Klinefelter syndrome, neurofibromatosis type 1, acquired testicular failure, or androgen receptor defects. Also, the use of drugs like marijuana, anabolic steroids, corticosteroids, cimetidine, digitalis, and tricyclic antidepressants is reported to cause gynecomastia. Ultrasound will show the development of otherwise normal breast tissue. Obesity can also cause pseudogynecomastia, in which the breasts are filled with fatty tissue. Imaging will show fatty tissue without glandular tissue. In juvenile or virginal hypertrophy, a rapid development of either symmetric or asymmetric breast tissue appears in girls, usually after menarche or during pregnancy. Imaging will show diffuse enlargement of the breast with normal glandular tissue and without signs of pathology.

Inflammation Inflammation of breast tissue occurs from the neonatal age (mastitis neonatorum) up to adolescence. In most cases, S. aureus is the causative agent. Causes can be obstruction of a mammary duct, infection of retroareolar cysts, injury of the nipple, or cellulitis of the breast area. Breast abscesses result clinically in tender or fluctuating masses with surrounding erythematous skin. Imaging will show either a cystic lesion, often with a thick wall, or a more complex mass, with increased blood flow on Doppler in the periphery of the lesion. Ultrasound can be useful to guide fine needle aspiration. Mastitis usually will appear as a more complex mass with diffuse flow on ultrasound, whereas an abscess will show flow only at the periphery (▶ Fig. 7.49 and ▶ Fig. 7.50). Mastitis can be complicated by abscess formation. Fig. 7.45a,b Seven-month-old boy with respiratory insufficiency due to pneumonia. a Chest X-ray shows a consolidation on the right and some pleural fluid. b Ultrasound confirms the pleural fluid and also shows consolidated lung parenchyma with air bronchograms.

Fig. 7.46a,b One-year-old boy with respiratory insufficiency after a convulsion. Ultrasound (a) shows complete collapse of the left lung, with flow on Doppler (b).

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Tips from the Pro When fine needle aspiration is planned, it is useful to instruct the referring physician to prescribe Emla cream, an oil–water emulsion of lidocaine and prilocaine. A generous dose of Emla cream should be applied between 60 to 120 minutes before the procedure. It should be covered with a transparent dressing.

Hematoma Acute hematomas will appear as a hyperechoic mass on ultrasound. With the passing of time, this will show more anechoic portions or even cystic portions and will eventually resolve. Usually trauma can be remembered, but in active children there will sometimes be no recollection of trauma. Hematoma can also occur after surgical procedures (▶ Fig. 7.51).

Cystic Lesions

Fig. 7.47a,b Two-week-old premature infant with a persistent opacification in the left upper lung on chest X-ray. b Ultrasound shows hyperechoic tissue with vascular structures running through it, which can be followed to the hilum. No air is seen in the lobe. The tissue resembles liver tissue (open arrow) ( Video 7.47a,b).

Mammary duct ectasia can cause bloody discharge and can form a tender palpable mass when infected. Mammary duct ectasia is usually subareolar and appears as ectatic ducts with or without debris. Although galactoceles usually appear in lactating women, they may also appear in children, both boys and girls. The appearance on ultrasound depends on the amount of fat and water. Water is hypoechoic, whereas fat is more hyperechoic. This can give the appearance of a complex cyst. Usually, these are nontender swellings. Retroareolar cysts, also known as Montgomery cysts, will appear as simple cysts, either solitary or multiple, with or without some debris (▶ Fig. 7.52). These are usually bilateral and less than 2 cm in diameter.

Fig. 7.48 Six-year-old girl with a swelling of her right breast. Ultrasound shows normal retromammillary breast tissue (open arrows) and asymmetry without signs of pathology.

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Fig. 7.49a–c Female neonate at day 17 with a red left breast. Ultrasound shows normal glandular tissue, with infiltration of fat (a) and some hyperemia (b) on Doppler. The right breast (c) looks normal.

Fig. 7.50 Fourteen-year-old girl with a history of mastitis presenting with a red, swollen, painful left breast. Imaging shows diffuse infiltration of the breast without signs of collections or an abscess but with hyperemia. The diagnosis was again mastitis, for which she received antibiotics.

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Fig. 7.52 Thirteen-year-old girl with swelling behind the nipple. Ultrasound shows a simple bilobar cyst without solid tissue or flow.

Fig. 7.51 Fourteen-year-old girl after a Mirabel procedure for fibroadenoma, in which a soft-tissue lesion is removed via a biopsy needle with a vacuum system. Hematoma can be a complication. This girl presented with a persistent swelling. Ultrasound shows a hematoma.

Fig. 7.53a,b Thirteen-year-old girl with a swelling in the right breast. a Ultrasound shows an isoechoic, sharply delineated lobulated lesion with some flow and background enhancement. b Follow-up after 6 month showed no growth, confirming fibroadenoma.

Benign Solid Lesions Fibroadenoma is a slowly growing, painless, well circumscribed mass discovered either by palpation or by asymmetric breast development (▶ Fig. 7.53 and ▶ Fig. 7.54). The mean age at diagnosis is between 15 and 17 years. Usually, these lesions are located in the outer upper quadrant. Fibroadenoma is the most common mass in girls younger than 20 years of age. Ultrasound is a very sensitive method for diagnosing fibroadenomas. The typical appearance is a well circumscribed mass, either round

or oval, with posterior enhancement. Macrolobulation can be present. Fluid-filled clefts can be seen. The lesion is usually homogeneously hypoechoic. Inhomogeneous lesions can be necrotic or have dystrophic calcifications. Growth is either horizontal or parallel to the skin. Lesions usually do not show flow on Doppler examination, but some central flow can be detected. Other miscellaneous benign tumors of the breast are summarized in ▶ Table 7.4.

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Malignant Solid Lesions Malignant solid lesions of the breast in children are extreme rare. Usually, the clinical presentation differs from that of a benign lesion because malignant tumors tend to grow fast. These tumors are summarized in ▶ Table 7.5.

7.3.5 Diaphragm Congenital Anomalies Diaphragmatic Hernia

Fig. 7.54 Fourteen-year-old girl with a swelling in the right breast of long duration. Ultrasound shows a large lesion of 7 × 5 × 3 cm. The patient underwent surgery. This was a histologically proven giant fibroadenoma.

There are three types of diaphragmatic hernias. Bochdalek type: This is the most common type of diaphragmatic hernia, with an estimated frequency of 1 per 2,000 to 5,000 live births. Usually, a Bochdalek hernia is diagnosed on antenatal ultrasound. This type herniates through a laterodorsal defect. Eighty percent of Bochdalek herniations occur on the left side. Only 11% of cases are asymptomatic. A Bochdalek hernia is associated in 25 to 50% of cases with other anomalies, such as

Table 7.4 Imaging characteristic of miscellaneous benign breast tumors Type

Presentation

Imaging characteristics

Juvenile papillomatosis

This is a proliferative disorder in young women, which presents with a well-defined mass, usually in the periphery of the breast

An isoechogenic mass surrounded by normal glandular tissue, ill-defined with multiple small anechoic cysts, mostly in the periphery of the lesion. Calcifications can be seen on ultrasound

Pseudoangiomatous stromal hyperplasia

Hyperplasia of stroma, due to hormonal stimulation. Common in premenopausal women but also seen in young women

Variable, not characteristic. In general well circumscribed hypoechoic solid lesions, ovoid, long axis parallel to the skin. But the lesion can also be less well circumscribed. The lesion can be calcified. On US these lesions can mimic fibromas

Intraductal papilloma

Proliferation of epithelia into the mammary duct lumen. Clinical this lesion presents with serous or serosanguinous nipple discharge

A subareolar elongated duct with intraluminal mass, sometimes surrounded by multiple dilated ducts. Usually this is a solitary lesion

Table 7.5 Imaging characteristic of miscellaneous malignant breast tumors

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Type

Presentation

Imaging characteristics

Cystosarcoma/ phyllodes tumor

Most common primary malignant tumor of breast in children; accounts for 1% of breast lesions in children and adolescents; presents as painless, fast-growing mass in the breast; at presentation tends to be large (> 6 cm)

On imaging no differentiation between benign or malignant phyllodes cannot be made because of large overlap in imaging characteristics; on ultrasound a phyllodes tumor can appear as a fibroadenoma, a homogeneous hypoechoic macrolobulated mass, well delineated with posterior enhancement; lesion can also be more heterogeneous and hypoechoic with hypoechoic cysts or debris-filled cysts

Carcinoma

Extremely rare in children but may be related to BRCA1 and BRCA2 gene carriers

Usually a heterogeneous hypoechoic mass with irregular margins, with or without posterior shadowing; long axis usually perpendicular to chest wall

Metastasis

Metastatic disease of breast rare; can be caused by different primary tumors (e.g., rhabdomyosarcoma, neuroblastoma, hematologic and lymphoid malignancies); often bilateral

Imaging characteristics variable; most lesions heterogeneously hypoechoic, with internal hyperechoic foci, irregular margins, and posterior shadowing

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Fig. 7.55a–c Ten-month-old boy after repair of an omphalocele. The patient presented with shortness of breath. a Chest X-ray shows an opacification of the right hemithorax with air configurations. b, c Ultrasound confirms the suspected large diaphragmatic hernia, showing pleural fluid with atelectasis of the lung and bowel inside the thorax, including mesentery.

cardiovascular malformations; limb anomalies (polydactyly, syndactyly); genetic abnormalities (trisomy 18,21 and tetrasomy 12p); neural tube defects and hydrocephalus; cryptorchidism; cleft palate; and esophageal atresia. After birth, the first imaging of a hernia would be a plain film of the thorax, showing intrathoracic bowel loops or opacification of one side of the thorax (▶ Fig. 7.55 and 7.56). Ultrasound will confirm the presence of a hernia, containing bowel loops, liver or spleen. On US, the herniation of liver on the left side predicts the size of the hernia. Morgagni hernia: This is a hernia through the foramen of Morgagni, which is situated anteriorly in the diaphragm. This type is right sided in up to 90% of cases. Usually, a Morgagni hernia is asymptomatic and found by coincidence in older children or adults. Symptoms can be due to airway infection or to obstruction of herniated bowel loops. Liver, spleen, and omentum can also herniate.

Hiatal hernia: This is a hernia of a part of the stomach into the mediastinum through the esophageal hiatus in the diaphragm. Three types are recognized. A sliding hernia is a movement of the gastroesophageal junction into the thorax through the hiatus. In a paraesophageal hernia, a part of the stomach extends through the hiatus with a normal position of the gastroesophageal junction. A congenitally short esophagus causes fixation of a part of the stomach in the thorax. In the diagnosis of this type of hernia, ultrasound does not play a role. The hernia is usually detected on conventional imaging.

Eventration Eventration is probably due to the congenital absence of muscle fibers in the diaphragm. The diaphragm is intact, but part of it bulges into the thorax (▶ Fig. 7.57). An eventration can range in size; virtually the whole diaphragm may be affected, or the

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Fig. 7.56a,b Three-month-old girl with respiratory distress. a Conventional imaging raised the suspicion of a congenital pulmonary airway malformation (CPAM). b Ultrasound shows bowel loops above the liver, herniating into the thorax. The hernia was surgically corrected.

Fig. 7.57a,b One-month-old boy with dextrocardia and a paracardiac mass in the thorax with displacement of the cardiac structures (a). Ultrasound shows an eventration of the diaphragm on the medial paracardiac side (b). The diaphragm is intact without herniation of the abdominal structures.

eventration may be focal (▶ Fig. 7.58). Usually, there are no symptoms. An eventration is usually located anteromedially on the right side of the diaphragm. A complete eventration of a hemidiaphragm is usually located on the left and can be hard to distinguish from paralysis (▶ Fig. 7.59). Also, a focal eventration can be hard to distinguish from a hernia. Detection of a complete, intact diaphragm by ultrasound excludes a hernia.

Diaphragmatic Paralysis

Fig. 7.58 Eleven-month-old boy suspected of having an eventration on chest X-ray. Ultrasound confirms an eventration of the right hemidiaphragm, containing part of the liver and the right kidney. The indentation of the diaphragm caused by the liver can be seen clearly (closed arrowhead). The diaphragm is intact.

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Paralysis of the diaphragm is either unilateral or bilateral. Unilateral diaphragmatic paralysis can be without clinical symptoms, whereas bilateral paralysis almost always causes respiratory symptoms. Paralysis can lead to atelectasis and pneumonia due to inability to clear the lung parenchyma.

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Fig. 7.59a,b One-month-old boy with an elevated diaphragm on the left side. M-mode ultrasound shows normal movement/excursion of the right hemidiaphragm (a). On the left side, less movement is detected, in combination with small paradoxical excursions (b).

Diaphragmatic paralysis is caused by a lesion of the phrenic nerve and can occur after birth trauma or surgery (e.g., cardiac surgery). Other causes include mediastinal or cervical tumors and viral infection (e.g., Lyme disease and West Nile virus infection). On radiographs, an elevated hemidiaphragm can suggest paralysis, but this is not sufficiently specific. With ultrasound, movement of the diaphragm is readily appreciable in real time. Also, it is possible to correlate the diaphragmatic movement with the patient’s breathing. When the diaphragm is interrogated through the liver, normal movement is movement toward the probe on inspiration. Paradoxical movement is movement away from the probe on inspiration. Although there are no agespecific values, movement of less than 4 mm, paradoxical movement of a hemidiaphragm, or a difference in excursion of more than 50% between the hemidiaphragms is diagnostic for a hemiparalysis.

Trauma Traumatic injury of the diaphragm is uncommon in children and is usually associated with high-impact trauma or other severe trauma. Usually, traumatic injury is left-sided because the presence of the liver prevents injury on the right side. Diaphragmatic injury can lead to bowel strangulation or ischemia of the visceral organs due to constriction. Chest X-ray usually raises suspicion. The role of ultrasound in trauma resuscitation is limited because ultrasound in trauma is focused on the presence of free fluid, and further imaging is usually with CT.

Recommended Readings Baez JC, Lee EY, Restrepo R, Eisenberg RL. Chest wall lesions in children. AJR Am J Roentgenol 2013; 200: W402–19 Behr GG, Johnson CM. Vascular anomalies: hemangiomas and beyond—Part 2, Slowflow lesions. AJR Am J Roentgenol 2013; 200: 423–436 Behr GG, Johnson CM. Vascular anomalies: hemangiomas and beyond—Part 1, Fastflow lesions. AJR Am J Roentgenol 2013; 200: 414–422 Bernard SA, Murphey MD, Flemming DJ, Kransdorf MJ. Improved differentiation of benign osteochondromas from secondary chondrosarcomas with standardized

measurement of cartilage cap at CT and MR imaging. Radiology 2010; 255: 857– 865 Chang YW, Kwon KH, Goo DE, Choi DL, Lee HK, Yang SB. Sonographic differentiation of benign and malignant cystic lesions of the breast. J Ultrasound Med 2007; 26: 47–53 Chateil JF, Arboucalot F, Pérel Y, Brun M, Boisserie-Lacroix M, Diard F. Breast metastases in adolescent girls: US findings. Pediatr Radiol 1998; 28: 832–835 Chavhan GB, Babyn PS, Cohen RA, Langer JC. Multimodality imaging of the pediatric diaphragm: anatomy and pathologic conditions. Radiographics 2010; 30: 1797– 1817 Chung EM, Cube R, Hall GJ, González C, Stocker JT, Glassman LM. From the archives of the AFIP: breast masses in children and adolescents: radiologic-pathologic correlation. Radiographics 2009; 29: 907–931 Coley BD. Chest sonography in children: current indications, techniques, and imaging findings. Radiol Clin North Am 2011; 49: 825–846 Epelman M, Navarro OM, Daneman A, Miller SF. M-mode sonography of diaphragmatic motion: description of technique and experience in 278 pediatric patients. Pediatr Radiol 2005; 35: 661–667 Fefferman NR, Pinkney LP. Imaging evaluation of chest wall disorders in children. Radiol Clin North Am 2005; 43: 355–370 Fokin AA, Robicsek F. Poland’s syndrome revisited. Ann Thorac Surg 2002; 74: 2218– 2225 García CJ, Espinoza A, Dinamarca V et al. Breast US in children and adolescents. Radiographics 2000; 20: 1605–1612 Hedrick HL. Management of prenatally diagnosed congenital diaphragmatic hernia. Semin Fetal Neonatal Med 2010; 15: 21–27 Hidalgo A, Franquet T, Giménez A. 16-MDCT and MR angiography of accessory diaphragm. AJR Am J Roentgenol 2006; 187: 149–152 Kim OH, Kim WS, Kim MJ, Jung JY, Suh JH. US in the diagnosis of pediatric chest diseases. Radiographics 2000; 20: 653–671 Kronemer KA, Rhee K, Siegel MJ, Sievert L, Hildebolt CF. Gray scale sonography of breast masses in adolescent girls. J Ultrasound Med 2001; 20: 491–496, quiz 498 Mong A, Epelman M, Darge K. Ultrasound of the pediatric chest. Pediatr Radiol 2012; 42: 1287–1297 Nam SJ, Kim S, Lim BJ et al. Imaging of primary chest wall tumors with radiologicpathologic correlation. Radiographics 2011; 31: 749–770 Restrepo R, Lee EY. Updates on imaging of chest wall lesions in pediatric patients. Semin Roentgenol 2012; 47: 79–89 Shamberger RC, Grier HE. Chest wall tumors in infants and children. Semin Pediatr Surg 1994; 3: 267–276 Supakul N, Karmazyn B. Ultrasound evaluation of costochondral abnormalities in children presenting with anterior chest wall mass. AJR Am J Roentgenol 2013; 201: W336–41 te Winkel ML, Lequin MH, de Bruyn JR et al. Self-limiting sternal tumors of childhood (SELSTOC). Pediatr Blood Cancer 2010; 55: 81–84 van Schuppen J, van Doorn MM, van Rijn RR. Childhood osteomyelitis: imaging characteristics. Insights Imaging 2012; 3: 519–533

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Chapter 8

8.1 Normal Anatomy

214

8.2 Pathology

215

Peritoneal Cavity and Retroperitoneal Space

8

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8 Peritoneal Cavity and Retroperitoneal Space Rick R. van Rijn In this chapter, the peritoneal cavity and the retroperitoneal space will be discussed. The focus is solely on the anatomical region and not on the organs within (as these are discussed in separate chapters in this book).

8.1 Normal Anatomy The peritoneal cavity is the space between the parietal peritoneum and the visceral peritoneum, which covers all the intraperitoneal organs (i.e., the stomach, spleen, gallbladder, liver, and part of the intestines). Approximately 50 mL of fluid is produced daily and circulates throughout the peritoneal cavity in a well defined pattern. During the evaluation of patients with a possible malignancy, it is important to be aware of this pattern of circulation because there are certain areas of stasis where small deposits of, for example, malignancies can be found (▶ Fig. 8.1). Resorption of the peritoneal fluid is predominantly achieved in the subphrenic space. It is important to be aware of the fact that whereas in boys the peritoneal cavity is a completely enclosed environment, in

girls there is an opening at the level of the ovarian tubes. This can serve as a port of entry for infections such as pelvic inflammatory disease. The retroperitoneal space is the anatomical region behind the peritoneum, and it contains several organs, which can be remembered with the mnemonic SAD PUCKER (▶ Table 8.1). The retroperitoneal area surrounding the kidneys is divided into three separate parts. The perirenal space is bounded by the Zuckerkandl fascia on the posterior side and the Gerota fascia on the anterior side. This space contains the kidney, adrenal gland, and renal vessels. The anterior pararenal space is bounded posteriorly by the Gerota fascia and anteriorly by the posterior peritoneum. It contains the retroperitoneal duodenum, pancreas, and ascending and descending colon. Finally, the posterior pararenal space, which contains only fat, is bounded by the muscles of the posterior abdominal wall posteriorly and the Zuckerkandl fascia anteriorly. In children, the retroperitoneum can easily be visualized with ultrasonography. In most cases, a graded compression technique and a high-frequency linear transducer can be used (▶ Fig. 8.2).

Fig. 8.1 Graphic representation of the intraperitoneal cavity. Note the direction of the peritoneal circulation and the areas of stasis (asterisks).

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Fig. 8.2 Normal view of the retroperitoneum with the use of a linear probe in a 2-year-old boy.

8.2 Pathology 8.2.1 Abdominal Vessels Aorta In contrast to adults, pathology of the abdominal aorta in children is rare. There are only a handful of reported cases of congenital anomalies of the abdominal aorta, consisting mainly of atresia and duplication. Other reported pathologies of the abdominal aorta include middle aortic syndrome (▶ Fig. 8.3 and ▶ Fig. 8.4), Takayasu arteritis, thrombosis (▶ Fig. 8.5), and aneurysms. Of special interest are the long-term survivors of abdominal neuroblastoma. There have been reports of midaortic syndrome in these children, both in those who have and in those who have not had radiation therapy. In all of these rare cases, additional imaging with computed tomography (CT) and/or magnetic resonance (MR) imaging is mandatory.

Table 8.1 Organs contained within the retroperitoneal space S

Suprarenal glands

A

Aorta/inferior vena cava

D

Duodenum (second and third segments only)

P

Pancreas (tail is intraperitoneal)

U

Ureters

C

Colon (ascending and descending colon only)

K

Kidneys

E

Esophagus

R

Rectum

Fig. 8.3a,b a Ten-year-old boy with a significant narrowing over a short distance of the abdominal aorta. b Digital subtraction angiography shows the narrowing of the abdominal aorta and hypertrophy of the inferior mesenteric artery.

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Fig. 8.4a,b a Eleven-year-old girl with midaortic stenosis (arrow). b Magnetic resonance angiography of the abdominal aorta confirms the finding on ultrasonography.

Fig. 8.5a,b Premature infant born at 27 weeks. a After placement of an arterial umbilical catheter, a large thrombus has formed in the aorta just below the renal and superior mesenteric arteries. (Courtesy of E. Beek, Department of Radiology, University Medical Center, Utrecht, The Netherlands.) b Color duplex shows obstructed flow in the aorta.

Inferior Vena Cava Congenital anomalies of the inferior vena cava (IVC) are in general an incidental finding and do not warrant specific follow-up. Because of the complex embryology of the IVC (which comprises four different segments: hepatic, suprarenal, renal, and infrarenal), multiple variants can be encountered. The most common variant is absence of the hepatic segment of the IVC, leading to the azygos continuation (▶ Fig. 8.6; Video 8.6). Other variants include left-sided IVC, double IVC, and anomalous/multiple origins of the veins draining into the IVC (▶ Fig. 8.7 and ▶ Fig. 8.8). Knowledge of the normal variants of the IVC is important in differentiating between left-sided para-aortic masses and an

216

aberrant IVC and, in cases of percutaneous venous intervention, in IVC stent placement. Thrombosis/occlusion of the IVC can be encountered in children with central lines and in oncology patients (especially Video 8.10 and children with Wilms tumor; ▶ Fig. 8.9; ▶ Fig. 8.10). Ultrasound (US) is in these cases the imaging method of choice. The optimal way to visualize the IVC is from the front. However, in some children this will yield a suboptimal view because of such factors as body shape and gasdistended bowels. In such cases, a lateral approach to the IVC can be used, in which the retroperitoneum is used as a window.

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Fig. 8.7 Accessory hepatic vein draining segments 5 and 6 in a healthy 13-year-old boy. Note the portal vein (arrow) in relation to the hepatic vein (open arrow).

Fig. 8.6a,b Four-day-old girl with an antenatally diagnosed cardiac anomaly and situs inversus. a Sagittal view of the liver shows absence of the hepatic segment of the caval vein. b A cross-sectional view of the retroperitoneum just below the level of the left renal vein shows that the inferior vena cava (arrow) is located to the left of the aorta (open arrow) ( Video 8.6).

Fig. 8.8a,b Thirteen-year-old girl referred for routine follow-up after treatment for a Wilms tumor. a Ultrasound shows an accessory hepatic vein draining segments 5 and 6. b Color Doppler shows the flow from the liver toward the caval vein.

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Fig. 8.9a–c Ten-month-old boy with a Wilms tumor of the left kidney. a Note the grossly abnormal upper and middle poles of the kidney. b Sagittal view shows a large tumor thrombus obstructing the inferior vena cava (arrow). c In the axial view, the thrombus (arrow) can be more difficult to detect.

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Fig. 8.10a–c Ten-year-old boy with a history of treatment for abdominal neuroblastoma. a On ultrasound, absence of the inferior vena cava is noted. b A collateral hypertrophic vein is noted to pass behind the right psoas muscle and drain into the azygos system ( Video 8.10). c Color Doppler shows flow toward the retroperitoneum. (This image shows a significant amount of aliasing, making flow interpretation difficult.)

8.2.2 Lymphadenopathy Mesenteric Lymphadenopathy The mesenteric lymph nodes in children are easily visualized, and to the inexperienced radiologist they can look like a pathologic finding. The normal short-axis diameter of the mesenteric lymph nodes is up to 8 mm (▶ Table 8.2). Mesenteric lymphadenopathy is commonly seen in mesenteric adenitis, which is most often caused by a viral infection. However, enlarged, ovoid lymph nodes can also be seen in a significant proportion of otherwise healthy children (▶ Fig. 8.11 and ▶ Fig. 8.12). The sole finding of such lymph nodes should not lead to a further workup. If, however, the lymph nodes show a change in texture, with loss of the hilum and a round, hypoechoic appearance, further analysis is mandatory, either by additional work-up, including cross-sectional imaging, or by biopsy (▶ Fig. 8.13). In patients

with large and bulky lymph nodes, further work-up is mandatory. In many cases, a percutaneous or a surgical biopsy must be performed.

Retroperitoneal Lymphadenopathy Unlike mesenteric lymphadenopathy, enlargement of the retroperitoneal lymph nodes should always be regarded as abnormal (▶ Fig. 8.14). Therefore, this finding warrants further follow-up. In children, the most common causes of retroperitoneal lymphadenopathy are malignancies, such as Wilms tumor, neuroblastoma, rhabdomyosarcoma, and malignant lymphoma; however, infectious diseases can also cause lymph node enlargement. On US, lymphadenopathy can be obscured by gastrointestinal gas or, in an increasingly large group of children, obesity. In children with large abdominal tumors, the retroperitoneum can

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Fig. 8.11 Five-year-old girl referred for follow-up after urologic surgery at the age of 1 year. During routine follow-up, normal lymph nodes are seen.

Fig. 8.12 Screening abdominal ultrasound in a boy with vague abdominal pain shows a normal lymph node (arrow). Note the normal appendix (open arrow).

Fig. 8.13 Ten-year-old refugee from sub-Saharan Africa. Screening abdominal ultrasound shows multiple lymph nodes with central calcification (arrows). He and both his parents tested positive for tuberculosis.

Table 8.2 False-positive rate for enlarged mesenteric lymph nodes with varying lymph node threshold size Threshold size (mm)

No. of enlarged lymph nodes

False-positive rate (%)

≥5

33

54

>6

18

30

>7

8

13

>8

3

5

>9

3

5

> 10

0

0

Source: Reprinted with permission from Karmazyn B, Werner EA, Rejaie B, Applegate KE. Mesenteric lymph nodes in children: what is normal? Pediatr Radiol 2005;35(8):774–777. Note: In this retrospective study, 61 children (36 boys and 25 girls; mean age, 10.7 years; range, 1.1–17.3 years) underwent noncontrast abdominal computed tomography for the evaluation of suspected or known renal stones; abdominal lymph node size was evaluated. Enlarged mesenteric lymph nodes (short axis > 5 mm) were found in 33 (54%) of the 61 children. The majority of the enlarged mesenteric lymph nodes was found in the right lower quadrant (88%). Based on their findings, the authors stated that a short-axis diameter of > 8 mm might be a more appropriate definition for mesenteric lymphadenopathy in children.

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Fig. 8.14a,b Ten-year-old boy with malaise and weight loss. a Abdominal ultrasound shows a large round lymph node adjacent to the psoas muscle. Note the absence of a normal fat center. b Enlarged lymph nodes near the inferior vena cava. Burkitt lymphoma was diagnosed based on a lymph node biopsy.

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Fig. 8.15 Thirteen-year-old girl referred for follow-up ultrasound (US) for cholelithiasis. US shows a minute amount of physiologic ascites (arrow). This finding should not lead to a further work-up.

Fig. 8.17 One-year-old girl with an ovarian germ cell tumor. On ultrasound, a significant amount of ascites is seen.

be difficult to visualize. In these children, disease staging with additional imaging (e.g., MR imaging) is mandatory.

Tips from the Pro ●

If the retroperitoneum is obscured by intestinal gas, graded compression, as in the diagnosis of appendicitis, should be applied. Compression should be applied during inspiration.

8.2.3 Intraperitoneal Fluid Collections Ascites Ascites is the accumulation of free fluid in the peritoneal cavity. In healthy girls, a small amount of fluid in the Douglas pouch is

Fig. 8.16a,b Seventeen-day-old male neonate with hepatic failure, as part of multiple-organ failure, and hemorrhages. a Abdominal ultrasound (US) was requested, which showed a homogeneously enlarged liver with ascites (arrow). Laboratory investigation showed a herpes simplex infection. b The portal vein is dilated and hyperechogenic (arrow). During US, the flow in the portal vein was extremely slow ( Video 8.16).

a normal physiologic finding (▶ Fig. 8.15). In all other cases, ascites should be regarded as a pathologic finding. The causes of ascites can be differentiated according to whether a transudate, with a low protein content, or an exudate is present. The most common cause of a transudate is portal hypertension, and therefore a transudate is seen in children with cirrhosis and heart failure (▶ Fig. 8.16; Video 8.16). A transudate can also be seen in severe malnutrition (kwashiorkor) and nephrotic syndrome. An exudate is seen primarily in peritoneal metastatic disease and infection (▶ Fig. 8.17, ▶ Fig. 8.18, ▶ Fig. 8.19, ▶ Fig. 8.20; Videos 8.18 and 8.20). There is, however, a large differential diagnosis for the presence of ascites, which is different for neonates (▶ Table 8.3) and children (▶ Table 8.4; ▶ Fig. 8.21 and ▶ Fig. 8.22).

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Fig. 8.20 Fifteen-month-old boy admitted to the pediatric intensive care unit with severe gastroenteritis. Abdominal ultrasound shows a significant amount of ascites, which contains small particles. Given the child’s poor condition, an abdominal tap was performed to rule out peritonitis. The ascites was clear on visual inspection, and culture yielded no pathogenic growth ( Video 8.20).

Fig. 8.18a,b Twelve-year-old boy being treated for a relapse of alveolar rhabdomyosarcoma. The child presented with discomfort and abdominal distention. a On ultrasound, ascites is seen. b Power Doppler shows respiratory-dependent flow of ascites ( Video 8.18).

Fig. 8.19a,b Sixteen-year-old boy with an exacerbation of known Crohn disease. a Ultrasound shows a thickened and inflamed terminal ileum. b A significant amount of ascites is seen in this patient.

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Fig. 8.21a–f Eight-month-old girl with increased abdominal girth. a Ultrasound shows a diffusely enlarged pancreas with a focal lesion (arrow). b Ascites in the pelvis. c Cystic lesion with septa of unknown origin in the mesentery. d On T2-weighted magnetic resonance imaging, there is a discrete pancreatic lesion of high signal intensity (arrow). e The mesenteric cystic lesion has high signal intensity on T1-weighted imaging (arrow). On T2-weighted imaging, the signal intensity was also high. f Endoscopic retrograde cholangiopancreatography shows contrast extravasation due a laceration in the pancreatic duct. Based on these findings, the diagnosis of child abuse needs to be excluded. The outcome of this investigation is unknown.

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Fig. 8.22a,b One-month-old girl with infantile acute lymphocytic leukemia. a There is hepatomegaly with ascites (arrow). b Ascites. Note the clear depiction of the walls of the small bowel.

Table 8.3 Causes of neonatal ascites

Table 8.4 Causes of ascites in infants and children

Hepatobiliary disorders

Genitourinary disorders

Hepatobiliary disorders

Cirrhosis

Obstructive uropathy

Cirrhosis

Lymphoma

Alpha1-antitrypsin deficiency

Posterior urethral valves

Congenital hepatic fibrosis

Wilms tumor

Congenital hepatic fibrosis

Ureterocele

Acute hepatitis

Clear cell renal sarcoma

Viral hepatitis

Lower ureteral stenosis

Budd–Chiari syndrome

Glioma

Budd–Chiari syndrome

Ureteral atresia

Bile duct perforation

Germ cell tumor

Biliary atresia

Imperforate hymen

Liver transplantation

Bile duct perforation

Bladder rupture

Portal venous malformation

Bladder injury from umbilical artery catheterization

Ruptured mesenchymal hamartoma

Nephrotic syndrome

Gastrointestinal disorders

Ruptured corpus luteum cyst

Intestinal malrotation

Cardiac disorders

Intestinal perforation

Arrhythmia

Acute appendicitis

Heart failure

Intestinal atresia

Hematologic disorder

Pancreatitis

Neonatal hemochromatosis

Chylous ascites Parenteral nutrition Extravasation Metabolic disease

Other Congenital cutis marmorata telangiectatica Intravenous vitamin E Pseudoascites Small-bowel duplication Abdominal trauma Idiopathic

Source: Reprinted with permission from Giefer MJ, Murray KF, Colletti RB. Pathophysiology, diagnosis, and management of pediatric ascites. JPGN 2011;52(5):503–513.

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Neoplasm

Ovarian tumor Mesothelioma Neuroblastoma

Gastrointestinal disorders

Metabolic disease

Acute appendicitis

Genitourinary disorders

Intestinal atresia

Nephrotic syndrome

Pancreatitis

Peritoneal dialysis

Pyloric stenosis

Cardiac disorder

Serositis

Heart failure

Crohn disease

Pseudoascites

Eosinophilic enteropathy

Celiac disease

Henoch-Schönlein purpura

Cystic mesothelioma

Chylous ascites

Omental cyst

Intestinal lymphangiectasia

Ovarian cyst

Lymphatic duct obstruction

Other

Lymphatic duct trauma

Systemic lupus erythematosus

Parenteral nutrition extravasation

Ventriculoperitoneal shunt Vitamin A toxicity Chronic granulomatous disease Nonaccidental trauma Idiopathic

Source: Reprinted with permission from Giefer MJ, Murray KF, Colletti RB. Pathophysiology, diagnosis, and management of pediatric ascites. JPGN 2011;52(5):503–513.

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Peritoneal Cavity and Retroperitoneal Space A rare cause of hematoperitoneum is tumor rupture; this has been reported in a variety of abdominal tumors, mainly of the liver, kidney, and ovaries (▶ Fig. 8.25).

8.2.4 Peritonitis

Fig. 8.23 Fourteen-year-old girl with blunt abdominal trauma. Focused assessment with sonography for trauma (FAST) shows free fluid in the Morrison pouch (arrow).

Hematoperitoneum The main cause of a hematoperitoneum in children is blunt abdominal trauma (see Chapter 9, section 9.3.4 Trauma; ▶ Fig. 8.23). The diagnosis is initially based on focused assessment with sonography for trauma (FAST). FAST has been shown to have a sensitivity of up to 50%, a specificity of 91%, a positive predictive value of 68%, and a negative predictive value of 83%. If the FAST examination is positive, additional imaging consisting of contrast-enhanced CT may, based on the clinical situation of the patient, be performed (▶ Fig. 8.24; Video 8.24).

Peritonitis is a diffuse infection of the peritoneum, in contrast to a peritoneal abscess, in which the infection is localized. In children, the latter is mostly due to a perforated appendicitis (▶ Fig. 8.26 and ▶ Fig. 8.27; Videos 8.26 and 8.27). Peritonitis can be either primary or secondary. Primary peritonitis (i.e., a bacterial infection of ascites) is seen in children with, for example, nephrotic syndrome or liver failure. Secondary peritonitis is the more common form and is generally caused by the rupture of a hollow organ, an extensive infection, or necrotizing pancreatitis (▶ Fig. 8.28 and ▶ Fig. 8.29; Video 8.28). An at-risk population are children on peritoneal dialysis. An annual rate of peritonitis of 0.68 (one episode every 17.8 months) in children has been reported, which is higher than the rate in adults. A rare form of peritonitis is sclerosing encapsulating peritonitis, which is seen in patients on long-term peritoneal dialysis or ventriculoperitoneal shunting (▶ Fig. 8.30). In children with suspected peritonitis, US is able not only to confirm the presence of peritonitis but also to guide the diagnostic tapping of ascitic fluid. It is important to be aware of the fact that a negative culture will not always exclude peritonitis.

Tips from the Pro ●

Locate the inferior epigastric artery before performing a puncture of the peritoneal cavity close to the midline.

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Fig. 8.24a–c Sixteen-year-old boy stabbed with a kitchen knife in the right upper abdomen. a Focused assessment with sonography for trauma (FAST) shows a minor amount of free fluid in the Morrison pouch (arrow). b Contrast-enhanced computed tomography shows a laceration in the liver (arrow), free fluid around the liver (open arrow), and a hydropic gallbladder with an adjoining fluid collection (arrowhead). Given the patient’s clinical condition, a nonoperative approach was chosen. c Abdominal ultrasound performed 4 days after the incident shows a perforation of the gallbladder wall (arrow) ( Video 8.24).

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Fig. 8.26 Two-year-old boy with a prolonged history of abdominal pain. After initial spontaneous improvement, the patient presented with severe abdominal pain and fever. Ultrasound shows an abscess in the right lower quadrant. Note the hyperechoic structure (arrow). This was surgically proved to be an appendiceal abscess with a fecalith ( Video 8.26).

Fig. 8.25a,b a Ten-year-old girl with a Wilms tumor of the lower pole of the right kidney. b A small amount of blood is seen in the Douglas space (arrow), making it a stage IIIc Wilms tumor.

Fig. 8.27 Two-year-old girl with a short history of abdominal pain and fever. After a short period of improvement, she presented with a high fever and pain in the right lower quadrant. Ultrasound shows an abscess in the right lower quadrant (arrow) ( Video 8.27).

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Fig. 8.29 Twenty-eight-day-old premature girl with necrotizing enterocolitis. On ultrasound, thick mucoid fluid is seen between the bowel loops, which was percutaneously drained.

Fig. 8.28a,b Two-month-old boy, born prematurely, with fever and general malaise for 1 day. Imaging performed on the night before this examination showed portal air, ascites, and intestinal pneumatosis. On the morning of this ultrasound (US) scan, he underwent a rapid clinical deterioration. a Abdominal US shows persistent pneumatosis (arrow). b Purulent fluid, in keeping with pus, surrounds the small bowel (arrow). At surgery, approximately 20 cm of gangrenous small bowel with several perforations was resected ( Video 8.28).

Fig. 8.30a,b Seven-year-old girl with caudal regression syndrome. After long-term ventriculoperitoneal drainage, resorption of the cerebrospinal fluid ceased, leading to accumulation in the peritoneal cavity. a Ultrasound (US) shows a significant amount of ascites with multiple membranes. b Abdominal US shows the tip of the drain in the loculate collection (arrow). Sclerosing encapsulating peritonitis was diagnosed, and the drain had to be replaced with a ventriculocardial drain.

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Fig. 8.31a,b Three-day-old prematurely born neonate with feeding intolerance and abdominal distention. a Ultrasound shows a linear area of increased echogenicity with a clear ring-down artifact (arrow). Note that part of the liver is obscured by the ring-down artifact. b Abdominal radiograph of the same child shows a classic pneumoperitoneum with a continuous diaphragm sign (arrow) and a football sign, which is a large oval radiolucency in the shape of an American football with free air on both sides of the falciform ligament (open arrow).

8.2.5 Pneumoperitoneum Pneumoperitoneum is to the presence of free air in the peritoneal space, and although US is not the first imaging modality of choice, it is excellently suited to diagnose pneumoperitoneum as an incidental finding. The most common cause of pneumoperitoneum in children is perforation of a viscus. In the neonatal period, this results mostly from necrotizing enterocolitis. Other causes are blunt abdominal trauma, abdominal surgery/ laparoscopy, peritoneal dialysis, pneumomediastinum, and barotrauma. On US, pneumoperitoneum is seen as a linear area of increased echogenicity with a clear ring-down artifact (▶ Fig. 8.31; Video 8.31 and ▶ Fig. 8.32). If air is located inside a bowel loop, US will show the bowel wall superficial to the air collection.

been described only in the adult population. Secondary tumors of the peritoneum can spread via four routes:

Peritoneal tumors in children ●

●

●

Tips from the Pro ●

Pneumoperitoneum is best visualized in the perihepatic space; look for small bubbles of air.

8.2.6 Peritoneal Tumors Peritoneal or mesenteric tumors can be divided into primary and secondary tumors (see Box Peritoneal tumors in children). Primary peritoneal tumors are extremely rare, and most have

●

●

Primary malignant tumors ○ Rhabdomyosarcoma ○ Desmoplastic small round cell tumors ○ Mesothelioma Primary benign tumors ○ Vascular malformation ○ Lymphangioma ○ Lipoma ○ Lipoblastoma Secondary malignant tumors ○ Lymphoma ○ Pseudomyxoma peritonei ○ Sarcomatosis ○ Gliomatosis peritonei Infectious disease ○ Granulomatous peritonitis ○ Inflammatory pseudotumor ○ Sclerosing encapsulating peritonitis Miscellaneous ○ Endometriosis ○ Melanosis ○ Splenosis

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Fig. 8.32a,b Two-month-old prematurely born girl. a A small amount of free air in the peritoneal cavity is seen in front of the liver ( Video 8.31). b Abdominal cross-table radiograph shows small amounts of free air. A “telltale triangle” is visible (arrow).

1. Lymphatic dissemination, mostly in cases of lymphoma; however, soft-tissue malignancies can also spread via this route. 2. Hematogenous spread is less commonly seen in children. 3. Direct extension of tumor is less commonly seen in children. 4. Seeding is seen in, for example, ovarian tumors, but in children this can also be the result of tumor rupture. (Wilms tumors can present with tumor rupture leading to peritoneal involvement.)

Desmoplastic Small Round Cell Tumors Desmoplastic small round cell tumors are rare, aggressive softtissue sarcomas that are seen mainly in males (5:1 male-tofemale ratio). The most common location is the peritoneal cavity (▶ Fig. 8.33). The presentation is dependent on the location of disease, but in general, because of the insidious course, patients usually present with advanced disease. In children, the differential diagnosis on imaging includes rhabdomyosarcoma, lymphoma, neuroblastoma, and mesenteric carcinoid. On US, the tumor has homogeneously hypoechoic. Given the rarity of this tumor, additional imaging and tissue sampling are mandatory for the diagnosis. The use of positron emission tomography/computed tomography (PET/CT) has been described by

230

Fig. 8.33a–c A 9-year-old boy presented with a subcapsular renal hematoma after minor trauma. a Secondary work-up revealed a hypoechoic solid tumor behind the bladder (arrow). b T2-weighted axial magnetic resonance (MR) image shows a homogeneous mass situated between the bladder and rectum. c Coronal T2-weighted MR image shows a subcapsular hematoma of the left kidney (asterisk). A mesenteric metastasis is visible between the kidney and the spleen (arrow). During surgery, numerous small peritoneal metastases were found.

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Peritoneal Cavity and Retroperitoneal Space Arora et al and in their study has been shown to have a sensitivity of 96.1% and a specificity of 98.6%. There are limited treatment options for desmoplastic small round cell tumors. They are relatively insensitive to chemotherapy, and radical surgery in many cases is not possible. As a result, the outcome in general is poor, with a reported 3-year survival of approximately 30%.

Lipoblastoma Lipoblastoma, which is almost exclusively seen in infants and young children, is a rare benign tumor. It can be either a well circumscribed mass (▶ Fig. 8.34), as is the case in the majority of patients, or an infiltrating mass (▶ Fig. 8.35; Videos 8.35a and 8.35b). The latter is also known as lipoblastomatosis. Although histologically identical, lipoblastoma is a more superficial tumor, whereas lipoblastomatosis is found in deeper anatomical locations. If on imaging of a child a well circumscribed soft-tissue lesion that contains predominantly fat is seen, the primary differential diagnosis should be a lipoblastoma. On US, lipoblastoma and lipoblastomatosis in general are homogeneous echogenic masses. In patients with superficial, well circumscribed lesions, US suffices for the diagnosis and presurgical work-up. More deeply seated lipoblastoma and especially lipoblastomatosis need further imaging, preferably with MR imaging.

Lymphoma In children, non-Hodgkin lymphoma, which has numerous subclasses, is more commonly encountered than Hodgkin lymphoma. Differentiation between the different types of lymphoma cannot be achieved solely with US. Tissue diagnosis is mandatory in all cases. On US, retroperitoneal and mesenteric involvement of lymph nodes is seen mostly as a mass, either single or multiple (▶ Fig. 8.36 and ▶ Fig. 8.37). The lymph nodes may show signs of central necrosis or calcification, and encasement of vessels is often encountered.

Lymphangioma Intra-abdominal lymphangioma is considered to be a benign tumor of congenital origin, caused by a maldevelopment of the lymphatic system. It is an extremely rare tumor with a reported incidence of 1 to 4 per 100,000 individuals. Only a minority of cases are encountered in the peritoneum or retroperitoneum. As the main presenting symptom in children is abdominal pain, either with or without the presence of a palpable mass, US is the initial imaging of choice. On US, lymphangioma can present as a single cystic lesion, but more commonly it presents as a Video large, multiloculate, septate cystic mass (▶ Fig. 8.38; 8.38). Surgical resection is the preferred method of treatment, so cross-sectional imaging will in most cases be mandatory.

Metastases In children, peritoneal metastases are a rare finding. Metastatic disease is found primarily in the lungs, liver, and skeleton. Peritoneal metastases present mostly as thin plaques, which makes the sensitivity and specificity of US for the diagnosis relatively

Fig. 8.34a–c One-year-old girl with failure to thrive. a Abdominal ultrasound (US) shows a well defined hypoechoic mass. Color Doppler US of the mass shows no vascularization. b Coronal T1-weighted magnetic resonance (MR) image shows a lipomatous tumor in the right lower abdomen. The lesion was proved on pathology to be a lipoblastoma. c Axial T1-weighted MR image shows involvement of the rectus abdominis muscle (arrow).

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Fig. 8.35a–d One-year-old girl with failure to thrive. a Abdominal ultrasound (US) shows an ill-defined heterogeneous mass in the mid abdomen. b Color Doppler US demonstrates absence of flow within the lesion. c US can assess the relation between the tumor and the other organs. There is no relation between the liver (L) and the tumor (asterisk) ( Video 8.35a). d Abdominal T2 weighted magnetic resonance imaging with fat saturation shows a heterogeneous tumor containing fat. The areas of high signal intensity were proved on pathology to be necrotic ( Video 8.35b).

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Fig. 8.37 Conglomerate of enlarged lymph nodes in a 6-year-old boy with Burkitt lymphoma. VCI, inferior vena cava; AO, aorta. Fig. 8.36 Four-year-old boy with recurrence of Burkitt lymphoma. Large para-aortic lymph nodes are seen on ultrasound.

Fig. 8.38a–c Two-year-old girl who presented with abdominal distention. a Abdominal ultrasound shows a multiloculate, septate cystic tumor displacing the abdominal organs. b T2-weighted coronal magnetic resonance (MR) imaging shows the extent of the tumor. c T2-weighted axial MR imaging shows septa within the lymphangioma ( Video 8.38).

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Fig. 8.39a,b Thirteen-year-old girl with a history of bilateral germ cell tumor of the ovaries. a On follow-up ultrasound, a lesion was detected between the liver and diaphragm. b On presurgical coronal T1-weighted magnetic resonance imaging, the lesion is visible between the liver and diaphragm (arrow).

poor (▶ Fig. 8.39). In some cases, larger “drop” metastases can be found in the Douglas pouch (▶ Fig. 8.40), or they can present as omental cake (▶ Fig. 8.41 a–c). In cases of suspected peritoneal metastatic disease, MR imaging is the preferred imaging technique, although the use of diagnostic laparoscopy is also advocated.

Retroperitoneal tumors in children ●

8.2.7 Retroperitoneal Tumors The most common retroperitoneal tumors in childhood are Wilms tumors (discussed in Chapter 13, Wilms Tumor) and neuroblastomas. Although retroperitoneal tumors are rare, they deserve attention because the majority of them is malignant (see box Retroperitoneal tumors in children). There is an overlap between peritoneal and retroperitoneal tumors, and the imaging findings are similar.

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●

Malignant ○ Adrenal carcinoma ○ Desmoid tumor ○ Liposarcoma ○ Lymphoma ○ Malignant peripheral nerve sheath tumor ○ Metastasis (e.g., testis) ○ Neuroblastoma ○ Rhabdomyosarcoma ○ Teratoma ○ Wilms tumor Benign ○ Adrenal adenoma ○ Fibroma ○ Ganglioneuroma ○ Lipoma/lipoblastoma ○ Neurofibroma ○ Schwannoma

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Peritoneal Cavity and Retroperitoneal Space

Ganglion Cell Tumors In children, ganglion cell tumors can be divided into neuroblastomas (malignant), ganglioneuroblastomas (intermediate tumor with a malignant potential), and ganglioneuromas (benign). These tumors present as a spectrum, with the highest percentage of malignant tumors in younger children. Although these tumors are often found in the adrenal gland (see Chapter 13), they can arise elsewhere in the sympathetic nervous system. On US, ganglion cell tumors range from homogeneously hypoechoic (mostly ganglioneuromas) to heterogeneous (mostly neuroblastomas) and well circumscribed. In neuroblastomas, fine as well as coarse calcifications are seen (▶ Fig. 8.42; Video 8.42). Neuroblastomas tend to encase vascular structures, and all neurogenic tumors can extend into the spinal canal.

Sacrococcygeal Teratoma In children, sacrococcygeal teratoma is the most common form of germ cell tumor. It has been reported that up to 75% of cases are diagnosed in utero or in the neonatal period. It is of interest to note that this is the most common form of congenital tumor. The remainder of cases are diagnosed before the age of 4 years. Approximately three-quarters of sacrococcygeal teratomas are benign, and the incidence of malignancy increases with age at detection. Sacrococcygeal teratomas are classified into four subtypes: type 1, the most common, is externally located, protruding from the sacral region. Type 2 is externally located with an internal presacral component. Type 3 is located mostly presacrally but has a minor extension externally (▶ Fig. 8.43). The location of type 4 is entirely presacral (intrapelvic; ▶ Fig. 8.44 and ▶ Fig. 8.45). On US, this tumor can be either solid or cystic; in the latter case, the tumor is most likely a mature sacrococcygeal teratoma. The correlation between imaging findings on US and histologic grading of malignancy is poor. Given the location of the tumor, additional imaging with MR imaging is mandatory in most cases. Sacrococcygeal teratoma, or any other presacral anomaly, can be associated with anorectal malformation and sacral defects; this is known as the Currarino triad (▶ Fig. 8.46). Fig. 8.40a,b Four-year-old girl treated for an embryonal rhabdomyosarcoma located within the pelvis. a On routine follow-up abdominal ultrasound, after complete surgical resection, a large mass is seen located behind the bladder. b Color Doppler demonstrates flow within the tumor.

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Fig. 8.41a–c Twelve-year-old boy being treated for a relapse of alveolar rhabdomyosarcoma (see ▶ Fig. 8.16). a A large metastasis is visible. b A large metastatic mass arising from the pelvis is visualized. Note the hypervascularity of the tumor mass. c Non contrast-enhanced computed tomography, performed for planning radiotherapy, clearly shows the omental cake (arrows).

Fig. 8.42a,b One-year-old boy who presented to a general practitioner because of fever and a limp of the left leg. On physical examination, a mass was found in the right upper abdomen. The general practitioner referred the patient for abdominal ultrasound (US) and clinical evaluation. a On US, a large tumor, assumed to arise from the right adrenal gland, was found (arrow). Note the calcifications throughout the tumor. b Axial T2-weighted magnetic resonance imaging shows the large retroperitoneal tumor with clear encasement of the aorta, right renal artery, celiac trunk, and superior mesenteric artery ( Video 8.42).

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Fig. 8.43a–c One-day-old girl with an antenatally detected presacral cystic mass. a Abdominal ultrasound shows a large cystic tumor located in front of the sacrum and lumbar spine. b View from the buttock shows the presacral cystic tumor (asterisk), the sacrum (arrow), and a second cystic tumor just below the os coccygis (asterisks). c Sagittal T2-weighted magnetic resonance imaging clearly depicts the extent of the tumor and the close relation to the sacrum and os coccygis. The tumor was a histologically proven mature teratoma.

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8.2.8 Cystic Congenital Anomalies Cystic congenital intraperitoneal anomalies are a rare finding in children. There are two distinct entities to be discerned, duplication cysts and mesenteric cysts, both of which are extremely rare.

Enteric Duplication Cyst Enteric duplication cysts can be found along the entire gastrointestinal tract. The most common presenting symptoms are nausea and pain as a result of obstruction. These cysts are closely related to an adjoining segment of the alimentary tract and in all cases possess at least a layer of smooth muscle and mucosa. As a result, on US the cyst shows a double wall, known as the “muscular rim sign” (▶ Fig. 8.47). This sign, however, is not 100% specific for enteric duplication cysts, as it has been described in rare cases of mesenteric cyst, mature cystic teratoma, torted ovarian cyst, and Meckel diverticulum. Cheng et al proposed a new sign, the “Y-configuration,” to identify enteric duplication cysts (▶ Fig. 8.48). The Y-configuration is a result of splitting of the shared hypoechoic muscularis propria layer (▶ Fig. 8.49; Video 8.49). Finally, if all five layers of the alimentary tract are identified in a cystic abdominal lesion, the diagnosis of an enteric duplication cyst can safely be made. If the cyst has been infected, the multilayered appearance can be lost.

Mesenteric Cyst

Fig. 8.44a,b Three-year-old boy with obstipation and failure to thrive. a Abdominal ultrasound shows a mass located between the sacrum (asterisk) and rectum (arrow). b Sagittal T2-weighted magnetic resonance imaging shows the extent of the tumor. Note the cystic component (arrow).

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Mesenteric cysts are rare cystic lesions arising from the mesentery or near the mesentery. The reported incidence in children is 1 in 20,000 hospital admissions. Embryologically, mesenteric cysts are thought to be benign proliferations of ectopic lymphatics that do not have a communication with the normal lymphatic system. The majority of mesenteric cysts is found in the mesentery of the small bowel. On US, mesenteric cysts appear fluid-filled. They can be simple or contain multiple septa (▶ Fig. 8.50). The echogenicity depends on the presence of hemorrhage or infection. Additional cross-sectional imaging, in most cases, is not indicated.

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Peritoneal Cavity and Retroperitoneal Space

Fig. 8.45a,b Three-year-old girl with a history of long-standing obstipation. a On abdominal ultrasound, a mass located between the rectum and sacrum is visible. Note the catheter in the bladder (asterisk). b Magnetic resonance imaging shows a solid presacral mass (arrow). This was a histologically proven mature teratoma.

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Fig. 8.46a–d One-month-old girl presenting with a defecation disorder. a Ultrasound (US) of the spine, performed to assess the position of the conus medullaris, shows an abnormal sacrum (arrow) and a small mass caudal to the sacral bone (asterisk). b Radiograph of the sacrum shows asymmetric development (arrow). c T2-weighted sagittal magnetic resonance imaging of the lumbar spine shows a tethered cord, previously shown on US (arrow), and a tumor caudal to the sacral bone (open arrow). At resection, this tumor was proven to be a mature teratoma. d A radiograph of the sacrum obtained when the patient was 2 years of age clearly shows the abnormal development.

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Fig. 8.47 One-day-old girl with an antenatally detected cystic mass in the upper abdomen. Note the muscular rim sign (arrow).

Fig. 8.48 Y-sign as seen in an enteric duplication cyst. (Courtesy of D. Soboleski, Department of Diagnostic Radiology, Queen’s University, Kingston General Hospital, Kingston, Ontario, Canada.)

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Fig. 8.49a–c Fifteen-day-old girl with an antenatally detected cystic mass in the right upper abdomen. a Abdominal ultrasound shows a well defined large cystic mass displacing the small bowel and compressing the caval vein (asterisk). Multiple layers of the wall are seen (arrow). b The lesion is not related to the ovary. Most cystic lesions in young girls are of ovarian origin, and the radiologist should actively look for a relation between the cyst and the ovary. c The Y-sign is present (dots) ( Video 8.49).

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Fig. 8.50a,b Six-year-old boy with increased abdominal girth. a A cystic multiloculate lesion is seen on ultrasound. The lesion is located on the left side of the abdomen from the spleen to the bladder. (Courtesy of E. Beek, University Medical Center, Utrecht, The Netherlands.) b The panoramic view can show the extent of the lesion in a single image.

Recommended Readings Arora VC, Price AP, Fleming S et al. Characteristic imaging features of desmoplastic small round cell tumour. Pediatr Radiol 2013; 43: 93–102 Bass JE, Redwine MD, Kramer LA, Huynh PT, Harris JH, Jr. Spectrum of congenital anomalies of the inferior vena cava: cross-sectional imaging findings. Radiographics 2000; 20: 639–652 Cheng G, Soboleski D, Daneman A, Poenaru D, Hurlbut D. Sonographic pitfalls in the diagnosis of enteric duplication cysts. AJR Am J Roentgenol 2005; 184: 521–525 Giefer MJ, Murray KF, Colletti RB . Pathophysiology, diagnosis, and management of pediatric ascites. JPGN 2011; 52: 503: 513 Johnson CC, Baldessarre J, Levison ME. Peritonitis: update on pathophysiology, clinical manifestations, and management. Clin Infect Dis 1997; 24: 1035–1045, quiz 1046–1047 Karmazyn B, Werner EA, Rejaie B, Applegate KE. Mesenteric lymph nodes in children: what is normal? Pediatr Radiol 2005; 35: 774–777 Kocaoglu M, Frush DP. Pediatric presacral masses. Radiographics 2006; 26: 833–857 Konen O, Rathaus V, Dlugy E et al. Childhood abdominal cystic lymphangioma. Pediatr Radiol 2002; 32: 88–94 Kurtz RJ, Heimann TM, Holt J, Beck AR. Mesenteric and retroperitoneal cysts. Ann Surg 1986; 203: 109–112

Levin TL, Roebuck D, Berdon WE. Long-segment narrowing of the abdominal aorta and its branches in a survivor of infantile neuroblastoma treated without radiation therapy. Pediatr Radiol 2011; 41: 933–936 Levy AD. Peritoneum and Mesentery - Part II - Pathology. Radiology Assistant. . Accessed February 19,2014) Levy AD, Arnáiz J, Shaw JC, Sobin LH. From the archives of the AFIP: primary peritoneal tumors: imaging features with pathologic correlation. Radiographics 2008; 28: 583–607, quiz 621–622 Minniti S, Visentini S, Procacci C. Congenital anomalies of the venae cavae: embryological origin, imaging features and report of three new variants. Eur Radiol 2002; 12: 2040–2055 Rathaus V, Shapiro M, Grunebaum M, Zissin R. Enlarged mesenteric lymph nodes in asymptomatic children: the value of the finding in various imaging modalities. Br J Radiol 2005; 78: 30–33 Shah RU, Lawrence C, Fickenscher KA, Shao L, Lowe LH. Imaging of pediatric pelvic neoplasms. Radiol Clin North Am 2011; 49: 729–748, vi Sigaroudinia MO, Baillie C, Ahmed S, Mallucci C. Sclerosing encapsulating peritonitis —a rare complication of ventriculoperitoneal shunts. J Pediatr Surg 2008; 43: E31–E33 Sutton EJ, Tong RT, Gillis AM et al. Decreased aortic growth and middle aortic syndrome in patients with neuroblastoma after radiation therapy. Pediatr Radiol 2009; 39: 1194–1202

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Chapter 9 Liver and Biliary System

9.1 Normal Anatomy and Variants

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9.2 Normal Measurements

249

9.3 Pathology

249

9

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9 Liver and Biliary System Rick R. van Rijn and RAJ Nievelstein Diagnosing liver and biliary tract disease requires, besides obtaining a solid clinical examination and a thorough clinical history, proper radiologic imaging. As in all pediatric imaging, close collaboration between the radiologist and the clinician is key to success. Ultrasonography (US) plays an important role in imaging the pediatric liver and biliary tract. As children are optimal candidates for US, this is even more so the case than in adults. Computed tomography (CT) and magnetic resonance (MR) imaging are second-line imaging strategies, and because of radiation issues, MR imaging is preferred to CT. The US examination should start with an overview of the whole liver and biliary tract in order not to miss abnormalities once a more focused examination of the liver is undertaken. A curved transducer with an appropriate frequency (for children who are not obese, in the range of 4 to 9 MHz) suffices. For the detection of more subtle changes in the liver architecture, a high-frequency linear transducer should be used. Assessing flow in the hepatic veins, portal veins, and hepatic artery should be seen as a standard part of liver imaging as abnormalities in flow can lead to a correct diagnosis of disease. For a proper evaluation of the biliary tract, it is important that the patient has fasted before the examination. A normal distended gallbladder is a sign that the patient has indeed fasted (▶ Fig. 9.1). In addition, imaging of the liver is incomplete if the spleen is not evaluated (see Chapter 10).

Tips from the Pro ●

Younger children, in general, do not hold their breath if you ask them to do so. However, if you make it a challenge (e.g., a game between the child and radiologist), you will be amazed about how long they can hold their breath.

9.1 Normal Anatomy and Variants The liver is the largest solid organ of the human body, accounting for approximately 2 to 3% of the total body weight. In young children, the liver is relatively large compared to the liver in adolescents and adults (▶ Table 9.1, ▶ Table 9.2, ▶ Table 9.3, ▶ Table 9.4). The anatomy of the liver can be described in two ways: anatomically and functionally. The anatomical description is based on the external surface anatomy and as such is not useful in daily clinical practice. The functional anatomy is based on the relationship between vessels and the biliary tract. Claude Couinaud (1922–2008) was the first to recognize the importance of this functional segmentation in relation to surgery. For imaging purposes, the liver is divided into eight segments (▶ Fig. 9.2). The middle hepatic vein divides the liver into left and right lobes. The liver vasculature has many normal variants, ranging from a relatively commonly seen accessory hepatic vein draining directly into the inferior caval vein (▶ Fig. 9.3) to hepatic

Table 9.1 Liver length in premature infants and neonates Gestational age (weeks)

Liver length in the midclavicular line (cm) No. of patients

Mean length (±1 SD)

Minimum– maximum

24–31

29

3.7 (0.7)

2.8–5.8

32–35

33

4.6 (0.7)

3.2–6.2

36–37

35

5.4 (0.6)

3.5–6.3

38–41

153

5.5 (0.8)

3.9–7.8

Abbreviation: SD, standard deviation. Source: Reprinted with permission of Elsevier from Soyupak SK, Narli N, Yapicioglu H, Satar M, Aksungur EH. Sonographic measurements of the liver, spleen and kidney dimensions in the healthy term and preterm newborns. Eur J Radiol 2002;43(1):73–78. Note: An ultrasonographic study was performed in 261 healthy newborn infants. Craniocaudal dimensions of the liver in the midclavicular line were determined. Fig. 9.1 Well distended gallbladder in a 12-year-old girl. For patient comfort, these examinations, which require fasting, should be planned in the morning.

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Liver and Biliary System Table 9.2 Liver length in children Age (years)

Table 9.3 Common bile duct diameter in children Liver length in the midclavicular line (cm)

Age (years)

Diameter of common bile duct (mm)

95% confidence interval

No. of patients

Mean (SD)

Limits of normal

0

0.7

0.2–1.6

1

1.2

0.2–1.7

0–0.25

53

6.4 (1.0)

4.0–9.0

2

1.0

0.3–1.8

0.25–0.5

40

7.3 (1.1)

4.5–9.5

3

1.3

0.3–1.9

0.5–0.75

20

7.9 (0.8)

6.0–10.0

4

1.1

0.4–2.0

1–2.5

18

8.5 (1.0)

6.5–10.5

5

0.8

0.5–2.1

3–5

27

8.6 (1.2)

6.5–11.5

6

1.2

0.5–2.2

5–7

30

10.0 (1.4)

7.0–12.5

7

1.3

0.6–2.3

7–9

38

10.5 (1.1)

7.5–13.0

8

1.5

0.6–2.4

9–11

30

10.5 (1.2)

7.5–13.5

9

1.9

0.7–2.5

11–13

16

11.5 (1.4)

8.5–14.0

10

1.7

0.7–2.6

13–15

23

11.8 (1.5)

8.5–14.0

11

1.7

0.8–2.7

15–17

12

12.1 (1.2)

9.5–14.5

12

1.9

0.8–2.8

Abbreviation: SD, standard deviation. Source: Reproduced with permission of the American Journal of Roentgenology from Konus OL, Ozdeimer A, Akkaya A, Erbas G, Celik H, Isik S. Normal liver, spleen, and kidney dimensions in neonates, infants, and children: evaluation with sonography. AJR Am J Roentgenol 1998;171(6):1693–1698. Note: This study included 307 pediatric subjects (169 girls and 138 boys). The age range was from full-term newborns (5 days) to 16 years. The subjects were imaged in the supine position. The upper margin of the midclavicular liver dimension was defined as the uppermost edge under the dome of the diaphragm; the lower margin was defined as the lowermost edge of the lobe.

Table 9.4 Gallbladder volume in term and preterm infants Gallbladder volume (mL) Term neonates

Preterm neonates

Number of observations

46

50

At birth

1.1 (0.2–2.4)

0.7 (0.1–1.2)

At 6 hours after birth

1.0 (0.2–2.2)

0.7 (0.1–1.2)

Number of observations after regular feeding

46

50

After 3 hours of fasting

0.08 (0–0.02)

0.08 (0–0.2)

After 6 hours of fasting

0.7 (0.1–1.3)

0.3 (0.1–0.9)

Source: Reprinted with permission from Ho ML, Chen JY, Ling UP, Su PH. Gallbladder volume and contractility in term and preterm neonates: normal values and clinical applications in ultrasonography. Acta Paediatr 1998;87:799–804. Note: Ultrasound assessment of gallbladder volume (length × width × height × π/6) was performed in 50 preterm infants (mean gestational age, 31.7 ± 2.5 weeks) and 46 term infants (mean gestational age, 38.3 ± 1.2 weeks).

Source: Adapted from Hernanz-Schulman M, Ambrosino MM, Freeman PC, Quinn CB. Common bile duct in children: sonographic dimensions. Radiology 1995;195:193–195. Note: This study included 173 children (100 boys and 73 girls) ranging in age from 1 day to 13 years (median age, 5.0 years). The diameter of the common bile duct was ≤ 3.3 mm in all children.

arteries arising from the superior mesenteric arteries. The same holds true for the biliary anatomy, as the classic anatomy (in which the right and left hepatic ducts drain into a common hepatic duct) occurs in only 58% of the population. For surgical planning, these normal variants can be of importance, and in complex cases, cross-sectional imaging with CT or MR imaging is warranted. In pediatric radiology, it is important, when caring for neonates, to be aware of the fetal vascular anatomy. Especially in premature infants, the umbilical vein and the ductus venosus can be visualized, and sometimes a closing vein can be depicted (▶ Fig. 9.4; Video 9.4).

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Fig. 9.2 Schematic depiction of the eight liver segments as defined by Couinaud.

Middle hepatic vein Right hepatic vein Left hepatic vein

2

8 7

3 4 5 Common hepatic artery

6

Falciform ligament

Common bile duct

Portal vein

Fig. 9.3a,b a Accessory hepatic vein draining segment 6 in a 13-year-old girl who underwent abdominal ultrasonography as part of a routine follow-up for treated Wilms tumor. b Color Doppler imaging shows the direction of flow in the accessory hepatic vein.

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Liver and Biliary System Table 9.5 Normal portal venous diameter Portal venous diameter

Fig. 9.4 Thrombus formation in the umbilical vein (arrow). Note the relation to the portal vein (open arrow); Video 9.4.

9.2 Normal Measurements 9.2.1 Portal Venous Flow The portal vein in children shows a homogeneous hepatopetal flow in the range of 20 cm/s (▶ Table 9.5; ▶ Fig. 9.5); this is comparable to the adult situation. Respiration leads to a slight fluctuation in the flow pattern.

Age (years)

Mean (mm)

Limits of error

0

4.5

3.0–6.3

1

5.7

3.6–7.8

2

6.5

4.2–8.8

3

7.0

5.5–8.5

4

6.8

5.5–8.2

5

7.0

5.2–8.7

6

7.7

5.0–10.3

7

7.7

4.8–10.6

8

7.2

5.3–9.0

9

7.6

5.7–9.5

10

8.2

5.0–11.3

11

8.7

6.1–11.3

12

9.5

6.7–12.1

13

9.2

6.9–11.4

14

9.0

6.2–12.0

15

10.2

9.0–11.5

16

11.0

7.8–14.2

Source: Table created from data within Patriquin HB, Perreault G, Grignon A, et al. Normal portal venous diameter in children. Pediatr Radiol 1990:20:451–453, with kind permission from Springer Science + Business Media. Note: The study included 150 children, ages 0 to 16 years, without clinical evidence of liver or intestinal disease referred for abdominal Ultrasound. The portal vein was visualized in the longitudinal axis from the splenomesenteric junction to the liver hilum. The greatest anteroposterior (AP) diameter was measured at the site where the hepatic artery crosses the portal vein.

9.2.2 Hepatic Arterial Flow The hepatic artery shows a hepatopetal arterial flow with a characteristic low-resistance and high-velocity diastolic flow (▶ Fig. 9.6). In adults, the reported peak systolic flow is 30 to 40 cm/s, and the end-diastolic flow is 10 to 15 cm/s.

9.2.3 Hepatic Venous Flow The hepatic veins show a triphasic flow consisting of two waves toward the heart (i.e., atrial diastole and ventricular systole) and a small wave away from the heart (i.e., atrial systole) (▶ Fig. 9.7).

Tips from the Pro ●

Children love it when you tell them that they have a bunny in their tummy. If you try, you can depict the hepatic veins as resembling the well-known Playboy Bunny™ sign (▶ Fig. 9.8).

9.3 Pathology 9.3.1 Congenital Anomalies Biliary Atresia Biliary atresia is a congenital obstruction of the intra- and/or extrahepatic ducts, usually presenting with neonatal jaundice. The overall incidence is approximately 1 in 15,000 births, but it is far more common in the Asian population. The most common finding on US (seen in almost two-thirds of neonates with biliary atresia) is an absent, small (< 1.5 cm), or empty gallbladder in a neonate who has been fasting for several hours (▶ Fig. 9.9a). Furthermore, a triangular or tube-shaped echogenic focus with a thickness of 4 mm or more that follows the portal veins can be seen at the porta hepatis (▶ Fig. 9.9b). This so-called triangular cord sign has a reported sensitivity of 62 to 93% and a specificity of 96 to 100%, but can be difficult to distinguish from periportal echogenicity due to inflammation or cirrhosis. Other signs that suggest the presence of biliary atresia include an absent common bile duct, a hypertrophic hepatic artery (▶ Fig. 9.9b,c), and increased hepatic subcapsular flow on color Doppler US (▶ Fig. 9.9d).

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Fig. 9.5a–c a Normal portal venous flow in the main portal vein. b Normal portal venous flow in the left portal vein. c Normal portal venous flow in the right portal vein.

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Fig. 9.6 Normal hepatic arterial flow.

Fig. 9.7 Normal hepatic triphasic flow in a healthy 10-year-old boy.

Fig. 9.8 Bunny sign.

Choledochal Cysts Choledochal cysts are rare congenital saccular or fusiform dilatations of the biliary tree with an incidence of approximately 1 to 2 in 100,000 to 150,000 live births. Again, they are far more common in the Asian population, with a reported prevalence of 1 in 1,000 persons in Japan. Choledochal cysts are usually classified according to Todani into five subtypes (▶ Fig. 9.10). Type I cysts, the most common, occur in up to 80 to 90% of all cases (▶ Fig. 9.11 and ▶ Fig. 9.12). They are often associated with an abnormal junction of the common bile duct with the pancreatic duct. Frequent complications include ascending cholangitis and/or pancreatitis, liver cirrhosis, portal hypertension, and

spontaneous cyst rupture. There is an increased risk for developing cholangiocarcinoma, especially after the age of 10 years. In cases of delayed presentation, these cysts can become extremely large (▶ Fig. 9.13). With US, the location and degree of bile duct dilatation can be easily depicted. Sludge or bile stones can be identified by bile stasis in the dilated ducts. In type V choledochal cysts (Caroli disease), the kidneys should be examined as well because this type is often associated with autosomal-recessive polycystic kidney disease (▶ Fig. 9.14). Pathognomonic for Caroli disease is the so-called central dot sign (▶ Fig. 9.15), which is the result of fibrovascular bundles, consisting of portal vein and hepatic artery branches, crossing the dilated choledochal cysts. Although originally described on CT, this sign is well visualized on US. The differentiation of a choledochal cyst (▶ Fig. 9.16a–c) from a simple hepatic cyst, hepatic abscess, or pancreatic pseudocyst is sometimes difficult. Additional imaging consists of either endoscopic retrograde cholangiopancreatography (ERCP), which can be performed only in specialized centers by welltrained gastroenterologists and allows intervention, and/or magnetic resonance cholangiopancreatography (MRCP), which can be performed on all modern MR scanners, although sedation may be necessary (▶ Fig. 9.16d, e; Video 9.16).

Congenital Portosystemic Shunts Congenital portosystemic shunts are rare congenital anomalies that are mostly detected on US. The children can present with abnormal liver tests, elevated blood ammonia, and/or serum bile acid levels, or the shunt can be found incidentally on US. A portosystemic shunt can be intrahepatic (▶ Fig. 9.17), in which case there is a connection between a portal vein and either a hepatic vein or the inferior caval vein, or extrahepatic, in which case the portal trunk or a branch of it is in direct contact with the inferior caval vein. Extrahepatic portosystemic shunts are

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Fig. 9.9a–d One-month-old girl with persistent neonatal cholestasis. a There is a small gallbladder (arrow) after prolonged fasting. b Ultrasonography shows increased echogenicity in the porta hepatis (triangular cord sign; arrow) and an enlarged hepatic artery (open arrow). c Color Doppler imaging shows the enlarged hepatic artery (arrow). d Color Doppler imaging shows increased subcapsular vascularity in the liver parenchyma. These imaging findings are characteristic for biliary atresia, which was biopsy-proven in this girl.

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Fig. 9.10 Schematic representation of the classification of choledochal cysts according to Todani: type I, fusiform dilatation of the common bile duct below the cystic bile duct (Ia) or of the common bile duct and main hepatic ducts (Ib); type II, one or more cystic diverticula of the common bile duct; type III, focal dilatation of the distal common bile duct in the papillary region into which the pancreatic ducts drain (also called choledochocele); type IV, multiple dilatations of the intra- and extrahepatic (IVa) or of only the extrahepatic (IVb) bile ducts; and type V, Caroli disease (segmental ectasia of the large intrahepatic ducts throughout the liver).

Fig. 9.11a,b Type 1 choledochal cyst in a 1-month-old boy. a Ultrasound shows dilatation of the common bile duct. b Cholangiopancreatography performed during surgery shows the dilatation of the common bile duct (arrow). The intrahepatic bile ducts are visible because of the reflux of contrast (open arrow). Note the poor collimation during surgery.

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Fig. 9.12a,b Thirteen-year-old girl with chronic upper abdominal pain. a Ultrasonography shows a fusiform dilatation of the extrahepatic bile duct and choledochal duct (arrow). b Mild dilatation of the central intrahepatic bile ducts (arrow). These findings are consistent with choledochal cyst, Todani type I.

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Fig. 9.13a–c Eleven-year-old girl presenting with abdominal distention and upper abdominal pain. a Abdominal ultrasound shows a grossly dilated common bile duct and intrahepatic bile ducts. b Axial T2-weighted magnetic resonance (MR) imaging shows the dilated common bile duct (arrow) and intrahepatic bile ducts (open arrows). c Coronal T2-weighted MR imaging shows the extent of the grossly dilated common bile duct. The imaging findings are in keeping with a Todani type IV choledochal cyst. During surgery, a cyst with a volume of approximately 1,700 mL was resected.

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Fig. 9.14a,b One-day-old boy with antenatally diagnosed liver cysts and enlarged kidneys. a Ultrasonography (US) of the liver directly after birth shows multiple fusiform and cystic dilatations of the intrahepatic bile ducts (Todani type V choledochal cysts). One of the cysts shows the “central dot” sign, which can be explained by the portal fibrovascular bundle surrounded by the dilated bile duct (arrow). b US of the kidneys shows extremely enlarged kidneys with diffusely increased echogenicity, absent corticomedullary differentiation, and multiple tiny cysts, characteristic of polycystic kidney disease (Caroli disease).

Fig. 9.15a,b Central dot sign in a 7-year-old boy with known Caroli disease. b Color Doppler shows flow within the central dot.

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Fig. 9.16a–e Type IVb choledochal cyst in a 4-year-old girl. a Ultrasound (US) of the liver shows dilatation of the common bile duct. b US of the liver shows intrahepatic dilatation of the bile ducts in the left and right liver lobes. c T2-weighted axial magnetic resonance imaging shows dilatation of the common bile duct (arrow). d Endoscopic retrograde cholangiopancreatography (ERCP) shows the abrupt change in caliber of the intrahepatic bile ducts. e Magnetic resonance cholangiopancreatography (MRCP) also shows the abrupt change in caliber of the intrahepatic bile ducts (arrow), but the resolution is less and intervention is not possible. Note the presence of ascites (open arrow) ( Video 9.16).

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Fig. 9.17a–c Nine-day-old boy with Down syndrome, known to have an association with congenital portosystemic shunt. a A congenital portosystemic shunt is detected as an incidental finding on screening abdominal ultrasonography (US). b Color Doppler US shows the congenital portosystemic shunt between the left portal vein and the middle hepatic vein. c Duplex US shows a turbulent flow pattern.

classified according to Abernethy. Type I consists of an atretic portal vein with the splenic and superior mesenteric veins terminating either separately in the inferior vena cava (type Ia) or as a common venous trunk (type Ib; ▶ Fig. 9.18). In Abernethy type II, there is a normal or hypoplastic portal vein with partial shunting into the inferior vena cava. Intrahepatic portosystemic shunts can regress spontaneously before the age of 2 years, but if they persist, intervention may be needed. Long-term consequences of these shunts are the development of liver tumors (see later section on focal nodular hyperplasia), hepatic encephalopathy, hepatopulmonary syndrome, and pulmonary hypertension.

258

9.3.2 Infection Hepatitis Hepatitis is an inflammation of the liver. The most common cause is viral infection, but hepatitis can also be a result of autoimmune disease, metabolic disorders, or drug use. In the acute phase, imaging plays no significant role other than to rule out other diseases. The role of imaging is the follow-up of patients with hepatitis, in which case the interest lies in the detection of cirrhosis, portal hypertension, and tumors (especially hepatocellular carcinoma after hepatitis caused by hepatitis B virus or hepatitis C virus; ▶ Fig. 9.19).

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Fig. 9.18a,b Eleven-year-old boy presenting with chronic upper abdominal pain. a Gray scale ultrasonography (US) shows a direct connection (arrow) between the portal vein (PV) and the right hepatic veins (RHV), consistent with an Abernethy type Ib congenital portosystemic shunt. b Color/duplex Doppler US shows flow in the shunt.

Pyogenic Abscess Although relatively rare in the Western world, pyogenic liver abscesses are the most frequent abscesses encountered in children. The most common pathogen is Escherichia coli (▶ Fig. 9.20 and ▶ Fig. 9.21; Video 9.21). There is a wellknown relation between appendicitis and the formation of liver abscesses; however, with the improved detection of appendicitis, this cause is decreasing. The most common pathways of infection are through the biliary tract and the portal system. Also, penetrating trauma can be the cause of abscess formation (▶ Fig. 9.22). On US, a liver abscess usually appears as a rounded or ovoid hypoechoic lesion, but it can have a heterogeneous appearance, as well. The wall may be thick and irregular. Septa and debris can be encountered. Less commonly, pyogenic microabscesses are encountered (▶ Fig. 9.23). Although not pathognomonic, a diffuse pattern is seen in Staphylococcus aureus infection, and a clustered pattern is seen in E. coli infection.

Fungal Infections Fungal hepatic infections are characterized by the presence of numerous microabscesses (often also present in the spleen). They are encountered in children with hematologic malignancies or a compromised immunologic system. The most common causative agent is Candida albicans (▶ Fig. 9.24). On US, four patterns have been described: wheel within wheel, bull’s-eye, uniformly hypoechoic, and focally echogenic.

Parasitic Infections The most common parasitic infection of the liver is due to Entamoeba histolytica, and infection of the liver is actually the most common extraintestinal presentation of this infection. US does

not discriminate between a pyogenic abscess and an Entamoeba abscess. However, on aspiration of the abscess, the typical chocolate-colored pus can be encountered. Hydatid or echinococcal cysts are caused by infection with Echinococcus granulosus, which is endemic around the Mediterranean but can also be encountered in areas where sheep are bred. On US, a purely cystic lesion may be seen, but often daughter cysts and/or calcification of the cyst wall is encountered. A pathognomonic finding is the so-called water lily sign, which is seen if the endocyst becomes detached from the outer pericyst (▶ Fig. 9.25).

Cholecystitis Cholecystitis is relatively rare in young children, but it becomes more common with increasing age when related to cholelithiasis. Acalculous cholecystitis also occurs, but usually only in critically ill children after trauma, major surgery, or burns, or during sepsis. On US, the gallbladder is typically enlarged and tender, with thickening of the wall. Pericholecystic fluid may be seen, and gallstones may be present (▶ Fig. 9.26). Cholecystitis should be distinguished from hydrops of the gallbladder. In the latter, the distended gallbladder lacks wall thickening, and patients are usually not as ill as in cholecystitis. Isolated gallbladder wall thickening without other signs of cholecystitis does occur in children with ascites and hepatitis/cholangitis.

Infectious Cholangitis Infectious cholangitis occurs in children and usually has a bacterial origin, although viral, fungal, and parasitic infections are also possible, especially in the immune-compromised host. Infectious cholangitis is often associated with congenital or immune-related bile duct abnormalities, surgically corrected biliary atresia (Kasai procedure; ▶ Fig. 9.27 and ▶ Fig. 9.28),

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Fig. 9.19a–d Fifteen-year-old boy with autoimmune hepatitis. a Note the coarse aspect of the liver, in keeping with cirrhosis. b Doppler ultrasound shows decreased flow in the portal vein, in keeping with portal hypertension. c In the liver hilum, cavernomatous transformation is seen (arrow). d T1weighted magnetic resonance imaging after gadolinium confirms the presence of cavernomatous transformation.

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Fig. 9.20 Three-year-old boy with a liver abscess, which was treated with percutaneous drainage and intravenous antibiotics. Culture showed Pseudomonas aeruginosa, Escherichia coli, and Streptococcus milleri.

Fig. 9.21a–c Thirteen-year-old boy presenting with persistent fever after visiting Indonesia. a Ultrasonography (US) shows a large heterogeneous mass with cystic components in the right liver lobe (arrow). b Axial T1 fat-saturated (THRIVE, T1 W high-resolution isotropic volume examination) magnetic resonance (MR) image after the intravenous administration of contrast confirms the presence of a heterogeneously enhancing, multiloculate abscess in the right liver lobe. c A percutaneous drain has been placed in the abscess under US guidance (arrows), and pus has been aspirated. The US and MR imaging characteristics are consistent with a bacterial liver abscess, which was confirmed by culture of the aspirate ( Video 9.21).

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Fig. 9.22a–c Twenty-six-week-old premature neonate. a An umbilical venous line has been inserted. Note the small amount of gas around the tip of the line (arrow). b Ultrasonography reveals a lobulated hypoechoic lesion, in keeping with abscess formation. c A lineogram shows the relation between the tip of the umbilical venous line and the abscess (Image courtesy of A. Paterson).

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Fig. 9.23 Ten-year-old girl with known tuberculosis. Ultrasound shows a microabscess caused by the tuberculosis infection.

Fig. 9.24a,b Eight-year-old girl with persisting fever and aplasia. a Ultrasonography shows multiple hypoechoic lesions (arrows), in keeping with microabscesses. b With the use of a high-frequency linear probe, a bull’s-eye configuration is clearly seen within the microabscess. This patient also had splenic involvement.

Fig. 9.25a,b Thirteen-year-old girl with an echinococcal cyst. a Note the water lily sign (arrow). b Interventional radiologic treatment consists of percutaneous evacuation of the cyst contents. This is a safe and effective method for the percutaneous treatment of multivesicular echinococcal cysts with or without cystobiliary fistulas that contain nondrainable material.

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Fig. 9.26a–c Eighteen-day-old boy with right upper quadrant abdominal pain and fever. a Ultrasound (US) shows a thickened wall of the gallbladder (arrow). A collection adjacent to the gallbladder is seen (asterisk). b Sagittal US shows the elongated aspect of the abscess adjacent to the gallbladder. c Percutaneous drainage of the gallbladder was performed under general anesthesia. A 9F pigtail catheter (arrow) was placed.

Fig. 9.27a–c Nine-month-old girl with a history of biliary atresia and a Kasai procedure (hepatic portoenterostomy), presenting with fever and upper abdominal pain. a Ultrasonography shows irregular, dilated intrahepatic ducts and inhomogeneous liver parenchyma (arrow). b, c Axial turbo spin echo (TSE) T2-weighted magnetic resonance (MR) images illustrating the irregular, dilated intrahepatic bile ducts and increased periportal echogenicity, suspicious for ascending cholangitis (arrows).

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Fig. 9.28a–d Nineteen-year-old girl with a history of biliary atresia and a Kasai procedure (hepatic portoenterostomy), now presenting with sepsis and cholangitis. a Ultrasonography shows inhomogeneous liver parenchyma with dilated intrahepatic bile ducts and periportal echogenicity (arrow). b Furthermore, a fluid collection is seen ventral to the liver (arrow). c Coronal multiplanar reconstruction of a computed tomographic scan of the abdomen shows massive splenomegaly (asterisk), irregular dilatation of the biliary tree (arrows), and a complex, multiloculate fluid collection with the suggestion of a connection with the biliary tree (bilioma, open arrow). d Maximum intensity projection reconstruction of a respiration-triggered 3D turbo spin echo T2-weighted sequence also shows the irregular dilatation of the biliary tree (open arrow) and the close relation of the biliary tree to the biloma (closed arrow). Furthermore, ascites is visible surrounding the liver.

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Fig. 9.29a,b Ten-month-old boy presenting with jaundice. a Ultrasound shows choledocholithiasis, with stones in the common bile duct. Note the acoustic shadow (arrow) in the gallbladder (open arrow). No underlying cause was found. b Endoscopic retrograde cholangiopancreatography (ERCP) was performed to remove the stones (arrow) from the common bile duct.

liver transplant, and certain immunodeficiency states. Therefore, the primary goal of US when infectious cholangitis is suspected is to search for anatomical abnormalities and/or obstruction of the biliary tract.

9.3.3 Acquired Biliary Pathology Chole(docho)lithiasis Gallstones are relatively uncommon in children, with a reported prevalence of up to 1.9%. They are more frequently detected in asymptomatic children because of the more widespread use of US. Chole(docho)lithiasis may be idiopathic (▶ Fig. 9.29), but in neonates and young infants it is often associated with sepsis, the use of diuretics, or total parenteral nutrition. In older children, gallstone formation may be related to obesity (an increasing problem in the pediatric age group; ▶ Fig. 9.30), sickle cell disease (▶ Fig. 9.31), hemolytic anemia, cystic fibrosis (▶ Fig. 9.32), and disease of the small bowel. On US, gallstones will appear as echogenic foci with or without acoustic shadowing (▶ Fig. 9.33 and ▶ Fig. 9.34). Gallstones are calcified in approximately 50% of cases, particularly if associated with a hemolytic disorder. When located in the gallbladder, they often change in position with gravity. In the biliary tree, gallstones may cause biliary dilatation due to obstruction, which in most cases can be easily visualized on US (▶ Fig. 9.35 and ▶ Fig. 9.36). The differentiation of biliary sludge from small, nonshadowing gallstones may be difficult (▶ Fig. 9.37). In children treated with ceftriaxone, pseudochole(docho) lithiasis, as a result of biliary precipitation, can be encountered. In these children, follow-up US, after the discontinuation of

266

treatment, will show resolution of the pseudochole(docho)lithiasis (▶ Fig. 9.38). In cases of symptomatic chole(docho)lithiasis, the surgical technique of choice is laparoscopic cholecystectomy. With this new surgical technique, new complications are encountered, the most important of which is damage to the biliary tree. There are four different types of injury, which can be classified as follows: 1. Type A: leakage of the cystic duct or peripheral intrahepatic biliary tract; 2. Type B: leakage from the common bile duct without the presence of a stricture; 3. Type C: stricture of the common bile duct without leakage; 4. Type D: complete transsection of the common bile duct with or without resection of a section of the common bile duct (▶ Fig. 9.39). In these postsurgical patients, US should be used to detect intraperitoneal fluid collections, especially around the liver hilum, and dilatation of the biliary tree.

Cholestatic Diseases The differential diagnosis for cholestatic disease entities in children is wide and includes congenital bile duct abnormalities (e.g., biliary atresia, choledochal cysts), prematurity, chole (docho)lithiasis, inspissated bile secretion, dehydration, infections, endocrine disorders (e.g., hypothyroidism), genetic and metabolic diseases (e.g., cystic fibrosis, Alagille syndrome, alpha1-antitrypsin deficiency), toxic causes (e.g., parenteral nutrition, drugs), and systemic disorders (e.g., shock, heart failure). However, cholestatic disease can also be idiopathic.

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Fig. 9.30a,b Obese 15-year-old girl with colicky right upper abdominal pain. a Ultrasound shows multiple gallstones (arrow). b T2-weighted magnetic resonance imaging shows cholelithiasis (arrow).

Fig. 9.31 Seventeen-year-old asymptomatic boy with sickle cell disease. On routine abdominal ultrasound, multiple gallstones are seen within the gallbladder.

Fig. 9.32 Twelve-year-old girl with cystic fibrosis. On routine abdominal ultrasound, multiple gallstones are seen (arrow).

Fig. 9.33 Thirteen-year-old boy with colicky right upper quadrant abdominal pain. Ultrasound shows numerous gallstones filling the gallbladder. Note the acoustic shadow behind the stones (arrow).

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Fig. 9.34a,b Sixteen-year-old girl presenting with colicky upper abdominal pain. a Ultrasound shows multiple echogenic foci (arrow) with acoustic shadowing in the gallbladder. b Axial view of the same patient.

Fig. 9.35a,b Eleven-year-old girl with colicky upper abdominal pain. a Transverse ultrasound (US) of the pancreas shows an echogenic focus (arrow) in the intrapancreatic part of the dilated choledochal duct, consistent with obstructing choledocholithiasis. b Longitudinal US shows a dilated choledochal duct (arrow).

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Fig. 9.36a–c Eleven-year-old girl with jaundice and abdominal pain. a Ultrasound shows multiple gallstones in the gallbladder (arrow). b An impacted gallstone is shown in the distal common bile duct (arrow). c Endoscopic retrograde cholangiopancreatography (ERCP), performed to remove the gallstone, shows the location of the distal gallstone (arrow).

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Fig. 9.37 Three-year-old boy admitted to the pediatric intensive care unit. Note the multiple echogenic reflections in the gallbladder. On follow-up, these resolved spontaneously, in keeping with sludge.

Fig. 9.38a,b Nine-year-old girl treated with ceftazidime. a On abdominal ultrasound, hyperechoic structures with acoustic shadowing are seen (arrow). b Five weeks later, after the discontinuation of ceftazidime treatment, the precipitated bile has disappeared.

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Fig. 9.39a–c Sixteen-year-old girl with persistent abdominal pain and fever after laparoscopic cholecystectomy. a Ultrasound shows a dilatation of the proximal common bile duct (arrow), which could not be visualized more distally. b Ascites is present. c Percutaneous transhepatic cholangiography shows a complete disruption of the common bile duct (arrow), with leakage of contrast into the peritoneal cavity (open arrow).

Thickening of the bile within the ducts is often the primary cause of cholestasis (bile plug syndrome), but gallstones may develop in combination with bile sludging. US findings include bile sludge or sludge balls in the gallbladder and/or biliary ducts with or without ductal dilatation (▶ Fig. 9.40). The sludge appears sonographically as low-level echoes or as echoic material without posterior attenuation. When the patient changes position, the sludge moves toward the dependent side (▶ Fig. 9.41).

Inflammatory Diseases of the Bile Ducts Primary (or infantile) sclerosing cholangitis (PSC) is a chronic and usually progressive cholestatic liver disease of unknown

origin that is increasingly found in children. It is characterized by an inflammatory obliterative fibrosis that infiltrates the intra- and extrahepatic biliary ducts. PSC is associated with inflammatory bowel disease (IBD); 70 to 80% of patients with PSC have IBD, whereas up to 7% of patients with IBD will develop PSC (▶ Fig. 9.42 and ▶ Fig. 9.43). PSC can result in liver cirrhosis, portal hypertension, and liver failure. There is a small but increased risk for the development of malignant cholangiocarcinoma. Although imaging with MRCP is the modality of choice if PSC is suspected, US may reveal intra- and/or extrahepatic (irregular) bile duct dilatation. In cases of cirrhosis, the liver parenchyma may show increased echogenicity and heterogeneity. Splenomegaly and ascites will develop in patients with portal hypertension.

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Fig. 9.40 One-month-old neonate admitted to the neonatal intensive care unit at birth. Sludge is seen in the gallbladder.

Fig. 9.41a–c Twelve-year-old boy with ulcerative colitis and autoimmune hepatitis. a Ultrasound shows echogenic material without acoustic shadowing (sludge) in the gallbladder (arrow). b Oblong view of the gallbladder showing the presence of sludge (arrow). c The sludge moves when the patient is positioned on his left side (arrow).

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Fig. 9.42a–d Seven-year-old boy with inflammatory bowel disease. a On ultrasound (US), mild dilatation of the intrahepatic bile ducts in the left liver lobe is seen (arrow). b On US, dilatation of the intrahepatic bile ducts in the right liver lobe is seen (arrow). c Magnetic resonance cholangiopancreatography (MRCP) shows intrahepatic bile duct dilatation in all liver segments (maximum intensity projection). d Endoscopic retrograde cholangiopancreatography (ERCP) shows intrahepatic bile duct dilatation and (as a result of the higher resolution compared with MRCP), irregularity and “beading” of the bile duct dilatation are clearly visible.

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Fig. 9.43a–e Elevenyear-old boy presenting with bloody diarrhea and increased liver enzymes. a Ultrasound (US) shows increased periportal echogenicity throughout the liver (arrows). b US shows an irregularly shaped choledochal duct with a thickened wall (arrows). c Another US view showing the irregularly shaped choledochal duct with a thickened wall (arrow). d Coronal T1weighted fat-saturated (THRIVE, T1 W highresolution isotropic volume examination) magnetic resonance (MR) imaging after the intravenous administration of contrast confirms the presence of an accentuated and irregularly shaped choledochal duct (arrow). e The same MR imaging shows accentuated and irregular intrahepatic bile ducts (arrow) with enhancement of the wall. These US and MR imaging findings are consistent with a primary sclerosing cholangitis associated with inflammatory bowel disease (ulcerative colitis).

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Cirrhosis

Fig. 9.44 Ten-year-old obese boy with grade 3 nonalcoholic fatty liver disease. Liver histology showed significant steatosis (60%) and mild fibrosis.

Diffuse Parenchymal Disease Nonalcoholic Fatty Liver Disease Nonalcoholic fatty liver disease (NAFLD), as a result of the increasing number of obese children, is an increasingly encountered entity in childhood. NAFLD is considered to be a disease that can lead to liver cirrhosis, and it seems to be an indicator of the development of type II diabetes and atherosclerosis (▶ Fig. 9.44 and ▶ Fig. 9.45). On US, NAFLD can be graded as follows: (1) absent: normal liver parenchyma; (2) mild: minimally diffuse increase in echogenicity with normal visualization of the diaphragm and portal vein borders; (3) moderate: moderately diffuse increase in echogenicity with slightly impaired visualization of the portal vein borders and diaphragm; and (4) severe: increased echogenicity without visualization of the portal vein borders, diaphragm, and posterior portion of the right lobe. A relatively novel technique is the use of elastography, a technique that measures the propagation of sound waves through the liver parenchyma. As the propagation depends on tissue elasticity, it is a measure of liver stiffness. The definitive diagnosis of NAFLD, however, has to be made on liver biopsy.

Cirrhosis is the outcome of chronic liver disease in which liver tissue is gradually replaced by fibrosis, scar tissue, and regenerative nodules (▶ Fig. 9.46). Based on histology, five stages are recognized, graded S0 through S4. In S0, no fibrosis is present. S1 is mild fibrosis seen only at the portal area. S2 is moderate fibrosis between the portal areas, but without destruction of the lobular structure. S3 is severe fibrosis. At S4, in addition to the changes of S3, pseudolobules have formed, and the final stage, cirrhosis, is present. On US, the liver can show several abnormalities as a result of cirrhosis. In many cases, the right liver lobe shows atrophy, and as a consequence the left liver lobe and the caudate lobe are hypertrophic (▶ Fig. 9.47). In cirrhosis, the surface of the liver becomes irregular, and the liver edge is rounded. The parenchymal echogenicity changes and becomes coarse, with areas of uneven echogenicity (▶ Fig. 9.48), and nodular changes can be seen. Cirrhosis can be divided into micronodular and macronodular cirrhosis; in micronodular cirrhosis, the nodules are less than 3 mm in diameter. For a proper evaluation of the liver parenchyma, the use of a linear high-frequency probe is mandatory. Because the changes in the liver parenchyma can be asymmetric, both the left and the right liver lobes should be visualized. As a result of cirrhosis, portal hypertension (described in the later section) can develop. Doppler imaging of the portal vein should be standard in the evaluation of these patients. The vasculature itself, as a result of compression, can be difficult to visualize, especially in the periphery of the liver.

Cystic Fibrosis Approximately 13 to 25% of children with cystic fibrosis will develop chronic liver disease, usually during the first decade of life. Nowadays, liver disease is one of the major complications of cystic fibrosis. Histologically, three types of liver disease are seen: steatosis, focal biliary fibrosis, and multilobular cirrhosis. On US, the liver parenchyma will show increased echogenicity in approximately 50% of patients, of which 70% is homogeneous and 30% heterogeneous (▶ Fig. 9.49). This increased echogenicity is related to steatosis or focal biliary fibrosis. Because of the inspissated bile with periductal inflammatory changes, US may show a prominent periportal echogenicity. This is seen in approximately 37% of patients. During the course of the disease, the gallbladder atrophies or becomes filled with thickened bile or stones (24%). Finally, multilobular cirrhosis will develop in the early phase, with undulating contours of the liver surface (▶ Fig. 9.50 and ▶ Fig. 9.51) or endothelial lining of

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Fig. 9.45a–c Sixteen-old-boy with morbid obesity. a Ultrasound shows hepatomegaly (midclavicular height, 20 cm). There is portal hypertension with a preserved hepatopetal flow. b There is significant splenomegaly, with the spleen measuring 21.5 cm. c Abdominal magnetic resonance imaging, performed because of a thoracic paravertebral paraganglioma, shows esophageal varices (arrow).

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Fig. 9.46a,b Nine-year-old girl with histologically proven autoimmune hepatitis type I. b Ultrasound shows a heterogeneous aspect of the liver parenchyma.

Fig. 9.47 Nine-year-old girl with tyrosinemia type I, an autosomalrecessive inherited metabolic disorder caused by a deficiency of the enzyme fumarylacetoacetate hydrolase. In tyrosinemia type I, an accumulation of several metabolites toxic to the liver occurs, with possible complications of liver cirrhosis, acute liver failure, and/or liver carcinoma. Abdominal ultrasound shows an irregular aspect of the liver parenchyma and hypertrophy of the caudate lobe.

Fig. 9.48 Thirteen-year-old boy with cirrhosis. The liver is enlarged with an irregular aspect of the parenchyma.

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Fig. 9.49a,b Eleven-year-old boy with cystic fibrosis. a The liver shows definite signs of cirrhosis. b The flow in the portal vein is reduced but still toward the liver. There also is splenomegaly as a sign of portal hypertension.

Fig. 9.50a–c Sixteen-year-old girl with cystic fibrosis–related liver disease. a Sagittal ultrasound (US) shows an inhomogeneously echogenic and enlarged liver. b Axial US view of the inhomogeneously echogenic and enlarged liver. c Detailed transverse US image with a high-frequency (12.5-mHz) linear transducer illustrates the undulating contours of the liver parenchyma, consistent with cystic fibrosis–related liver cirrhosis.

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Liver and Biliary System the liver veins (▶ Fig. 9.52). Later on, the liver parenchyma will show nodularity (▶ Fig. 9.53), atrophy, and signs of portal hypertension. Transient elastography might play a role in the non invasive assessment and follow-up of CF-related liver disease.

Portal Hypertension

Fig. 9.51 Fifteen-year-old girl with cystic fibrosis–related liver cirrhosis. Abdominal ultrasound shows an undulating contour of the liver.

In portal hypertension, blood pressure is increased in the portal vein and its tributaries. Causes of portal hypertension can be prehepatic, of which the most important is portal vein thrombosis; intrahepatic, such as hepatic veno-occlusive disease, cirrhosis, and fibrosis; and posthepatic, such as cardiac anomalies or venous thrombosis obstructing the outlet of the liver to the right atrium. US is the primary imaging tool in the diagnosis of portal hypertension. Radiologically, the most important complications of portal hypertension consist of ascites, portacaval anastomoses (▶ Fig. 9.54 and ▶ Fig. 9.55), and splenomegaly. (The spleen should therefore always be imaged when a child is suspected of

Fig. 9.52a,b Seventeen-year-old girl with cystic fibrosis–related liver cirrhosis. a On abdominal ultrasound (US), an inhomogeneous liver is seen. b Color Doppler US shows an irregular aspect of the left portal vein. On Doppler measurements, the flow, in keeping with portal hypertension, was reduced.

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Fig. 9.53a–c Eight-year-old girl with cystic fibrosis–related liver cirrhosis. a Ultrasound of the liver shows an inhomogeneous liver parenchyma with multiple regeneration nodules. b With the use of a linear high-frequency transducer, the nodular liver surface is clearly visible (arrow). c On T1weighted contrast-enhanced magnetic resonance imaging, the regeneration nodules are well defined (arrow).

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Fig. 9.54a–c Fifteen-year-old boy with type I autoimmune hepatitis. a The liver has a coarse parenchyma and an irregular surface. A significant amount of ascites is present. b The portal vein shows hepatopetal flow, although on measurement this was decreased. c The falciform ligament shows recanalization, with flow directed away from the liver.

Fig. 9.55a,b Four-year-old boy presenting with failure to thrive. a The liver surface is slightly irregular, and ascites is noted. b The hepatopetal flow in the portal vein, in keeping with portal hypertension, is decreased.

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Portal Vein Thrombosis Portal vein thrombosis is thrombosis of the portal vein and/or its tributaries (i.e., the splenic vein, superior mesenteric vein, and inferior mesenteric vein). With respect to the portal venous system, the thrombus can be found within the main portal vein or in the intrahepatic portal vein branches. The thrombus itself can totally or partially occlude the portal vein; in the latter case, flow is seen along the course of the thrombus. Unlike in adults, portal vein thrombosis is relatively rare in children. The causes, among others, are injury to the portal vein (e.g., umbilical catheterization, abdominal/surgical trauma, tumors at the porta hepatis) and indirect factors (e.g., neonatal sepsis, dehydration, hypercoagulable states). However, in many cases, the underlying cause of portal vein thrombosis is not clear. Some of the clinically long-term outcomes of portal vein thrombosis are cavernous transformation of the portal vein (i.e., the formation of venous collaterals around the occlusion; ▶ Fig. 9.57 and ▶ Fig. 9.58) and the formation of varices (see ▶ Fig. 9.45c). The latter can lead to variceal hemorrhages, a potentially life-threatening condition. In cases of severe variceal formation, one of the treatment options is to create a shunt, thus diverting the blood flow and lowering the portal blood pressure. These shunts can be created by surgery (e.g., Rex shunt; ▶ Fig. 9.59) or by interventional radiology (i.e., TIPS).

Hepatic Veno-occlusive Disease Fig. 9.56 Sixteen-year-old girl with human immunodeficiency virus (HIV) infection as a result of vertical transmission. Because of portal hypertension, a transjugular intrahepatic portosystemic shunt (TIPS) procedure was performed. Follow-up ultrasound shows patency of the shunt.

having portal hypertension; for normal values of the spleen, refer to ▶ Table 10.1 and ▶ Table 10.2.) In all children suspected of having portal hypertension, or who have proven portal hypertension, measurement of the portal venous flow is of the utmost importance. In these children, the flow pattern not only in the main portal vein but also in the left and right portal veins should be assessed because hepatofugal flow may be present in only one of two intrahepatic portal veins. The interventional radiologist can play a role in the treatment of advanced portal hypertension by performing a transjugular intrahepatic portosystemic shunt (TIPS) procedure, in which a direct connection between the portal vein and the inferior caval vein is created, thus reducing the pressure gradient to normal (▶ Fig. 9.56).

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Hepatic veno-occlusive disease is seen primarily in children after chemotherapy or bone-marrow transplant. The clinical diagnosis rests on the combination of several signs, such as ascites, hepatomegaly, hyperbilirubinemia, weight gain, and right upper quadrant pain. There have been conflicting reports on the usefulness of imaging in hepatic veno-occlusive disease, but the general consensus is that it has a low diagnostic yield (▶ Fig. 9.60).

Budd–Chiari Syndrome Budd–Chiari syndrome is an extremely rare disease in children in which occlusion of one or more hepatic veins leads to increased portal venous pressure (▶ Fig. 9.61 and ▶ Fig. 9.62). Patients with Budd–Chiari syndrome in general present with a range of clinical problems ranging from almost none to portal hypertension and liver failure. The presentation and outcome depend on the rapidity of onset and the presence or absence of underlying disease.

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Fig. 9.57a–d Nine-year-old boy presenting with fever and elevated liver enzymes. a Thrombus is visible in the portal vein on gray scale and color Doppler ultrasonography (US; arrows). b Color Doppler US shows obstructed flow in the portal vein (arrows). c Follow-up color Doppler US shows multiple collaterals in the porta hepatis (arrow) and cavernous transformation of the portal vein (open arrow). d Color Doppler shows the presence of flow in the collaterals in the porta hepatis (arrow) and cavernous transformation of the portal vein (open arrow).

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Fig. 9.58a,b Fifteen-year-old boy with autosomal-recessive polycystic kidney disease and congenital liver fibrosis. a Ultrasound shows a cirrhotic small liver with nearly absent flow in the portal vein (arrow). b Coronal contrast-enhanced T1-weighted magnetic resonance imaging shows a small cirrhotic liver, splenomegaly, and splenorenal convolution (arrow).

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Fig. 9.59a–c a Eighteen-year-old boy a few months after the initial diagnosis of portal vein thrombosis. The only factor identified was the presence of an umbilical venous catheter during admission to the neonatal intensive care unit. b A Rex shunt, in which an internal jugular vein is used as a shunt between the superior mesenteric vein and the left portal vein, was created to bypass the portal vein thrombosis. c Color Doppler shows flow in the direction of the liver through the Rex shunt.

Fig. 9.60 Nine-year-old girl treated for Ewing sarcoma with ablative chemotherapy and stem cell reinfusion. She is experiencing right upper quadrant abdominal pain. Ultrasound shows a significantly decreased flow in the portal vein. The diagnosis of hepatic veno-occlusive disease was based on the combination of clinical findings and laboratory abnormalities.

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Fig. 9.61a–d Seven-year-old boy with persistent ascites as a result of portal hypertension. a Ultrasound shows occlusion of the hepatic veins (arrow), in keeping with the diagnosis of Budd–Chiari syndrome. b Via a transjugular venous approach, the right portal vein is punctured. The catheter is advanced into the superior mesenteric vein, and a flush series shows collateral veins (arrow). c A second flush series with the tip of the catheter in the portal vein shows patency of the portal vein main stem. d A 6-cm-long, 8-mm-diameter covered stent is placed over a balloon catheter. Before deployment of the stent, the portal pressure was 27 mmHg. After placement, this was reduced to 18 mmHg.

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Fig. 9.62a,b Eight-year-old girl with Budd–Chiari syndrome. a Ultrasonography shows an inhomogeneous liver parenchyma with multiple nodules due to liver cirrhosis with regenerating nodules (arrows). b In order to treat the portal hypertension, an artificial channel (stent) has been created between the hepatic veins or inferior caval vein and the portal vein, a so-called transjugular intrahepatic portosystemic shunt (TIPS; arrow).

Abdominal US is the first imaging method of choice, and with the use of color Doppler, the diagnosis can be made with a high level of certainty; the reported sensitivity is up to 85%. Hypertrophy of the caudate lobe, especially in long-standing disease, can be seen in a proportion of children.

Table 9.6 Classification of blunt hepatic trauma Grade

Criteria

1

Subcapsular hematoma < 10% of surface area, capsular tear < 1 cm in parenchymal depth

2

Subcapsular hematoma 10–50% of surface area, intraparenchymal hematoma < 10 cm in diameter, laceration 1–3 cm in parenchymal depth and < 10 cm in length

3

Subcapsular hematoma > 50% of surface area or expanding, ruptured subcapsular or parenchymal hematoma, intraparenchymal hematoma > 10 cm or expanding, laceration > 3 cm in parenchymal depth

4

Parenchymal disruption involving 25–75% of hepatic lobe or 1–3 Couinaud segments within a single lobe

5

Parenchymal disruption involving > 75% of hepatic lobe or > 3 Couinaud segments within a single lobe, juxtahepatic venous injuries (retrohepatic vena cava, central major hepatic veins)

6

Hepatic avulsion

9.3.4 Trauma The liver is the most commonly injured abdominal organ in pediatric cases of blunt abdominal trauma, and in keeping with APLS (Advanced Pediatric Life Support) guidelines, first-line imaging in these patients consists of focused abdominal sonography for trauma (FAST). FAST allows a rapid assessment of the abdominal cavity and pericardial space and is aimed solely at detecting free peritoneal fluid (▶ Fig. 9.63 and ▶ Fig. 9.64). FAST has shown to have a sensitivity of up to 50%, a specificity of 91%, a positive predictive value of 68%, and a negative predictive value of 83%. If the FAST result is positive, additional imaging consisting of contrast-enhanced CT can be performed to find the location of the hemorrhage, in order to guide radiologic intervention or surgery, and to grade parenchymatous organ damage (▶ Fig. 9.65). Liver injuries are usually divided according to the American Association for the Surgery of Trauma CT-based classification system into six grades of severity (▶ Table 9.6.). The sensitivity of contrast-enhanced US in cases of blunt abdominal trauma is reportedly higher than that of conventional US (▶ Fig. 9.66). Several studies have suggested that in cases of minor blunt abdominal trauma, contrast-enhanced US should be used as a first imaging modality, and that CT should be reserved for severe trauma cases.

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Fig. 9.63a–c Sixteen-year-old trauma patient. a Focused assessment with sonography for trauma (FAST) shows a minor amount of free fluid in the Morrison’s pouch (arrow). b There is a significant amount of free fluid in the pelvic space. c Contrast-enhanced computed tomography shows a laceration of the right liver lobe (arrow) and the spleen (open arrow).

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Fig. 9.64a,b Sixteen-year-old trauma patient. a Focused assessment with sonography for trauma (FAST) shows a minimal amount of free fluid along the liver contour (arrow). Although not a part of FAST, distortion of liver architecture is most prominently noted (open arrow). b Venous-phase, contrast-enhanced computed tomography shows free fluid surrounding the liver (arrow) and a liver laceration (open arrow).

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Fig. 9.65a–c Eight-year-old boy who crashed with his bicycle onto an “Amsterdammertje” (parking pole). a Besides a positive focused assessment with sonography for trauma (FAST), an irregular area is noted in segment 7. b Contrast-enhanced computed tomography (CT) shows a laceration of the liver (arrow) and free fluid surrounding the liver (open arrow). c Coronal reconstruction of the CT scan is useful in assessing the extent of the laceration (arrow).

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Fig. 9.66a–d. Seven-year-old child with blunt abdominal trauma. a Conventional ultrasound (US) shows a diffuse zone of increased echogenicity. b On contrast-enhanced US, the true extent of the liver laceration is evident (arrow). c On delayed contrast-enhanced US, active hemorrhage is noted (arrows). d On contrast-enhanced computed tomography, the presence of a liver laceration with active contrast extravasation (arrow) is proven. (Courtesy of V. Miele, Department of Cardiovascular and Emergency Radiology, San Camillo-Forlanini Hospital, Rome, Italy.)

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Fig. 9.67a–d Twenty-one-day-old girl with antenatally detected liver lesions. a Ultrasound shows a solitary, heterogeneous, relatively well circumscribed mass in the right liver lobe with a diameter of 2.5 cm. b Color Doppler shows vascularization of the tumor. c On T2-weighted magnetic resonance imaging, the tumor has a high, almost homogeneous, signal intensity. d After intravenous gadolinium, the tumor shows peripheral consistent with congenital hemangioma (arrow).

9.3.5 Tumors

Hemangioma

Liver tumors are a rare finding in childhood; they account for approximately 5% of all abdominal masses in children. US is the first-line imaging technique, and in some cases (e.g., hemangioma) the only imaging technique. However, in many cases (in all cases if malignancy is suspected), additional imaging is mandatory. In this situation, MR imaging is preferred to CT.

Hemangiomas are the most commonly encountered liver tumors in the pediatric population. The majority present in the first 6 months of life (▶ Fig. 9.67 and ▶ Fig. 9.68) and display a characteristic initial phase of rapid growth followed by spontaneous resolution. In a minority of cases, hepatic hemangiomas will produce clinically relevant symptoms related to size and/or flow. It is important to differentiate congenital from infantile hemangioma (▶ Table 9.7), and in congenital hemangioma, a further differentiation between noninvoluting congenital hemangioma (NICH; ▶ Fig. 9.69) and rapidly involuting congenital

Benign Tumors Approximately one-third of liver tumors in childhood are benign. Most benign tumors are of vascular origin.

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Fig. 9.68a–e Twomonth-old boy with increasing abdominal girth. a Ultrasound (US) shows a large heterogeneous tumor in the right liver lobe. b Color Doppler US shows flow within the tumor and displacement of the hepatic veins. c T2-weighted magnetic resonance (MR) imaging shows a heterogeneous tumor with fluid–fluid levels, in keeping with hemorrhage. d T1weighted MR imaging shows a tumor with homogeneous low signal intensity. e After the administration of intravenous gadolinium, the tumor on dynamic MR imaging shows nodular peripheral enhancement (arrow). Pathologic examination showed the presence of a hemangioendothelioma.

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Fig. 9.69a–d a Large hemangioendothelioma of the right liver lobe in a 3-year-old boy (see also ▶ Fig. 10.31). b Sagittal ultrasound showing the volume (volume = width × length × height × 0.52). c T1-weighted magnetic resonance (MR) imaging shows a homogeneous tumor with low signal intensity in the right liver lobe. A second tumor is seen in the spleen. d T2-weighted MR imaging shows a homogeneous tumor with high signal intensity in the right liver lobe. A second tumor is seen in the spleen.

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Fig. 9.70a–c a One-month-old girl with a partly solid and partly cystic tumor in the right liver lobe (transverse view). b Sagittal view of the same tumor. c After 10 months, the hemangioma shows spontaneous regression. Multiple calcifications are seen within the involuting tumor. This finding is in keeping with a rapidly involuting congenital hemangioma (RICH).

Table 9.7 Difference between congenital and infantile hemangiomas Congenital hemangiomas

Infantile hemangiomas

Enhancement

Absent centrally

Centripetal

Focality

Almost always solitary

Almost always multiple or diffuse

Histology (immunohistochemistry)

GLUT1 negative

GLUT1 positive

Behavior

Usually involute spontaneously

Progress before involution

Hypothyroidism

Not reported

Common

Treatment

Embolization, resection

Propranolol

Source: Courtesy of D. Roebuck, Great Ormond Street Hospital, London, United Kingdom.

hemangioma (RICH; ▶ Fig. 9.70) should be made; the latter is significantly more prevalent. On US, hemangiomas are in general circumscribed hypoechoic lesions (▶ Fig. 9.71). A significant proportion may contain calcifications. Occasionally, the burden of disease can be very extensive, in which case the diagnosis of diffuse hepatic hemangiomatosis can be made (▶ Fig. 9.72 and ▶ Fig. 9.73). On duplex imaging, the rich vascularization can be seen in larger hemangiomas.

Tips from the Pro ●

In imaging hepatic hemangiomas, do not forget to look at the abdominal aorta, which may show a significant decrease in caliber below the celiac trunk, and the common hepatic artery, which may show an increase in caliber. This sign is found in high-flow hemangiomas.

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Fig. 9.71a–c Four-month-old girl with multiple tumors in the liver. a In the left liver lobe, a well-defined cystic lesion is seen (arrow). b In the right liver lobe, a solid tumor is seen (arrow). c Dynamic contrast-enhanced magnetic resonance imaging shows that the lesions enhance at different rates. All the tumors show peripheral nodular enhancement, in keeping with hemangioma. Note a third lesion in the caudate lobe.

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Fig. 9.72a–d One-day-old boy with antenatally diagnosed hemangiomatosis. a Ultrasound shows multiple hypoechoic circumscribed lesions. b Color Doppler shows flow within the lesion. c T2-weighted magnetic resonance imaging shows numerous well circumscribed hyperintense lesions. d Angiography shows the rich vascularization of the hemangioendotheliosis.

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Fig. 9.73a–c a Nine-month-old girl with multiple hypoechoic rounded tumors throughout the liver. No segment is spared, and normal liver parenchyma is hardly seen. This finding is in keeping with hemangiomatosis. b Color Doppler imaging shows flow in the tumors. c On T2-weighted fatsaturated magnetic resonance (MR) imaging, the tumors have a high signal intensity. MR imaging clearly depicts the extent of disease.

Mesenchymal Hamartoma Mesenchymal hamartomas are relatively rare benign liver tumors of childhood, comprising approximately 6% of all liver tumors in children. They are diagnosed mostly before the age of 2 years. These tumors are usually cystic in nature, showing septa, and can present as multicystic large tumors (▶ Fig. 9.74; Video 9.74 and ▶ Fig. 9.75). In rare cases, the major proportion of the tumor is solid with cystic areas, resembling a Swiss cheese.

Focal Nodular Hyperplasia Focal nodular hyperplasia is a rare tumor in childhood. On US, the lesion can show a variable homogeneous echogenicity, ranging from hypo- to hyperechoic. As the lesion can also be isoechoic, the sensitivity of US is lower than that of MR imaging. The characteristic central scar is seen in a minority of cases, with a reported incidence ranging from 18 to 30%. Focal nodular hyperplasia is increasingly seen in childhood cancer

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survivors, and the radiologist should keep this in mind if a solitary liver lesion is found on follow-up imaging (▶ Fig. 9.76 and ▶ Fig. 9.77). Lesions resembling focal nodular hyperplasia are also seen in children with portosystemic shunts, both intrahepatic and extrahepatic shunts. The suggested etiology is either hepatic ischemia and a compensatory increase in hepatic arterial flow and/or inadequate delivery of growth factors and hormones as a result of low portal flow.

Benign Masses of the Gallbladder and Biliary Tract The most common gallbladder mass in children is the cholesterol polyp. It is rare and seen in association with cholesterolosis, which is characterized by an abnormal accumulation of triglycerides and cholesterol esters (or precursors) in the mucosa and submucosa of the gallbladder. On US, cholesterol polyps are small, nonmobile, echogenic masses that protrude from the

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Fig. 9.74a–e Ten-month-old girl with increasing abdominal girth. a Ultrasound shows a large cystic tumor with multiple septa. b Some of the cysts contain debris, which could be the result of internal hemorrhage (arrow). c On T1-weighted magnetic resonance (MR) imaging, the tumor has a low signal intensity. d On T2-weighted MR imaging, the tumor has a high signal intensity. Note some fluid–fluid levels within the cysts, in keeping with intracystic hemorrhage (arrows). e Coronal T2-weighted MR imaging shows the size of the tumor, which extends into the pelvis. The imaging features are characteristic for mesenchymal hamartoma ( Video 9.74).

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Fig. 9.75a–c One-year-old girl with increasing abdominal girth. a Ultrasound shows a cystic tumor with thick septa. b Several cysts show debris (arrow). c Computed tomographic (CT) scan from an outside hospital shows a large cystic tumor. On CT, the septa are not well appreciated. CT of liver tumors should not be performed in children if magnetic resonance imaging is available. The imaging features are characteristic for mesenchymal hamartoma.

Fig. 9.76a,b Fifteen-year-old girl, long-term survivor of neuroblastoma. a On routine follow-up ultrasound, focal irregular lesions are noted. The liver parenchyma shows a slightly increased echogenicity and an irregular surface. b On T2-weighted magnetic resonance imaging, the lesions are difficult to identify (arrow). The imaging features are characteristic for focal nodular hyperplasia.

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Fig. 9.77a,b Six-year-old boy 3 years after the end of treatment for stage III neuroblastoma. a On routine follow-up ultrasound, a solid single lesion, initially feared to be a sign of tumor recurrence, is seen. b After the administration of intravenous gadolinium, homogeneous enhancement is seen. No central scar is noted. With image-guided percutaneous biopsy, the lesion was proved to be focal nodular hyperplasia.

a malignant lesion should be suspected, but this is extremely rare in children. A rare benign tumor of the biliary tract is the granular cell tumor. This tumor tends to affect young girls of African origin. US shows an intraductal echogenic mass with intra- and extrahepatic bile duct dilatation proximal to the tumor. Hydrops (with or without sludge) can be seen, depending on the level of obstruction.

Malignant Tumors Malignant liver tumors comprise approximately 1% of all malignant tumors in childhood. The five most common malignant liver tumors will be discussed briefly.

Hepatoblastoma

Fig. 9.78 Polyp of the gallbladder in a 17-year-old girl.

wall into the gallbladder lumen and do not cause shadowing (▶ Fig. 9.78). Other benign lesions of the gallbladder and biliary tract include adenomas, papillomas, hamartomas, inflammatory polyps, fibroepithelial polyps, mucus retention cysts, and heterotopic pancreatic and gastric tissue. These lesions usually present as hyperechoic, pedunculated or sessile masses that may fill a large proportion of the gallbladder lumen. In a patient with thickening of the gallbladder wall adjacent to the “polyp,”

Hepatoblastoma is the most common of the malignant liver tumors of childhood; it has a slight male preponderance. Well over 90% of cases are found in children younger than 4 years of age. Radiology plays a pivotal role in the diagnosis and treatment of hepatoblastoma, as treatment depends largely on the extent of the tumor before treatment. For this, the PRETEXT classification has been constructed in which the tumor is described based on its anatomical location (▶ Table 9.8 Video 9.79 ▶ Fig. 9.80, ▶ Fig. 9.81, ▶ Fig. 9.82, ▶ Fig. 9.79; ▶ Fig. 9.83) and further characterized based on involvement of the caudate lobe, extrahepatic abdominal disease, tumor focality, tumor rupture, distant metastases, lymph node metastases, portal vein involvement, and hepatic vein/inferior vena cava involvement (▶ Table 9.9).

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Liver and Biliary System Table 9.8 A PRETEXT classification, tumor distribution Classification

Tumor distribution

I

Only the left lateral segment or the right posterior section is involved. Surgery requires resection of one lobe.

II

III

IV

Most commonly encountered classification. These tumors involve either the whole right lobe or left lobe of the liver, or the right anterior or the left medial lobe. Surgery requires resection of two lobes.

Classification Caudate lobe involvement C11

Tumor involving the caudate lobe

C0

All other patients

Extrahepatic spread in abdomen2 E0

No evidence of tumor spread in the abdomen (except M or N)

Only the left lateral or right posterior section is spared in the case of unifocal tumors, or in the case of multifocal tumors, two noncontiguous sections are involved. In general, surgery requires resection of three lobes, although with advancing surgical techniques, sometimes a skipped segment in patients with multifocal tumors can be spared.

E1

Direct extension of tumor into adjacent organs or diaphragm

E2

Peritoneal nodules

All liver sections are involved. There is no other surgical option than liver transplant.

Tumor rupture

Multifocal tumor F0

Solitary tumor

F1

Two or more discrete tumors

H0

Imaging and clinical findings of intraperitoneal hemorrhage

On US, hepatoblastoma presents mostly as a solitary, large, illcircumscribed mass. In general, the tumor is heterogeneous but slightly hyperechoic. However, as a result of tumor necrosis and hemorrhage, hypoechoic areas are found, as well. Calcifications can be found throughout the tumor (▶ Fig. 9.84). It is important to delineate the portal vein, hepatic veins, and hepatic arteries to identify the vascularization of the tumor and relation of the tumor with these vessels (▶ Fig. 9.85; Video 9.79).

H1

All other patients

Hematogenous metastases M0

No metastases

M1

Any metastasis (except E and N)

Nodal metastases N0

No nodal metastases

N1

Abdominal lymph node metastases only

Hepatocellular Carcinoma

N2

Extra-abdominal lymph node metastases

Hepatocellular carcinoma is the second most common malignant liver tumor in childhood. In contrast to hepatocellular carcinoma in adults, in which underlying liver disease such as cirrhosis is an important risk factor, the disease in children arises mostly de novo. There is, however, an increased incidence in Southeast Asia and sub-Saharan Africa, where hepatitis B is endemic. On US, the imaging findings can be variable, ranging from a small, hyperechoic lesion to a large hypoechoic lesion (▶ Fig. 9.86). A rare but important diagnostic finding is invasion of the hepatic veins, as this occurs almost exclusively in hepatocellular carcinoma. In order to differentiate between tumor invasion and thrombosis of the hepatic vein, color Doppler US should be performed.

Portal venous involvement3

Fibrolamellar Carcinoma Although initially considered to be a subclass of hepatocellular carcinoma, fibrolamellar carcinoma is now seen as a distinct entity. Compared with hepatocellular carcinoma, fibrolamellar carcinoma has a significantly better prognosis; however, caution should be taken here because hepatocellular carcinoma occurs mainly in cirrhotic livers, whereas fibrolamellar carcinoma occurs mainly in previously normal liver parenchyma. This difference is, of course, reflected in patient outcome.

302

Table 9.9 PRETEXT classification, subclassification

P0

No involvement of the portal vein or its left or right branches

P1

Involvement of either the left or the right branch of the portal vein

P2

Involvement of the main portal vein

Systemic venous involvement4 V0

No involvement of the hepatic veins or IVC

V1

Involvement of one hepatic vein but not the IVC

V2

Involvement of two hepatic veins but not the IVC

V3

Involvement of all three hepatic veins and/or the IVC

Abbreviation: IVC, inferior vena cava. Source: Reprinted with permission from Roebuck DJ, Aronson D, Clapuyt P, et al. 2005 PRETEXT: a revised staging system for primary malignant liver tumors of childhood developed by the SIOPEL group. Pediatr Radiol 2007;37(2):123–132. 1 All C1 patients are at least classified as PRETEXT stage II. 2 Add suffix “a” if ascites is present. 3 Add suffix “a” if intravascular tumor is present. 4 Add suffix “a” if intravascular tumor is present

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Liver and Biliary System

Fig. 9.79a,b Six-year-old boy with PRETEXT stage I hepatoblastoma. a Note the heterogeneous appearance of the tumor, with multiple diffuse calcifications. The hypoechoic areas represent tumor necrosis. b Axial contrast-enhanced computed tomographic scan of the same patient shows compression, but no invasion, of the right kidney. The right hepatic vein (arrow) is clearly visible, and there is no relation with the tumor. Magnetic resonance imaging is the preferred imaging technique in the assessment of pediatric liver tumors.

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Liver and Biliary System

Fig. 9.80a–e Seven-year-old girl with a PRETEXT stage II hepatoblastoma. a The tumor shows a heterogeneous pattern but is well demarcated. b The middle hepatic vein is displaced by the tumor; a small rim of normal liver can be seen (arrow). c Color Doppler shows patency of the middle hepatic vein; this, in combination with the gray-scale images, rules out hepatic vein thrombosis. d The tumor shows a strong color Doppler signal. This is a sign seen in many malignant liver tumor. e Axial T2-weighted magnetic resonance imaging shows good correlation with the assessment of tumor extent on the ultrasound examination ( Video 9.79).

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Fig. 9.81a,b Two-day-old boy. a Ultrasound shows a heterogeneous tumor in the posterior right and anterior right lobe, PRETEXT stage II hepatoblastoma. Note the displaced and compressed middle liver vein (M). b T2-weighted axial magnetic resonance imaging clearly shows the extent of disease.

Fig. 9.82a–d Three-month-old boy presenting with increasing abdominal girth. a Abdominal ultrasound (US) shows an inhomogeneous liver parenchyma. b The tumor reaches up to the right hepatic vein (arrow) without invading segments 6 or 7. c Doppler US shows hepatopetal flow in the portal vein. During US, no tumor thrombus in the portal vein was detected. d T2-weighted magnetic resonance imaging shows sparing of segments 6 and 7, making the tumor a PRETEXT stage III hepatoblastoma. Treatment consisted of presurgical chemotherapy followed by an extended left hemihepatectomy. There were no signs of recurrence during long-term follow-up.

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Liver and Biliary System

Fig. 9.83a–c Six-year-old boy with a 2-month history of abdominal pain, weight loss, and increasing abdominal girth. a Ultrasound (US) shows a hypertrophic liver with grossly abnormal parenchyma. b All three hepatic veins are encased by tumor, and during US, no spared segments were found. c Because of the patient’s poor clinical condition, abdominal magnetic resonance imaging was not possible. Computed tomography shows an abnormal aspect of the whole liver. On biopsy, this was proved to be a stage IV hepatoblastoma. The boy’s condition rapidly deteriorated, and 1 month after the diagnosis, he died of liver failure.

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Liver and Biliary System

Fig. 9.84a–e Two-year-old boy with PRETEXT stage II hepatoblastoma. a Ultrasound (US) shows an ill-defined heterogeneous tumor. b Color Doppler US shows that the middle hepatic vein is compressed but patent. c A large calcification, with acoustic shadowing, is clearly seen in the hepatoblastoma. LVH, left hepatic vein; MVH, middle hepatic vein. d Coronal T2-weighted magnetic resonance (MR) imaging shows the craniocaudal extent of the tumor. e Axial T2-weighted MR imaging shows the heterogeneous aspect of the tumor and the close relation with the middle hepatic vein (arrow).

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Liver and Biliary System In most cases, fibrolamellar carcinoma presents with relatively few clinical findings. The most common of these are malaise and weight loss. A rare clinical presentation is gynecomastia as a result of conversion of androgens to estrogens by aromatases produced by the tumor. On US imaging, a mostly heterogeneous solitary tumor is seen surrounded by normal liver parenchyma (▶ Fig. 9.87). In a significant proportion of tumors, a central scar is noted, and differentiation from focal nodular hyperplasia is therefore of the utmost importance. The tumor may show calcifications, most commonly in the region of the central scar.

Liver Metastases

Fig. 9.85 With the use of a high-frequency linear probe, the arterial supply of a hepatoblastoma is well visualized ( Video 9.85). (Courtesy of D. Roebuck, Great Ormond Street Children’s Hospital, London, United Kingdom.)

The two main tumors of childhood that metastasize to the liver are Wilms tumor (▶ Fig. 9.88) and neuroblastoma (▶ Fig. 9.89; ▶ Fig. 9.90; Video 9.90). However, any other solid tumor can present with liver metastases, and differentiation among the various underlying malignancies based on imaging is not possible (▶ Fig. 9.91, ▶ Fig. 9.92, ▶ Fig. 9.93).

Fig. 9.86a–d Seventeen-year-old boy with hepatocellular carcinoma. a Ultrasound shows a homogeneous hypoechoic solid tumor in segment 4 of the liver. b Color Doppler shows displacement of the middle hepatic vein (arrow). The tumor does not invade the hepatic vein. c On arterial-phase contrast-enhanced computed tomography, the lesion is hyperdense because of the arterial vascularization. d Twenty minutes after the administration of Primovist, the lesion is well demarcated from the surrounding normal hepatic tissue.

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Liver and Biliary System

Fig. 9.87a–e Seventeen-year-old boy presenting with weight loss. a Ultrasound shows a large heterogeneous tumor in the right liver lobe. b Small foci of calcification are spread throughout the tumor. c Some large calcifications are visible. d Noncontrast computed tomography shows a scar in the liver parenchyma overlying the tumor (arrow). Multiple calcifications are seen. e On T2-weighted magnetic resonance imaging, the lesion has a heterogeneous, slightly increased signal intensity. These imaging findings are suspicious of fibrolamellar carcinoma.

309

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Liver and Biliary System

Fig. 9.88 Five-year-old girl with a recurrent Wilms tumor 2 1/2 years after the initial diagnosis. Computed tomography shows multiple metastases in all liver segments (study performed at an outside hospital; ultrasound not available for review).

Fig. 9.89a,b Six-month-old girl with neuroblastoma and liver metastases. a Note the discrete hypoechoic lesion. b T1-weighted magnetic resonance imaging after gadolinium shows enhancement of the liver metastasis (arrow). The primary tumor is in a left paravertebral location (open arrow).

310

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Liver and Biliary System

Fig. 9.90a,b Eleven-month-old boy with massive retroperitoneal neuroblastoma (see also ▶ Fig. 8.42). a Ultrasound shows multiple discrete hypoechoic lesions. b T2-weighted magnetic resonance imaging shows multiple lesions in all liver sections. The primary tumor is in a retrocrural (arrow), retroperitoneal location and extends into the pelvis ( Video 9.90).

In general, liver metastases appear on US as discrete hypoechoic lesions, but this is not always the case. Neuroblastoma metastases can show calcifications (▶ Fig. 9.94), and they can also present as a single large heterogeneous lesion that can be mistaken for a primary liver tumor. Although leukemia is not, in the strictest sense, a metastatic disease, it can also involve the liver. In the majority of cases, the liver shows a homogeneous, often slightly hyperechoic, parenchyma with clear hepatomegaly (▶ Fig. 9.95). However, focal hypoechoic lesions can also been seen in these patients (▶ Fig. 9.96).

Malignant Tumors of the Gallbladder and Biliary Tract

Fig. 9.91 Ultrasound of an 18-year-old boy shows numerous diffusely distributed calcified lesions. This boy had a history of medullary thyroid gland carcinoma. Pathologic examination revealed that these lesions represented metastatic disease.

Malignant tumors of the gallbladder and biliary tract in children are very rare. Although rhabdomyosarcoma (approximately 20% of all cases of which are encountered outside the head and neck region, genitourinary tract, or extremities) is the most common tumor of the biliary tree, it accounts for only approximately 0.04% of all childhood tumors. The most common presenting symptom is jaundice and abdominal pain. On US, a solid lesion is seen in the liver hilum, and in most cases dilatation of the intrahepatic bile duct is present at diagnosis. MR imaging, including MRCP, is mandatory for presurgical evalVideo 9.98). Although rare, uation (▶ Fig. 9.97; ▶ Fig. 9.98; peritoneal metastases do occur.

311

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Fig. 9.92a,b Six-year-old boy with Ewing sarcoma. a Ultrasound shows a large, partially calcified lesion in the right liver lobe. b Contrast-enhanced computed tomography shows a partly necrotic liver metastasis (arrow).

312

Fig. 9.93a–c Three-month-old boy with multiple locations of myofibroma. a Ultrasound (US) of the liver with a high-frequency linear probe shows several circumscribed hypoechoic lesions. b US shows a circumscribed hypoechoic subcapsular lesion in the right liver lobe (between the markers). c Coronal STIR (short T1 inversion recovery)–weighted magnetic resonance imaging shows the geographic distribution of the lesions.

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Liver and Biliary System

Fig. 9.94a,b One-year-old girl with neuroblastoma arising from the right adrenal gland. a Ultrasound shows the primary tumor (asterisk) and a relatively well-demarcated liver metastasis (arrow). b In the same patient, the liver shows diffuse metastatic disease. Scattered microcalcifications are seen within the metastases.

Fig. 9.95a,b Five-year-old girl with acute lymphoblastic leukemia. a Ultrasound shows an enlarged liver without focal parenchymal changes. b The liver has a homogeneous parenchyma.

313

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Liver and Biliary System

Fig. 9.96a,b One-month-old girl with infantile acute lymphoblastic leukemia. a The liver is enlarged; exact measurement not possible on ultrasound (normal upper limit is 9.0 cm). b Multiple focal hypoechoic lesions are seen throughout the liver (arrow).

314

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Liver and Biliary System

Fig. 9.97a–f Eight-year-old boy with abdominal pain and jaundice. a Abdominal ultrasound (US) shows a large, hypoechoic, slightly heterogeneous tumor in the liver hilum. b The tumor extends to the level of the pancreas. There are some dilated intrahepatic bile ducts (arrow). c Dilated bile ducts are visible; note the “tram tracking” or “double barrel” sign (arrow). d T2weighted MRI shows the tumor, with high signal intensity, situated within the liver hilum. The dilated intrahepatic bile ducts are shown (arrow). e Because of jaundice, endoscopic retrograde cholangiopancreatography (ERCP) was performed; a narrow and irregular common bile duct is visible. Intrahepatic bile duct dilatation, mainly in the right liver lobe, is clearly visible. f US after stent placement. The stent is clearly visible (arrow). In cases of suspected stent obstruction or dislocation, US is the first imaging method of choice. The imaging findings are characteristic for rhabdomyosarcoma of the biliary tract.

315

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Liver and Biliary System

Fig. 9.98a–e Two-year-old boy, transferred from an outside hospital, with a history of failure to thrive, weight loss, and jaundice. In the referring hospital, a mass in the liver hilum was seen. a Abdominal ultrasound shows a hypoechoic tumor in the liver hilum. b Sagittal view shows an elongated aspect of the tumor. c The common bile duct is dilated (arrow) and obstructed by the tumor. d Color Doppler imaging is useful in demonstrating dilated intrahepatic bile ducts. e Coronal T2-weighted magnetic resonance imaging shows the extent of the tumor with a close relation to the portal vein (arrow), dilatation of the gallbladder (asterisk), and dilatation of the intrahepatic bile ducts (open arrow). The imaging findings are characteristic for rhabdomyosarcoma of the biliary tract ( Video 9.98).

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Liver and Biliary System

Fig. 9.99a–c a One-month-old premature neonate with necrotizing enterocolitis, plain abdominal radiograph shows intestinal pneumatosis. b US shows air in the portal system. The ring down artefact is visible. c US shows air in the portal system, note the linear distribution (arrow). Video 9.99 US shows air in the portal system.

9.3.6 Pneumobilia

9.3.7 Miscellaneous Conditions

Pneumobilia is the presence of air in the biliary tree, and it should be distinguished from portal venous air. On imaging, the air, like portal venous air, appears as small hyperechoic foci in the liver. However, in pneumobilia the air does not move and is seen mainly in the periphery of the liver. In children, pneumobilia may develop after ERCP (▶ Fig. 9.99), in association with incompetence of the sphincter of Oddi, and after biliary–enteric anastomoses (▶ Fig. 9.100).

Portal Venous Air With the increasing quality of US systems, the detection of portal venous air is no longer limited to severely ill children. In neonates, the clinically most important and severe cause of portal air is Bell stage IIb or higher necrotizing enterocolitis Videos 9.99 and (▶ Fig. 9.101, ▶ Fig. 9.102, ▶ Fig. 9.103; 9.101). However, portal venous air can also be encountered

317

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Liver and Biliary System

Fig. 9.100a,b a One-month-old premature neonate with necrotizing enterocolitis, plain abdominal radiograph shows intestinal pneumatosis and air in the portal venous system (arrow). b US shows air in the portal system.

Fig. 9.101 Two-month-old neonate with a complex cardiac congenital anomaly and necrotizing enterocolitis. Ultrasonography of the upper abdomen shows branching echogenic foci in the periphery of the liver parenchyma (arrow), consistent with air bubbles in the portal vein Video 9.101 Movie shows motion of air bubbles in the branches. portal vein branches.

318

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Fig. 9.102a–c a Female premature with antenatal CMV infection, a routine abdominal US on the NICU ward was requested by the attending neonatologist. The liver shows a normal parenchyma. b During the US exam the NICU nurse flushed the venous umbilical line. On US of the liver iatrogenic portal air was directly seen. c Intravascular air, as a result of retrograde flow during flushing, is even visible within the spleen.

Fig. 9.103a,b a Seven-year-old male with primary sclerosing cholangitis. An ERCP with stent placement was performed. b Abdominal US performed after the ERCP shows pneumobilia (arrow).

319

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Liver and Biliary System

Fig. 9.104a,b a Nine-year-old girl, 1 year after hemi-hepatectomy for hepatoblastoma. A hepatico-jejunostomy is present and air is visible within the biliary tract. This should be an expected finding. b Color Doppler shows that the air is indeed within the biliary tree and not within the portal venous system.

Fig. 9.105a,b Three-week-old boy. On antenatal ultrasound (US), hepatic calcification was detected. a Postnatal US (sagittal view) confirms the presence of three discrete liver calcifications (between the calipers). Further work-up revealed no abnormalities. b On this image of the intrahepatic calcifications, the acoustic shadow (arrow) is better appreciated.

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Liver and Biliary System

Fig. 9.106a,b One-day-old neonate, a On plain abdominal radiography, discrete calcifications over the liver region are noted (arrow). b Ultrasound shows parenchymal calcifications (arrow) and calcifications on the surface of the liver (open arrow). Further work-up revealed no abnormalities.

after placement of an umbilical venous line (▶ Fig. 9.102) and in gastroenteritis, and it has been described as an incidental finding in pyloric hypertrophy. It can be also be encountered in older children with neutropenic enterocolitis. On US, portal venous air is detected as small, hyperechoic moving foci, with a ring-down artifact, within the portal venous system. On Doppler US, sharp spikes in the spectral pattern are seen and heard.

Tips from the Pro ●

After stent placement in the biliary tract, the absence of air within the biliary tract is a sign of potential stent obstruction.

Neonatal Liver Calcifications In the neonate, liver calcifications can be a rare chance finding that is more often encountered on antenatal than on postpartum US (▶ Fig. 9.105 and ▶ Fig. 9.106). If neonatal liver calcification is encountered, the child should be evaluated for congenital malformations, chromosomal anomalies, and congenital viral infections (including rubella, toxoplasmosis, and herpes simplex). If these causes are excluded, the outcome in general is good. There are no set guidelines for routine follow-up imaging.

Recommended Readings Akata D, Akhan O. Liver manifestations of cystic fibrosis. Eur J Radiol 2007; 61: 11– 17 Behr GG, Johnson CM. Vascular Anomalies: Hemangiomas and Beyond–Part 1. FastFlow Lesions AJR 2013; 200: 414–422 Behr GG, Johnson CM. Vascular anomalies: hemangiomas and beyond—Part 2, Slowflow lesions. AJR Am J Roentgenol 2013; 200: 423–436 Bronshtein M, Blazer S. Prenatal diagnosis of liver calcifications. Obstet Gynecol 1995; 86: 739–743

Görg C, Riera-Knorrenschild J, Dietrich J. Pictorial review: Colour Doppler ultrasound flow patterns in the portal venous system. Br J Radiol 2002; 75: 919–929 Catalano OA, Singh AH, Uppot RN, Hahn PF, Ferrone CR, Sahani DV. Vascular and biliary variants in the liver: implications for liver surgery. Radiographics 2008; 28: 359–378 Chaudry G, Navarro OM, Levine DS, Oudjhane K. Abdominal manifestations of cystic fibrosis in children. Pediatr Radiol 2006; 36: 233–240 Chavhan GB, Parra DA, Mann A, Navarro OM. Normal Doppler spectral waveforms of major pediatric vessels: specific patterns. Radiographics 2008; 28: 691–706 Colombo C. Liver disease in cystic fibrosis. Curr Opin Pulm Med 2007; 13: 529–536 De Bruyne R, Van Biervliet S, Vande Velde S, Van Winckel M. Clinical practice: neonatal cholestasis. Eur J Pediatr 2011; 170: 279–284 Ferri PM, Ferreira AR, Fagundes ED, Liu SM, Roquete ML, Penna FJ. Portal vein thrombosis in children and adolescents: 20 years experience of a pediatric hepatology reference center. Arq Gastroenterol 2012; 49: 69–76 Fletcher BD, Magill HL. Wheel-within-a-wheel patterns in hepatosplenic infections. Radiology 1988; 169: 578–579 Franchi-Abella S, Branchereau S, Lambert V et al. Complications of congenital portosystemic shunts in children: therapeutic options and outcomes. J Pediatr Gastroenterol Nutr 2010; 51: 322–330 Goyal N, Jain N, Rachapalli V, Cochlin DL, Robinson M. Non-invasive evaluation of liver cirrhosis using ultrasound. Clin Radiol 2009; 64: 1056–1066 Horton JD, San Miguel FL, Membreno F et al. Budd–Chiari syndrome: illustrated review of current management. Liver Int 2008; 28: 455–466 Humphrey TM, Stringer MD. Biliary atresia: US diagnosis. Radiology 2007; 244: 845–851 Jha P, Chawla SC, Tavri S, Patel C, Gooding C, Daldrup-Link H. Pediatric liver tumors— a pictorial review. Eur Radiol 2009; 19: 209–219 Lee MS, Kim MJ, Lee MJ et al. Biliary atresia: color doppler US findings in neonates and infants. Radiology 2009; 252: 282–289 Lee WK, Chang SD, Duddalwar VA et al. Imaging assessment of congenital and acquired abnormalities of the portal venous system. Radiographics 2011; 31: 905–926 Lowe LH. Imaging hepatobiliary disease in children. Semin Roentgenol 2008; 43: 39–49 McCarville MB, Hoffer FA, Howard SC, Goloubeva O, Kauffman WM. Hepatic venoocclusive disease in children undergoing bone-marrow transplantation: usefulness of sonographic findings. Pediatr Radiol 2001; 31: 102–105 Meng D, Cao Y, Fu J, Chen R, Lu L, Tu Y. Sonographic assessment of ceftriaxoneassociated biliary pseudolithiasis in Chinese children. J Int Med Res 2010; 38: 2004–2010 Miele V, Buffa V, Stasolla A et al. Contrast enhanced ultrasound with second generation contrast agent in traumatic liver lesions. Radiol Med ( Torino ) 2004; 108: 82–91

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Liver and Biliary System Mortelé KJ, Segatto E, Ros PR. The infected liver: radiologic-pathologic correlation. Radiographics 2004; 24: 937–955 Nievelstein RA, Robben SG, Blickman JG. Hepatobiliary and pancreatic imaging in children-techniques and an overview of non-neoplastic disease entities. Pediatr Radiol 2011; 41: 55–75 Roebuck DJ, Aronson D, Clapuyt P et al. International Childrhood Liver Tumor Strategy Group. 2005 PRETEXT: a revised staging system for primary malignant liver tumours of childhood developed by the SIOPEL group. Pediatr Radiol 2007; 37: 123–132, quiz 249–250 Roebuck DJ, Yang WT, Lam WW, Stanley P. Hepatobiliary rhabdomyosarcoma in children: diagnostic radiology. Pediatr Radiol 1998; 28: 101–108

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Rozel C, Garel L, Rypens F et al. Imaging of biliary disorders in children. Pediatr Radiol 2011; 41: 208–220 Schneider BL Portal hypertension in liver disease in children. In: Suchy FJ, Sokol RJ, Balistreri WF, eds. Shannon A, Alkhouri N, Carter-Kent C et al. Ultrasonographic quantitative estimation of hepatic steatosis in children With NAFLD. J Pediatr Gastroenterol Nutr 2011; 53: 190–195 Sola JE, Cheung MC, Yang R et al. Pediatric FAST and elevated liver transaminases: An effective screening tool in blunt abdominal trauma. J Surg Res 2009; 157: 103–107

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Chapter 10 Spleen

10.1

Normal Anatomy and Variants

324

10.2

Pathology

332

10.3

Acknowledgements

354

10

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10 Spleen Samuel Stafrace The spleen is a pyramid-shaped organ normally located in the left upper quadrant. It forms part of and is the largest organ within the lymphoproliferative system. It plays a major role in the immune system and also functions as a filter of damaged and abnormal red blood cells. Imaging of the spleen starts and often rests very much with ultrasound. Depending on a child’s age, this organ can be imaged with transducers of different frequencies. Exquisite images can be obtained with higher frequency, particularly in the younger child. Requests for examining this organ are often related to a clinically palpable increase in its size. Other frequent indications are for the assessment of hematologic conditions and in the setting of trauma. The assessment and measurement of the spleen are part of the normal ultrasound examination of the pediatric abdomen. This chapter describes the normal appearances, variants, and most common pathologies of the spleen as seen with ultrasound.

10.1 Normal Anatomy and Variants 10.1.1 Embryology The spleen begins to develop at the fifth week of fetal life. It develops from multiple cellular nests located within the dorsal mesogastrium (▶ Fig. 10.1). Symmetrical splenic precursors are thought to exist with preferential development of the left sided splenic tissue. These cellular nests eventually fuse to form a single organ. The small anterior notch often seen in the anterior aspect of the spleen is thought to result from this fusion process. The presence of accessory small spleens (splenunculi), seen in about 10% of normal individuals, results from incomplete fusion of all the splenic tissue into one organ.

Given its embryonal development in the dorsal mesogastrium, the final location of splenic tissue is very much dependent on normal situs and normal bowel rotation. At 8 weeks’ gestation, the liver rotates to the right, and the stomach and spleen rotate to the left. The peritoneal reflections between these organs follow their rotational movement.

10.1.2 Anatomical Considerations The final anatomical splenic position and the layout of its associated peritoneal reflections are demonstrated in ▶ Fig. 10.2. The spleen is surrounded by peritoneum, with folds that meet in positions anterior and posterior to the organ. The gastrosplenic ligament connects the spleen with the greater curvature of the stomach anteriorly. The lienorenal ligament in turn connects the spleen to the retroperitoneum posteriorly. The tail of the pancreas is partly located within this latter peritoneal reflection and can be easily seen in close relation to the splenic hilum on ultrasound. The splenic hilum effectively points medially between the stomach and the left kidney, both of which leave an indentation. Medial to the gastrosplenic and lienorenal ligaments is the lateral aspect of the lesser sac of the peritoneal cavity. Further peritoneal reflections run from the spleen superiorly to the diaphragm (phrenicosplenic ligament) and inferiorly to the colon (splenocolic ligament). Superiorly, the spleen is related to the diaphragm, lying in a concavity within the left hemidiaphragm. Anteriorly, the organ is related to the stomach and left colon. Posteriorly lie the diaphragm, left pleura, lung base, and chest wall. Arterial blood supply comes through the splenic artery, which is a branch of the celiac trunk of the aorta. This courses behind the pancreas and reaches the spleen through the lienorenal ligament. The splenic artery divides into a number of branches before entering the spleen. This is described to follow two main patterns. In the distributed type (70%), the primary trunk is short and many long branches reach the splenic hilum. Right

Left

FL

Stomach GH Right

Left

GS

Liver

Liver

Spleen

LS IVC AO

Stomach RK

LR LK

Spleen

Fig. 10.1 Developmental status of the spleen within the dorsal mesogastrium at 5 weeks’ gestational age.

324

Fig. 10.2 Anatomical drawing demonstrating the final position of the spleen with the associated peritoneal reflections. AO, aorta; IVC, inferior vena cava; FL, falciform ligament; GH, gastrohepatic ligament; GS, gastrosplenic ligament; LR, lienorenal ligament; LS, lesser sac; LK, left kidney; RK, right kidney

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Spleen

Fig. 10.3a,b Normal transverse ultrasound images of the spleen. a Position of the probe in the left lateral aspect. b Corresponding ultrasound image. The stomach (St) can be seen anterior to the spleen.

Alternatively, in the magistral type (30%), the main trunk is long with short arterial branches at the hilum. The splenic vein forms in the lienorenal ligament from venous tributaries, which leave the spleen at the hilum. The unified vein travels with the artery behind the pancreas to join with the superior mesenteric vein and form the portal vein. Histologically, the spleen is formed by a fibrous capsule that supplies a network of trabeculations serving as a supportive framework for the functional tissue. The functional tissue consists of two types. The white pulp (which derives its name from its appearance on gross pathology specimens) consists of groups of lymphocytes and lymphoid follicles. The red pulp comprises the remainder of the spleen (approximately 75% of the volume) and is composed of venous sinusoids through which the blood slowly filters.

10.1.3 Technique and Normal Ultrasound Appearances On interrogation with ultrasound, the normally located spleen is identified in the left upper quadrant, above the left kidney and under the left hemidiaphragm, either through a window under the left lower rib margin or through the lower intercostal spaces. Images should be obtained in the transverse and coronal oblique planes along the length of the organ (▶ Fig. 10.3 and ▶ Fig. 10.4). These images can generally be obtained in the supine position, although rotating the child into the lateral decubitus position (▶ Fig. 10.5) can assist in obtaining a suitable window when imaging in the supine position is proving difficult. Occasionally, the lung and pleura can partially obscure the superior aspect of the spleen. The examiner can ask compliant children, particularly older children, to hold their breath briefly in expiration while he or she gently slides the probe up and

down the lower left intercostal spaces until the organ comes into view (▶ Fig. 10.6; Video 10.6).

10.1.4 Echogenicity and Changes in Echogenicity with Age As a rule of thumb, the spleen is expected to have echogenicity similar to that of the liver and appear more echogenic than the adjacent kidney. This is assuming that the hepatic and renal echogenicity is normal when these organs are used as a comparison for assessing the echogenic appearance of the spleen. The spleen appears diffusely homogeneous. When it is evaluated with higher-frequency probes, the echotexture can appear rather heterogeneous, and this finding should not be misinterpreted as pathology (▶ Fig. 10.7). The degree of heterogeneity ranges from mild granularity to better-defined tiny areas of hypoechogenicity throughout the organ. Some authors have clearly demonstrated that these heterogeneous appearances change with age and are best identified in children between the ages of 1 and 5 years. Such appearances are attributed to the presence of white pulp/lymphoid follicles in the spleen, which are thought to account for the tiny focal areas of low echogenicity described. The inability to demonstrate such heterogeneity in infants is thought to result from the immaturity of the organ at this tender age. Difficulty in seeing such detail in older children may result from their increased size, reducing the resolution obtained, although the literature indicates that the chances of demonstrating such heterogeneity increases both with age and with organ size. It is very important to become comfortable with normal splenic appearances at different frequencies and with the various probes that are part of one’s regular equipment.

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Fig. 10.4a–c Normal coronal oblique ultrasound images of the spleen. a Position of the ultrasound probe. b Corresponding ultrasound image. c The left kidney (LK) anterior to the spleen is visualized in the more coronal posterior plane.

Fig. 10.5 The lateral decubitus position can be helpful when images of the spleen are obtained, particularly in the coronal/coronal oblique.

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Fig. 10.6 Coronal oblique ultrasound image demonstrating artifact from the lung (white arrows), which obscures visualization of the spleen (black arrow).

10.1.5 Vascularity When interrogated with color Doppler ultrasound, the spleen appears hyperemic. The splenic artery is seen to arise from the celiac trunk and can be followed along its course behind the pancreas into the lienorenal ligament and splenic hilum, where its branches can be identified (▶ Fig. 10.8). Similarly, the draining venous tributaries are seen in the splenic hilum forming the splenic vein. This can be followed behind the pancreas close to the artery to its junction with the superior mesenteric vein (▶ Fig. 10.9).

Fig. 10.7 Coronal oblique image of the spleen obtained with a highfrequency (12 MHz) planar probe in a 4-year-old child. The subtle, diffuse, heterogeneous appearances throughout the organ should not be misinterpreted as pathology.

identified incidentally on scanning. Their echogenicity is similar to that of the main spleen. Splenunculi derive their blood supply from branches of the splenic artery. Splenunculi are common and often of no clinical significance. They rarely can present with torsion and infarction (▶ Fig. 10.11). They can also significantly enlarge and become hypertrophic, assuming the function of the larger spleen, in hematopoietic conditions after a splenectomy, resulting in recurrent hypersplenism.

Splenic Notch

10.1.6 Normal Variants Splenunculi In around 10% of healthy individuals, failure of all the embryonic splenic tissue to join and form a single spleen may result in the presence of a small round or oval area of normal splenic tissue adjacent to the main splenic organ, known as an accessory spleen or splenunculus. If multiple areas are present, these are referred to as splenunculi (▶ Fig. 10.10). These are often

A small notch/cleft can occasionally be identified on the medial aspect of the undersurface of the spleen (▶ Fig. 10.12). This is thought to be a remnant from the fusion of the splenic nests of tissue during embryonal development. This is easier to appreciate in cross-sectional imaging than with ultrasound. In the context of trauma, the notch can be mistaken for a peripheral laceration. However, one would expect some free fluid/hemoperitoneum adjacent to such a finding in the case of an acute traumatic laceration.

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Fig. 10.8a–c Normal appearances of the splenic arterial blood supply. a Transverse midline ultrasound image of the retroperitoneum. b Same image plane with color Doppler. In both images (a and b) the splenic artery can be seen originating from the celiac trunk and coursing behind the pancreas toward the left (arrows). c Coronal oblique image at the splenic hilum with color Doppler showing the distal splenic artery (arrows) and its branches within the spleen (arrowheads).

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Fig. 10.9a–c Normal appearances of the splenic venous drainage. a Transverse midline ultrasound image of the retroperitoneum. b Same image plane with color Doppler. In both images (a and b) the distal splenic vein (white arrows) can be seen behind the body of the pancreas, forming the portal vein (black arrow) after it joins with the superior mesenteric vein (out of plane) behind the neck of the pancreas. c Coronal oblique image at the splenic hilum with color Doppler showing the venous tributaries in the hilum (arrows). These join to form one splenic vein.

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Fig. 10.10a,b Curvilinear (a) and planar high-frequency (b) coronal oblique ultrasound images from a normal 10-year-old boy demonstrating an accessory spleen at the splenic hilum (arrows). Note that the echogenicity and texture of the splenunculus and the larger spleen are similar with both probes.

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Fig. 10.11a,b Fifteen-year-old boy presenting with acute abdominal pain and fever. a Transverse ultrasound image demonstrates an oval hypoechoic mass in the left upper quadrant (arrows). b Axial computed tomography after contrast shows that the nonenhancing mass (white arrows) lies anterior to the normal spleen (black arrow). This mass represented an infarcted torted splenunculus.

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Fig. 10.12 Axial computed tomographic scan demonstrating a splenic cleft/notch (arrow), which should not be misinterpreted as pathology.

Fig. 10.13 Coronal oblique ultrasound image in a normal 10-year-old child demonstrating the appropriate method for measuring the length of the spleen.

Table 10.1 Splenic length in premature infants and neonates Splenic length (cm) Gestational age (weeks)

No. of patients

Mean length (± 1 SD)

Minimum– maximum

24–31

29

2.4 (0.4)

1.6–3.2

32–35

34

2.8 (0.5)

1.7–4.0

36–37

35

3.3 (0.4)

2.6–4.2

38–41

155

3.4 (0.5)

2.4–4.9

Abbreviation: SD, standard deviation. Source: Reprinted with permission of Elsevier from Soyupak SK, Narli N, Yapicioglu H, Satar M, Aksungur EH. Sonographic measurements of the liver, spleen and kidney dimensions in the healthy term and preterm newborns. Eur J Radiol 2002;43(1):73–78. Note: This study was performed in 261 healthy newborn infants. Craniocaudal dimensions of the spleen were determined with ultrasonography.

10.1.7 Normal Splenic Size The spleen grows with the growing child. Normal data are available for splenic length in premature infants, neonates, and older children (▶ Table 10.1 and ▶ Table 10.2). ▶ Fig. 10.13 demonstrates the appropriate method of measuring the spleen in the coronal plane. At birth, the spleen measures between 2.5 and 4.9 cm in length. At full growth, the spleen is expected to measure between 8.7 and 11.0 cm in a girl and 9.5 and 12.5 cm in a boy.

Tips from the Pro ●

The spleen should be assessed systematically in two planes. Always measure and document the craniocaudal length of the spleen. Do get into the habit of assessing the splenic echotexture with a higher-frequency probe. Although this may not allow the full depth of the spleen to be assessed, it provides great views of the echotexture and makes it possible to detect subtle lesions that, when small and diffuse, may not be seen with standard probes and settings. Do not mistake the normal heterogeneity seen with higher-frequency probes for pathology.

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Spleen Table 10.2 Splenic length in childhood Spleen length (cm)

Spleen length (cm)

Age and sex

Number

Mean

SD

Min-max

Age and sex

Number

Mean

SD

Min-max

Age and sex

Number

Mean

SD

Min-max

Age and sex

Number

Mean

SD

Min-max

0–3 mo

6–8 y

F

22

4.4

0.57

3.2–5.5

F

25

8.2

0.99

6.6–10.0

M

35

4.6

0.84

2.8–6.8

M

26

8.9

0.91

7.4–10.5

F

6

5.2

0.47

4.5–5.6

F

26

8.7

0.92

6.4–10.5

M

10

5.8

0.65

4.9–7.0

M

15

9.0

1.02

7.4–11.2

F

15

6.3

0.68

5.1–7.5

F

34

9.1

1.09

6.8–11.4

M

12

6.4

0.78

5.4–7.4

M

19

9.8

1.05

7.3–11.3

3–6 mo

8–10 y

6–12 mo

10–12 y

1–2 y

12–14 y

F

18

6.3

0.69

5.1–8.2

F

30

9.8

1.02

7.9–11.6

M

17

6.8

0.72

5.6–8.3

M

18

10.2

0.81

8.5–11.7

F

24

7.5

0.83

5.7–8.9

F

13

10.3

0.69

8.7–11.0

M

22

7.6

1.07

5.9–9.9

M

13

10.7

0.90

9.5–12.5

F

36

8.0

0.74

6.7–9.5

M

18

8.1

1.01

6.4–9.9

2–4 y

14–17 y

4–6 y

F, female; M, male; SD, standard deviation. Source: Robben S. Van Rijn R. Normal values. In: Differential diagnosis in Paediatric Radiology. Stuttgart: Thieme Medical Publishers. 2001:636–637.

10.2 Pathology 10.2.1 Abnormalities of Location and Number Wandering Spleen The splenic peritoneal ligaments, which are pivotal in supporting the spleen, may be elongated, allowing the spleen to be displaced inferiorly from its expected location, even down to the pelvis. An abnormally located spleen can be detected incidentally during a routine ultrasound examination or palpated clinically and may be suspected to represent an abdominal mass. A wandering spleen may present with abdominal pain in either of two different clinical scenarios: recurrent abdominal pain from intermittent torsion or severe acute pain from torsion, secondary ischemia and infarction of part or all of the spleen. In the scenario of torsion, an ultrasound examination shows the spleen to be absent from its normal location in the left upper quadrant. Once identified, the spleen is found to be enlarged, with a heterogeneous appearance. Focal infarctions appear as areas of lower echogenicity with absence of flow on interrogation with color Doppler. A whirlpool appearance of the vascular blood supply at the hilum and secondary ascites can be seen (▶ Fig. 10.14).

Splenic Fusion Abnormalities Splenogonadal fusion is a rare developmental anomaly in which aberrant splenic tissue is fused to ovarian or testicular tissue.

332

Congenital fusion of splenic tissue with the kidneys (splenorenal fusion) has also been rarely described.

Splenosis After traumatic rupture of the spleen or occasionally after surgical splenectomy, splenic cells can seed within the peritoneal cavity and enlarge into functional masses of splenic tissue. The splenic nodules/masses can be found anywhere in the peritoneal cavity. Extra-abdominal splenosis in the thoracic cavity is also described. Such nodules may mimic other pathology (e.g., lymphoma) and can result in complications such as torsion or recurrence of hemolytic disease after splenectomy.

Rotation Abnormalities and Heterotaxy Syndrome In complete situs inversus, the splenic tissue is located in the right upper quadrant and the liver in the left upper quadrant. All the vascular structures and solid organs are inverted in a mirror image of the norm. In such cases, one may find multiple splenules on the right instead of a spleen (▶ Fig. 10.15) Heterotaxy syndrome is characterized by visceral malposition and indeterminate atrial arrangement. This spectrum of conditions is generally rather simply classified as heterotaxy syndrome with asplenia or heterotaxy syndrome with polysplenia, although patients with heterotaxy syndrome may not fit into either category, and a number of anomalies may be present in both groups.

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Fig. 10.14a–d Wandering spleen presenting with torsion and focal infarction in an infant. a Longitudinal panoramic view of the lower abdomen and pelvis demonstrating the displaced enlarged spleen in the pelvis (white arrow), extending behind the bladder (black arrow). b, c Color Doppler axial and longitudinal views of the vascular pedicle with whirlpool appearances (arrows). d Focal hypoechoic areas in the upper pole with absence of Doppler signal are in keeping with areas of infarction (arrows).

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Fig. 10.15a–e Situs inversus with multiple splenules/polysplenia. a Plain chest X-ray demonstrating dextrocardia with a left-sided liver. b Transverse ultrasound of the left upper quadrant demonstrating a left-sided liver that is a mirror image of normal. c Left-sided transverse ultrasound image showing the gallbladder (black arrow) located in the left upper quadrant. d, e Longitudinal images of the right upper quadrant demonstrating multiple right-sided splenunculi (arrows). As the spleen develops in the dorsal mesogastrium, these would be located on the same side of the stomach.

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Spleen In heterotaxy syndrome with asplenia, as the name suggests, there is absence of the spleen or splenic tissue. This is also referred to as right-sided isomerism. In the chest, the bronchial tree follows the right-sided pattern bilaterally, and there are bilateral systemic atria. Complex cardiac malformations are common. The spectrum of abnormalities in the abdomen includes absence of the spleen, a midline location of the liver, an indeterminate position of the stomach, and a location of the aorta and inferior vena cava on the same side of the spine. Clinically, apart from all the issues related to the above anomalies, the absence of splenic tissue predisposes such children to sepsis. In heterotaxy syndrome with polysplenia, multiple small spleens/splenunculi are seen, with no large single splenic organ (▶ Fig. 10.16 and ▶ Fig. 10.17). This is also referred to as bilateral left-sidedness or left isomerism because the bronchial tree follows the left-sided pattern and there are usually bilateral pulmonary atria. The spectrum of abnormalities in the abdomen include a central liver, indeterminate position of the stomach, extrahepatic biliary atresia, interruption of the inferior vena cava with continuation of the azygos system, and the presence of common celiac and mesenteric arteries. In 90% of cases, cardiovascular anomalies are present. There are described cases in which other features of left isomerism are present without an increased number of spleens. The accessory splenic tissue does not necessarily have to lie in the left upper quadrant but may even be seen in the right upper quadrant dependant on the location of the stomach. These splenic anomalies in heterotaxy syndromes can be explained from an embryological aspect. It has been demonstrated that splenic tissue precursors exist at both sides of the midline but, in normal cases, there is preferential unilateral development of the left sided tissue. Therefore, in bilateral left sidedness one would expect the end result to be increased/accessory splenic tissue. In bilateral right sidedness the end result would be the absence of splenic tissue. The incidence of malrotation and nonrotation (▶ Fig. 10.17) is increased throughout the spectrum of heterotaxy syndromes.

Abnormal Location of a Normal Spleen Secondary to Disease Occasionally, the spleen can be displaced from its normal location by other pathologic processes, such as left-sided retroperitoneal masses. ▶ Fig. 10.18 demonstrates a normal spleen displaced by neuroblastoma in a 2-year-old child. The normal spleen never returned to its normal location, even after treatment.

10.2.2 Abnormalities of Size Enlargement of the spleen is a nonspecific finding. A small number of children can have a normal palpable spleen under the rib margin. Abnormalities in the splenic size may be secondary to generalized enlargement of the spleen or to focal abnormalities within the spleen, both of which may be clinically detected as splenomegaly.

Generalized Splenomegaly In generalized splenomegaly, the spleen increases in size in all planes, but elongation is evident mostly in the craniocaudal dimension. Measurements should be obtained as demonstrated in ▶ Fig. 10.13. Indications of enlargement include a rounded, bulky lower splenic pole and extension of the spleen beyond the lower pole of the left kidney. Given the constant gradual increase in size with growth in children, unlike in the adult population, it is less useful to classify causes of enlargement according to the degree of splenomegaly. Pathologically, the most common causes of splenomegaly are infection (▶ Fig. 10.19), malignancy, hemolytic anemia (▶ Fig. 10.20), storage disorders, and portal hypertension (▶ Fig. 10.21). ▶ Table 10.3 outlines the most common causes of splenomegaly in children.

Focal/Localized Abnormalities Splenic Cysts Simple cysts in the spleen are often identified incidentally, although when large, these can present with splenomegaly or mass effect. Cysts in the spleen can be congenital or acquired (see box Possible causes of cysts in the spleen). Congenital cysts are also referred to as epithelial or epidermoid cysts. On ultrasound, these typically appear as well-defined, round or oval, anechoic thin-walled areas with posterior acoustic shadowing surrounded by normal splenic tissue. Internal echoes can also be demonstrated. On interrogation with Doppler ultrasound, there is an absence of blood supply within these lesions. Congenital cysts can be detected antenatally, and it can be quite challenging to be specific about the anatomical location of the cyst. (▶ Fig. 10.22 and ▶ Fig. 10.23).

Table 10.3 Causes of pediatric generalized splenomegaly Cause

Examples

Infection

Viral infection (e.g., Epstein–Barr virus) Bacterial infection (e.g., tuberculosis, brucellosis; ▶ Fig. 10.19) Fungal infection (e.g., candidiasis) Protozoal infection

Hematopoietic conditions

Abnormal red blood cells (e.g., spherocytosis; ▶ Fig. 10.20) Hematopoietic activity of the spleen

Malignancy

Lymphoma, either generalized enlargement or focal lesions; typically hypoechoic lesions with no Doppler within (▶ Fig. 10.32)

Storage disorders

Gaucher syndrome; Niemann–Pick disease

Portal hypertension

Most frequent in cases of previous portal vein thrombosis (▶ Fig. 10.21)

Congestive cardiac failure

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Fig. 10.16a–c Heterotaxy syndrome with polysplenia in a 15-year-old. a Reformatted coronal computed tomographic (CT) scan demonstrating a normal left-sided cardiac apex (white arrow), a left-sided liver, and a right-sided stomach (black arrow). b Reformatted coronal CT scan demonstrating multiple small splenules (splenunculi) in the right upper quadrant (arrows). c Equivalent right-sided longitudinal ultrasound image demonstrating the same splenules in the right upper quadrant (arrows).

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Fig. 10.17a–d Heterotaxy syndrome with polysplenia in a neonate. a Chest X-ray demonstrates dextrocardia. A bilateral left-sided bronchial pattern can be seen. b Midline transverse ultrasound image demonstrating a central liver. c Oblique coronal ultrasound image demonstrating numerous adjacent splenules in the left upper quadrant (arrows). d Image from barium follow-through examination demonstrating a left-sided stomach and nonrotation of the bowel, with the small bowel located in the right side of the abdomen.

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Spleen Acquired cysts (pseudocysts) may be the end result of a traumatic contusion, infection, or infarction (▶ Fig. 10.24). Patients with traumatic cysts would be expected to have a relevant history, and previous imaging at the time of trauma may be available, although not always. The ultrasound appearance of these can be completely identical to that of true congenital splenic cysts. Cysts that are clearly thick-walled and/or contain irregular contents are more likely to be infective. One further consideration would be a simple cyst that has subsequently bled.

Pyogenic Splenic Abscesses A pyogenic splenic abscess can result from focal infection in the spleen with secondary necrotic breakdown into an infected cyst. Secondary septic abscesses in the spleen are described in a myriad of distant infections (e.g., subacute bacterial endocarditis, urinary tract infections, respiratory tract infections). Secondary infection may also develop in a previously sterile cyst, in a splenic infarct, or in a traumatic hematoma. The history and previous imaging can help in this scenario. Patients with hemoglobinopathies are at increased risk for splenic abscesses. Findings suggesting infection are an ill-defined complex cyst with heterogeneous echogenic contents and possibly septa in the context of a child with sepsis. Fig. 10.18a,b Abnormal location of a normal spleen after resection of a large intra-abdominal neuroblastoma. a Axial T2 magnetic resonance (MR) image showing the location of the spleen (white arrows) to be medial to the normal, expected position. Note residual disease in the left paraspinal region (black arrow). b MR imaging ADC (apparent diffusion coefficient) map showing normal, expected restricted diffusion of the spleen (arrows).

Possible causes of cysts in the spleen ●

●

●

338

Congenital cysts ○ True (epidermoid) cyst (▶ Fig. 10.23) Acquired ○ Secondary to infection: pyogenic abscess, echinococcosis, fungal microabscesses (small and multiple; ▶ Fig. 10.25) ○ Secondary to traumatic contusion (▶ Fig. 10.24) ○ Secondary to previous splenic infarction ○ Cystic benign tumor (e.g., hemangioma) ○ Lymphangioma (may appear as predominantly cystic, characteristically with septa; ▶ Fig. 10.28) ○ Pancreatic pseudocyst Cystic metastasis (rare)

Multiple Abscesses Fungal microabscesses typically show up as multiple tiny, hypoechoic cystic areas in the spleen (▶ Fig. 10.25). In the correct clinical context, such as a child with febrile neutropenia, such appearances are very characteristic and should be actively sought. This may not be appreciated unless the organ is carefully assessed with a higher-frequency probe.

Solid Focal Heterogeneities in the Spleen (Solid Splenic Abnormalities) The majority of solid masses in the spleen in children is benign. ▶ Table 10.4 outlines the differential diagnosis for hypoechoic and hyperechoic solid lesions in the spleen. The following section describes in detail some of the most common causes.

Hemangiomas Hemangiomas are nonencapsulated vascular channels of variable size that are thought to arise congenitally. They are most

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Spleen

Fig. 10.19a–d Confirmed brucellosis in a 10-year-old. a, b Coronal oblique ultrasound images of the left upper quadrant demonstrating a significantly enlarged spleen (measuring up to 17 cm). Note that the distal pole of the spleen extends beyond the lower pole of the left kidney (arrows). c Longitudinal ultrasound image of the gallbladder demonstrating associated marked edema of the gallbladder wall (arrows). d Transverse image at the liver hilum demonstrating associated periportal lymphadenopathy (arrows).

Fig. 10.20a,b Splenomegaly in a 16-year-old with hereditary spherocytosis. a Coronal oblique ultrasound image of the left upper quadrant demonstrating a significantly enlarged spleen extending inferiorly beyond the rib cage. b Transverse midline abdominal image at the level of the distal splenic vein demonstrating associated enlargement of the splenic vein (arrows).

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Fig. 10.21a–c Splenomegaly in a 14-year-old with portal hypertension. a Coronal oblique ultrasound image of the left upper quadrant demonstrating a significantly enlarged spleen (measuring up to 18 cm). b Coronal oblique ultrasound image at the liver hilum showing enlargement of the portal vein (arrows). c Doppler ultrasound evaluation of the falciform ligament demonstrates venous flow, in keeping with venous recanalization (arrow).

Table 10.4 Solid lesions of the spleen Hypoechogenic solid lesions ● ● ● ●

● ● ● ●

340

Hemangioma (hypervascular on Doppler; ▶ Fig. 10.27) Hamartoma (▶ Fig. 10.30) Inflammatory pseudotumor (hypervascular) Vascular tumors (with heterogeneous appearances), such as hemangioendothelioma (▶ Fig. 10.31), lymphoma (▶ Fig. 10.32; Video 10.32), leiomyoma (▶ Fig. 10.33), Langerhans cell histiocytosis (▶ Fig. 10.36) Peliosis Storage disorders (e.g., Gaucher disease) Infarction (may mimic mass in early stage) Infection (before breakdown into abscess may mimic a mass)

Hyperechogenic solid lesions ●

● ● ●

● ●

Calcifications (see box Causes of focal calcifications in the spleen (may be single or multiple)) Hemangioma (▶ Fig. 10.26) Lymphangioma (▶ Fig. 10.28) Vascular tumors (with heterogeneous appearances), such as hemangioendothelioma (▶ Fig. 10.31) Storage disorders (rarely increased echogenicity) Acute hematoma (may mimic hyperechoic mass lesion; ▶ Fig. 10.38)

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Lymphangiomas Pathologically, lymphangiomas consist of abnormal dilated vascular channels of the lymphatic system. They can occur in isolation, involving only the spleen (▶ Fig. 10.28), or can be multiple or part of a more generalized process referred to as lymphangiomatosis (▶ Fig. 10.29). Focal lymphangiomas can have varying appearances on ultrasound, depending on the size of the cystic spaces containing lymph. Typically, such lesions demonstrate septate hypoechoic cystic areas, as in other regions of the body, or less commonly are seen as solid, hyperechoic abnormalities (microcystic, in which case the cysts are not well appreciated). Calcifications may occasionally be seen in the septa/walls of the lesion.

Splenoma/Hamartoma This is the most common benign tumor mass in the spleen, thought pathologically to consist of unorganized vascular channels with intervening disorganized stroma with or without lymphoid follicles. The ultrasound appearances are nonspecific, and such masses can appear hyper- or hypoechoic on ultrasound. Hamartomas can have cystic elements and calcifications. There is retained blood supply on interrogation of the solid components with Doppler ultrasound (▶ Fig. 10.30).

Other Vascular Tumors of the Spleen Because it is such a vascular organ, the spleen is affected by a number of tumors of vascular origin. Littoral cell angiomas and hamartomas (see above) occur in the spleen. Other hypervascular tumors described include hemangioendothelioma (▶ Fig. 10.31), sclerosing angiomatoid nodular transformation, and angiosarcoma (malignant outcome).

Splenic Focal Abnormalities Associated with Storage Disorders Fig. 10.22a,b a Longitudinal ultrasound of a neonate with a cyst at the splenic hilum (arrows). This was detected on antenatal scans. Note the absence of Doppler signal within the cyst. b Axial T2 magnetic resonance image demonstrates the location of the cyst in the medial aspect of the splenic hilum (arrows). It can be difficult to identify the organ of origin of such a cyst if the cyst is not surrounded by a rim of normal tissue from the organ of origin.

often small and identified incidentally, but they may be large and complicated by excess red blood cell breakdown. The ultrasound appearances are nonspecific, and these masses most commonly appear hyperechoic in comparison with the rest of the spleen (▶ Fig. 10.26). They may also appear hypoechoic (▶ Fig. 10.27) or isoechoic, or rarely as cystic lesions. Hemangiomas typically demonstrate increased Doppler flow (▶ Fig. 10.26 and ▶ Fig. 10.27). Echogenic calcifications within the lesions are also described. Hemangiomas usually occur in isolation but may be multiple, more commonly in the context of underlying conditions that predispose to such lesions, such as Klippel-Trenaunay syndrome.

Rare storage disorders such as Gaucher disease and Newman– Pick disease can involve the spleen. Focal splenic ultrasound lesions are identified. These appear as hypoechoic, hyperechoic, or mixed hypo- and hyperechoic abnormalities and can alter in appearance with treatment.

Lymphoma The spleen can be involved in lymphoma. Appearances are variable and nonspecific, either with a generalized increase in the size of the organ or with focal single or multiple masses appreciated on ultrasound. Focal masses generally appear hypoechoic and can be hypovascular when interrogated with Doppler ultrasound (▶ Fig. 10.32).

Tips from the Pro ●

When a solid lesion is identified in the spleen, evaluate the Doppler characteristics of the mass. This may help shorten the differential diagnosis. Absence of Doppler signal does not mean that the mass is not solid. Pathologies manifesting as solid focal splenic deposits with decreased Doppler signal compared with the adjacent normal splenic tissue include lymphoma and sometimes lymphangioma.

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Fig. 10.23a–d Sixteen-year-old with learning disabilities and long-term issues with swallowing. a Abdominal radiograph from a barium follow-through series shows evident splenomegaly (arrows) and displacement of the duodenum and small bowel to the right. b, c Transverse ultrasound images demonstrating a large complex cystic lesion in the spleen (arrows) with posterior acoustic enhancement. d Coronal oblique image of the same complex cyst (arrows). The spleen was subsequently removed, and the cyst proved to be a congenital epidermoid cyst.

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Fig. 10.24 Coronal oblique ultrasound image showing a complex posttraumatic splenic cyst with echogenic cellular contents (arrows) in a 14-year-old patient.

Fig. 10.25a,b Fungal microabscesses in the spleen. Three-year-old immunosuppressed child with persistent fever. (a) Coronal oblique image of the spleen obtained with a curvilinear probe. (b, c) Images obtained with a higher-frequency planar probe. (continued)

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Fig. 10.25c–e (continued) (d) Higher-frequency image with color Doppler interrogation. Multiple focal hypoechoic areas are diffusely spread throughout the spleen. These were subsequently shown to represent Candida microabscesses. (e) Eight-year-old girl with confirmed Candida infection. Higher-frequency image of the lower pole of the spleen demonstrates a focal, well-defined hypoechoic area containing central echogenicities that probably represent early calcifications.

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Fig. 10.26a–c Four-year-old girl with a typical splenic hemangioma. a Coronal oblique curvilinear probe ultrasound image. b Coronal oblique higherfrequency ultrasound image. These images demonstrate a focal round area of increased echogenicity within the splenic lower pole (arrows). c Transverse higher-frequency ultrasound image with Doppler interrogation demonstrates increased Doppler blood flow within the hemangioma (arrows).

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Fig. 10.27a–c Twelve-year-old girl with an incidental splenic hemangioma. a Coronal oblique curvilinear probe ultrasound image. b Coronal oblique higher-frequency ultrasound image. These images demonstrate a focal round area of slightly decreased echogenicity within the center of the spleen (arrows). c Transverse higher-frequency ultrasound image with Doppler interrogation demonstrates increased Doppler blood flow within the hemangioma (arrows).

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Fig. 10.28a–d Eleven-year-old girl with a typical splenic lymphangioma. a Coronal oblique curvilinear probe ultrasound image demonstrates the overall appearance of the spleen, with multiple adjacent thin-walled cystic areas (arrows). b, c Higher-frequency planar images better show the cystic characteristics of the mass, with posterior acoustic enhancement (arrows) deep to the cysts. d Higher-frequency planar image obtained slightly more laterally in the same patient demonstrates smaller cysts within the same mass.

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Causes of focal calcifications in the spleen (may be single or multiple) ●

●

● ● ● ●

Previous infection (typically small multifocal calcifications), such as ○ histoplasmosis (▶ Fig. 10.34) ○ Tuberculosis/atypical mycobacterial infection ○ Candida albicans infection (▶ Fig. 10.35) ○ Brucellosis ○ Echinococcosis ○ Toxoplasmosis ○ Viral infection (e.g., cytomegalovirus infection, rubella) ○ Human immunodeficiency virus (HIV) infection (typically vascular) ○ Cat-scratch disease (Bartonella) ○ Previous pyogenic abscess In association with vascular tumors (e.g., hemangioma, lymphangioma, inflammatory pseudotumor) After trauma/hematoma After infarction Langerhans cell histiocytosis (▶ Fig. 10.36) Sickle cell disease

10.2.3 Traumatic Injury of the Spleen

Fig. 10.29a,b Three-year-old boy with lymphangiomatosis. a Coronal oblique curvilinear probe ultrasound image of the spleen demonstrates a heterogeneous echotexture throughout the organ. b Axial T2 bladetriggered magnetic resonance image demonstrates abnormal serpiginous high signal throughout the spleen. Abnormal soft tissue of similar signal is seen in the retrocrural spaces (arrows).

Calcifications in the Spleen Calcifications are commonly identified in the spleen on ultrasound examination. These appear as focal echogenicities that demonstrate posterior acoustic shadowing and are commonly multiple, although they can be seen in isolation. When identified, calcifications are nonspecific, although they most likely arise from an infective cause such as histoplasmosis (▶ Fig. 10.34), previous tuberculosis infection, previous fungal infection (▶ Fig. 10.35) or from Langerhans cell histiocytosis (▶ Fig. 10.36). The Box Causes of focal calcifications in the spleen (may be single or multiple) outlines the broader differential diagnosis for calcifications in the spleen.

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The spleen is one of the most commonly affected organs in abdominal trauma. Traumatic injury of the spleen can result from a number of mechanisms. In children, it is most commonly related to motor vehicle accidents, falls, and sports (including bicycle riding). Pathophysiologically, blunt trauma can result in a torsional movement related to the relative mobility of the spleen on its ligaments. This can lead to injury of the blood supply at the hilum, with hematoma formation in this location (▶ Fig. 10.37). Alternatively, the spleen can be injured by compression from the rib cage or direct penetration from fractured ribs. Finally, iatrogenic injury during surgery is also infrequently identified. Splenic hematomas/contusions are focal microscopic parenchymal lesions. Lacerations are linear areas of disruption within the structure of the spleen. These can extend to the splenic margin and the splenic capsule may remain intact or be disrupted. Hematomas are often associated with lacerations and can be contained by an intact capsule (referred to as a subcapsular hematoma). If a laceration extends across two surfaces of the spleen, it is referred to as a splenic rupture. The presence of hemoperitoneum suggests capsular rupture. On ultrasound, hematomas/contusions (▶ Fig. 10.38) are seen as areas of altered echogenicity with no vascular flow within. In the initial stages, they appear as hyperechoic oval areas and become hypoechoic as they resolve. Lacerations are seen as linear areas of hypoechogenicity often extending to the capsular margin (▶ Fig. 10.38 and ▶ Fig. 10.39). In traumatic injury of

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Spleen

Fig. 10.30a–c Eleven-year-old child with an incidental splenic hamartoma. a Coronal oblique curvilinear probe ultrasound image of the spleen demonstrates a focal, heterogeneous, mostly hypoechoic lesion in the subdiaphragmatic portion of the spleen (arrows). b Higher-frequency planar probe image better shows the slight heterogeneity within this lesion. c Power Doppler interrogation of this area of the spleen demonstrates retained blood supply within the mass.

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Fig. 10.31a–e Three-year-old boy with confirmed hemangioendothelioma involving the liver and spleen. a Axial ultrasound image demonstrating the lesion in the spleen (calipers). b Coronal oblique image demonstrating the same mass arising from the lower pole of the spleen (arrows). This has a heterogeneous appearance with some focal hypoechoic areas within it. c, d Appearances of the masses in the liver and spleen on axial T1 and T2 magnetic resonance imaging. e The splenic lesion on an anterior coronal T2 image.

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Fig. 10.32a–d Eleven-year-old boy with lymphoma. Coronal oblique ultrasound image (a) and transverse ultrasound image (b) demonstrate multiple focal hypoechoic lesions (arrows). c High-frequency planar ultrasound image with Doppler interrogation demonstrates absence of Doppler flow within these lesions. d: Corresponding computed tomographic scan also shows lymph nodes at the liver hilum (arrows).

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Fig. 10.34a,b Eleven-year-old child with confirmed histoplasmosis. a Coronal oblique ultrasound image of the spleen with a standard curvilinear probe shows multiple focal echogenicities (arrows) in the spleen, in keeping with small, calcified foci. b Detailed ultrasound image with planar higher-frequency probe better appreciates the posterior acoustic shadowing, characteristic of calcifications (arrow). Fig. 10.33a,b Leiomyoma of the spleen. Transverse (a) and coronal (b) oblique images from an 8-month-old boy with an incidental, welldefined, heterogeneous, mainly hypoechoic mass in the spleen (arrows). The ultrasound appearances are suggestive of a hamartoma. However, at partial splenectomy, this lesion was found to be a leiomyoma.

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Fig. 10.35a–d Ten-year-old girl with a history of previous leukemia and fungal infection. a, b Coronal oblique ultrasound images of the spleen with a standard curvilinear probe demonstrate multiple focal calcifications in the spleen (arrows). c Similar appearances on an image obtained with a higherfrequency planar probe (arrow, calcification). d On a transverse ultrasound image of the epigastric region, the liver has a similar appearance, with more diffuse calcified foci.

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Spleen the spleen, fluid/hemorrhage is often seen around the spleen itself and tracking down to the pelvis along the left paracolic gutter. The presence of fluid further confirms that the intrasplenic abnormalities identified are likely traumatic in origin (▶ Fig. 10.38). Vascular injury can lead to traumatic pseudoaneurysms (▶ Fig. 10.39) and assessment of the spleen with color Doppler is important in the setting of trauma and the immediate aftermath. Previous injury to the spleen can present late as intraparenchymal cysts. Although computed tomography is considered the gold standard for assessing the spleen in the setting of trauma, ultrasound has a major role in assessing the spleen in the stable child with trauma. If the splenic parenchymal echogenicity and color Doppler appearance are normal and free fluid/hemoperitoneum is absent, splenic injury is unlikely.

10.3 Acknowledgements We would like to thank the following radiologists for sharing cases published in this chapter: Dr. Erik Beek (Utrecht, The Netherlands); Prof. Jean-Francois Chateil (Bordeaux, France); Dr. Pablo Caro (Dublin, Ireland); Dr. Veronica Donoghue (Dublin, Ireland); Dr. Ingmar Gassner (Innsbruck, Austria); Dr. Kieran McHugh (London, United Kingdom); Prof. Rick R. Van Rijn (Amsterdam, The Netherlands); and Dr. Marina Vakaki (Athens, Greece). We would also like to thank Mr. David Adams (Aberdeen, United Kingdom) for help with the anatomical drawings.

Fig. 10.36a,b One-month-old infant with confirmed Langerhans cell histiocytosis. a Coronal oblique ultrasound image of the spleen demonstrates a group of adjacent small calcifications (arrow) located within the central area of a slightly hypoechoic mass close to the splenic hilum. Note the associated posterior acoustic shadowing. b More detailed ultrasound image obtained with a higher-frequency planar probe better appreciates the hypoechoic mass (arrows) with multiple central calcifications.

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Fig. 10.37a–d Perisplenic hematoma in a 14-year-old girl with blunt abdominal trauma. a Coronal oblique ultrasound image demonstrates focal areas of decreased echogenicity in the splenic hilum, representing perisplenic hematoma (arrows). b Coronal oblique ultrasound image of the lower pole of the spleen demonstrates further fluid, with some septa around this area (arrows). c Transverse ultrasound image demonstrates the appearance of the perisplenic hematoma in this different plane (arrows). d Coronal oblique ultrasound image with color Doppler demonstrates normal Doppler signal in the splenic parenchyma.

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Fig. 10.38a–d Ten-year-old boy with blunt abdominal trauma. a Coronal oblique ultrasound image demonstrates a focal area of increased echogenicity, in keeping with a small hematoma (white arrows). The associated adjacent area of low echogenicity is in keeping with a laceration (black arrows). b Transverse ultrasound image of the spleen shows the laceration (white arrows) to extend to the splenic hilum (black arrow). c Coronal oblique ultrasound image with color Doppler interrogation demonstrates an absence of color Doppler flow within the area of the laceration (white arrows). d Coronal oblique ultrasound image of the splenic lower pole demonstrates associated free fluid (white arrows) around the spleen, which is commonly seen in the context of traumatic changes in the splenic parenchyma.

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Fig. 10.39a–c Splenic pseudoaneurysm and laceration in a 14-year-old boy with blunt abdominal trauma. a Coronal oblique ultrasound image demonstrates a well defined focal oval area of decreased echogenicity in the splenic parenchyma (white arrow) just adjacent to a larger, more poorly defined area of subtly decreased attenuation (black-rimmed arrows). b Same image with color Doppler interrogation demonstrating increased turbulent flow within the well defined oval area. This represented a pseudoaneurysm adjacent to a large splenic laceration. c Single image from a formal angiographic study confirms the presence of the pseudoaneurysm (black-rimmed arrow). This was successfully embolized.

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Recommended Readings Abbott RM, Levy AD, Aguilera NS, Gorospe L, Thompson WM. From the archives of the AFIP: primary vascular neoplasms of the spleen: radiologic-pathologic correlation. Radiographics 2004; 24: 1137–1163 Al Ahmad A, Jourabian M, Pipelzadeh M. Splenorenal fusion in a 26-month-old girl. Pediatr Radiol 2009; 39: 735–738 Applegate KE, Goske MJ, Pierce G, Murphy D. Situs revisited: imaging of the heterotaxy syndrome. Radiographics 1999; 19: 837–852, discussion 853–854 Benter T, Klühs L, Teichgräber U. Sonography of the spleen. J Ultrasound Med 2011; 30: 1281–1293 Berrocal Frutos T, del Pozo Garcia G, Albillow Merino JC. The abdomen and gastrointestinal tract. In: van Rijn RR, Blickman JG, eds. Differential Diagnosis in Pediatric Imaging. New York, NY: Thieme Medical Publishers; 2011:167–172 Brook I, Frazier EH. Microbiology of liver and spleen abscesses. J Med Microbiol 1998; 47: 1075–1080 Brown CV, Virgilio GR, Vazquez WD. Wandering spleen and its complications in children: a case series and review of the literature. J Pediatr Surg 2003; 38: 1676– 1679 Chippington S, McHugh K, Vellodi A. Splenic nodules in paediatric Gaucher disease treated by enzyme replacement therapy. Pediatr Radiol 2008; 38: 657–660 Doria AS, Daneman A, Moineddin R et al. High-frequency sonographic patterns of the spleen in children. Radiology 2006; 240: 821–827 Duddy MJ, Calder CJ. Cystic haemangioma of the spleen: findings on ultrasound and computed tomography. Br J Radiol 1989; 62: 180–182 Hwajeong L, Koichi M. Hamartoma of the spleen. Arch Pathol Lab Med 2009; 133:147(96);151 Hollingsworth CL, Rice HE. Hereditary spherocytosis and partial splenectomy in children: review of surgical technique and the role of imaging. Pediatr Radiol 2010; 40: 1177–1183 Gozman A. Pediatric splenomegaly. In: Arceci RJ, ed. Medscape. http://emedicine. medscape.com/article/958739-overview. Accessed February 22, 2014 Impellizzeri P, Montalto AS, Borruto FA et al. Accessory spleen torsion: rare cause of acute abdomen in children and review of literature. J Pediatr Surg 2009; 44: e15– e18 Kanwar VS, Aceci RJ. Pediatric splenomegaly. Medscape Radiology. Available online at: www.emedicine.com/article/958739 Karaman MI, Gonzales ET, Jr. Splenogonadal fusion: report of 2 cases and review of the literature. J Urol 1996; 155: 309–311

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Komatsuda T, Ishida H, Konno K et al. Splenic lymphangioma: US and CT diagnosis and clinical manifestations. Abdom Imaging 1999; 24: 414–417 Körner M, Krötz MM, Degenhart C, Pfeifer KJ, Reiser MF, Linsenmaier U. Current role of emergency ultrasound in patients with major trauma. Radiographics 2008; 28: 225–242 Lachman RS. Taybi and Lachman’s Radiology of Syndromes, Metabolic Disorders and Skeletal Dysplasias. 5th ed. Philadelphia, PA: Mosby Elsevier; 2007:63–65 and 645–647 Lee H, Maeda K. Hamartoma of the spleen. Arch Pathol Lab Med 2009; 133: 147–151 Lynn KN, Werder GM, Callaghan RM, Sullivan AN, Jafri ZH, Bloom DA. Pediatric blunt splenic trauma: a comprehensive review. Pediatr Radiol 2009; 39: 904–916, quiz 1029–1030 Mathurin J, Lallemand D. Splenosis simulating an abdominal lymphoma. Pediatr Radiol 1990; 21: 69–70 Paterson A, Frush DP, Donnelly LF, Foss JN, O’Hara SM, Bisset GS, III. A pattern-oriented approach to splenic imaging in infants and children. Radiographics 1999; 19: 1465–1485 Patterson KD, Drysdale TA, Krieg PA. Embryonic origins of spleen asymmetry. Development 2000; 127:167-175 Pomara G. Splenogonadal fusion: a rare extratesticular scrotal mass. Letter to the editor. Radiographics 2004; 24:417 Poulin EC, Thibault C. The anatomical basis for laparoscopic splenectomy. Can J Surg 1993; 36: 484–488 Riera M, Buczacki S, Khan ZAJ. Splenic regeneration following splenectomy and impact on sepsis: a clinical review. J R Soc Med 2009; 102: 139–142 Robben S. Van Rijn R. Differential diagnosis in Paediatric Imaging. Sttutgart: Thieme Medical Publishers. 2001:625-659 Schoenwolf GC, Bleyl SB, Brauer PR, Francis-West PH. Development of the gastrointestinal tract. In: Larsen’s Human Embryology. 4th ed. Philadelphia, PA: Churchill Livingstone Elsevier; 2009:435–477 Standring S, Borley NR, Healy JC, Collins P, Wigley C, The Spleen. In: Gray’s Anatomy: The Anatomical Basis of Clinical Practice. 40th ed. Philadelphia, PA: Churchill Livingstone Elsevier; 2008:1191–1195 Toma P, Granata C, Rossi A, Garaventa A. Multimodality imaging of Hodgkin disease and non-Hodgkin lymphomas in children. Radiographics 2007; 27: 1335–1354 Wadsworth DT, Newman B, Abramson SJ, Carpenter BL, Lorenzo RL. Splenic lymphangiomatosis in children. Radiology 1997; 202: 173–176 Xu WL, Li SL, Wang Y, Li M, Niu AG. Role of color Doppler flow imaging in applicable anatomy of spleen vessels. World J Gastroenterol 2009; 15: 607–611

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Chapter 11 Pediatric Intestinal Ultrasonography

11.1

Esophagus

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11.2

Gastroesophageal Junction

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11.3

Stomach

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11.4

Small Bowel

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11.5

Appendix

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11.6

Large Bowel

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11.7

Rectum

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11.8

Anus

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11.9

Neonatal Bowel Obstruction

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11 11.10 Conclusion

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11 Pediatric Intestinal Ultrasonography Simon Robben Ultrasonography (US) is the imaging modality of choice for the initial evaluation of intestinal diseases in children for many reasons: ● It is relatively inexpensive. ● It is patient-friendly. ● It lacks radiation and motion artifacts. ● The small size of the child compensates for the limited penetration of sound waves. ● The small size of the child facilitates the use of highfrequency transducers. ● US involves direct contact with the patient, offering a unique opportunity to ask specific questions and perform additional physical examination, emphasizing the role of the radiologist as a clinician. ● Flow studies are possible with the Doppler mode. ● Real-time imaging allows visualization of movements (e.g., peristalsis).

●

●

●

●

●

Actually, US has become the most important imaging technique in children and can be considered the workhorse of pediatric radiology. Initially, US of the stomach and intestines was not popular for obvious reasons: bowel gas has the annoying characteristic of reflecting all sound waves or creating artifacts because of its abnormally low acoustic impedance. However, increased knowledge, improved technique (e.g., graded compression), improved hardware (high-frequency transducers), and improved software (adaptive imaging, compound imaging) have changed this concept. Nowadays, it is impossible to imagine US without intestinal US, especially in pediatrics! The hallmark of intestinal ultrasonography is the “gut signature.” This is the characteristic appearance of the layers of the gut (▶ Table 11.1; ▶ Fig. 11.1). The wall of the intestine is considered stratified when the submucosal echogenicity is present and the mucosa, submucosa, and muscularis propria are separately visible. Nonstratification means indistinctness of the mucosa and submucosa or of all layers. Here are some practical tips for a successful intestinal ultrasonographic examination: ● Have patience. Infants have limited sympathy for the workload of a pediatric radiologist. ● Use graded compression whenever necessary, always realizing that children are not as delicate as porcelain (▶ Fig. 11.2; Video 11.2). If they can withstand vaginal delivery, they can tolerate serious graded compression.

Table 11.1 Gut signature

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Layer

Echogenicity

Mucosal surface

Hyperechoic

Mucosa

Hypoechoic

Submucosa

Hyperechoic

Muscularis propria

Hypoechoic

Serosal surface

Hyperechoic

●

●

●

●

Use warm ultrasound gel. It is almost unimaginable how a peacefully sleeping infant can be turned into a raging beast solely by administering cold gel to its belly. Take advantage of domestic sedation whenever possible. A pacifier with a few drops of syrup will do the trick. The infant will stop crying and relax the abdomen. We have syrup in every US room. Some parents object to the administration of nonsterile, cariogenic, obesity-inducing drugs that inevitably will lead to overindulgence. For these reluctant parents, sterile sucrose (24%) is available in the neonatal intensive care unit in single-patient twist cap vials for the same purpose and the same results at a greater expense (▶ Fig. 11.3). Start the examination with a structure that always will be recognized—the descending colon. That will give you confidence. A small amount of peritoneal fluid at the base of the cecum and behind the bladder is physiologic in children. Try to hold the transducer still for a while, and try to appreciate the bowel movements (or absence of peristalsis) and the passage of gas bubbles through vessels or a fistula. Gentle compression of the transducer at a fixed position will reveal fluctuation of unexpected pus. Make liberal use of color Doppler US. It may reveal the solid nature of hypoechoic infiltrates or lymph nodes (simulating fluid) and the avascularity of an apparently normal bowel loop. Observe at least the following: length of the affected segment, wall thickness, degree of stratification, vascularity, presence of peritoneal fluid (and its clarity), and peristalsis. Be aware of hyperechoic islands of mesentery or omentum with hypoechoic surroundings (▶ Fig. 11.4; Video 11.4). In our experience, they are virtually pathognomonic for infiltrative pathology (inflammatory or neoplastic). Always be aware of this: “An uncommon presentation of a common disease is more common than a common presentation of an uncommon disease” (▶ Fig. 11.48 and ▶ Fig. 11.49).

This chapter provides an overview of the diagnostic potential of pediatric gastrointestinal US.

11.1 Esophagus Endoscopic US is a useful technique to evaluate the esophageal wall and its adjacent mediastinum in a variety of congenital and acquired diseases. However, it is an invasive method that requires sedation or anesthesia and will not be discussed in this chapter on conventional US. The cervical esophagus can be visualized by conventional US in all children as an oval structure between the trachea and vertebral column. It can be seen to a better advantage by using the thyroid gland as an acoustic window and rotating the head 45 degrees to the opposite site (▶ Fig. 11.1a). The esophageal wall can be recognized by its gut signature with five clearly defined layers (▶ Table 11.1). The mean wall thickness is 2.8 mm (range, 2.2–3.8 mm) at all ages.

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Pediatric Intestinal Ultrasonography

Fig. 11.1a–d Gut signature in the esophagus (arrow, a), stomach (b), ileum (c), and appendix (arrow, d). T, trachea.

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Fig. 11.2a,b Juvenile polyp in the descending colon. Without compression, a normal descending colon is seen filled with gas (a). Mild compression reveals a juvenile polyp (between arrows, b).

Fig. 11.3a,b Syrup (not diluted!) and pacifier (a) and a single-patient vial of 24% sucrose (b) for annoying infants.

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Fig. 11.4a,b Isolated hyperechoic islands of mesenteric or omental fat (arrowheads). a Patient with mesenteric Burkitt lymphoma and infiltrative invasion of the mesentery, best seen on the video. b Patient with peritonitis caused by necrotic and perforated intussusception. Note the slight dilatation of the appendix (open arrowhead). Only the base of the appendix was involved in the intussusception ( Video 11.4).

Fig. 11.5a,b Patient with trisomy 21 and esophageal atresia without a tracheoesophageal fistula. Because of the absence of gas, the intestines cannot be evaluated on the abdominal radiograph (a). Note the malposition of the venous umbilical line. Ultrasonography discovered a peculiar gastric outlet configuration (arrow) causing gastric outlet obstruction (b). See also the video. During surgery, an annular pancreas was found, with complete obstruction ( Video 11.5).

In patients with esophageal atresia without a tracheoesophageal fistula, the abdomen can be examined with US to reveal additional abnormalities (▶ Fig. 11.5). More on esophageal atresia is presented in Chapter 6 (Section 6.2.3 Esophagus).

11.2 Gastroesophageal Junction The gastroesophageal junction (▶ Fig. 11.6) can be visualized with US in 87 to 95% of children with suspected

gastroesophageal reflux disease (GERD), and reflux of the gastric contents into the esophagus can be demonstrated. A threshold of three reflux periods within 10 minutes has a sensitivity of 82% and a specificity of 85% for GERD. Farina et al increased the sensitivity to 98% by using color Doppler US. However, in premature infants, the results differ; the sensitivity is 38% and the specificity is 100% when compared with 24-hour PH-metry. US studies have also shown that there is a positive correlation between GER and the length of the abdominal esophagus,

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Pediatric Intestinal Ultrasonography

Fig. 11.6a,b Sagittal slice of a normal gastroesophageal junction (arrowheads) in a 3-month-old boy (a). Same slice during the transit of air (b). The direction of transit can easily be appreciated during real-time ultrasonography. S, stomach; L, liver.

Fig. 11.7 Five-month-old infant with food in the stomach. This may appear as a solid tumor between the left diaphragm (arrow) and spleen (S), and the gas bubbles simulate calcifications such as those seen in neuroblastoma.

protrusion of the gastric mucosa, and an increased gastroesophageal angle (angle of His). Therefore, US can be the initial imaging technique in patients suspected of having GERD. Moreover, US can evaluate the postoperative situation after a fundoplication and gastric emptying, another important contributing factor to the pathogenesis of GERD.

11.3 Stomach US can be used to evaluate gastric emptying in patients with vomiting. Both dynamic and anatomical abnormalities can be depicted. A food-filled stomach should not be mistaken for a tumor (▶ Fig. 11.7). Gastric duplication cysts: The stomach is the second most common location of duplication cysts (▶ Fig. 11.8). A detailed

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discussion of duplication cysts is found in the section of this chapter on the small bowel. Gastric volvulus (mesenteroaxial and organoaxial) in children is rare. In the organoaxial type (more common), the rotation is along the longitudinal axis of the stomach. In the mesenteroaxial type, the stomach twists along the axis of its mesentery and flips into an inverted position (▶ Fig. 11.9). Volvulus is facilitated by poor fixation by the gastric ligaments and gastroperitoneal attachments. It is associated with diaphragmatic herniation, eventration, asplenia/polysplenia syndrome, and hypermobility of the spleen. The typical presentation is vomiting with epigastric distention. US signs are gastric dilatation caused by gastric outlet obstruction and an abnormal position of the antrum in the mesenteroaxial type, ventral and superior to the fundus (▶ Fig. 11.9; Video 11.9). Gastritis and peptic ulcer disease are uncommon in children. US shows a small lumen and stratified wall thickening with hyperemia. In severe cases (i.e., accompanied by deep ulcer disease), the stratification may become less distinct. When present, the ulcer is difficult to visualize. Eosinophilic gastritis is a rare disorder often involving the antropyloric region that may even cause gastric outlet obstruction, simulating hypertrophic pyloric stenosis. Stomach wall stratification is usually preserved. The detection of multifocal small-bowel involvement is highly suggestive of the diagnosis. Foveolar hyperplasia consists of a polypoid thickening of the mucosal layer. It may be seen after long-standing prostaglandin therapy (▶ Fig. 11.10), hypertrophic gastropathy, or cow’s milk allergy, or it may be idiopathic (▶ Fig. 11.11; Video 11.11). It may simulate pyloric hypertrophy, but on closer US examination, the obstruction will appear to be caused by thickened mucosa instead of thickened muscle (▶ Fig. 11.11c, d). Other rare causes of gastric wall thickening and gastric outlet obstruction include pyloric spasm, food allergy, chronic granulomatous disease, hyperlipidemia, chemotherapy (▶ Fig. 11.12; Video 11.12), duplication cysts (▶ Fig. 11.8), ectopic pancreas, benign and malignant tumors, and bezoars.

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Pediatric Intestinal Ultrasonography

Fig. 11.8a–c Duplication cyst of the stomach. Prenatal ultrasound (US) showed a cyst in the left upper abdomen. This was confirmed by postnatal magnetic resonance imaging (arrow, a). US demonstrated a common muscle layer with the stomach (arrowheads, b) and a gut signature (between arrowheads, c), favoring duplication cyst. This was confirmed during surgery. S, stomach

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Pediatric Intestinal Ultrasonography

Fig. 11.9a–d One-year-old boy with acute abdominal distention and vomiting. Initial ultrasonography shows massive dilatation of the stomach (a). After decompression with a nasogastric tube, (b) severe thickening of the gastric wall and (c) an abnormal ventral position of the antrum (A) toward the fundus (F) are visible. Upper gastrointestinal examination confirmed the mesenteroaxial volvulus. Note the eventration of the left hemidiaphragm (arrowheads, d) ( Video 11.9).

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Pediatric Intestinal Ultrasonography length of the pyloric canal, relaxation, and peristalsis. The examination can be performed in a very short time with an accuracy approaching 100%. Inexperienced sonographers are encouraged to introduce a nasogastric tube (many children already have one) to remove the air and introduce 20 mL of clear fluid (e.g., saline) and to turn the child in an oblique rightsided position (to pour the water into the antrum). This will show the anatomy to the best advantage. And always remember that the pylorus lies next to the gallbladder.

11.4 Small Bowel

Fig. 11.10 Two-month-old girl with cyanotic heart disease on prostaglandin E1 therapy. Progressive vomiting. Ultrasonography shows lobulated thickening of the mucosa (arrowheads) with subsequent narrowing of the antral lumen, caused by prostaglandin E1–induced foveolar hypertrophy. The pylorus was normal.

Hypertrophic pyloric stenosis: Infantile hypertrophic pyloric stenosis is of unknown etiology. It affects young infants ages 2 to 8 weeks, in whom the antropyloric portion of the stomach becomes abnormally thickened and obstructs gastric emptying. The male-to-female ratio is approximately 4:1. Typically, infants with infantile hypertrophic pyloric stenosis are clinically normal at birth; during the first few weeks of life, they develop nonbilious, “projectile” vomiting that leads to weight loss, dehydration, and hypochloremic alkalosis, and eventually to death. Surgical treatment is curative. The clinical diagnosis relies on palpation of the thickened pylorus. Abdominal palpation is accurate but not always successful, depending on factors such as the experience of the examiner, the presence of gastric distention, and the cooperation of the infant. In virtually all patients, US is very accurate in facilitating the diagnosis. US, therefore, plays a key role in the initial care of these infants. It is important that the radiologist understands the anatomical changes of the pyloric channel in affected infants as reflected by US, which shows pyloric muscle hypertrophy to a variable degree during the examination. Also, a certain amount of thickening of the mucosa is present (▶ Fig. 11.13; Video 11.13a, b). A muscle thickness of 3 mm or more throughout the examination is considered to be diagnostic of infantile hypertrophic pyloric stenosis, although some authors state that the overall morphology and dynamic impression during the examination are as important, including the

Conventional radiography and US are the initial imaging modalities in children with abdominal pain or obstruction. The most important additional value of US over conventional abdominal radiography in these children is the capability to visualize peristalsis, vascularity, bowel-wall characteristics, dilatation of fluid-filled loops, and extraintestinal abnormalities (e.g., ascites and other fluids). The jejunum and ileum can be distinguished from the colon based on their anatomical location, caliber, contents, folds, and peristalsis. Anatomical location: The colon has a peripheral location in which the ascending colon and descending colon lie dorsally in both flanks and the transverse colon is located ventrally in the upper abdomen. The sigmoid colon traverses the left psoas muscle and courses into the pelvis. In contrast, the small bowel has a more central position. Caliber: The diameter of the small bowel is small and the diameter of the large bowel is relatively large (explaining the nomenclature). Contents: The small bowel is either empty or filled with liquid contents and little air, whereas the colon is generally filled with gas-filled, bulky stool. Folds: The folds in the jejunum are more numerous, longer, thinner, and closer together than the ileal folds. In the terminal ileum, the mucosa may be thickened by hyperplasia of lymphoid tissue. The colon is recognized by its haustra. Infants have few or no haustra. Peristalsis: The small bowel is continuously moving because of peristaltic waves, whereas the colon shows sparse movement. Baud proposed a systematic US approach for differentiating small-bowel disease, based on wall thickening. 1. Determine wall thickening: normal, up to 3 mm; mild thickening, 3 to 6 mm; moderate thickening, 6 to 9 mm; severe thickening, more than 9 mm. 2. Determine location (proximal or distal) and extent (focal, 5 cm; segmental, 6–40 cm; diffuse, more than 40 cm) 3. Determine stratification. Bowel wall is stratified when the hyperechogenicity of the submucosa is preserved and the mucosa, submucosa, and muscularis propria are visible as separate layers. Nonstratification means the absence of a distinction between the mucosa and submucosa or between all three layers (▶ Fig. 11.1 and ▶ Fig. 11.18). 4. Determine the valvular fold pattern; normal, thickened, thumbprinting, or hyperplastic valvular folds.

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Fig. 11.11a–d Fourteen-day-old boy with signs of hypertrophic pyloric stenosis. However, ultrasonography (US) clearly shows wall thickening virtually obliterating the antral (a) and pyloric (b) lumen. Especially the mucosa and submucosa are affected. The US images of the pylorus (b, c) resemble pyloric hypertrophy, but it is not the muscularis propria that is thickened (best seen on the video). For comparison, a genuine pyloric hypertrophy is shown (d). The cause was not found, but the complaints disappeared after the introduction of hypoallergenic feedings (because of severe allergies of the father) ( Video 11.11).

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Fig. 11.12a–c Four-year-old girl with acute lymphatic leukemia in whom abdominal pain, fever, and moderate vomiting developed during chemotherapy (daunorubicin, vincristine, and asparaginase). Ultrasonography shows massive, nonstratified wall thickening of the stomach of 1.2 cm (arrowheads, a) The hyperechoic linear reflection represents the collapsed lumen (arrow). Despite the thickening, there is virtually no hyperemia (b). The stomach returned to normal within 2 weeks (c). Cultures were negative on several occasions ( Video 11.12).

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Fig. 11.14 Normal anatomical position of the D3 segment of the duodenum (between arrowheads). Also note the normal relation between the superior mesenteric artery (A) and the superior mesenteric vein (V). AO, aorta; ICV, inferior caval vein Video 11.14.

Fig. 11.13 Hypertrophic pyloric stenosis. Muscle thickening is indicated by the arrowheads. A, antrum of the stomach with retained fluid. Compare with normal anatomy and normal function in Video 11.13a,b.

Fig. 11.15 Inversion of the superior mesenteric artery (SMA) and superior mesenteric vein (SMV) in a patient with malrotation. AO, aorta; ICV, inferior caval vein; RV, renal vein.

In general, thickened small-bowel loops show decreased peristalsis and contain little air, and they are therefore easily visualized and measured. At least three patterns can be distinguished: Stratified thickening of the small bowel is found in infectious ileitis, advanced appendicitis, early Crohn disease, and graftversus-host disease. Nonstratified thickening of the small bowel is found in Henoch–Schönlein purpura, advanced Crohn disease, tuberculous ileitis, protein-losing enteropathy, hereditary angioedema,

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ischemia, celiac disease, Burkitt lymphoma, Kawasaki disease, and viral enteritis. Nonstratified thickening with hyperplastic valvular folds is found in viral (and sometimes bacterial) lymphoid hyperplasia and Yersinia ileitis. Malrotation and midgut volvulus: The portion of the intestine that is supplied by the superior mesenteric artery is referred to as the midgut, extending from the midportion of the second part of the duodenum to the distal third of the transverse colon. The term malrotation is widely used to describe the spectrum of developmental anomalies that are associated with abnormal position and fixation of the midgut. Patients with malrotation have a mesenteric root with a small fixation to the retroperitoneum. This situation predisposes to midgut volvulus, which is a life-threatening event that can result in necrosis of the entire small bowel. No single technique is 100% accurate in diagnosing malrotation, and one should weigh the balance of evidence from all examinations to determine the correct diagnosis. Most institutions prefer the use of upper gastrointestinal series in cases of suspected malrotation, but technical difficulties and problems of interpretation may result in inconclusive results. These problems are also encountered with the barium enema. US is gaining importance for the initial work-up of patients with suspected malrotation/volvulus. US features of malrotation are an abnormal relation between the superior mesenteric artery (SMA) and superior mesenteric vein (SMV), wide proximal duodenum, absence of the D3 (horizontal) segment of the duodenum, and abnormal position of the cecum and ascending colon. The normal anatomical position of the SMV is to the right of the SMA in the transverse plane (▶ Fig. 11.14). This is easily visualized with US, even in patients with overlying air-filled bowel loops, by using graded compression or sedation (see introduction). Greater deviation from this normal anatomical relation increases the sensitivity for malrotation (▶ Fig. 11.15 and ▶ Fig. 11.16). In a series of 211 children suspected of having malrotation/ volvulus, the sensitivity and specificity of an anterior–posterior orientation of SMV and SMA for malrotation were 19% and 81%, and the positive predictive value (PPV) and negative predictive value (NPV) were 10% and 90%. In contrast, the sensitivity and

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Fig. 11.16a–c Patient with malrotation without volvulus. a Conventional abdominal radiograph shows an abnormal distribution of air-filled bowel loops, suspicious for malrotation or a space-occupying lesion on the right. b Ultrasonography did not reveal abnormalities except for an inverse relation between the superior mesenteric artery (A) and the superior mesenteric vein (V). Moreover, the cecum and appendix could not be visualized. c Consecutive upper gastrointestinal series confirmed malrotation.

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Fig. 11.17a–c Infant with bilious vomiting caused by malrotation and midgut volvulus. a Bilious vomit is as green as grass. b Transverse ultrasonographic image of the whirlpool sign. The superior mesenteric vein contributors (arrowheads) are twisting around the superior mesenteric Video 11.17. AO, aorta; ICV, inferior caval vein. c Volvulus is confirmed with a contrast artery (A). This phenomenon is better appreciated in the study. The nasogastric tube is advanced into the proximal duodenum. An abnormal position of the duodenum is seen with the corkscrew pattern (arrow). The diagnosis was confirmed at surgery.

specificity of an inverted SMV and SMA for malrotation were 71% and 89%, and the PPV and NPV were 42% and 97%. The normal anatomical position of the D3 (horizontal) segment of the duodenum is between the aorta and the SMA. Moving the transducer in the transverse plane in a craniocaudal direction, one will first encounter the root of the SMA, second the traversing left renal vein, and finally the duodenum (▶ Fig. 11.14; Video 11.14). According to Yousefzadeh, a

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normal position of the D3 segment virtually excludes the presence of malrotation. In midgut volvulus, the midgut is twisted around its vascular pedicle, facilitated by the small mesenteric base in patients with malrotation. US in the transverse plane shows the whirlpool sign (▶ Fig. 11.17). In this situation, the SMV twists around the SMA when the transducer is moved in a craniocaudal or caudocranial direction ( Video 11.17). The sensitivity and

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Fig. 11.18a,b Difference between stratified wall thickening in early Crohn disease (a) and nonstratified wall thickening in advanced Crohn disease (b).

Fig. 11.19 Protracted Crohn disease of the small bowel. There is a transition zone of a normal to an affected segment (skip lesion). The normal segment is dilated because of the relative obstruction caused by the skip lesion. Disproportionate thickening of the hyperechoic submucosa and some indistinctness between the mucosa and submucosa (open arrowhead) are seen, the first sign of loss of stratification.

specificity of the whirlpool sign for volvulus were 45% and 99%, and the PPV and NPV were 71% and 97%. Crohn disease is a chronic inflammatory bowel disease characterized by a granulomatous component, transmural inflammation, a tendency to affect the surrounding tissues, and the formation of fistulas and sinus tracts. The exact cause is still unknown. Crohn disease can occur after 5 years of age, but most often adolescents and young adults are affected. The initial course is insidious, with recurrent diarrhea, abdominal pain, and weight loss. Also, atypical features as growth failure,

malnutrition, anorexia nervosa, amenorrhea, arthritis, and cutaneous and ocular manifestations may be present. Levels of calprotectin in the stools are increased. Calprotectin is a neutrophil protein that is released from activated leukocytes. Although the calprotectin level is a relatively new test, it is regularly used as an indicator of inflammatory bowel disease. Crohn disease can affect the digestive tract from mouth to anus but has a predilection for the terminal ileum. Initially, the inflammation starts as aphthoid ulcers in the mucosa and progresses to a transmural inflammation that eventually also involves the surrounding fat. Finally, the inflammation may proceed to other surrounding structures, such as the skin, bowel loops, and urinary, bladder forming sinus tracts, fistulas, and even abscesses. On US, the bowel-wall stratification is initially preserved (▶ Fig. 11.18a). In advanced disease, the stratification is lost, and the affected bowel loop is surrounded by thickened, inflamed, echogenic fat, more or less isolated from the other bowel loops (▶ Fig. 11.18b, ▶ Fig. 11.19, ▶ Fig. 11.20). Close attention should be paid to small hypoechoic spurs that extend into the echogenic fat. They probably represent insidious sinus tract formation and predict future fistula or abscess formation (▶ Fig. 11.21, ▶ Fig. 11.22, ▶ Fig. 11.23; Video 11.21). US is of great value in the diagnosis and follow-up of children with inflammatory bowel disease. It has a sensitivity for inflammatory bowel disease of 75 to 88% and a specificity of 82 to 93%. Faure even reports a sensitivity of 100% for terminal ileitis in Crohn disease. Intestinal polyps in the small bowel are usually hamartomatous polyps in patients with Peutz–Jeghers syndrome (▶ Fig. 11.24; Video 11.24). These polyps occur more often in the jejunum than in the ileum. US is able to detect moderate and large polyps and therefore may serve as a screening method for the detection of uncomplicated polyps. However, one should take into account the high specificity but relatively low sensitivity. US is valuable in diagnosing complications

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Fig. 11.20a,b Advanced Crohn disease of the jejunum. Longitudinal (a) and transverse (b) ultrasonographic images. Note the effacement of folds, loss of stratification, and impressive volume of the inflamed echogenic mesenteric fat.

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Fig. 11.21a–d Advanced Crohn disease with the formation of a sinus tract over time a Thirteen-year-old girl with Crohn disease of the terminal ileum. Hypoechoic strands are seen protruding into the inflamed echogenic mesenteric fat (open arrows). b Two years later, these have progressed to frank sinus tracts (open arrow), forming a hypoechoic suppurative inflammation (I). The linear reflection (open arrowhead) is a gas bubble moving between the ileum and the abscess. This can better be appreciated on the video. c Computed tomography confirms the presence of the sinus tract seen on ultrasonography (open arrow). d Upper gastrointestinal series in a similar patient demonstrates the complexity of these cases. TI, terminal ileum ( Video 11.21).

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Fig. 11.22 Crohn disease of the distal ileum forming a cutaneous fistula (open arrow). Calipers depict the wall thickening of the inflamed ileum, which is surrounded by edematous hyperechoic fat.

associated with small-bowel polyps (e.g., intussusceptions). One should be aware that specific particles within the stools may mimic polyps (e.g., undigested food, foreign bodies; ▶ Fig. 11.25; Video 11.25). Henoch–Schönlein purpura is a systemic vasculitis of unknown cause involving the small vessels of the skin, gut, and kidneys in children between approximately 3 and 8 years of age. Patients develop a typical skin rash and intestinal problems such as nausea, vomiting, abdominal pain, melena, and bloody stools. Arthralgia, proteinuria, and hematuria are additional findings. Abdominal symptoms are present in two-thirds of the patients and can even mimic acute abdomen. The intestinal symptoms may precede the skin rash, and therefore the radiologist may be the first to suggest the diagnosis. The small bowel is affected, including the duodenum (▶ Fig. 11.26a). Involvement is frequently multifocal with skipped lesions. US findings include symmetric thickening of the bowel wall up to 11 mm, loss of stratification, intramural hematoma, enlargement and smoothening of folds, hypoperistalsis, hyperemia, lymphadenopathy, and often some anechoic Video 11.26a, b). These US peritoneal fluid (▶ Fig. 11.26; findings can subside within several days, and exacerbations and remissions may occur. The sensitivity, specificity, PPV, and NPV

Fig. 11.23a,b Sixteen-year-old patient with long-standing Crohn disease. a Longitudinal image of an ileal loop with three hypoechoic sinus tracts (open arrowheads) ending in a large phlegmonous area (I) surrounded by thickened, hyperechoic fat (F). b Formation of a fistulous tract between two adjacent ileal loops in the same patient (open arrow). In addition, developing sinus tracts are heading downward (open arrowheads). Eventually, this patient underwent surgery, and a long segment of distal ileum was resected.

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Fig. 11.24a–e Jejunal hamartomatous polyp. A lobulated hamartomatous polyp in the jejunum was found during routine ultrasonography in this 9-year-old girl with Peutz–Jeghers syndrome. Transverse ultrasonographic (US) image (a) shows the polyp (P) surrounded by some gas (open arrowheads) in the jejunum. The hypoechoic wall of the jejunum is well recognized (closed arrowheads). Longitudinal image demonstrates the stalk (between arrowheads, b), confirmed by color Doppler US (c). Video 11.24 clearly shows the lobulated character of the polyp and the vessels in the stalk. On magnetic resonance enterography (d), the polyp is less prominent (open arrow). Double-balloon endoscopy (e) shows the lobulated polyp during snare removal. The white linear structure is the snare catheter. (Courtesy of Dr. R. de Ridder, Maastricht University Medical Center, Maastricht, The Netherlands.)

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Fig. 11.25 Food particles simulating polyps or duplication cysts. This was a green pea in the bowel as a result of poor table manners (not chewing well). Diagnostic clues are absence of the gut signature, vascularization, mobility, and connection to the wall. Note the small but evident interface between the pea and the stratified bowel wall (open arrow) ( Video 11.25).

of US for gastrointestinal involvement with Henoch–Schönlein purpura are 83%, 100%, 100%, and 54%, respectively. Complications include pathologic small-bowel intussusception, bleeding, and rarely necrosis and perforation, pancreatitis, cholecystitis, and appendicitis. Henoch–Schönlein purpura is a self-limiting disease, although persisting proteinuria due to nephritis is a well-known complication (▶ Fig. 11.26d). Note the abnormally decreased echogenicity of the submucosa (arrowheads), thought to represent fluid accumulation within the submucosa caused by the vasculitis, and the peritoneal fluid (arrow, ▶ Fig. 11.26c). The hypoperistalsis and hyperemia are best appreciated on the videos. Increased echogenicity of the right kidney is due to nephritis (▶ Fig. 11.26d). A small rim of peritoneal fluid is seen between the liver and the kidney. Numerous enlarged mesenteric lymph nodes are present (▶ Fig. 11.26e). Ascaris lumbricoides is the most common helminthic infestation wordwide, affecting mainly children and young adults. Many children are not symptomatic or have minor, nonspecific abdominal complaints. The US images are quite characteristic, depending on the image plane; in the longitudinal plane, the worms appear as parallel echogenic lines, whereas in transverse images, they appear as round dots inside the lumen (▶ Fig. 11.27). The administration of fluid before the examination improves visualization of the worms. Differentiation from intraluminal lines may be difficult, and the movement of the worms can aid in the differentiation. Tubes and lines do not move by themselves. Ascaris residing in the small intestines may migrate into the biliary system, pancreatic duct, and appendix, causing symptoms of biliary stones, pancreatitis, or appendicitis.

Meckel diverticulum most commonly presents as painless rectal bleeding due to ulceration caused by ectopic gastric mucosa. These patients are usually adequately diagnosed and managed following a radionuclide scan. In fewer than 50% of children presenting with Meckel diverticulum, the clinical findings will be more complex, with a combination of abdominal pain, vomiting, and occasionally rectal bleeding. In children with acute pain, the diagnosis is often difficult and nonspecific. US can be used successfully to document the presence of an inflamed or hemorrhagic Meckel diverticulum. In this situation, the Meckel diverticulum has a variable appearance and may simulate an inflamed duplication cyst, appendicitis, or sometimes a small intussusception. When one finds this somewhat atypical appearance on US, one should consider the diagnosis of a complicated Meckel diverticulum rather than the other pathologies it simulates (▶ Fig. 11.28 and ▶ Fig. 11.29; Video 11.28). Necrotizing enterocolitis usually presents in infants in the neonatal intensive care unit, more commonly in premature neonates. The classic presentation includes abdominal distention and blood in the stool. The radiologist plays an important role at the time of the diagnosis of this condition, during follow-up, and in the detection of later complications such as strictures. At the time of diagnosis, three abnormalities may be present on abdominal X-ray, which include bowel dilatation, intramural gas, and portal venous gas. Bowel dilatation is present in almost 100% of the patients with necrotizing enterocolitis, and the degree of bowel distention usually correlates well with the clinical severity. Follow-up abdominal X-ray may show asymmetric dilatation and fixed loops in those infants whose condition deteriorates. Intramural gas is not present in all patients, and the amount of intramural gas does not always correlate well Video 11.30). Portal with the clinical severity (▶ Fig. 11.30; venous gas usually is present in those with severe necrotizing enterocolitis (▶ Fig. 11.31). Disappearance of the intramural gas and portal venous gas does not always correlate with clinical improvement because the gas will eventually disappear even in those children who deteriorate clinically. Moreover, intramural gas is not pathognomonic for necrotizing enterocolitis because it can be seen in children with rotavirus or enterovirus enterocolitis. In fact, any severe colitis in combination with increased intraluminal pressure can produce pneumatosis and even portal gas (▶ Fig. 11.31; Video 11.31). US is an extremely useful modality in the investigation of patients with necrotizing enterocolitis because it can provide information regarding bowel-wall thickness, bowel perfusion (color or power Doppler sonography), and the presence of intraperitoneal fluid. US is much more accurate than abdominal radiographs in documenting the presence of free and focal intraperitoneal fluid and can also define the character of such fluid. It is well-known that not all patients with necrotizing enterocolitis will show free air on abdominal radiographs following perforation and may present only with free fluid. Moreover, US in experienced hands can be extremely useful in detecting small amounts of free abdominal air, especially between the liver and anterior abdominal wall, in supine infants (▶ Fig. 11.32; Video 11.32). In the early phases of necrotizing enterocolitis, the bowel wall will be quite thickened, but in those patients who are more

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Fig. 11.26a–e Henoch–Schönlein purpura. a Extremely nonstratified wall thickening of the duodenum (7 mm) as the first ultrasonographic sign in an 11-year-old patient with Henoch–Schönlein purpura. The hyperechoic area may represent hematoma (open arrow). b–e Nine-year-old boy with Henoch–Schönlein purpura. There are thickening and loss of stratification in the jejunum (b). Note the abnormally decreased echogenicity of the submucosa (white arrowheads, b) thought to represent fluid accumulation within the submucosa caused by the vasculitis, and peritoneal fluid (open arrow, c). The hypoperistalsis and hyperemia are best appreciated on the video. Increased echogenicity of the right kidney is due to nephritis (d). A small rim of peritoneal fluid is seen between the liver and the kidney. Numerous enlarged mesenteric lymph nodes are present (e) ( Video 11.26).

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Fig. 11.27a,b Worm infestation in an 11-year-old boy with recurrent abdominal pain. Longitudinal (a) and transverse (b) ultrasound images. Slight segmental dilatation of a proximal jejunal loop filled with some fluid and linear structures on the longitudinal image, and round structures on the transverse image. No bowel wall thickening.

Fig. 11.28 Meckel diverticulum in an 8-year-old boy with intermittent rectal blood loss and anemia. Gastroscopy, colonoscopy, video capsule endoscopy, and Meckel scan (nuclear medicine) were negative. Ultrasound shows a blind-ending bowel loop (length, 1.2 cm) originating from the distal ileum (I), compatible with Meckel diverticulum. The tip demonstrates a small area with loss of the submucosa (open arrow). The diagnosis was confirmed by laparoscopy and pathology. A small area of gastric mucosa and glandular structures was seen in the lamina propria, with chronic inflammation and eosinophilic granulocytes ( Video 11.28).

severely affected, the mucosa and submucosa of the bowel slough into the lumen, leaving a markedly thinned bowel wall (▶ Fig. 11.33; also refer to Video 11.33). These patients are much more prone to perforation, and the thinning of the bowel wall can be documented with sonography. It is shown that in necrotizing enterocolitis the bowel (particularly thickened bowel) becomes markedly hyperemic, and this indicates the presence of viable bowel. However, the absence of perfusion in single or multiple loops of bowel (particularly when the bowel wall is thinned) indicates the presence of necrosis, and surgical intervention may be warranted even if there is no free air present on the plain radiograph. US plays a major role in the follow-up of patients who are not responding to medical management and who deteriorate clinically. In these patients, US may provide information that is not depicted with abdominal X-ray. Intestinal duplication cysts can occur anywhere along the alimentary tract, but the most common location is the ileum. Therefore, they are discussed in this section on the small bowel. Duplication cysts are spherical or tubular masses adherent to the gastrointestinal tract that sometimes communicate with it. They are lined with intestinal epithelium, and there is smooth muscle within the wall. The most common site is the ileum, followed by the stomach. Most patients present within the first year of life, with symptoms including gastrointestinal

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Fig. 11.29a,b Meckel diverticulum in a 1-year-old girl with melena for 3 days and severe anemia. Gastroscopy, colonoscopy, and Meckel scan (nuclear medicine) were negative. Sagittal (a) and transverse (b) ultrasound slices showed a wide, blind-ending ileal loop (I) with a small inversion at the tip (open arrows), resembling a small-bowel intussusception. However, the “intussusception” did not show peristalsis, in contrast to benign small-bowel intussusceptions. One week later, laparoscopy and pathology confirmed a Meckel diverticulum with a length of 3.5 cm. By that time, the inversion had disappeared.

Fig. 11.30a,b Premature infant with necrotizing enterocolitis and intestinal pneumatosis in the ileum (a) and descending colon (b). Small intramural air bubbles are seen (arrowheads). The intramural location of the gas bubbles can better be appreciated in Video 11.30.

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Fig. 11.31a,b Intramural gas resulting in portal venous gas. A 4-weekold infant with Hirschsprung disease developed a fulminant colitis caused by bacterial overgrowth. Gas bubbles (arrowheads) are passing the wall of the transverse colon (a) toward the portal vein and liver parenchyma (b). The speed of these gas bubbles and their intraluminal origin can better be appreciated on Video 11.31.

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Fig. 11.32 Pneumoperitoneum in necrotizing enterocolitis. Small gas bubbles (arrowheads) are detected between the liver and anterior abdominal wall. Slight compression will induce movement of these bubbles, as can be seen on Video 11.32.

obstruction. Less common presentations include a palpable mass, intussusception, and abdominal distention. US easily appreciates the cystic nature of duplication cysts. The contents are often anechoic but may contain mucoid material or debris after hemorrhage. Rarely, a cyst appears completely hyperechoic after hemorrhage. Two signs are virtually diagnostic of duplication cysts: (1) a double-layered wall consisting of echogenic mucosa and hypoechoic muscularis propria (▶ Fig. 11.34 and ▶ Fig. 11.35) and (2) peristalsis in the cyst ( Video 11.35). In 15 to 20% of cases, the cyst contains gastric mucosa, which causes the above-mentioned hemorrhages. Moreover, meticulous US examination may identify the primary bowel loop from which the cyst originates; the cyst shares the muscularis propria and serosa with the primary bowel loop (▶ Fig. 11.8 and ▶ Fig. 11.35). Ovarian cysts, urachal cysts, lymphatic malformations, and hemorrhage can all mimic duplication cysts (▶ Fig. 11.36 and ▶ Fig. 11.37). Benign small-bowel intussusception is a recently described entity. It differs from classic symptomatic ileocolic intussusception in that benign small-bowel intussusception occurs predominantly in the right lower quadrant or periumbilical region, has a smaller diameter (mean diameter, 1.4 cm vs 2.5 cm) and a thinner outer rim, and does not contain mesenteric lymph nodes (▶ Fig. 11.38). Moreover, peristalsis in the intussuscepted loop persists, unlike in an ileocolic intussusception ( Video 11.38). Often, benign small-bowel intussusception is an incidental finding, but it occurs with increased frequency and number in celiac disease (▶ Fig. 11.39). In general, benign smallbowel intussusceptions do not require immediate reduction because of their spontaneously resolving nature. Children with ileocolic, ileo-ileocolic, or colocolic intussusceptions commonly do not present with the classic clinical triad of abdominal pain, red currant jelly stool, and a palpable abdominal mass. The presentation may therefore be nonspecific. For this reason, the clinician often has to rely on imaging procedures to diagnose or exclude intussusception promptly and accurately. The diagnosis can be made by ultrasonography, plain abdominal radiography, or contrast studies of the colon.

Fig. 11.33a–c Sloughing of the mucosa in a premature infant with transient ischemia, the sudden onset of abdominal distention, and an increased level of serum lactate. Abdominal radiography (a) shows an abnormal distribution of bowel gas, dilatation, and wall thickening. Ultrasound (b) shows complete sloughing of the mucosa of dilated smallbowel loops (open arrows) and a swirl of the mesenteric vessels (not shown). No folds can be seen anymore. The video confirms that the bowel gas is seen exclusively within the lumen of the sloughed mucosa. Surgery revealed a congenital band that was kinking the bowel loops. Two weeks, later the mucosa has recovered (c) ( Video 11.33).

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Fig. 11.35 Duplication cyst of the ileum in a newborn child. Note the gut signature of its wall and the local thickening (open arrows), representing the collapsed true lumen. Peristalsis is seen on Video 11.35.

Fig. 11.34a,b Duplication cyst. Large right-sided cyst (C) on prenatal magnetic resonance imaging shows no typical features (a). Postnatal ultrasound demonstrates the gut signature in the wall of the cyst, suggestive of a duplication cyst (b). Pathology proved duplication cyst of the ileum.

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Ultrasonography has been shown in many series to be 100% accurate in depicting the presence or absence of the common types of ileocolic or ileo-ileocolic intussusception in children. These lesions have a characteristic sonographic appearance and are usually found just under the abdominal wall, most commonly on the right side of the abdomen (▶ Fig. 11.40). Because it is a noninvasive procedure and because of its accuracy, ultrasonography is the modality of choice for the evaluation of patients suspected of having an intussusception. An excellent review of the sonographic appearance of intussusception is provided in the article by delPozo et al. Conventional abdominal radiography shows some characteristic signs of an intussusception, which include the meniscus sign, target sign, and less commonly a soft tissue mass. However, the sensitivity and specificity of conventional radiography are low. Only when there is a clinical consideration of peritonitis is the conventional radiograph essential to exclude perforation, which is the major contraindication to attempted enema reduction. Pathologic lead points are found in about 5 to 7% of all intussusceptions. The most common are Meckel diverticulum, polyps, Henoch–Schönlein purpura, and cystic fibrosis. Less common causes are lymphoma, duplication cyst, and various inflammatory lesions of the bowel (▶ Fig. 11.41; ▶ Fig. 11.42; ▶ Fig. 11.43). Management of these patients remains a challenge. Contrast or air enema techniques are not always diagnostic of a pathologic lead point. Sonography is extremely useful in this regard; it has been shown that it may depict two-thirds of pathologic lead points and may provide a specific diagnosis in one-third of these. However, it remains a diagnostic challenge as to how to search for a pathologic lead point when there is a high index of suspicion for such a lesion but ultrasonography is negative. In such cases, the choice of which other imaging

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Fig. 11.36a–c Duplication cyst look-alike in an 8-year-old girl with abdominal pain and vomiting. Abdominal radiograph (a) shows proximal ileus. Ultrasonography (b) shows a large cyst with a whirlpool sign, suggestive of a twist of the bowel loops or midgut volvulus. The surgeon found a volvulus of the jejunum caused by a duplication cyst of the jejunum (c). However, histology of the cyst wall showed a lymphatic malformation cyst.

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Fig. 11.38 Two benign small-bowel intussusceptions in a patient with celiac disease. Fig. 11.37 Duplication cyst look-alike in a 3-week-old infant with a resolving postsurgical hematoma or a hemorrhagic seroma resembling a duplication cyst because of its well-organized wall, simulating the gut signature. However, no peristalsis was present, and during prior surgery no duplication cysts had been found. The lesion disappeared during follow-up ( Video 11.37).

Fig. 11.39 Extremely large benign small-bowel intussusception in a 4year-old patient with celiac disease. Although the diameter was 3.0 cm and some lymph nodes were present in the intussusception (very atypical for a benign small-bowel intussusception), this was considered a benign small-bowel intussusception because of the persisting peristalsis of the intussusceptum and intussuscipiens ( Video 11.39) and the relatively short length. A wait-and-see policy was pursued, and the complaints subsided while the patient was on a gluten-free diet ( Video 11.39).

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Fig. 11.40 Ileocolic intussusception in a 2-year-old girl. Successful hydrostatic reduction. Note the target sign composed of alternating hyper- and hypoechoic layers. The small trapped loop is probably the appendix (open arrow).

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Fig. 11.41a,b Recurrence of an ileocolic intussusception 2 days after a successful hydrostatic reduction. The pathologic lead point was not appreciated during the initial ultrasonography. (a) Recurring ileocolic intussusception in the ascending colon. (b) A small duplication cyst (C) is seen at the tip of the intussusception at the hepatic flexure.

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Fig. 11.43 Ileocolic intussusception in a 13-year-old girl caused by a Burkitt lymphoma. Sagittal image of the right flank demonstrates an intussusception (between open arrows) and a hypochoic mass at the top of the intussusception (arrowheads). K, kidney.

Fig. 11.42a–c Colocolic intussusception caused by a pedunculated juvenile polyp in the descending colon. In a craniocaudal direction, (a) the intussusception in a transverse image, (b) the intussusception and lead point in the longitudinal plane, and (c) the typical ultrasonographic appearance of the juvenile polyp in a detailed view. The polyp contains small cysts, and the stalk is evident (between arrowheads).

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modalities to use will depend on the individual patient’s clinical situation. Many series in the recent literature have shown a reduction rate of intussusception varying from 80% to as high as 95%. These series have used either fluoroscopic or ultrasonographic guidance for reducing the intussusception and either hydrostatic (barium, water-soluble contrast, saline) or pneumatic reduction. The fact that different techniques have been used with similar success rates suggests that it is not important which technique is used. Nonoperative reduction of an intussusception should be attempted only after the surgical team has evaluated the patient and the patient is clinically stable and well hydrated, has no evidence of peritonitis, and has an intravenous line in place. The major contraindications to an enema are clinical findings of peritonitis or shock and signs of perforation on an abdominal radiograph. Absence of vascularization on color Doppler US and the presence of trapped fluid predict necrosis and/or unsuccessful hydrostatic reduction (▶ Fig. 11.44). In order to improve one’s reduction rates, delayed or repeated attempts at reduction can be used as long as the intussusception does move during the initial attempted reduction and the child becomes asymptomatic and maintains stable vital signs. It has been shown that this approach is a safe and effective technique with a good success rate. Navarro et al used this approach in approximately 15% of patients with intussusception and achieved successful reduction in 50% of those intussusceptions not reduced on the first attempt. There does not appear to be a fixed optimal timing between attempts, and delayed second or third attempts can be made several hours after the first attempt. Recently, US-guided external manual reduction was proposed as a safe and effective method to treat ileocolic intussusceptions.

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Fig. 11.44a–d Different types of trapped fluid, all predicting difficult reduction. a Ileo-ileal intussusception with absence of local perfusion on color Doppler ultrasound. Pathology showed a Meckel diverticulum with hemorrhagic ischemia. b Ileo-ileal intussusception. No attempt at hydrostatic reduction. Surgical resection. c Ileocolic intussusception in a 4-month-old girl. Hydrostatic reduction was not successful. Ileocecal resection with hemorrhagic necrosis. d Ileo-ileocolic intussusception. Hydrostatic reduction not successful. Meckel diverticulum.

11.5 Appendix Acute appendicitis is a common clinical entity in pediatrics. In many patients, it is easy to make the diagnosis clinically with certainty, and no imaging is required before appendectomy. However, imaging is extremely important in those children with nonspecific features. We have used US as the modality of initial choice and try to reserve computed tomography or magnetic resonance imaging for those patients whose US examination is inconclusive or who have abscesses, so that the extent of the abscesses can be defined before drainage by the interven-

tional radiology team. The normal appendix can be visualized with US in 82% of asymptomatic children. It is compressible, has a mean diameter of 4 mm (range, 2–6 mm), and is empty in 62% of children (▶ Fig. 11.45). The diagnosis of appendicitis is made on US when the diameter of the appendix is greater than 6 mm and the appendix is noncompressible. This should not be considered an absolute measurement, and other features should be considered, including edema of the mesentery, hyperemia of the wall of the appendix on color or power Doppler examination, and the presence of an appendicolith, local fluid collections or abscess

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Fig. 11.45a–e The many faces of a normal appendix. Normal appendix (a, b) with a diameter of 5 mm. An increase in diameter of up to 1.2 cm (c) is normal in patients with cystic fibrosis if no other inflammatory signs are present. Note the feces (F) in the lumen. Some echogenic fluid may be present (arrowhead, d) that can be evacuated by contractions (e) of the same appendix.

formation, and local dilated bowel loops (▶ Fig. 11.45, ▶ Fig. 11.46, ▶ Fig. 11.47, ▶ Fig. 11.48). There are other conditions that may cause the appendix to become thick-walled and to dilate; these include cystic fibrosis (▶ Fig. 11.45c), Henoch– Schönlein purpura, hemolytic uremic syndrome (▶ Fig. 11.57b), and inflammatory bowel disease.

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As stated at the beginning of this chapter, an uncommon presentation of a common disease is more common than a common presentation of an uncommon disease. Always consider appendicitis when confronted with remarkable structures in the right lower quadrant (▶ Fig. 11.48 and ▶ Fig. 11.49; Video 11.48).

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Fig. 11.46a–f The many different faces of appendicitis. a, b Abortive appendicitis in a 9-year-old boy. The patient had local peritoneal tenderness for 1 day exactly at the site of the appendix and a normal temperature. Ultrasound (US) shows a borderline appendix diameter (6 mm) and slight edema of the appendiceal mesentery (open arrow), but no surrounding edema (a). Color Doppler US demonstrates marked hyperemia (b). Complaints subsided within 2 days without therapy. Phlegmonous appendix surrounded with thickened, inflamed periappendiceal fat (c–e), indistinct borders (arrowhead, d), and incomplete vascularization (e). Sealed-off perforation (f). Appendix with perforation at the tip (open arrow) that is sealed off by an ileal loop (I) and inflamed hyperechoic fat ( Video 11.46). (continued)

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Fig. 11.46g,h (continued) g Retrocecal appendicitis, located in the right flank with a sealed-off perforation. C, colon. h Appendicitis with a wide lumen caused by a large appendicolith (open arrows).

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Fig. 11.47a–c The many faces of appendiceal abscesses. Periappendicular abscess (a) with a thick wall adjacent to the inflamed appendix (open arrow). Abscess in the Douglas pouch with several fluid–fluid levels (arrowheads, b) and an appendicular abscess with an appendicolith on the bottom (c). Note the hypoechoic inflammatory changes around the islands of hyperechoic inflamed fat (arrowheads, a, c). U, uterus.

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Fig. 11.48a–c Torsion and subsequent hydrops and gangrene of the appendix in a 10-month-old boy with a painful, distended abdomen and fever. Ultrasound (US) shows a distended, blind-ending loop (diameter, 2.0 cm) in the right abdomen (a). No peristalsis, no vascularization of its wall on color Doppler US (b), and cloudy ascites (A) in the left paracolic gutter (c). Tentative diagnosis was obstruction of a Meckel diverticulum. Surgery revealed a hydropic gangrenous appendix with a torsion at its base ( Video 11.48).

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Fig. 11.49a,b Peculiar presentation of appendicitis in an 8-year-old boy with pain in the right lower quadrant for 2 days and low-grade fever. a Ultrasonography (US) showed a multilayered structure (open arrows) adjacent to the base of the appendix (arrowhead) with some hyperechoic, thickened surrounding fat. b In vitro US of the surgical specimen showed the multilayered pattern to better advantage. The tentative diagnosis was appendiceal intussusception, but histology revealed “just” appendicitis.

Fig. 11.50a,b Sixteen-year-old patient with long-standing Crohn disease. a Transverse image of the sigmoid with an inflammatory mass adjacent to the dorsal wall (open arrows) and a hypoechoic inflammatory tract (arrowhead) toward a large, hypoechoic phlegmon (P). b This inflammatory mass caused hydronephrosis of the left kidney. Infliximab temporarily improved the clinical situation, but eventually the patient needed surgery (same patient as in ▶ Fig. 11.23).

11.6 Large Bowel The differences between the normal small bowel and the normal large bowel have previously been described in the section on the small bowel. Similar to the systematic approach to the small bowel, Baud proposed a systematic approach to the colon. 1. Determine wall thickening: normal, up to 3 mm; mild thickening, 3 to 6 mm; moderate thickening, 6 to 9 mm; and severe thickening, more than 9 mm. 2. Determine the extent and location of disease: diffuse, cecum, ascending colon, proximal and distal transverse colon, descending colon, and rectosigmoid.

3. Determine stratification, best seen on transverse images. The bowel wall is stratified when the hyperechogenicity of the submucosa is preserved and the mucosa, submucosa, and muscularis propria are visible as separate layers. Nonstratification means the absence of a distinction between the mucosa and submucosa or between all three layers. 4. Determine the haustral pattern, best seen on longitudinal images: the absence or presence of haustral folds and their length (normal or shortened) and aspect.

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Fig. 11.51 Pancolitis in a 5-year-old girl with a clinical diagnosis of Crohn disease. Partial loss of stratification of the colon and evident thickening and increased echogenicity of the pericolic fat. No sinus tracts.

In this way, three patterns can be distinguished: Stratified thickening is found in infectious colitis, advanced appendicitis, and inflammatory bowel disease (both ulcerative colitis and Crohn disease) Nonstratified thickening with loss of haustral folds is found in early hemolytic uremic syndrome and advanced Crohn disease. Nonstratified imaging with preservation of normal haustral fold length is found in pseudomembranous colitis and neutropenic colitis (typhlitis). Crohn disease is also discussed in the earlier section of this chapter on the small bowel. Right-sided colonic involvement is most common. In contrast to ulcerative colitis, Crohn disease will eventually lead to loss of stratification and pericolic fat proliferation. Because of its anatomical location (descending and ascending colon), the pericolic inflammation can extend into the retroperitoneal space and cause hydronephrosis (▶ Fig. 11.50). However, in early Crohn disease, these features are not yet present, and differentiation based on the imaging findings is difficult, even impossible, when there is a pancolitis without involvement of the terminal ileum (▶ Fig. 11.51). Ulcerative colitis is a noninfectious, diffuse, uniform inflammation of the mucosa and superficial submucosa (▶ Fig. 11.52). It is limited to the colon. The onset may be insidious, with abdominal pain, recurrent diarrhea, and weight loss. Nonintestinal symptoms may be present, such as growth failure, malnutrition, amenorrhea, arthritis, and cutaneous and ocular manifestations. Rectal bleeding is more common in ulcerative colitis than in Crohn disease. Ulcerative colitis begins in the rectum and advances proximally without skip lesions. Pancolitis is frequent in children. On US, the mural stratification is clearly visible because the inflammation remains superficial. The inflammation causes increased muscle tone, and the lumen is collapsed. Infectious colitis (Salmonella, Campylobacter, Shigella, Escherichia coli, Yersinia) has a US pattern similar to that of ulcerative colitis, with preserved stratification and normal pericolic fat. In contrast to ulcerative colitis, infectious colitis often involves the right side of the colon, and in over one-third of patients, the

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distal ileum and ileocecal valve are involved. Otherwise, however, the diagnosis of infectious colitis depends on stool and blood cultures and analysis. Neutropenic enterocolitis (typhlitis) is a severe infectious colitis that occurs in children with neutropenia (▶ Fig. 11.53). It involves mainly the cecum and ascending colon, but the small bowel can also be involved. The pathogenesis is complex and involves mucosal damage, compromised immunity, bacterial invasion, distensibility, and vascularization. Clostridial toxins have been proposed as causative agents. Neutropenic enterocolitis often develops in children with leukemia during chemotherapy. Symptoms are fever, diarrhea, and right lower quadrant pain. US demonstrates severe colonic wall thickening with loss of stratification, a redundant inner layer of increased echogenicity, and intense mural hypervascularity. Pseudomembranous colitis is usually caused by an overgrowth of Clostridium difficile and its toxin in patients on antibiotic therapy. Symptoms include abdominal pain, watery diarrhea, fever, and leukocytosis after the recent use of antibiotics. The pseudomembranes originate from deep crypt abscesses that erupt to the surface and are formed by the coalescence of mucus, fibrin, epithelial cell debris, inflammatory cells, and exudate. Depending on its composition, the pseudomembrane can have varying thickness and varying echogenicity (▶ Fig. 11.54, ▶ Fig. 11.55). The haustra are preserved and not shortened, as they are in many other types of colitis. The pattern of swollen, preserved haustra is known as the accordion sign (▶ Fig. 11.54d).

11.6.1 Other Causes of Colitis Other causes of colitis in children are rare and include druginduced colitis (▶ Fig. 11.56), collagenous colitis, chronic granulomatous disease, Behçet’s disease, dietary protein-induced enterocolitis and colitis secondary to Hirschsprung’s disease, Hermansky-Pudlak syndrome, and glycogen storage disease type Ib. Hemolytic uremic syndrome is a triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure. It is thought to be caused by the systemic spread of bacterial toxins (e.g., Shiga toxin–producing E. coli, or STEC). Most cases occur in children younger than 5 years of age. US features include considerable thickening of the colon wall and increased echogenicity of the renal parenchyma. The thickened wall shows loss of stratification and is strikingly avascular on color Doppler US, especially in the prodromal phase. Because the colitis often precedes the full-blown clinical presentation of hemolytic uremic syndrome, the radiologist may be the first to suggest the diagnosis in a child with colitis and bloody diarrhea (▶ Fig. 11.57; Video 11.57). Juvenile polyps are the most common neoplasms in the large bowel in children. The sigmoid and rectum are preferential locations. The presenting symptom is rectal bleeding in more than 90% of patients. Occasionally, a colocolic intussusception is the first manifestation of a juvenile polyp. US will demonstrate a pedunculated spherical nodule with a diameter varying from 10 to 25 mm containing multiple 2- to 3-mm cysts Video 11.58). The administration of fluid (▶ Fig. 11.58; within the bowel lumen will greatly improve the visualization of these polyps; however, the assessment of rectal polyps is still

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Fig. 11.52a–c Mild ulcerative colitis in a 15-year-old boy with fatigue and colicky pain. Calprotectin levels in the stools were increased. Transverse ultrasound images of the descending colon (a, b) show mild, stratified wall thickening (4 mm) and some reactive lymph nodes (arrowhead, b). The lumen is empty, and there is no significant pericolic inflammation. The transverse colon has a slightly prominent submucosa but is not thickened and relaxes well (c).

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Fig. 11.53a–e Neutropenic enterocolitis. An 8-year-old boy on chemotherapy for non-Hodgkin lymphoma developed a high fever and watery diarrhea during a period of severe neutropenia and Streptococcus milleri sepsis. Abdominal radiography (a) shows nonspecific bowel wall thickness and a remarkable absence of gas on the right side. Ultrasonography reveals massive wall thickening of up to 9 mm (b) and hyperemia of the ascending colon involving all layers (c). Especially the submucosa is thickened (asterisk, b) and shows a loss of homogeneity. The haustral pattern is preserved but effaced. After 2 weeks of antibiotic treatment, the wall thickening has disappeared (d). Small bowel with stratified wall thickening on longitudinal images (e). Note edema of the mesentery (arrow) and some peritoneal fluid ( Video 11.53). (continued)

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11.7 Rectum

Fig. 11.53f (continued) and loss of stratification on transverse images (f).

known to be unreliable. Specific particles within the stool may mimic polyps (e.g., undigested food, pellets of stool; ▶ Fig. 11.59; Video 11.59). Epiploic appendagitis is a localized inflammation caused by torsion and ischemia of an epiploic appendage. This is a small, peritoneum-covered fat tag at the serosal or antimesenteric border of the colon with a single artery and vein in its pedicle Video 11.60). Epiploic appendagitis is rare in (▶ Fig. 11.60; children, but its recognition is important to prevent surgery in this self-limiting disease. It causes localized pain that will direct the sonographer toward the correct site. The inflamed appendage is seen on US as a hyperechoic mass sometimes surrounded by thickened, hyperechoic pericolic fat. Meconium calcifications can be seen in patients with anal atresia and large rectourethral or rectovesical fistulas. Apparently, the mixture of meconium and urine causes the meconium to calcify. This results in a specific pattern of discrete, punctate flecks within the course of the colon that can be appreciated on abdominal radiographs as well as on US (▶ Fig. 11.61). Meconium calcifications should not be confused with meconium peritonitis, in which the calcifications are linear and plaquelike.

The rectum can be easily visualized by US when the bladder is filled with urine (▶ Fig. 11.62 and ▶ Fig. 11.63). Several studies measured the transverse diameter of the rectum with US. This measurement seems to be a reliable tool to identify rectal impaction and may replace digital rectal examination; all children with rectal impaction on digital examination had a rectal diameter of more than 30 mm. Moreover, several studies showed that the mean diameter of the rectum is significantly larger in children with constipation than in normal children. In a series of 225 children, the mean rectal diameter in the normal children was 32 mm (standard deviation, 8.2), and in the children with constipation it was 43 mm (standard deviation, 9.7). To overcome the problem of age dependency of the rectal diameter in normal children, Bijos et al proposed the rectopelvic ratio: the ratio of the rectal diameter (US) to the distance between the anterior superior iliac spines. When the ratio is higher than 0.189, the sensitivity for rectal impaction is 88% compared with proctoscopy. The rectal diameter can also be used to monitor therapy.

11.8 Anus Anal atresia is a relatively frequent congenital abnormality in which the anus is absent, and a rectoperineal, rectovestibular, rectovaginal, rectourethral, or rectovesical fistula may be identified in almost all cases. The “fistula” has an internal sphincter, and therefore some prefer the term ectopic anus or anorectal malformation instead of anal atresia. During preoperative evaluation, it is important to assess the type of anal atresia: high type (distal rectal pouch above the puborectal sling), intermediate type (at the sling), or low type (through the sling). Transperineal US is a good diagnostic modality for defining the type of anal atresia by measuring the distance between the rectal Video pouch and the perineum (P-P distance; ▶ Fig. 11.64; 11.64). A P-P threshold value of 15 mm discriminates the low type of atresia from the intermediate and high types with a sensitivity of 100% and a specificity of 86%. Moreover, in 82% of the patients with a high type of anal atresia, the internal fistula can be correctly identified. Transperineal sonography is also a useful method for differentiating between an anteriorly displaced anus, which is a normal anatomical variant, and a low type of imperforate anus

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Fig. 11.54a–d Pseudomembranous colitis. A 3-month-old boy with prolonged nonbilious vomiting developed ileus following antibiotic therapy (amoxicillin, gentamicin, and ceftriaxone). Stool cultures were positive for Clostridium difficile. Abdominal radiograph shows ileus and virtually no gas in the colon (a). Transverse ultrasound (US) view of the ascending colon (b). Thick, hypoechoic pseudomembrane (asterisks) surrounds an eccentric narrow lumen filled with air. The wall of the colon shows nonstratified thickening and hyperemia on Doppler US, but no flow in the pseudomembrane (c). Hyperechoic strand of mucus between the pseudomembrane and mucosa (arrowhead). US longitudinal view (d) of the descending colon: the pseudomembrane is less conspicuous. Hyperechoic mucus between the swollen folds (arrowheads) creates an accordion pattern ( Video 11.54).

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Fig. 11.55a,b Pseudomembranous colitis. A 4-year-old boy with pre-B acute lymphocytic leukemia during chemotherapy (doxorubicin, vincristine, asparaginase) and antibiotic treatment (itraconazole, ciprofloxacin, cotrimoxazole) was suspected of having neutropenic colitis. Stool cultures were negative, but stool analysis was positive for Clostridium difficile toxins. a Ultrasonography shows preserved haustral fold length despite the evident mural (submucosal) thickening. There is a partial loss of stratification. b The pseudomembranes are well recognized as a heterogeneous, hypoechoic layer between gas in the collapsed lumen (open arrow) and the mucosa (white arrow). No vascularization within the pseudomembranes ( Video 11.55).

Fig. 11.56a,b Colitis as a side effect of azathioprine. A 17-year-old boy on prednisone, azathioprine, and antihypertensive drugs for Takayasu disease developed watery diarrhea (once with blood) for 7 days and vomiting for 2 days without fever. a Ultrasound shows wall thickening of the descending colon with loss of stratification and pericolic edema. b The pancolitis is confirmed by computed tomography, which demonstrates an abnormal descending and ascending colon (white arrows).

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Fig. 11.57a–c Hemolytic uremic syndrome in a 2-year-old boy with bloody diarrhea and colicky abdominal pain. Ultrasonography (US) shows impressive nonstratified wall thickening of the rectum and sigmoid with concomitant hyperechoic thickening of the mesentery and peritoneal fluid (a). No vascularity is visible in the sigmoid on color Doppler US, in contrast to the thick-walled appendix (open arrowhead) and ascending colon (b). The kidneys are enlarged with increased echogenicity of the cortex and narrowing of the medullary pyramids (c). The patient developed anuria, and during surgery for peritoneal dialysis, the surgeon found necrosis of the sigmoid, which was resected. F, peritoneal fluid; M, thickened mesentery ( Video 11.57).

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Fig. 11.58a–d Juvenile polyps of the colon. a Juvenile polyp in the descending colon of a 13-year-old girl. The wall of the descending colon is depicted between the open arrowheads. b In vitro ultrasound (US) shows the internal architecture of the polyp to best advantage. Note the small cystic structures within the polyp (arrows). c Juvenile polyp within the descending colon of a 3-year-old child with blood-stained stools. The wall of the colon is depicted between arrowheads. The stalk (arrows) is often well recognized during US, especially color Doppler US (between open arrows, d). The video shows the real-time examination and the radiating vascular pattern within the polyp. P, polyp ( Video 11.58).

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Fig. 11.59 Encrusted stool in the colon. The wall of the colon is depicted between the arrowheads. A 9-year-old boy with abdominal pain had two hypoechoic nodules with central linear hyperechoic reflections (arrow) is his distal descending colon and proximal sigmoid. No connection to the wall, no vascularization on color Doppler ultrasound. After laxation, the nodules (and complaints) disappeared. Apparently, the nodules represented encrusted pellets of stool in the colon. The video nicely depicts the absence of connection to the wall ( Video 11.59).

Fig. 11.60 A 3-month-old boy with pseudomembranous colitis (same patient as in ▶ Fig. 11.54) showing a normal appendage of the colon (open arrow). The narrow pedicle, predisposing to torsion, is clearly seen. The mobility of the appendage is better appreciated on the video. C, colon ( Video 11.60).

Fig. 11.61a,b Patient with anal atresia and meconium calcifications in wide, fluid (urine)–filled colon loops (a). Ultrasound shows multiple hyperechoic particles floating in the fluid-filled colon, representing meconium. Some of the particles are calcified (open arrows, b). Note the resemblance to the meconium periorchitis in ▶ Fig. 11.72e.

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Pediatric Intestinal Ultrasonography with perineal fistula, which is a pathologic developmental abnormality requiring surgical repair. Perianal abscesses: In adults, transperineal US is a simple, painless, cost-effective, and real-time method to detect and classify perianal fluid collections, abscesses, fistulas, and sinus tracts. These data may probably be extrapolated to the pediatric population (e.g., children with Crohn disease).

11.9 Neonatal Bowel Obstruction

Fig. 11.62 Example of rectal ultrasound (US) in a newborn with anal atresia. Transverse US image. The rectum is filled with multilayered inspissated meconium (diameter between open arrows). B, bladder.

Many cases of neonatal bowel obstruction are caused by diseases mentioned in previous sections (e.g., duplication cysts, malrotation or volvulus, meconium peritonitis, necrotizing enterocolitis, anal atresia, and pyloric hypertrophy). Additional causes of neonatal obstruction include various types of atresia, annular pancreas, meconium ileus, Hirschsprung disease, and meconium plug syndrome. These diseases are diagnosed by conventional abdominal radiography and/or conventional contrast studies, but US may be of additional value. Atresia is a congenital interruption of the lumen of the alimentary canal caused by a failure of canalization during organogenesis or by a prenatal vascular event. It results in dilatation proximal to the atresia and complete collapse distal to the atretic Video 11.65). The clinical and radiosegment (▶ Fig. 11.65; graphic presentation is typical, but US may be used to demonstrate accompanying pathology:

Fig. 11.63a,b Example of rectal ultrasound (US) in a 7-year-old girl with inflammatory bowel disease and severe proctitis. The widened rectal diameter (between open arrows, a) is caused by massive wall thickening, not by stools, as shown with color Doppler US (b). B, bladder.

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Fig. 11.64a–c A newborn with a bucket handle deformity of the anus. Coronal (a, b) and sagittal (c) ultrasound images show the rectum in a central position within the well-developed external sphincter complex (a). During straining (b, c), a stenotic segment can be appreciated (between calipers); low anal atresia with perineal fistula was confirmed during surgery ( Video 11.64).

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Exclusion of associated malrotation in cases of high obstruction. Evaluation of the colon and rectum in cases of high obstruction. A single atresia is associated with a normal-sized colon, whereas multiple atresias are associated with a microcolon. Evaluation of associated malformations of the heart, kidneys, and biliary tree. Demonstration of extrinsic duodenal compression in cases of high obstruction (e.g., duplication cysts, preduodenal portal vein, annular pancreas). Demonstration of signs of prenatal meconium peritonitis as a cause of small-bowel atresia (meconium cysts, subtle peritoneal or scrotal calcifications).

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Differentiation from meconium ileus by confirming the fluid content of the dilated bowel loops. In meconium ileus, the contents consist of thick, echogenic meconium. See also the discussion of meconium ileus.

Inspissated milk syndrome (milk curd syndrome) is a rare disease that occurs in premature infants and usually results from high-calorie or concentrated powdered milk formulas containing high levels of calcium and fat, or from expressed fortified breast milk. Milk curds may also occur in locations proximal to a congenital or acquired stenosis. The inspissated milk curds in the distal ileum and proximal colon obstruct the bowel. Compared

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Fig. 11.65a–d Jejunal atresia in a newborn with a distended abdomen and bilious vomiting. a Dilated small-bowel loops on a radiograph are suggestive of proximal obstruction. b Ultrasound (US) shows dilated, fluid-filled jejunal loops and microcolon (arrowhead). The video demonstrates hyperperistalsis. c A US image of the left lower quadrant shows both dilated proximal jejunal loops and completely collapsed distal jejunal and ileal loops, indicative of complete obstruction. No signs of malrotation or volvulus. d During surgery, jejunal atresia was confirmed. A small atretic segment is seen (arrowhead). (Image courtesy of Dr. B. Verhoeven, Radboud University Medical Center, Nijmegen, The Netherlands.) K, left kidney ( Video 11.65).

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Fig. 11.66a,b Inspissated milk syndrome in a premature infant. a The lateral abdominal radiograph shows an air crescent around the milk curd (white arrow). b The hyperechoic milk curds completely fill the lumen of the wide bowel loops on ultrasound. Note the small rim of fluid between the milk curd and bowel wall.

with other neonatal obstruction syndromes, inspissated milk syndrome has a somewhat delayed onset of symptoms. Because the milk curds do not adhere to the bowel wall, air or fluid can be seen between the curds and the bowel wall on US or radiography. The air between the curd and the bowel wall may even simulate pneumatosis intestinalis. US depicts the milk curds as hyperechoic spherical structures within the bowel loops, occasionally with a surrounding small rim of fluid (▶ Fig. 11.66). Recognition of this entity is important because a therapeutic hypertonic iodine contrast enema may been used in these infants. Meconium plug syndrome is best compared with neonatal obstipation. Most often, premature infants are affected and present with a distended abdomen and failure to pass meconium. There are no signs of peritonitis. The abdominal radiograph shows distal obstruction with moderate dilatation of the small-bowel loops, no wall thickening, and often no air–fluid levels. US demonstrates moderate dilatation of the entire colon without a transition zone, echogenic colonic contents, and proximal small-bowel dilatation. US can exclude meconium ileus and malrotation by visualizing the hyperechoic meconium in the colon (▶ Fig. 11.67) and confirming a normal position of

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Fig. 11.67a–c Premature infant with meconium plug syndrome. The filling defects on the hypertonic iodine contrast enema represent meconium (a). During the examination, the child produced large amounts of meconium (b). In vitro ultrasound demonstrates the hyperechoic nature of the meconium and entrapped air collections within the meconium (c).

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Pediatric Intestinal Ultrasonography

Fig. 11.68a–f Newborn with cystic fibrosis and meconium ileus. a The abdominal radiograph shows lower intestinal obstruction with no gas in the rectum. b Ultrasonography reveals the dilated, fluid-filled proximal jejunum (J) with peristalsis in the right upper quadrant. Note the ascending microcolon (white arrow). c More distally in the dilated jejunum, the contents become more echogenic, the peristalsis is lost, and the wall shows some thickening. d The proximal ileum is dilated and filled with thickened, heterogeneous meconium without any peristalsis. e The distal ileum is small and filled with meconium pellets (white arrowheads). f An enema with hyperosmolar iodinated contrast medium demonstrates microcolon and meconium pellets in distal ileum (white arrowheads). The procedure was complicated by a perforation, and subsequent surgery confirmed meconium ileus. Surgical removal of the meconium was difficult because of its tenacious nature ( Video 11.68). (Video courtesy of Dr. H. Scharbatke, Maastricht University Medical Center, Maastricht, The Netherlands.)

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Fig. 11.69a–c Another newborn with meconium ileus illustrating the sticky nature of the meconium in patients with cystic fibrosis. a Small bubbles of air are trapped in the meconium and between the meconium and the bowel wall (white arrowheads). b The tenacious meconium adheres to the wall, creating a circular or semicircular pseudo-thickening (open arrows). c The pseudo-thickening is not vascular on color Doppler ultrasound.

the mesenteric vessels, cecum, and D3 segment of the duodenum (▶ Fig. 11.14). Meconium ileus is a congenital intestinal obstruction caused by abnormally thick meconium. It occurs in approximately 10 to 20% of newborns with cystic fibrosis. A child with meconium ileus has cystic fibrosis until proven otherwise. The obstruction is usually located in the distal ileum. Because of the cystic fibrosis, the meconium is very sticky and adheres to the bowel wall. The relatively weak contractions of the small bowel are not capable of transporting the meconium distally. Therefore, the colon is unused and remains a microcolon. Prenatal complications caused by the antenatal obstruction are volvulus, atresia, and meconium peritonitis (antenatal perforation). Abdominal radiographs show nonspecific lower abdominal obstruction with, however, less dilatation and fewer air–fluid levels than in atresia (▶ Fig. 11.68a). US reveals a microcolon (mean diameter, 4 mm) and wide proximal small-bowel loops (▶ Fig. 11.68b). The most proximal jejunal loops are wide but usually show peristalsis and are filled with fluid. More distally, however, the jejunal loops are wide without peristalsis, and the contents become more hyperechoic and heterogeneous (▶ Fig. 11.68c, d). Finally, the distal ileum is filled with hyperechoic

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small pellets of impacted meconium (▶ Fig. 11.68e). The sticky meconium adheres to the wall, creating a pseudo-thickening, and in the proximal bowel small collections of air are trapped in the meconium (▶ Fig. 11.69 and ▶ Fig. 11.70). The sticky texture of the pathologic meconium is extremely well demonstrated during surgery in Video 11.68. (video courtesy of Dr. Scharbatke, Maastricht, The Netherlands.) An important difference from small bowel atresia is the echogenicity of the bowel content, which is hypoechoic in atresia and hyperechoic in meconium ileus. Moreover, in atresia the bowel content is less inspissated. Meconium peritonitis is caused by antenatal gastrointestinal perforation leading to a sterile peritonitis (▶ Fig. 11.71). This often results in peritoneal and sometimes scrotal calcifications (▶ Fig. 11.72a, b). Approximately 50% of patients with meconium peritonitis have cystic fibrosis, whereas virtually 100% of patients with meconium ileus have cystic fibrosis. Bowel perforation is secondary to intestinal obstruction (meconium ileus, atresia, or volvulus) or idiopathic. Sometimes, the digestive tract remains normally patent, and only peritoneal calcifications are silent witnesses of the antenatal perforation. There are several types of meconium peritonitis: the generalized type

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Pediatric Intestinal Ultrasonography

Fig. 11.70 Same patient as in ▶ Fig. 11.68 several days after the surgical removal of meconium pellets throughout the small bowel. Despite surgery, there is still meconium (asterisks) adhering to the wall, simulating wall thickening. M, muscularis propria; Mu, mucosa; S; submucosa.

(▶ Fig. 11.71), the cystic type (▶ Fig. 11.72b), and the fibroadhesive type (▶ Fig. 11.72d). Meconium pseudocyst is a manifestation of the cystic type of meconium peritonitis that results from in utero bowel perforation. The spilled meconium is encapsulated and forms a large meconium-filled (hyperechoic) cyst lined by a thick, inflammatory, fibrotic membrane that often contains calcifications (▶ Fig. 11.72a–c). The perforation may still communicate with the cyst postnatally. If the perforation occurs when the processus vaginalis is still patent, meconium enters the tunica vaginalis and causes meconium periorchitis (▶ Fig. 11.72e; Video 11.72).

Fig. 11.71 Patient with meconium ileus and meconium peritonitis. Dilated loops are covered by yellowish inflammatory tissue. (Courtesy of Dr. H. Scharbatke, Maastricht University Medical Center, Maastricht, The Netherlands.)

Hirschsprung disease is caused by an absence of ganglion cells, resulting in abnormal motility and lack of relaxation. The length of the aganglionic segment is variable, but the distal end of the intestinal tract is always affected. In a small number of patients, the entire colon, even the ileum and jejunum, are involved. US is of limited value because of the air artifacts in the dilated bowel loops. However, on very early neonatal US, air is not yet present, and a distended colon in a neonate with distal occlusion suggests Hirschsprung disease. Sometimes, a necrotizing enterocolitis causes stenosis of the colon that may mimic Hirschsprung disease, and initial US examination may suggest the proper diagnosis (▶ Fig. 11.73).

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Fig. 11.72a–e Different types of meconium peritonitis. a–c In the cystic type, the perforated (open arrowheads in a, b) meconium is encapsulated by a fibrous membrane (between closed arrowhead in b) containing calcifications (open arrowheads in, a, b). Note the microcolon (arrow, b) and the lumpy aspect of the encapsulated meconium (c). d In this patient with the fibroadhesive type, the bowel loops adhere in a central position, surrounded by fluid. e Patient with meconium periorchitis. A large amount of meconium (arrows) floats around the testicles. E, epididymis; T, testicle. Best seen on Video 11.72.

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Fig. 11.73a–c Stenosis in the descending colon mimicking Hirschsprung disease in a 6-week-old infant presenting with a distended abdomen and vomiting. No signs of peritonitis. a On an abdominal radiograph, a much-dilated ascending and transverse colon is seen, suggestive of long-segment Hirschsprung disease. b Ultrasonography demonstrates a sudden change in diameter in the proximal descending colon (open arrows versus white arrows). No signs of a transition zone. c A contrast enema reveals a stenosis, probably the complication of a “silent” necrotizing enterocolitis in the recent past, confirmed by surgery and pathology.

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11.10 Conclusion US is a reliable initial imaging technique to evaluate a variety of gastrointestinal pediatric diseases and malformations. A solid knowledge of the pathophysiology of bowel disease is necessary to understand the US manifestations of such disease. This chapter is intended to create an awareness of the diagnostic possibilities of pediatric intestinal US.

Recommended Readings Alexander JE, Williamson SL, Seibert JJ, Golladay ES, Jimenez JF. The ultrasonographic diagnosis of typhlitis (neutropenic colitis). Pediatr Radiol 1988; 18: 200–204 Anagnostara A, Koumanidou C, Vakaki M, Manoli E, Kakavakis K. Chronic gastric volvulus and hypertrophic pyloric stenosis in an infant. J Clin Ultrasound 2003; 31: 383–386 Aomatsu T, Yoden A, Matsumoto K et al. Fecal calprotectin is a useful marker for disease activity in pediatric patients with inflammatory bowel disease. Dig Dis Sci 2011; 56: 2372–2377 Baldisserotto M, Maffazzoni DR, Dora MD. Sonographic findings of Meckel’s diverticulitis in children. AJR Am J Roentgenol 2003; 180: 425–428 Baud C, Saguintaah M, Veyrac C et al. Sonographic diagnosis of colitis in children. Eur Radiol 2004; 14: 2105–2119 Baud C. Infectious and inflammatory colitis. In: Couture A, Baud C, Ferran J, Saguintaah M, Veyrac C, eds. Gastrointestinal Tract Sonography in Fetuses and Children. 1st ed. Berlin, Heidelberg, Germany: Springer; 2008:297–339 Baud C. Small bowel wall thickening. In: Couture A, Baud C, Ferran J, Saguintaah M, Veyrac C, eds. Gastrointestinal Tract Sonography in Fetuses and Children. 1st ed. Berlin, Heidelberg, Germany: Springer; 2008:253–296 Bijoś A, Czerwionka-Szaflarska M, Mazur A, Romañczuk W. The usefulness of ultrasound examination of the bowel as a method of assessment of functional chronic constipation in children. Pediatr Radiol 2007; 37: 1247–1252 Bohnhorst B. Usefulness of abdominal ultrasound in diagnosing necrotising enterocolitis. Arch Dis Child Fetal Neonatal Ed 2013; 98: F445–F450 Bonatti H, Lugger P, Hechenleitner P et al. [Transperineal sonography in anorectal disorders] Ultraschall Med 2004; 25: 111–115 Choi YH, Kim IO, Cheon JE, Kim WS, Yeon KM. Imperforate anus: determination of type using transperineal ultrasonography. Korean J Radiol 2009; 10: 355–360 Couture A, Baud C, Ferran J, Saguintaah M, Veyrac C, eds. Gastrointestinal Tract Sonography in Fetuses and Children. Berlin, Heidelberg, Germany: Springer; 2008 Couture A. Bowel obstruction in neonates and children. In: Couture A, Baud C, Ferran J, Saguintaah M, Veyrac C, eds. Gastrointestinal Tract Sonography in Fetuses and Children. 1st ed. Berlin, Heidelberg, Germany: Springer; 2008:131–251 Cribbs RK, Gow KW, Wulkan ML. Gastric volvulus in infants and children. Pediatrics 2008; 122: e752–e762 Dalby K, Nielsen RG, Kruse-Andersen S, Fenger C, Durup J, Husby S. Gastroesophageal reflux disease and eosinophilic esophagitis in infants and children. A study of esophageal pH, multiple intraluminal impedance and endoscopic ultrasound. Scand J Gastroenterol 2010; 45: 1029–1035 Daneman A, Lobo E, Alton DJ, Shuckett B. The value of sonography, CT and air enema for detection of complicated Meckel diverticulum in children with nonspecific clinical presentation. Pediatr Radiol 1998; 28: 928–932 Daneman A, Navarro O. Intussusception. Part 2: An update on the evolution of management. Pediatr Radiol 2004; 34: 97–108, quiz 187 Daneman A. Malrotation: the balance of evidence. Pediatr Radiol 2009; 39 Suppl 2: S164–S166 Darge K, Anupindi S, Keener H, Rompel O. Ultrasound of the bowel in children: how we do it. Pediatr Radiol 2010; 40: 528–536 delPozo G, Albillos JC, Tejedor D et al. Intussusception in children: current concepts in diagnosis and enema reduction. Radiographics 1999; 19: 299–319 delPozo G, González-Spinola J, Gómez-Ansón B et al. Intussusception: trapped peritoneal fluid detected with US—relationship to reducibility and ischemia. Radiology 1996; 201: 379–383 Dietrich CF. Significance of abdominal ultrasound in inflammatory bowel disease. Dig Dis 2009; 27: 482–493 Dördelmann M, Rau GA, Bartels D et al. Evaluation of portal venous gas detected by ultrasound examination for diagnosis of necrotising enterocolitis. Arch Dis Child Fetal Neonatal Ed 2009; 94: F183–F187 Faingold R, Daneman A, Tomlinson G et al. Necrotizing enterocolitis: assessment of bowel viability with color doppler US. Radiology 2005; 235: 587–594

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Farina R, Pennisi F, La Rosa M et al. Contrast-enhanced colour-Doppler sonography versus pH-metry in the diagnosis of gastro-oesophageal reflux in children. Radiol Med ( Torino ) 2008; 113: 591–598 Faure C, Belarbi N, Mougenot JF et al. Ultrasonographic assessment of inflammatory bowel disease in children: comparison with ileocolonoscopy. J Pediatr 1997; 130: 147–151 Flikweert ER, La Hei ER, De Rijke YB, Van de Ven K. Return of the milk curd syndrome. Pediatr Surg Int 2003; 19: 628–631 Fox VL, Nurko S, Teitelbaum JE, Badizadegan K, Furuta GT. High-resolution EUS in children with eosinophilic “allergic” esophagitis. Gastrointest Endosc 2003; 57: 30–36 Fraquelli M, Colli A, Casazza G et al. Role of US in detection of Crohn disease: metaanalysis. Radiology 2005; 236: 95–101 Fraser JD, Aguayo P, Leys CM, St Peter SD, Ostlie DJ. Infarction of an epiploic appendage in a pediatric patient. J Pediatr Surg 2009; 44: 1659–1661 Friedland JA, Herman TE, Siegel MJ. Escherichia coli O157:H7-associated hemolyticuremic syndrome: value of colonic color Doppler sonography. Pediatr Radiol 1995; 25 Suppl 1: S65–S67 Haber HP, Busch A, Ziebach R, Dette S, Ruck P, Stern M. Ultrasonographic findings correspond to clinical, endoscopic, and histologic findings in inflammatory bowel disease and other enterocolitides. J Ultrasound Med 2002; 21: 375–382 Haber HP, Seitz G, Warmann SW, Fuchs J. Transperineal sonography for determination of the type of imperforate anus. AJR Am J Roentgenol 2007; 189: 1525–1529 Haber HP, Warmann SW, Fuchs J. Transperineal sonography of the anal sphincter complex in neonates and infants: differentiation of anteriorly displaced anus from low-type imperforate anus with perineal fistula. Ultraschall Med 2008; 29: 383–387 Hernanz-Schulman M. Infantile hypertrophic pyloric stenosis. Radiology 2003; 227: 319–331 Hollerweger A, Macheiner P, Rettenbacher T, Gritzmann N. Primary epiploic appendagitis: sonographic findings with CT correlation. J Clin Ultrasound 2002; 30: 481–495 Joensson IM, Siggaard C, Rittig S, Hagstroem S, Djurhuus JC. Transabdominal ultrasound of rectum as a diagnostic tool in childhood constipation. J Urol 2008; 179: 1997–2002 Kamijo Y, Kondo I, Kokuto M, Kataoka Y, Soma K. Miniprobe ultrasonography for determining prognosis in corrosive esophagitis. Am J Gastroenterol 2004; 99: 851–854 Karnsakul W, Fallon KB, Swart S. Exudative hemorrhagic duodenitis as a primary event in a child with Henoch–Schönlein purpura. Clin Gastroenterol Hepatol 2008; 6: A24 Khan KM, Foker JE. Use of high-resolution endoscopic ultrasonography to examine the effect of tension on the esophagus during primary repair of long-gap esophageal atresia. Pediatr Radiol 2007; 37: 41–45 Khong PL, Cheung SC, Leong LL, Ooi CG. Ultrasonography of intra-abdominal cystic lesions in the newborn. Clin Radiol 2003; 58: 449–454 Kim WY, Kim WS, Kim IO, Kwon TH, Chang W, Lee EK. Sonographic evaluation of neonates with early-stage necrotizing enterocolitis. Pediatr Radiol 2005; 35: 1056–1061 Lampl B, Levin TL, Berdon WE, Cowles RA. Malrotation and midgut volvulus: a historical review and current controversies in diagnosis and management. Pediatr Radiol 2009; 39: 359–366 Maconi G, Ardizzone S, Greco S, Radice E, Bezzio C, Bianchi Porro G. Transperineal ultrasound in the detection of perianal and rectovaginal fistulae in Crohn’s disease. Am J Gastroenterol 2007; 102: 2214–2219 Mateen MA, Kaffes AJ, Sriram PV, Rao GV, Reddy DN. Modified technique of highresolution ultrasonography of the normal cervical esophagus. J Gastroenterol Hepatol 2006; 21: 1660–1663 Miller JP, Smith SD, Newman B, Sukarochana K. Neonatal abdominal calcification: is it always meconium peritonitis? J Pediatr Surg 1988; 23: 555–556 Navarro OM, Daneman A, Chae A. Intussusception: the use of delayed, repeated reduction attempts and the management of intussusceptions due to pathologic lead points in pediatric patients. AJR Am J Roentgenol 2004; 182: 1169–1176 Nchimi A, Khamis J, Paquot I, Bury F, Magotteaux P. Significance of bowel wall abnormalities at ultrasound in Henoch–Schönlein purpura. J Pediatr Gastroenterol Nutr 2008; 46: 48–53 Neal MR, Seibert JJ, Vanderzalm T, Wagner CW. Neonatal ultrasonography to distinguish between meconium ileus and ileal atresia. J Ultrasound Med 1997; 16: 263–266, quiz 267–268 Nylund K, Hausken T, Gilja OH. Ultrasound and inflammatory bowel disease. Ultrasound Q 2010; 26: 3–15 Orzech N, Navarro OM, Langer JC. Is ultrasonography a good screening test for intestinal malrotation? J Pediatr Surg 2006; 41: 1005–1009

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Pediatric Intestinal Ultrasonography Palabiyik FB, Bayramoglu S, Guner NT, Daglar S, Cimilli T. Use of sonography for evaluation of the cervical and thoracic esophagus in children. J Ultrasound Med 2012; 31: 1375–1379 Park NH, Park SI, Park CS et al. Ultrasonographic findings of small bowel intussusception, focusing on differentiation from ileocolic intussusception. Br J Radiol 2007; 80: 798–802 Pezzati M, Filippi L, Psaraki M et al. Diagnosis of gastro-oesophageal reflux in preterm infants: sonography vs. pH-monitoring. Neonatology 2007; 91: 162–166 Sadler TW, Rasmussen SA. Examining the evidence for vascular pathogenesis of selected birth defects. Am J Med Genet A 2010; 152A: 2426–2436 Segal SR, Sherman NH, Rosenberg HK et al. Ultrasonographic features of gastrointestinal duplications. J Ultrasound Med 1994; 13: 863–870 Stewart LK, McGee J, Wilson SR. Transperineal and transvaginal sonography of perianal inflammatory disease. AJR Am J Roentgenol 2001; 177: 627–632 Strouse PJ. Disorders of intestinal rotation and fixation (“malrotation”). Pediatr Radiol 2004; 34: 837–851 Suarez B, Kalifa G, Adamsbaum C, Saint-Martin C, Barbotin-Larrieu F. Sonographic diagnosis and follow-up of diffuse neutropenic colitis: case report of a child treated for osteogenic sarcoma. Pediatr Radiol 1995; 25: 373–374 Swischuk LE. Imaging of the Newborn, Infant, and Young Child. Baltimore, MD: Williams & Wilkins; 1997 Usui N, Kamata S, Kawahara H et al. Usefulness of endoscopic ultrasonography in the diagnosis of congenital esophageal stenosis. J Pediatr Surg 2002; 37: 1744–1746

Vazquez JL, Ortiz M, Doniz MC, Montero M, Del Campo VM. External manual reduction of paediatric idiopathic ileocolic intussusception with US assistance: a new, standardised, effective and safe manoeuvre. Pediatr Radiol 2012; 42: 1197–1204 Wagener S, Cartwright D, Bourke C. Milk curd obstruction in premature infants receiving fortified expressed breast milk. J Paediatr Child Health 2009; 45: 228– 230 Westra SJ, Derkx HH, Taminiau JA. Symptomatic gastroesophageal reflux: diagnosis with ultrasound. J Pediatr Gastroenterol Nutr 1994; 19: 58–64 Wiersma F, Allema JH, Holscher HC. Ileoileal intussusception in children: ultrasonographic differentiation from ileocolic intussusception. Pediatr Radiol 2006; 36: 1177–1181 Wootton-Gorges SL, Thomas KB, Harned RK, Wu SR, Stein-Wexler R, Strain JD. Giant cystic abdominal masses in children. Pediatr Radiol 2005; 35: 1277–1288 Wootton-Gorges SL, Thomas KB, Harned RK, Wu SR, Stein-Wexler R, Strain JD. Giant cystic abdominal masses in children. Pediatr Radiol 2005; 35: 1277–1288 Wu S. Sonographic findings of Ascaris lumbricoides in the gastrointestinal and biliary tracts. Ultrasound Q 2009; 25: 207–209 Yang WT, Ho SS, Metreweli C. Case report: antenatal sonographic diagnosis of meconium peritonitis and subsequent evolving meconium pseudocyst formation without peritoneal calcification. Clin Radiol 1997; 52: 477–479 Yousefzadeh DK. The position of the duodenojejunal junction: the wrong horse to bet on in diagnosing or excluding malrotation. Pediatr Radiol 2009; 39 Suppl 2: S172–S177

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Chapter 12

12.1

Examination Technique

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12.2

Normal Anatomy, Variants, and Pseudo-lesions

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12.3

Pathology

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Pancreas

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12 Pancreas Maria Raissaki and Marina Vakaki The pancreas is a challenging organ to visualize with ultrasonography (US), and it is less commonly scrutinized than other intra-abdominal organs. It is a long, multilobular gland with important endocrine functions that include the secretion of insulin, glucagon, and somatostatin, as well as important exocrine functions that include the excretion of the enzymes amylase and lipase through the pancreatic ducts to the duodenum. The endocrine functions of the pancreatic islet cells regulate blood glucose levels, whereas the exocrine functions of the pancreas promote the digestion of carbohydrates and fat in the alimentary tract. A thorough evaluation of the pancreas may reveal significant abnormalities, either isolated or in combination with lesions elsewhere. US is an excellent screening tool for the evaluation of the pediatric pancreas, although there are age groups and conditions in which other modalities may serve better. Highfrequency transducers (7–12 MHz in neonates, 5–7 MHz in older children) and state-of-the-art machines equipped with Doppler imaging provide excellent visualization of the pediatric pancreas that compares favorably with that of other cross-sectional imaging techniques. A complete US evaluation of the pancreas requires a meticulous technique with multiple views, in addition to knowledge of the important anatomical landmarks, normal changes in the appearance of the organ with age, and disorders that most frequently affect the pediatric pancreas. US changes looked for include alterations in size with focal or diffuse enlargement or atrophy, alterations in echogenicity, focal cystic or solid lesions inside or at the periphery of the organ, calcifications, adjacent lymphadenopathy, and alterations in the size of the pancreatic duct. The pancreas should be scrutinized routinely during abdominal US, particularly in children with acute or chronic abdominal pain, increased amylase levels, known inherited diseases that can potentially affect the pancreas morphologically or functionally, hypoglycemic attacks, vomiting, a palpable mass, weight loss, increased levels of tumor markers, failure to thrive, jaundice, or anorexia. The following paragraphs will describe conditions that affect the pediatric pancreas, with an emphasis on those that are appreciable with US.

views in the same direction, in an attempt to visualize the uncinate process of the pancreas, may be achieved by displacing the probe more caudally or by tilting the probe toward the patient’s feet (▶ Fig. 12.2). The distal body and tail of the pancreas may prove difficult to visualize anteriorly, and a rotated clockwise coronal view through the splenic hilum while the patient is turned toward the right (▶ Fig. 12.3), or through the left kidney while the patient is lying prone, may prove useful. Longitudinal views of the head and body through the hepatic left lobe complement the evaluation (▶ Fig. 12.4). Gaseous distention of the stomach, small bowel, or colon may compromise an evaluation of the pancreas. Gentle or graded compression and patience are usually what works during sonography of the pancreas, together with tilting the probe toward the patient’s feet and slight rotation counterclockwise. Drinking liquids may not be as effective in children as in adults because children tend to swallow air as well, unless the examiner allows enough time for the bubbles to settle (▶ Fig. 12.5). One trick is to turn the patient on the right side for a few minutes and then back to a supine position, so that liquids may occupy the antrum and gas may move toward the fundus and colonic flexures for a few seconds, enough time to compress with the probe (▶ Fig. 12.6). The pancreas is better visualized after fasting; therefore, lastly, you may repeat the test following a 4-hour fast in children and a 3-hour fast in neonates.

12.1 Examination Technique Examination of the pancreas with US usually occurs as part of an upper abdominal study, or of an upper and lower abdominal study. It is important to start the ultrasound examination with an evaluation of the pancreas before the child swallows air by talking or crying, and before air normally migrates toward the gastric antrum and transverse colon. The patient is scanned in a supine position. The hepatic left lobe is used as an appropriate window, combined with a subxiphoid transverse view. An oblique transverse view, following slight rotation counterclockwise parallel to the oblique orientation of the organ, evaluates as much of the body and tail as possible (▶ Fig. 12.1). More caudal

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Fig. 12.1 Normal pancreas in a 4-year-old boy. The test was performed without preparation. The position of the probe rotated slightly counterclockwise, shown at the right lower part of the image, allowed a demonstration of a large part of the tail (t). h, head; i, isthmus; b, body; S, empty stomach. The echogenic linear structure coursing at the center of the organ represents the middle part of the pancreatic duct (arrow). Arrowheads indicate the pancreas.

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Pancreas

Fig. 12.3 Same neonate as in ▶ Fig. 12.2. Longitudinal scan with and without color Doppler through the spleen (spl) visualizes the echogenic lateral aspect of the pancreatic tail (t) at the splenic hilum. Note the area of the splenic vein and artery (open arrows) and the neonatal left adrenal gland (arrowhead).

Tips from the Pro ●

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The pancreas should be the first organ evaluated during an upper abdominal study and the second organ (after the urinary bladder) during an upper and lower abdominal US examination. Scanning the child in the prone, lateral decubitus, or erect position may improve visualization through the liver or left kidney and may move the transverse colon out of the way. Asking a cooperative child to exhale or push the tummy out for seconds may also help.

12.2 Normal Anatomy, Variants, and Pseudo-lesions Fig. 12.2a,b a Echogenic normal neonatal pancreas (between arrowheads) seen during a subxiphoid transverse scan with minimal counterclockwise rotation. The liver (L) serves as an acoustic window. The area of the common bile duct in its intrapancreatic portion is minimally suggested (open arrow). Important landmarks include the confluence of the splenic vein and the portal vein (PV), the aorta (AO), and the inferior vena cava (IVC). Note that the gastric contents (S) may exhibit echogenicity similar to that of the neonatal pancreas. b Transverse scan with the same minimal counterclockwise rotation as in a, at a slightly more caudal level. The pancreatic head (h), lateral to the superior mesenteric vein (V), contains the distal common bile duct (small open arrow). Its posterior and medial part is the uncinate process (arrowhead). Important landmarks include the aorta (open arrowhead), inferior vena (white arrow), and superior mesenteric artery (A), etc. (A). S, gastric antrum; L, liver.

The pancreas is a long, unencapsulated, retroperitoneal organ that has an oblique orientation. It extends from the duodenal loop medially to the splenic hilum laterally and is located in the anterior pararenal space at the upper part of the abdomen, anterior to the splenic vein and portal venous confluence (▶ Fig. 12.1, ▶ Fig. 12.2, ▶ Fig. 12.5, ▶ Fig. 12.7). The pancreas is comma-shaped on transverse scans with a uniform echotexture and a smooth outline.

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Fig. 12.4a,b a Right parasagittal scan through the hepatic left lobe (L) in a 7-year-old girl. Part of the pancreatic head (h) is seen posterior to the stomach (S), inferior to the portal vein (PV), and anterior to the inferior vena cava (IVC). Note the hepatic artery (white arrowhead) and the right renal artery (open arrow), seen as dots because they run horizontally by the hepatic hilum and posteriorly to the IVC, respectively. b Left parasagittal scan through the liver left lobe (L) of the same patient. Part of the pancreatic body (b) is seen posterior to the liver and stomach (S), anterior to the obliquely coursing superior mesenteric vein (arrowhead), and anterior to the superior mesenteric artery (sma) coming off the aorta (AO). c, celiac trunk; arrow, left renal vein. The superior mesenteric vein is usually slitlike or ovoid at this section.

Fig. 12.5 Transverse abdominal scan in a 7-year-old child. Liquids in the stomach (S) enable identification of all relevant to pancreatic ultrasound landmarks in order of importance: 1, aorta; 2, inferior vena cava; 3, superior mesenteric artery; 4, splenic vein; 4b, portal venous confluence; 5, gastric wall (arrowheads); D, duodenum; V, vertebra.

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The pancreas consists of the head (which ends caudally and medially as the uncinate process), the isthmus (or neck), and the body and tail, with no clear distinction between them. The pancreatic head envelops the teardrop-shaped portal vein just at the junction of the splenic vein and superior mesenteric vein and extends caudally to wrap under the superior mesenteric vein as the uncinate process, which resembles a hook on transverse scans (▶ Fig. 12.2 and ▶ Fig. 12.7). This area is particularly important to examine because it includes the distal common bile duct and pancreatic duct and may reveal important pathology (▶ Fig. 12.8). A vascular landmark at this point is the gastroduodenal artery, which arises from the common hepatic artery and courses downward by the anterior surface of the pancreatic head or isthmus, parallel to the common bile duct (▶ Fig. 12.7 and ▶ Fig. 12.8). The neck or isthmus of the pancreas is the thinner part between the head and the body, anterior to the portal venous confluence (▶ Fig. 12.9). The pancreatic body lies posterior to the stomach or liver and anterior to the superior mesenteric artery. The superior mesenteric artery is anterior to the aorta and appears as the hole in a doughnut on transverse section because it is surrounded by a collar of echogenic fat (▶ Fig. 12.7 and ▶ Fig. 12.9). The bifurcation of the celiac artery into the hepatic and splenic arteries resembles a seagull in flight and is an important vascular landmark for the upper part of the pancreatic body (▶ Fig. 12.10). The tail of the pancreas is located anterior to the splenic vein and extends to the splenic hilum (▶ Fig. 12.1 and ▶ Fig. 12.3). Nonvascular landmarks are the pancreatic duct and common bile duct. The common bile duct courses downward parallel to the gastroduodenal artery and posterior to the pancreatic head, and it may not be visible in children unless dilated (▶ Fig. 12.8 and ▶ Fig. 12.11). The pancreatic duct courses centrally within the pancreatic parenchyma from the tail to the head, and parts of it can be identified by US as an echogenic line (▶ Fig. 12.1) or

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Fig. 12.7 Transverse section of the pancreas (white arrowheads) in a 6year-old child showing the relationship of the pancreas to the surrounding structures and vascular landmarks. The pancreatic head (h) is near the duodenal loop (D) and wraps around the portal venous confluence (*). Note the hooklike uncinate process (open arrow). The superior mesenteric artery and surrounding echogenic fat form a doughnut posterior to the splenic vein (sv). 1, aorta; 2, inferior vena cava; 3, left renal vein; 4, left renal artery. The gastroduodenal artery, which runs anterior to the pancreatic head in a course similar to that of the common bile duct, is seen as an anechoic dot with a thin echogenic wall (open arrowhead). L, liver; LtK, left kidney; RtK, right kidney; S, stomach.

Fig. 12.6a,b Ultrasound of an obese 11-year-old boy. a It is difficult to demonstrate the pancreas because of gas, which casts acoustic shadows and reverberations (g). b Following rotation of the patient to the right decubitus position and back in the supine position 4 minutes later, partial visualization of the pancreas (arrowheads) behind the stomach is feasible. The arrow points to the posterior wall of the antrum. The gas has moved back to the gastric fundus (g).

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Fig. 12.8a,b One-month-old boy with jaundice and a history of prematurity. Ultrasound revealed areas of echogenicity in the gallbladder (not shown) following the administration of diuretics. a Three transverse sections though the pancreatic head, which was seen between the stomach (S) and the splenoportal junction (p) or at a slightly lower level between the stomach and superior mesenteric vein (v). The common bile duct is dilated (open arrowhead), and echogenicity representing choledocholithiasis (between cursors) is depicted in the two right panels. Note the gastroduodenal artery anteromedial to the pancreatic head (white arrowhead). Compare with the normal neonatal uncinate process in ▶ Fig. 12.12. b Left: Longitudinal oblique section through the head of the pancreas (white arrowheads) shows dilatation of the common bile duct (open arrowhead) up to the choledochal stone (cursor). Right: Three days following medical treatment, the jaundice resolved and the common bile duct (open arrowhead) was normal. p, portal vein.

Fig. 12.9 Oblique longitudinal view with counterclockwise rotation pointing toward the patient’s right shoulder. The isthmus is visualized behind the pylorus and anterior to the splenoportal confluence. 1, splenic vein; 2, splenoportal confluence; 3, portal vein. Other visible landmarks include the gastric wall (between arrowheads), aorta (A), inferior vena cava (IVC), duodenal bulb (d), and superior mesenteric artery (4) with surrounding echogenic fat resembling a hole in a doughnut (open arrowheads).

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Fig. 12.10 Transverse view of the cephalic pancreas visualizing the celiac trunk (C) and bifurcation. The common hepatic artery (white arrowheads) and the splenic artery (open arrowheads) resemble the open wings of a seagull. The pancreatic body (B) and tail (T) are visualized in association with this landmark if the probe is tilted downward. A, aorta.

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Fig. 12.12 Part of the main pancreatic duct of Wirsung is seen as an echo-free lumen with echogenic walls (between ‘x’s). Note the similarity to the alternating hyperechoic serosa, hypoechoic muscular layer, and hyperechoic submucosa of the gastric wall (arrowheads).

Fig. 12.11a,b Visibility of the common bile duct during pediatric ultrasonography (US). a Transverse scan through the pancreatic head. b Corresponding magnetic resonance image, T2-weighted sequence. The normal terminal part of the common bile duct (arrow, a) is not visible or barely visible on US while it is a hyperintense dot (arrow, b) within the pancreatic head (h). Note how the various landmarks look with both methods. Ao, aorta; IVC, inferior vena cava; h, pancreatic head; u, uncinate process; PV, portal venous confluence; D, duodenal loop; g, gallbladder. The open arrows point toward the superior mesenteric artery. Note the visible diaphragmatic crus (arrowheads), occasionally seen at this level.

as an echo-free lumen with echogenic walls (▶ Fig. 12.12). A ductal diameter of 1.5 mm or more should be considered abnormal in children up to 6 years age until proved otherwise. The hypoechoic muscular wall of the stomach should not be mistaken for the pancreatic duct, especially when the body is imaged obliquely and the gastric contents are isoechoic to the pancreas and may be erroneously mistaken for the pancreatic body (▶ Fig. 12.13). The size of the pancreas varies depending on age. Measurements are shown in ▶ Fig. 12.14 and normal values in ▶ Table 12.1. As a rule of thumb, when the thickness of the body is more than 1.5 cm, the pancreas is enlarged. The pancreatic head appears relatively voluminous compared with the body in children, which is normal. Care should be taken not to include the duodenal loop in the measurements or in the appreciation of the pancreatic head (▶ Fig. 12.15). The echogenicity of the pancreas varies; in general, it is equal to or slightly greater (but not much) than that of the normal liver, and its echotexture is smooth or minimally coarse (▶ Fig. 12.16). In about 10% of infants and children, it may be less echogenic than the liver. Care should be taken to evaluate the liver echogenicity as well, and not to mistake an isoechoic pancreas for a hypoechoic one in cases of hepatic steatosis (▶ Fig. 12.17) or for a hyperechoic one in cases of a hypoechoic

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Fig. 12.13a-d Examples of the gastric wall looking like a lucent tube with echogenic walls (open arrowheads). This structure simulates the pancreatic duct; however, it is located more anteriorly than the expected pancreatic duct and is adjacent to the gastric contents (g). Compare also with ▶ Fig. 12.12. a Neonate. b Eight-year-old. c Four-month-old. d Sixteen-year-old.

Table 12.1 Normal values of the pancreas in children

Fig. 12.14 Anteroposterior diameter of the head (1) and body (2) and oblique anteroposterior diameter of the tail (3) in a 10-year-old child.

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Duct of Wirsung

Age

Head

Body

Tail

Newborn infants

1.0 (0.4)

0.6 (0.2)

1.0 (0.4)

1 month–1 year

1.5 (0.5)

0.8 (0.3)

1.2 (0.4)

1–3 years

1.7 (0.3)

1.0 (0.2)

1.8 (0.4)

1.13 (0.15)

3–5 years

1.7 (0.3)

1.0 (0.2)

1.8 (0.4)

1.35 (0.15)

5–10 years

1.6 (0.4)

1.0 (0.3)

1.8 (0.4)

1.67 (0.17)

10–12 years

2.0 (0.5)

1.1 (0.3)

2.0 (0.4)

1.78 (0.17)

13–15 years

2.0 (0.5)

1.1 (0.3)

2.0 (0.4)

1.92 (0.18)

16–19 years

2.0 (0.5)

1.1 (0.3)

2.0 (0.4)

2.05 (0.15)

Abbreviation: SD, standard deviation. Source: Reprinted with permission of the Radiological Society of North America from Siegel MJ, Martin KW, Worthington JL. Normal and abnormal pancreas in children: US studies. Radiology 1987;165(1):15–18. Note: In total, 273 patients (sex distribution not reported) were included in this retrospective ultrasound study. The maximum anteroposterior diameters of the head, body, and tail of the pancreas (▶ Fig. 12.14) were measured on transverse and oblique images.

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Fig. 12.15a,b Scans of the pancreatic head a few seconds apart in a 6-month-old infant examined for gastroesophageal reflux. a There is an impression of a voluminous pancreatic head (h). b The duodenal loop (d) filled with fluid, and the true borders of the pancreatic head (arrowheads) and uncinate process (u) are appreciated.

Fig. 12.16a–d Four examples of different degrees of echogenicity of the pancreas (p) in relation to the liver (L). The echotexture is smooth (a, d) or minimally coarse (b, c and ▶ Fig. 12.14). a Echogenic pancreas in a premature baby with a gestational age of 25 weeks. b Mildly echogenic in a 7-yearold. c Almost isoechoic in a 6-year-old. d Isoechoic in an 11-year-old.

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Fig. 12.17a,b False impression of a hypoechoic pancreas in a 4-year-old. a The pancreas (p) is hypoechoic relative to the liver (L). b Upon inspection of the liver (L), the echogenicity is typical of hepatic steatosis with focal fatty sparing (open arrow) by the gallbladder (g).

Fig. 12.18a,b Hypoechoic appearance of the head and uncinate process in a 16-year-old girl. a Transverse scan shows a hypoechoic posterior pancreatic head and uncinate process (open arrowheads). b Longitudinal scan shows the hypoechoic derivatives of the ventral anlage (v) and the hyperechoic derivatives of the dorsal anlage in the remaining head (d). Note the lack of mass effect and lack of common bile duct (arrow) dilatation. Ao, aorta; IVC, inferior vena cava. See also embryology in ▶ Fig. 12.21.

liver due to hepatitis, in which the liver is also characterized by a starry sky appearance of the hepatic parenchyma. An important feature is the different echogenicity of the posterior pancreatic head and uncinate process. This area originates embryologically from the ventral anlage and exhibits a hypoechoic appearance because of its relatively low fat content. It has a geographic border like an area of focal fatty sparing and no mass effect (▶ Fig. 12.18). A cause of pseudo-lesions is the acoustic shadowing produced by the gastric contents (▶ Fig. 12.19) or by the fibrofatty ligamentum teres (▶ Fig. 12.20). Scanning with slight obliquity should help to distinguish a true focal lesion from a pseudo-lesion.

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Tips from the Pro ●

Knowledge of the vascular and nonvascular landmarks and multiple views with and without obliquity ensure visualization of all the pancreatic parts and avoid the misinterpretation of pseudo-lesions as true lesions. Routine measurements of the pancreas and pancreatic duct, and appreciation of its echogenicity compared with that of the liver, may increase the sensitivity of US in the detection of focal and diffuse pancreatic abnormalities.

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Fig. 12.19a,b Pseudo-lesion due to gastric contents in a 2-year-old. a Shadowing (open arrowhead) over the pancreatic head gives the impression of a focal lesion (open arrow). b Oblique scanning of the same region confirms a normal pancreatic head (open arrowheads).

Fig. 12.20a,b Pseudo-lesion in a 6-year-old. a Shadowing over the pancreatic head behind the ligamentum teres (open arrowhead) gives the impression of a hypoechoic lesion (open arrow). b Oblique scanning of the same region confirms a normal pancreatic head (open arrowheads).

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Pancreas

Bile duct Hepatic duct

Bile duct

Cystic duct

a

Dorsal pancreas

Ventral pancreas

Accessory pancreatic duct

b

Ventral pancreatic duct

Major papilla

Hepatic duct Gallbladder Main pancreatic duct

Uncinate process Ventral pancreatic duct

Bile duct

Stomach

Ventral pancreas

Bile duct c

Dorsal pancreatic duct

Minor papilla

d

Dorsal pancreas Main pancreatic duct

Accessory pancreatic duct

Fig. 12.21a–d Schematic representation of normal development and the more common congenital abnormalities of the pancreas. a The ventral and the dorsal pancreas have formed off the primitive gut from the ventral and dorsal buds, respectively. The ventral segment rotates around and posterior to the duodenum, together with the distal biliary tree. b The ventral and dorsal pancreas fuse. At this point, the pancreatic ducts do not communicate. In case development stops, this configuration corresponds to pancreas divisum. c Finally, a wide communication between the two ducts occurs. The duct of the ventral pancreas becomes the duct of Wirsung and drains into the major papilla together with the common bile duct. The duct of the dorsal pancreas at its distal part becomes the main pancreatic duct or part of the duct of Wirsung. At its proximal part it involutes, becoming smaller or atretic, and is then called the accessory pancreatic duct of Santorini, which drains into the minor papilla when intact. This is the normal completed evolution of the pancreas. d Incomplete rotation of the ventral anlage results in a tongue of pancreatic tissue surrounding the duodenum. The pancreatic duct may be seen encircling the duodenum.

12.3 Pathology 12.3.1 Developmental Anomalies A knowledge of basic embryology is helpful in understanding the morphology and clinical importance of the most common developmental pancreatic abnormalities (▶ Fig. 12.21). The ventral anlage forms the uncinate process and part of the pancreatic head, while the dorsal anlage forms the remaining, larger part of the organ. Pancreas divisum is the most common congenital anomaly of the pancreatic ductal system and is encountered in 4 to 10% of the population. Pancreas divisum results from failure of fusion between the ventral and dorsal pancreatic ducts (▶ Fig. 12.21 c). The ventral duct (duct of Wirsung) drains only the ventral pancreatic anlage, whereas most of the gland empties into the minor papilla through the dorsal duct (duct of Santorini). Pancreas divisum may be asymptomatic or present with chronic abdominal pain and recurrent pancreatitis in children ages 5 to 15 years because of functional stenosis at the minor papilla. US usually fails to diagnose this condition. Endoscopic retrograde pancreatography or magnetic resonance (MR) pancreatography demonstrates noncommunicating dorsal and ventral ducts, independent drainage sites, and a dominant dorsal pancreatic duct. The ventral duct is typically short and narrow.

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Annular pancreas is a rare congenital anomaly (1 in 2,000 persons) in which incomplete rotation of the ventral anlage causes a segment of the pancreas to encircle the second part of the duodenum (▶ Fig. 12.21 d). It occurs either in isolation or together with other congenital abnormalities, including tracheoesophageal fistula, duodenal stenosis or atresia in infants, Down syndrome, and congenital heart defects. Annular pancreas presents with proximal obstruction causing a “doublebubble” sign on radiographs in neonates, and with bile duct obstruction, associated pancreatitis, and “peptic ulcer”-like disease in older children. Annular pancreas can be diagnosed by US as pancreatic tissue encircling the duodenum, with proximal duodenal dilatation (▶ Fig. 12.22). Computed tomography (CT) and MR imaging may confirm these findings. Magnetic resonance cholangiopancreatography (MRCP) may demonstrate an annular duct encircling the descending duodenum. Ectopic pancreas occurs in 0.6 to 13.7% of the population and may be found in the stomach, duodenum, jejunum, a Meckel diverticulum, or ileum, and rarely in other abdominal sites (▶ Fig. 12.23). The ectopic tissue measures around 0.5 to 2.0 cm in diameter and is usually located in the submucosa. Ectopic pancreas is asymptomatic, although complications due to mass effect (stenosis, intussusception), ulceration, bleeding, pancreatitis, cystic degeneration, or malignancy may develop.

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Fig. 12.22a–d Annular pancreas. a There is lateral extension of the pancreatic head (p) with a triangular tongue of tissue (arrowheads) anterior to a dilated proximal duodenum (arrow) and a collapsed descending duodenum, which is a hypoechoic structure with the gut signature (*). The anterior arrow indicates the gastric wall. b The descending duodenum is seen with a collapsed lumen (arrowheads) coursing at the center of the pancreatic head. The arrow indicates the anterior surface of the pancreatic head. The open arrowheads indicate lateral surface of the pancreatic head encircling the duodenum. c Magnetic resonance imaging, axial true FISP (fast imaging with steady-state precession) sequence, shows the stomach and duodenum fluid-filled (arrows). Pancreatic tissue (*) almost completely encircles the duodenum (arrowhead). d Axial T2-weighted sequence lower confirms that the duodenum (arrow) enters the center of the pancreatic head and contains fluid and kissing folds (arrowhead). (Case courtesy of Dr. LilSofie Ording Müller, Norway.)

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Fig. 12.23a,b Ectopic pancreas. a Gastric pancreas. There is a mural lesion with the characteristic smooth echotexture of normal pancreas (p). Note the intact overlying mucosa, seen as a thin, hyperechoic layer (arrowheads). L, fluid within the gastric lumen; C, pyloric channel with hypoechoic muscular layer (open arrowheads). b Ectopic pancreas in a Meckel diverticulum, seen as a nodule with a characteristic echotexture (between cursors) at the periphery of the diverticulum (arrows). The echogenic luminal contents (*) are due to a previous barium study. (Case courtesy of Dr. Paolo Toma, Italy.)

Other congenital abnormalities include pancreatic agenesis, which is extremely rare and incompatible with life, and partial agenesis or hypoplasia or congenitally short pancreas, which can occur in isolation or be associated with heterotaxy/polysplenia syndromes. The pancreas in hypoplasia consists of a short, enlarged, or globular pancreatic head and agenesis of the pancreatic body and tail due to the absence of dorsal anlage development (▶ Fig. 12.24). Patients who have agenesis of the dorsal pancreas often present with nonspecific abdominal pain, which may or may not be caused by pancreatitis, and they are at increased risk for diabetes mellitus. Situs inversus is inversion of the intra-abdominal contents and anatomical landmarks, with an intact pancreas (▶ Fig. 12.25).

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adults, with trauma, infection, and medications (steroids, valproic acid, l-asparaginase, furosemide, acetaminophen) the more common causes (▶ Table 12.2). Gallstone-related pancreatitis is rare in children. In 25 to 50% of pediatric cases of pancreatitis, no underlying cause is found. Children with mild pancreatitis present with abdominal pain, tenderness, nausea, vomiting, and fever. In these cases, conservative therapy (supportive treatment with proper volume replacement, correction of the metabolic disturbances, and

Table 12.2 Causes of pancreatitis in children Trauma

12.3.2 Pancreatitis

Traffic accidents, blunt trauma, seat belt injuries, bicycle handlebar injuries

Acute Pancreatitis

Child abuse

Gallstones

Acute pancreatitis should always be considered in children with abdominal pain. Abdominal US findings may be abnormal in up to 80% of children with acute pancreatitis, and the radiologist may be the first to suggest this diagnosis (▶ Fig. 12.26). On the other hand, there is a strong possibility of a normal US scan in a child with elevated amylase levels and clinically diagnosed acute pancreatitis, especially in mild cases (▶ Fig. 12.27). Acute pancreatitis is an inflammatory process that usually affects the pancreas diffusely, with variable involvement of adjacent tissues. Pancreatitis can be mild (associated with interstitial edema and acinar cell necrosis), moderate, or severe/ necrotic (associated with ductal disruption, hemorrhage, and necrosis of pancreatic tissue and extrapancreatic fat). In children, the etiology of acute pancreatitis differs from that in

Iatrogenic/stem cell transplant

Hyperparathyroidism

Infection

Hyperlipidemia

Mumps, coxsackievirus B infection

Diabetic acidosis

Ascariasis

Systemic diseases or conditions

Metabolic disorders Malnutrition

Cytomegalovirus infection, AIDS

Sepsis, shock

Medications

Vasculitis, Crohn disease

Developmental/congenital anomalies

Henoch–Schönlein purpura

Pancreas divisum

Hemolytic–uremic syndrome

Common channel syndrome

Reye syndrome

Choledochal cyst

Idiopathic pancreatitis

Duplication cyst Cystic fibrosis

Familial hereditary pancreatitis

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Fig. 12.24a–f Heterotaxy syndrome with congenitally short pancreas, polysplenia, malrotation, preduodenal portal vein, biliary atresia, and azygos continuation. a Transverse scan shows a globular hourglassshaped pancreas (outlined by arrowheads) between the superior mesenteric artery (a), stomach (S), and portal vein (p). b At a more caudal level, the remaining lower head and uncinate process (arrowheads) are seen around the splenoportal confluence (psv). c At a more caudal level, the superior mesenteric vein (v) is located anterior and to the left of the superior mesenteric artery (open arrow), consistent with malrotation. The portal vein (p) is seen anterior to the duodenum (d; s, stomach). There is no pancreatic body or tail visible. d Longitudinal scan shows the portal vein (p) in gray-scale and color Doppler imaging lying anterior to the duodenum (open arrow), consistent with a preduodenal portal vein. e Multiple splenules (s) are identified on the left. f Computed tomographic evaluation. A nearly symmetric lobulated liver extending to the left hypochondrium (L) is associated with a midline gallbladder (g) and a portal vein (open arrows) anterior to the duodenum (white arrowheads). Note the polysplenia (*), hypoplastic or congenitally short pancreas (p), and absence of the dorsal pancreas. The left renal vein (v) drains into the azygos continuation (open arrowheads), which is best demonstrated on coronal reconstructions (bottom left). S, stomach. (Case courtesy of Dr. I. Gassner, Austria.)

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Fig. 12.25a–c Situs inversus. Transverse section of the pancreas (a, b) and coronal T2-weighted magnetic resonance (MR) imaging (c) in an 18-month-old boy investigated for neuroblastoma. The presence of situs inversus is easily diagnosed by the position of the large, solid abdominal organs and also by the inverted position of major vascular landmarks such as 1, aorta; 2, inferior vena cava; 3, superior mesenteric artery; and 4, portal venous confluence. MR imaging confirms the left-sided position of the pancreatic head (h), a rightsided tail (t), and inversion of the liver (L) and spleen (S).

specific nutritional therapy) results in improvement in the clinical and laboratory findings within 48 to 72 hours. Children with severe pancreatitis may have major organ failure, including renal and pulmonary insufficiency, gastrointestinal bleeding, and finally shock and convulsions. At presentation, the amylase and lipase levels are usually but not invariably elevated in the blood, urine, or both. Long-term complications are unusual, and mortality rates are lower than the rates for adults. The prognosis is variable owing to the heterogeneity of the clinical course of this illness in children. US is valuable for both diagnosis and follow-up. The most common finding is diffuse or focal glandular enlargement and altered echogenicity, with poorly defined borders (▶ Fig. 12.26, ▶ Fig. 12.28, ▶ Fig. 12.29, 12.30). Echogenicity may be normal, or it may be focally or diffusely decreased or increased. Pancreatic duct dilatation is common in acute pancreatitis (▶ Fig. 12.28 b), with a diameter larger than 1.5 mm in children 1 to 6 years of age, larger than 1.9 mm in children 7 to 12 years old, and larger than 2.2 mm in children 13 to 18 years old. Bile duct dilatation may occur during compression by a swollen pancreatic head. An abnormal junction between the pancreatic duct and common bile duct outside the duodenum (common channel), a choledochal or duplication cyst, or stones may rarely be encountered as the cause of acute pancreatitis. Inflammatory changes in the peripancreatic fat and soft tissues may be seen as hypoechoic/anechoic infiltration of fat or

Fig. 12.26a,b Acute pancreatitis in a 5-year-old girl with epigastric pain. The ultrasound diagnosis of acute pancreatitis was possible before the laboratory confirmation of amylasemia. a The pancreatic head (h) is inhomogeneous and enlarged. The duodenal wall is thickened (open arrows). Peripancreatic fluid (f) extends to the anterior pararenal space (arrowheads). Rt K, right kidney. b Close inspection with a 10-MHz linear probe confirms the extraluminal location of fluid (f) containing thin septa.

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Fig. 12.27a–d Six-year-old boy with spherocytosis presenting with abdominal pain due to pancreatitis. a Multiple calculi (open arrow) are seen within the gallbladder (g). b The spleen (between cursors) is enlarged, and the pancreatic tail (t) is unremarkable. c The pancreas has a normal size and an echotexture isoechoic to that of liver. d Close inspection of the pancreatic head (h) reveals no appreciable peripancreatic fluid.

Fig. 12.28a,b Acute pancreatitis as the first manifestation of cystic fibrosis in a 13-year-old girl. a Transverse scan shows a globally enlarged pancreas with hypoechoic areas (*), ill-defined contours (arrowhead), and a dilated pancreatic duct (arrow). b Scanning with a linear probe demonstrates a featureless pancreas with pancreatic duct dilatation (arrow). Note the lobulated anterior pancreatic contour (arrowheads).

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Fig. 12.29a,b Acute pancreatitis in a 9-year-old girl with abdominal pain, vomiting, and increased amylase and lipase levels. a The pancreas (p) is uniformly enlarged smooth and hyperechoic relative to the liver (L). b Close inspection of the pancreas and peripancreatic area (p) with a linear 15-MHz probe shows ill-defined and heterogeneous peripancreatic fat (arrowheads) and a fluid collection (f) at the lesser sac.

Fig. 12.30a–f Acute pancreatitis following a handlebar bicycle injury. The pancreas is globally enlarged (a, b). There is an area of increased echogenicity (open arrows, a, d) at the body and tail that surrounds a hypoechoic cleft (open arrowheads, a, b, d), representing edema and/or hemorrhage and laceration, respectively. Note the fluid at the splenorenal ligament (eff, c) and among bowel loops at the left hypochondrium (eff, f), and the peritoneal fluid around the spleen and liver (arrowheads, c, e).

anechoic effusions in adjacent spaces (▶ Fig. 12.26, ▶ Fig. 12.29, ▶ Fig. 12.30) and rarely within the pancreas. The most common sites of peripancreatic fluid include the pararenal spaces, lesser sac, lesser omentum, and transverse mesocolon. Associated bowel-wall thickening (▶ Fig. 12.30) and pleural and peritoneal fluid may be seen (▶ Fig. 12.29 and ▶ Fig. 12.30). In posttraumatic pancreatitis, the previously mentioned findings of acute pancreatitis may occur together with hypoechoic parenchymal lines, bands, or triangles, usually located at the body–

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tail junction, indicative of lacerations or transections (▶ Fig. 12.30 and ▶ Fig. 12.31). These contour lesions are difficult to appreciate acutely and are best seen on follow-up, especially when pseudocysts develop. Complications of acute pancreatitis include pseudocysts, which are more common in posttraumatic pancreatitis (▶ Fig. 12.32; see also the section on cystic masses); abscesses; hemorrhage; and rarely vascular abnormalities such as venous thrombosis and pseudoaneurysms.

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Fig. 12.31a–d Magnetic resonance imaging of the same patient 9 days later. Pancreatic laceration (black open arrowheads) and edema of the pancreatic body and tail (white open arrows) are confirmed. The black closed arrowheads point to fluid collections located at the gastrosplenic ligament (a), splenorenal ligament (b), and lesser sac/mesentery (c, d).

Fig. 12.32 Evaluation and follow-up of posttraumatic pancreatitis in an 11-year-old girl following a traffic accident. Upper row: Three ultrasound (US) images at day 7 of hospitalization. There is a small hypoechoic lesion at the anterior surface of the pancreatic body (arrowhead), consistent with contusion, and a large pseudocyst (*) at the lesser sac extending along the left flank, well below the spleen. Lower row: Three US images 2 weeks later show stability of the first lesion (arrowhead), which became an intrapancreatic pseudocyst. The known pseudocyst (between cursors) is significantly smaller and limited within the lesser sac. Note that all pseudocysts are anechoic or contain fine echoes and are sharply demarcated.

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Fig. 12.33 Same patient as in ▶ Fig. 12.32. High-resolution scanning of the pancreatic body with axial, longitudinal, and oblique views on the third week of hospitalization (upper row) and respective views 1 month later (lower row). The intrapancreatic pseudocyst (arrows, top row) has almost completely resolved and is seen as a semilunar fluid collection (arrows, bottom row). There is increasing dilatation of the pancreatic duct (arrowheads and between cursors), consistent with narrowing of the duct, and prestenotic dilatation with subsequent increased echogenicity of the pancreatic body distal to the narrowing (d) compared with the proximal (p) pancreatic body.

Follow-up with US is important for the evaluation of pseudocyst formation and evolution (▶ Fig. 12.32), pancreatic duct dilatation (▶ Fig. 12.33), and peripancreatic fluid resolution.

Chronic Pancreatitis Chronic pancreatitis is rare in childhood. It is a progressive inflammatory disorder of the pancreas characterized by irreversible morphological changes, fatty replacement, and fibrosis that lead to exocrine and endocrine pancreatic insufficiency. Exocrine insufficiency is associated with indigestion, steatorrhea, and weight loss, whereas endocrine insufficiency is associated with glucose intolerance progressing into type 1 diabetes mellitus. Chronic pancreatitis may be the result of persistent pancreatitis (> 6 weeks) or recurrent attacks of pancreatitis. In children, causes include cystic fibrosis, hereditary pancreatitis, fibrosing

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pancreatitis, steroid therapy, hyperparathyroidism, and possibly structural abnormalities like pancreas divisum, annular pancreas, and common channel syndrome. Chronic pancreatitis is characterized by recurrent or persistent abdominal pain, sometimes accompanied by pancreatic insufficiency. The lifetime risk for pancreatic adenocarcinoma is 4% but increases in hereditary pancreatitis to 40%. The US diagnosis in the early stages is difficult because of nonspecific findings of parenchymal inhomogeneity or increased echogenicity (▶ Fig. 12.34). Focal or diffuse enlargement may also occur. US manifestations at later stages include increased echogenicity, gland atrophy, parenchymal calcifications (▶ Fig. 12.35), which are more common in hereditary pancreatitis, and ductal dilatation, occasionally with pancreatic stones or sludge (▶ Fig. 12.36 and ▶ Fig. 12.37). MRCP should be performed to exclude structural abnormalities that predispose to recurrent pancreatitis.

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Fig. 12.34a,b Suspected chronic pancreatitis, serial imaging. a At age 17 months, in a child with clinically diagnosed acute pancreatitis, the pancreas is inhomogeneous and ill defined (between cursors). b Follow-up at 2 years of age shows early atrophy and a more echogenic pancreas with hypoechoic areas (arrowheads) that could correspond to focal fatty sparing.

Fig. 12.35a,b Hereditary pancreatitis. a On ultrasound, multiple pancreatic calcifications are seen as echogenic foci (arrowheads). b Computed tomography shows scattered calcifications, seen as hyperdense dots (arrowheads). (Case courtesy of Dr. F. Avni, Belgium.)

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Fig. 12.36a–d Chronic pancreatitis as the first manifestation of cystic fibrosis in a 9-year-old boy with abdominal pain. a, b Transverse scans of the pancreatic body (open arrowheads) show increased echogenicity and a dilated pancreatic duct (between cursors). There is a hypoechoic obstructing structure that proved to be pancreatic sludge (arrowhead). 1, aorta; 2, inferior vena cava;*, portal venous confluence. c Color Doppler confirms absence of flow within the dilated pancreatic duct (between cursors). Again, echogenic thinned parenchyma (open arrowheads). d Magnetic resonance cholangiopancreatography (MRCP) shows two filling defects (long arrows) in the dilated pancreatic duct (arrowhead) and in dilated side branches in the pancreatic head, as well (open arrowhead).

Medical treatment includes control of pain, replacement therapy with pancreatic enzymes, antioxidants, and insulin. Endoscopic interventions (sphincterotomy and/or stent placement) can be used to decompress the pancreatic duct. Surgical approaches are rarely used in pediatrics.

12.3.3 Inherited Disorders Cystic Fibrosis Cystic fibrosis (CF), a genetic disease with an autosomal-recessive transmission, is the most common disorder affecting the exocrine pancreas. It results from a mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. This mutation leads to diminished chloride transport across membranes, resulting in dehydrated and viscous secretions, organ dysfunction with sinusitis, nasal polyps, chronic bronchitis and bronchiectasis, male infertility, pancreatitis, and/or pancreatic insufficiency. Liver and biliary involvement with microgallbladder, stones, fatty liver, cirrhosis, and ultimately portal hypertension, as well as intestinal manifestations with

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meconium ileus, distal intestinal obstruction syndrome, intussusception, fibrosing colonopathy, and mucoid appendix, may also occur. Exocrine pancreatic insufficiency occurs in the great majority of patients with CF, caused by the inspissation of secretions within the pancreatic ducts, acinar cell damage, and ultimately interstitial fibrosis. Clinical manifestations are steatorrhea, poor growth related to fat malabsorption and hemolytic anemia, defective coagulation, and skin rashes related to deficiencies of fat-soluble vitamins and zinc. US findings reflect the degree of fatty pancreatic infiltration and fibrosis. The pancreas may be large, lobulated, and hyperechoic as a consequence of fatty replacement (▶ Fig. 12.38), or it may be hyperechoic and small as a result of pancreatic atrophy and replacement of the parenchyma by fibrous tissue and fat (▶ Fig. 12.39 and ▶ Fig. 12.40). Hypoechoic areas or a coarse echotexture representing pancreatic fibrosis (▶ Fig. 12.41) and pancreatic calcifications is sometimes found. Pancreatic duct calculi or sludge are rarely visible (▶ Fig. 12.42). Complete replacement of the pancreas by cysts is referred to as pancreatic cystosis. Pancreatic retention cysts (▶ Fig. 12.43) are uncommon, usually measure 1 to 3 mm, and

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Fig. 12.37a–d Chronic pancreatitis in a child with pancreatic insufficiency and chronic abdominal pain. a, b Transverse views of the pancreatic body. c Oblique scan through the tail. d Longitudinal scan through the body. The entire parenchyma is atrophic and not measurable around a dilated pancreatic duct (between cursors). There are macrocalcifications at the periphery of the duct, seen as echo-dense structures (open arrows) casting acoustic shadows (arrowheads), and microcalcifications, seen as minute echogenic foci associated with comet tail artifacts (open arrowheads). The intraparenchymal location of the calcifications is best depicted in d. 1, aorta, an important landmark. (Case courtesy of Dr. Ingmar Gassner, Austria.)

Fig. 12.38 Eleven-year-old girl with cystic fibrosis. The pancreas is diffusely and intensely hyperechoic (open arrowheads), consistent with fatty infiltration.

Fig. 12.39 Seven-year-old girl with cystic fibrosis. The pancreas (p) is rather small and hyperechoic compared with the liver (L). Compare with ▶ Fig. 12.7 and ▶ Fig. 12.16, in which normally echogenic pancreas is shown.

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Fig. 12.40a,b Seven-year-old boy with cystic fibrosis. a Ultrasound shows a hyperechoic atrophic pancreas (open arrowheads). b Computed tomography shows a hypodense fatty liver (L), gallbladder lithiasis (open arrowhead), and an atrophic pancreas (arrow) anterior to the splenic vein (open arrowhead).

Fig. 12.41 Coarse, inhomogeneous, echogenic pancreas containing small hypoechoic areas (arrowheads) in a 4-year-old patient with cystic fibrosis and pancreatic insufficiency.

Fig. 12.42 Three-year-old boy with cystic fibrosis. There is a small echogenic stone (arrow) inside a dilated pancreatic duct (arrowhead).

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Fig. 12.43a–d Sixteen-year-old girl with cystic fibrosis, pancreatic insufficiency, and retention cysts. a, b Transverse scan through the pancreatic body without and with color Doppler application. c Transverse section through the pancreatic tail. d Longitudinal section though the body. There are multiple cysts (arrows) that contain fluid–fluid levels between anechoic fluid and thin debris representing thick secretions (*). The intervening echogenic parenchyma is difficult to appreciate because it has the same echogenicity as retroperitoneal fat. L, liver.

are considered secondary to increased fluid pressure proximal to duct obstruction by inspissated secretions. Acute, recurrent or chronic pancreatitis develops in only 2% of patients with CF, can be a presenting manifestation of CF (▶ Fig. 12.28 and ▶ Fig. 12.35), and is much more common among those children with pancreatic sufficiency (10% prevalence) than those with pancreatic insufficiency (0.5% prevalence). This is true because the genotypes that lead to acute or chronic pancreatitis cause only a moderate loss of CFTR gene function. Enlargement of the pancreas, especially of the head, in a child with known CF should be investigated primarily for acute pancreatitis and secondarily for tumor. CF-related diabetes mellitus may present in 7% of children ages 11 to 17 years with CF. Its etiology is a combination of reduced insulin secretion (secondary to fibrosis of the pancreas and a reduced number of islet cells) and peripheral insulin resistance.

Other Inherited Disorders Related to Pancreatic Insufficiency/Tumor Development Shwachman–Diamond syndrome is the second most common cause of exocrine pancreatic insufficiency in children. It is characterized by metaphyseal dysostosis or epiphyseal dysplasia, bone marrow hypoplasia mainly in the form of neutropenia, and exocrine pancreatic insufficiency that leads to malabsorption. A normal sweat test excludes CF. Children present with failure to thrive, diarrhea, and short stature. There is also a greatly increased risk for the development of acute leukemia later in life. Other organs that can be affected include the teeth and oral cavity, liver, heart, kidneys, and skin. In addition, new evidence suggests that affected children may have learning difficulties and impaired psychological development. Pancreatic insufficiency may vary from mild to severe. The characteristic

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Fig. 12.44a,b Ultrasound of two sisters with Shwachman–Diamond syndrome. a The pancreas of the 11-year-old girl exhibits moderately increased echogenicity and a size at the lower limits of normal. b The pancreas of the 14-year-old is diffusely echogenic with a size at the lower limits of normal.

Fig. 12.45a,b Ultrasound of a 10-year-old boy with metabolic syndrome. Both the liver (L) and the pancreas (p) are normal in size and diffusely hyperechoic, contrasting with the normal right kidney (Rt K).

pathologic finding is fatty infiltration of the pancreas with reduction of acini and conservation of the islets. The pancreas is hyperechoic on US, usually with a normal or reduced size (▶ Fig. 12.44). The differential diagnosis of a diffusely hyperechoic pancreas consistent with pancreatic lipomatosis includes (besides CF and Shwachman–Diamond syndrome) obesity (▶ Fig. 12.45), steroid therapy, chemotherapy, Cushing syndrome, obstruction of the main pancreatic duct (▶ Fig. 12.33), chronic pancreatitis (▶ Fig. 12.36), and Johnson–Blizzard syndrome, which is characterized by congenital aplasia of nasal alae, deafness, hypothyroidism, dwarfism, and malabsorption. Beckwith–Wiedemann syndrome is characterized by the triad of omphalocele, macroglossia, and gigantism (macrosomia) with or without hemihypertrophy. Variable degrees of visceromegaly can affect the kidneys, liver, pancreas (mainly with a large pancreatic head), and adrenals. Patients with Beckwith–

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Wiedemann syndrome are at a greater risk for the development of malignancies such as pancreatoblastoma, necessitating routine survey abdominal ultrasound examinations. Cyst development may also occur.

12.3.4 Neoplasms Pancreatic neoplasms are rare in children, have a different histologic spectrum and a generally better prognosis than those in adults, and should be considered whenever a mass protrudes at the lesser sac. In general, these tumors are well demarcated and expansile rather than infiltrating. Pancreatic tumors can be classified as epithelial or nonepithelial in origin and can be benign or malignant (▶ Table 12.3). Epithelial pancreatic tumors may originate from endocrine (islet cell) or nonendocrine tissue, and they are therefore divided into endocrine and exocrine pancreatic tumors.

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Pancreas Table 12.3 Classification of pancreatic tumors more commonly encountered in children Origin

Benign

Malignant

Epithelial tumors Exocrine cell origin

Pancreatic cyst

Pancreatoblastomaa

Solid papillary tumor

Ductal adenocarcinoma

Duct adenoma

Acinar cell adenocarcinoma

Mucinous cystadenoma Serous cystadenoma Intraductal papilloma Endocrine cell originb

Insulinoma (90%)

Insulinoma (10%)

(secretory tumors)

Gastrinoma (40%)

Gastrinoma (60%)

Islet cell hyperplasia Nonepithelial tumors (connective tissue)

Lymphangioma

Lymphoma, particularly Burkitt lymphoma

Hemangioendothelioma

Sarcoma, particularly rhabdomyosarcoma

Dermoid cyst

Leiomyosarcoma

Source: Modified from Enríquez G, Vázquez E, Aso C, Castellote A, García-Peña P, Lucaya J. Pediatric pancreas: an overview. Eur Radiol 1998;8(7):1236–1244 and from Nijs E, Callahan MJ, Taylor GA. Disorders of the pediatric pancreas: imaging features. Pediatr Radiol 2005;35(4):358–373. aAssociation with Beckwith–Wiedemann syndrome. bAssociation with multiple endocrine neoplasia and von Hippel–Lindau disease.

Primary Tumors Most exocrine pancreatic tumors are malignant and are usually pancreatoblastomas or adenocarcinomas. Pancreatoblastoma, also known as pancreaticoblastoma or infantile carcinoma, is a rare epithelial tumor arising from the acinar cells. It occurs in children, usually 2 to 8 years of age, and is more frequent in Asia. It probably represents a unique childhood tumor of pluripotential nature and has a better prognosis than the adult pancreatic adenocarcinoma. Patients present with abdominal distention, a palpable mass, early satiety, and vomiting. As with other embryonal tumors, alpha fetoprotein levels may be elevated in 25 to 55% of patients. At imaging, pancreatoblastomas are heterogeneous, solid, and often multilocular cystic exophytic masses approximately 5 to 20 cm in diameter, with welldefined margins, hyperechoic areas, or septa. At CT and MR imaging, the solid components of the tumor enhance. Clustered or rim calcifications and bile or pancreatic duct dilatation may occasionally be encountered. Pancreatoblastoma may appear to arise from the pancreas or the liver and may also be mistaken for neuroblastoma. Because of these nonspecific signs, fine needle biopsy and histologic investigation are performed to establish the diagnosis. Adenocarcinomas in children may be ductal or acinar. Ductal adenocarcinoma clinically and radiologically behaves as in

adults and forms a small, hypovascular mass, usually at the pancreatic head, causing proximal obstruction of the bile and pancreatic duct system. Acinar adenocarcinoma presents with a large, nodular necrotic mass that may be situated anywhere within the organ. Solid papillary tumor (SPT) was formerly known as solid and papillary epithelial neoplasm (SPEN) and is also known as solid pseudopapillary tumor, solid and cystic tumor, papillary cystic neoplasm, or Frantz tumor. It affects adolescent girls and young women. It is considered a low-grade malignant tumor of unknown cellular origin and appears as a large, well-defined, encapsulated lesion of uniform (when small) or inhomogeneous echotexture, without calcifications (▶ Fig. 12.46 and ▶ Fig. 12.47). Pancreatic duct dilatation may coexist (▶ Fig. 12.46 b). Heterogeneity in the internal architecture, with a mixture of solid and cystic hemorrhagic and necrotic elements, reflects its hemorrhagic nature (▶ Fig. 12.48 a). The fibrous capsule is best shown as a dark rim on T1- or T2-weighted MR images, while hemorrhage exhibits hyperintense foci on T1-weighted images (▶ Fig. 12.48 b). Early peripheral heterogeneous enhancement with progressive fill-in on gadolinium-enhanced dynamic MR imaging occurs. Total resection carries a good prognosis. Endocrine tumors have been reported in older children and mainly in adults. Islet cell tumors are usually functioning and may be benign or malignant; they include insulinomas (47% of functioning islet cell tumors) and gastrinomas. Other types of functioning and nonfunctioning islet cell tumors are exceedingly rare or have never been reported in children. Endocrine tumors manifest early because of hormonal syndromes. Insulinomas may cause fasting hyperinsulinemic hypoglycemia and are distinguished by their small size (< 2 cm) and homogeneous hypoechoic appearance. Gastrinomas may cause Zollinger–Ellison syndrome, with peptic ulcers, heartburn, and gastroesophageal reflux. Nonfunctioning islet cell tumors and gastrinomas tend to be diagnosed later than insulinomas and are therefore usually larger and inhomogeneous at diagnosis. Insulinomas are usually seen in the body and tail of the pancreas, and gastrinomas are seen in the pancreatic head. Intense enhancement with intravenous contrast material is characteristic. Focal or diffuse neuroendocrine adenomatosis can be present in neonates, causing persistent neonatal hypoglycemia, now known as congenital hyperinsulinism and formerly known as nesidioblastosis. At US, the pancreas may be normally echogenic and normal or large in size (▶ Fig. 12.49). US, CT, and MR imaging do not provide diagnostic findings. Clinical and biochemical results and occasionally positron emission tomography/computed tomography (PET/CT) provide the diagnosis. Treatment is with total or subtotal pancreatectomy. Regeneration of the pancreas following subtotal pancreatectomy has been described. All malignant epithelial pancreatic neoplasms in children are capable of producing metastases, usually to the liver and lymph nodes; however, on the whole, these tumors have a better clinical outcome than most pancreatic tumors in adults. Nonepithelial tumors may primarily or secondarily involve the pancreas from distant sites or direct spread. Most pancreatic tumors arising from connective tissue are benign and include hamartomas, lymphangiomas, lipomas, neurinomas, and hemangioendotheliomas (▶ Fig. 12.51). They have the same characteristics as their counterparts located in the soft tissues

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Fig. 12.46a,b Solid papillary tumor in an 11-year-old girl. a There is a solid inhomogeneous epigastric mass (open arrowheads). The organ of origin is not identifiable. b Oblique view reveals the probable pancreatic origin of the mass (open arrowheads). P, pancreatic tail. Note the echogenic (open arrow) and cystic (arrowhead) components of the mass, representing hemorrhage and necrosis. The pancreatic duct (arrow) shows early dilatation. (Case courtesy of Dr. R. R. van Rijn, The Netherlands.)

Fig. 12.47a,b Solid papillary tumor in two adolescent girls. a There is a solid, rather homogeneous mass (open arrowheads) arising from the pancreatic head. P, pancreas. b Color Doppler reveals central (arrowhead) and peripheral (open arrowheads) vascularity, consistent with a solid mass. P, pancreas. (Case courtesy of Dr. R. R. van Rijn, The Netherlands.)

Fig. 12.48a,b Magnetic resonance imaging findings in two adolescent girls. a Axial T1-weighted sequence shows a hypointense mass (open arrowheads) arising from the pancreatic head and containing a large area of hyperintensity (arrowhead), which represents hemorrhage. b Coronal T2-weighted fat-saturated sequence shows an epigastric mass (m) of intermediate inhomogeneous intensity surrounded by a hypointense capsule (open arrowheads). (Cases courtesy of Dr. R. R. van Rijn, The Netherlands.)

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Fig. 12.49 Ultrasound (US) of the pancreas in a 2-week-old premature neonate with persistent hypoglycemia and a histologic diagnosis of nesidioblastosis. Transverse and oblique scans of the pancreas (arrowheads) show increased echogenicity similar to that of the normal pancreas at this age. The diagnosis cannot be established by US.

Fig. 12.50a,b Pancreatic hemangioendothelioma in a 3-month-old boy. a Isoechoic homogeneous mass (between cursors), best appreciated from the left subcostal approach. S, spleen. b Color Doppler confirms the vascular nature of the mass (open arrows), in which vessels are densely packed.

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Fig. 12.51a,b Metastatic neuroblastoma with peripancreatic masses. a Transverse scan shows echogenic nodes (arrowheads) in the pancreatic body (p), liver (L), and stomach (S). b Longitudinal scan confirms the presence of multiple echogenic nodes (*) in the pancreatic head (p). Arrowhead points to the superior mesenteric artery.

echogenicity (▶ Fig. 12.53). The latter appearances may also be due to secondary pancreatitis or pancreatitis related to tumor lysis syndrome. Clinical findings, associated disease in other organs, absence of biliary tree dilatation despite the presence of a bulky tumor, and associated extensive adenopathy should offer clues to the diagnosis of lymphoma. Focal masses from leukemia (granulocytic sarcoma “chloroma”) or diffuse leukemic infiltration can rarely affect the pancreas (▶ Fig. 12.54) Metastatic disease to the pancreas is rare in children but has been reported in rhabdomyosarcoma, neuroblastoma, osteosarcoma, and melanoma.

12.3.5 Cystic Masses

Fig. 12.52 Burkitt lymphoma. The pancreas (open arrowheads) is diffusely and significantly enlarged and hypoechoic. A satellite lesion (arrowhead) is also noted.

and neck. Primary nonepithelial malignant pancreatic tumors include lymphoma, peripheral primitive neuroectodermal tumor, and rhabdomyosarcoma. They may all present as large expansile masses.

Systemic–Metastatic Tumors The pancreas may be encased or displaced by adjacent tumors, such as neuroblastoma (▶ Fig. 12.51) or lymphoma. Pancreatic involvement in childhood lymphoma is unusual, may occur with widely disseminated preterminal disease, is most common with large-cell lymphoma, and is sporadic with Burkitt lymphoma. Pancreatic involvement with or without peripancreatic retroperitoneal lymph nodes may be seen as focal hypoechoic areas (▶ Fig. 12.52) or diffuse enlargement with reduced

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Cystic lesions of the pancreas in children may be inflammatory, congenital, or neoplastic. Inflammatory cystic lesions associated with acute pancreatitis include fluid collections that lack a wall (so-called pseudocysts), abscesses, and Echinococcus cysts. Pseudocysts are the most common local complication of acute pancreatitis, are more common in posttraumatic than in nontraumatic pancreatitis, and are the most common type of pancreatic cyst. In chronic and posttraumatic pancreatitis, they develop as a result of ductal disruption rather than from the peripancreatic fluid accumulations that lead to pseudocyst formation in the setting of acute pancreatitis. Pseudocysts can be extra- or intrapancreatic, single or multiple, small or large anechoic structures with well-defined borders and posterior acoustic enhancement (▶ Fig. 12.32). Debris may indicate hemorrhage or infection (▶ Fig. 12.55 and ▶ Fig. 12.56). Mature pseudocysts require at least 4 weeks to form, are relatively permanent, and change little in shape or location, whereas acute peripancreatic or pancreatic fluid collections are transient, poorly encapsulated, and variable in size and shape. The walls of pseudocysts are formed by adjacent structures such as the stomach, transverse mesocolon, gastrocolic

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Fig. 12.53a–d Acute presentation of Burkitt lymphoma with abdominal pain and weight loss in a 12-year-old. a The pancreas contains multiple hypoechoic masses (m) and is enlarged. b The kidneys (left shown) and ovaries (not shown) were diffusely enlarged with hypoechoic areas (arrowheads). c, d Computed tomography shows multiple hypodense pancreatic (m) and renal (*) masses. (Case courtesy of Dr. F. Avni, Belgium).

Fig. 12.54a,b Pancreatic splenic and renal involvement with leukemia in a neonate. a, b Transverse upper abdominal scans. The pancreas (open arrowhead) is diffusely and significantly enlarged, lobulated, and hypoechoic. The renal pyramids (arrows) and splenic parenchyma (S) are of identical echogenicity. Nephromegaly and splenomegaly are present. (Case courtesy of Dr. Ingmar Gassner, Austria.)

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Fig. 12.55a–c Posttraumatic pseudocyst 30 days following a traffic accident. a The pseudocyst (open arrowhead) is seen as a large cystic structure with anechoic contents and echogenic debris at its dependent aspect (arrow). p, pancreas; S, spleen. b At a more caudal level, the pseudocyst is filled with fine echoes, resulting in a “pseudo-solid” appearance. Note the lack of internal flow, contrasting with the solid and papillary epithelial neoplasm (SPEN) in ▶ Fig. 12.46, and the anechoic contents at the upper part of the cyst due to a sedimentation effect (arrowhead). c T2-weighted magnetic resonance imaging. The pseudocyst is seen between the pancreatic head (h) and tail (t) and contains a hypointense fluid–fluid level, consistent with hemorrhage.

omentum, and pancreas. The lining of pancreatic pseudocysts consists of fibrous and granulation tissue (fibrotic pseudocapsule), in contrast to the epithelial lining of a true cystic lesion of the pancreas. A clinical history of pancreatitis distinguishes a pseudocyst from tumor. Congenital cysts are caused by anomalous development of the pancreatic ducts. They are usually multiple, although they can be solitary (▶ Fig. 12.57). Multiple congenital cysts are seen in patients with adult polycystic disease or with von Hippel– Lindau disease, although this usually occurs in a much older age group, not in the pediatric population. Cysts may also be encountered in Beckwith–Wiedemann syndrome and Meckel– Gruber syndrome. Abscesses occur later than 4 weeks after the onset of pancreatitis and cannot be differentiated from noninfected pseudocysts or infected congenital cysts (▶ Fig. 12.58) by imaging alone. In clinically suspected abscesses, percutaneous aspiration to verify pus and obtain material for cultures may be necessary. Cystic neoplasms of the pancreas are uncommon tumors, accounting for 5 to 15% of pancreatic cystic lesions and fewer

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than 5% of pancreatic tumors. Histologically, pancreatic cystic tumors include serous (microcystic) and mucinous (macrocystic) neoplasms. The serous lesions are benign, are usually located in the pancreatic tail, and have seldom been reported in children. Their sonographic appearance varies from a homogeneous solid mass to a homogeneous liquid mass with occasional central calcifications. The mucinous lesions are malignant (cystadenocarcinoma) or potentially malignant and have been described in elderly women. In individuals with von Hippel– Lindau disease, simple cysts, serous cystadenomas, and neuroendocrine tumors may occur. In children, particularly older children, large islet cell tumors and large solid pseudopapillary tumors may be necrotic and also appear cystic with thick walls. Careful consideration of the US findings and of the history is important because cystic lesions, like solid papillary tumors and pseudocysts of the pancreatic head, may have similar characteristics on CT (▶ Fig. 12.59 and ▶ Fig. 12.60). Moreover, solid pseudopapillary tumors tend not to demonstrate the hypervascularity of the tumor periphery that characterizes islet cell tumors on post-contrast studies.

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Fig. 12.56 Posttraumatic pseudocysts. There is an anechoic intrapancreatic pseudocyst (arrow) with ragged edges and posterior acoustic enhancement (open arrow). There is a second pseudocyst in the pancreatic parenchyma with mixed echogenicity. Note the lack of a capsule, ill-defined borders (open arrowheads), and multiple internal septa (arrowhead).

Fig. 12.57 Histologically confirmed congenital pancreatic cyst in a 1-month boy with the antenatal diagnosis of a cyst. There is a large, thin-walled epigastric cyst (c) with debris at its dependent aspect (arrow). L, liver; S, stomach.

Fig. 12.58a,b Histologically confirmed infected congenital pancreatic cyst in a 3-year-old girl with recurrent episodes of abdominal pain and leukocytosis. a At the age of 2 years, there is a thick-walled (arrowheads) pancreatic cyst containing echogenic debris. b At the age of 3 years, the walls (open arrowheads) are thinner; fine echoes and sludge (white arrowheads) are visible inside the lumen.

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Fig. 12.59 Pseudocyst seen on computed tomography as a hypodense lesion (arrowhead) at the pancreatic neck.

Fig. 12.60 Solid papillary tumor, same case as in ▶ Fig. 12.47 b, seen on computed tomography as a hypodense, poorly enhancing lesion at the pancreatic head (arrowhead).

Tips from the Pro ●

Meticulous evaluation of the size and echogenicity of the pancreas may aid in the differential diagnosis of conditions with diffuse pancreatic involvement (▶ Table 12.4).

Table 12.4 Differential diagnosis of conditions diffusely affecting the pancreas based on ultrasonographic characteristics

Table 12.5 Differential diagnosis of focal pancreatic lesions based on ultrasonographic characteristics and multiplicity

Diffuse pancreatic involvement

Focal pancreatic lesions

Normal size hyperechoic pancreas

Enlargement hyperechoic pancreas

Neonates

Acute pancreatitis

Obesity

Congenital hyperinsulinism (nesidioblastosis)

Steroids/ chemotherapy

Reduced size hyperechoic pancreas

Solitary

Shwachman– Diamond syndrome

Acute pancreatitis

Storage disease

Normal variant

Hypoechoic pancreas

Hypoechoic pancreas

Acute pancreatitis

Acute pancreatitis Leukemia

Solitary Pseudocyst

Pancreatoblastoma

Congenital cyst

Solid papillary tumor

Islet cell tumors

Mucinous cystadenoma

Large islet cell tumors

Lymphoma

Cystic lymphangioma

Sarcomas

Microcystic adenoma

Echinococcal cyst

Pseudocyst/ pseudocysts

Leukemia

Adult polycystic disease

Abscess/abscesses

Solid papillary tumor

Solid papillary tumor

Sarcomas

Cystic fibrosis

Multiple

Multiple

Metastasis

Pseudocysts

Lymphoma

Adult polycystic disease

Leukemia

Pancreatic cystosis

Acute pancreatitis

Von Hippel–Lindau disease

Lymphoma Source: Modified from Berrocal T, Prieto C, Pastor I, Gutierrez J, al-Assir I. Sonography of pancreatic disease in infants and children. Radiographics 1995;15(2):301–313.

Mixed echogenicity Any large necrotic mass

Pancreatoblastoma

Normal echogenicity Shwachman– Diamond syndrome

Cystic

Acute/chronic pancreatitis Cystic fibrosis Chronic pancreatitis

Cushing syndrome

Solid

Source: Modified from Berrocal T, Prieto C, Pastor I, Gutierrez J, al-Assir I. Sonography of pancreatic disease in infants and children. Radiographics 1995;15(2):301–313.

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Pancreas Any space-occupying lesion that protrudes at the lesser sac may have a pancreatic origin. Pancreatic tumors may be mistaken for neuroblastoma or hepatoblastoma, and vice versa. The differential diagnosis of focal pancreatic lesions based on echogenicity and multiplicity is listed in ▶ Table 12.5. Pancreatic duct dilatation usually indicates acute pancreatitis when mild and chronic pancreatitis when severe; it may also be the result of posttraumatic stricture and is rarely due to a tumor.

Recommended Readings Anupindi SA. Pancreatic and biliary anomalies: imaging in 2008. Pediatr Radiol 2008; 38 Suppl 2: S267–S271 Benya EC. Pancreas and biliary system: imaging of developmental anomalies and diseases unique to children. Radiol Clin North Am 2002; 40: 1355–1362 Berrocal T, Prieto C, Pastor I, Gutierrez J, al-Assir I. Sonography of pancreatic disease in infants and children. Radiographics 1995; 15: 301–313 Chao HC, Lin SJ, Kong MS, Luo CC. Sonographic evaluation of the pancreatic duct in normal children and children with pancreatitis. J Ultrasound Med 2000; 19: 757– 763 Chaudry G, Navarro OM, Levine DS, Oudjhane K. Abdominal manifestations of cystic fibrosis in children. Pediatr Radiol 2006; 36: 233–240 Chung EM, Travis MD, Conran RM. Pancreatic tumors in children: radiologic-pathologic correlation. Radiographics 2006; 26: 1211–1238

Darge K. Anupindi p. Pancreatitis and the role of US, MRCP and ERCP. Pediatr Radiol 2009; 39 Suppl 2: S153–S157 De Boeck K, Weren M, Proesmans M, Kerem E. Pancreatitis among patients with cystic fibrosis: correlation with pancreatic status and genotype. Pediatrics 2005; 115: e463–e469 Dewhurst CE, Mortele KJ. Cystic tumors of the pancreas: imaging and management. Radiol Clin North Am 2012; 50: 467–486 Enríquez G, Vázquez E, Aso C, Castellote A, García-Peña P, Lucaya J. Pediatric pancreas: an overview. Eur Radiol 1998; 8: 1236–1244 Hall GW, Dale P, Dodge JA. Shwachman–Diamond syndrome: UK perspective. Arch Dis Child 2006; 91: 521–524 Manfredi R, Lucidi V, Gui B et al. Idiopathic chronic pancreatitis in children: MR cholangiopancreatography after secretin administration. Radiology 2002; 224: 675– 682 Mekitarian Filho E, Carvalho WB, Silva FD. Acute pancreatitis in pediatrics: a systematic review of the literature. J Pediatr ( Rio J) 2012; 88: 101–114 Montemarano H, Lonergan GJ, Bulas DI, Selby DM. Pancreatoblastoma: imaging findings in 10 patients and review of the literature. Radiology 2000; 214: 476–482 Montero M, Vázquez JL, Rihuete MA, , Serous cystadenoma of the pancreas in a child. J Pediatr Surg 2003;38(9):E6–E7 . Mortelé KJ, Rocha TC, Streeter JL, Taylor AJ. Multimodality imaging of pancreatic and biliary congenital anomalies. Radiographics 2006; 26: 715–731 Nijs E, Callahan MJ, Taylor GA. Disorders of the pediatric pancreas: imaging features. Pediatr Radiol 2005; 35: 358–373 Siegel MJ, Martin KW, Worthington JL. Normal and abnormal pancreas in children: US studies. Radiology 1987; 165: 15–18 Vaughn DD, Jabra AA, Fishman EK. Pancreatic disease in children and young adults: evaluation with CT. Radiographics 1998; 18: 1171–1187

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Chapter 13

13.1

Normal Anatomy and Variants

452

13.2

Congenital Anomalies of the Kidney and the Urinary Tract

456

13.3

Urolithiasis and Nephrocalcinosis

464

13.4

Kidney Cysts and Cystic Nephropathies

467

13.5

Autosomal-Dominant Polycystic Kidney Disease

469

13.6

Renal Tumors

474

13.7

Urinary Tract Infection

480

13.8

Renovascular Disease

481

13.9

Parenchymal Nephropathy

485

Kidneys

13 13.10 Renal Trauma

490

13.11 Pediatric Renal Transplantation

491

13.12 Bladder and Urethra

500

13.13 Contrast-Enhanced Cystosonography

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13 Kidneys Maria Beatrice Damasio, Ann Nystedt, Lil-Sofie Ording Muller, and Giorgio Pioggio Ultrasound (US) is the workhorse in imaging of the urinary tract. The US examination should ideally be performed by an investigator either experienced in pediatric US or supervised by a pediatric radiologist and using an up-to-date protocol for pediatric imaging. The child should be well hydrated, and a preand postvoid assessment must be included. The examination is performed with both curved and linear array, high-frequency transducers. Start with an assessment of the bladder shape, wall, and neck, and try to identify the ureter ostium and distal ureters. Proceed with the retrovesical space, where the internal genitalia can be visualized behind the full bladder. Assessment of the kidneys both before and after micturition is important in order to detect changes in the collecting system after voiding. The bladder must also be assessed before and after micturition, and the residual urine volume should be measured. The kidneys are best seen from the back, and scanning the patient in the prone or decubitus position will give the most detailed images of the renal parenchyma when both curved and linear transducers are used. If there is dilatation of the collecting system, measurements of the maximal width of the renal pelvis in the transverse plane, the maximal calyx diameter, and the narrowest parenchymal width should be provided. It is important to obtain measurements of the kidney in three planes. For serial measurements (e.g., in growth assessment), consistency is crucial, and measurements should ideally be obtained by scanning the patient from the back and using the same type of transducer every time (i.e., either curved or linear array transducer). Amplitude-coded Doppler and duplex Doppler are optional techniques to assess the renal vasculature and kidney perfusion, to differentiate prominent hilar vessels from the renal pelvis, and to depict the urine jet from the ureter ostium.

Tips from the Pro ●

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Always start the examination with an assessment of the bladder to ensure proper pre-micturition images. This is particularly important with children who are still in their nappies. Adjust the gain behind the bladder; otherwise, it is easy to miss dilated ureters. Color Doppler can be applied to differentiate prominent hilar vessels from the renal pelvis (▶ Fig. 13.1 c). Do not forget to assess the kidneys from behind the back to obtain detailed images of the renal parenchyma.

13.1 Normal Anatomy and Variants 13.1.1 Kidneys The normal sonographic appearances of the kidneys vary with age (▶ Table 13.1). In the neonate, the glomeruli occupy twice as much of the cortical volume as in adults, and medullary volume is larger in children. Therefore, the renal cortex in the neonate is isoechoic to the liver and spleen, and the relatively high echogenicity of the renal cortex contrasts with the prominent, hypoechoic medullary pyramids (▶ Fig. 13.1a, b). In premature infants, the renal cortex is even hyperechoic to the liver and spleen. The echogenicity of the renal cortex decreases gradually in the first year of life, and the cortex usually becomes hypoechoic to the liver when the child is 12 to 15 months old (▶ Fig. 13.2). Persistent fetal lobulation is a common finding in infants (▶ Fig. 13.1a). In infants and young children, the renal sinus lacks the echogenicity seen in adults and older children because of the paucity of fat (▶ Fig. 13.3).

Fig. 13.1a–c Normal appearance of the kidney in a neonate. Longitudinal (a) and transverse (b) scans of the right kidney in a neonate showing the isoechoic renal cortex compared with the liver (asterisk) and contrasting hypoechoic medullary pyramids. Fetal lobulation is a normal finding in infancy (arrow). Doppler examination may be helpful to differentiate the renal pelvis from prominent hilar vessels (c).

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Kidneys Table 13.1 Normal kidney length in infants and children Subjects

Longitudinal midclavicular dimension of the right kidney (mm)

Age range (months)

Number

Mean

SD

Minimum

Maximum

Percentile

Suggested limits of normal

5th

95th

Lowermost

Uppermost

1–3

50

50

5.8

38

66

40

58

35

65

4–6

39

53

5.3

41

66

50

64

40

70

7–9

17

59

5.2

50

70

52

66

45

70

12–30

18

61

3.4

55

66

55

65

50

75

36–59

22

67

5.1

57

77

59

75

55

80

60–83

26

74

5.5

62

83

65

83

60

85

84–107

32

80

6.6

68

93

70

91

65

95

108–131

27

80

7.0

69

96

69

89

65

100

132–155

89

6.2

6.2

81

102

82

100

70

105

159–179

22

94

5.9

83

105

85

102

75

110

180–200

11

92

7.0

80

107

83

102

75

110

Age range (months)

Number

Mean

SD

Minimum

Maximum

Percentile 5th

95th

Lowermost

Uppermost

1–3

50

50

5.5

39

61

42

59

35

65

Subjects

Longitudinal midclavicular dimension of the left kidney (mm) Suggested limits of normal

4–6

39

56

5.5

44

68

47

64

40

70

7–9

17

61

4.6

54

68

54

68

45

75

12–30

18

66

5.3

54

75

57

72

50

80

36–59

22

71

4.5

61

77

61

76

55

85

60–83

26

79

5.9

66

90

70

87

60

95

84–107

32

84

6.6

71

95

73

93

65

100

108–131

27

84

7.4

71

99

75

97

65

105

132–155

15

91

8.4

71

104

77

102

70

110

159–179

55

96

8.9

83

113

84

110

75

115

180–200

11

99

7.5

87

116

90

110

80

120

Abbreviation: SD, standard deviation. Note: This study included 307 pediatric subjects (169 girls and 138 boys) ranging in age from full-term newborns (5 days) to 16 years. The subjects were imaged in the supine or slightly right/left lateral decubitus position. The renal measurements were obtained in the coronal plane at the level of the hilum.

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Fig. 13.2 Normal appearance of the kidney in a toddler. The renal pyramids are often prominent throughout childhood, but the cortex becomes hypoechoic to the liver (asterisk) within the first year of life, as shown here in an 11-month-old child. The fetal lobulation will disappear in most individuals, and the renal surface becomes smooth. However, fetal lobulation may persist throughout life.

In the neonate, protein deposits may cause transient increased echogenicity at the tip of the medullary pyramids (▶ Fig. 13.4). In children with normal urine output, this is a selflimiting finding that disappears in a few days and does not require further work-up. A renal pelvis up to 10 mm in anteroposterior diameter is a normal finding in children and should not automatically be labeled as pathologic dilatation. Fetal lobulation of the kidneys may persist through adulthood and can be differentiated from renal scarring by the lack of parenchymal thinning. Renal scars are most often located over the calices, whereas the lobules in fetal lobulation contain a pyramid, so the lobulation lies between the pyramids. Cortical fusion defects may be seen as interrenuncular septa, which are hyperechoic lines extending from the cortex to the medulla of the kidney (▶ Fig. 13.5). There is no associated parenchymal thinning. A column of Bertin is a normal structure and represents the extension of renal cortical tissue that separates the pyramids. Occasionally, a prominent or hypertrophic column of Bertin may be seen in the middle part of the kidney and should not be mistaken for a renal tumor. The hypertrophic Bertin column is continuous with and similar in appearance to the renal cortex. The column may splay the calices, but the outline of the kidney is preserved (▶ Fig. 13.6). Compound calices can be seen in the upper and lower poles of the kidney as small, elongated, fluid-filled calices (▶ Fig. 13.7). They occur when more than one papilla drains into a single calyx. Compound calices have no mass effect, there is no dilatation of the calyx neck, and there is no thinning of the overlying renal cortex. Fig. 13.3a,b Normal appearance of the kidney in an 8-year-old child. There is a relative paucity of fat in the renal hilum in children compared with adults (a). An ultrasound examination of the kidneys in children must always include an assessment with a high-frequency linear transducer, which will provide a detailed depiction of the renal parenchyma (b).

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Kidneys

Fig. 13.4 Transient hyperechogenicity of the renal pyramids (arrows) can be seen in healthy neonates and normally disappears within a few days. The adrenal gland is easily seen above the kidney upper pole in a neonate (arrowhead).

Fig. 13.6 A hypertrophic column of Bertin is a normal extension of the renal cortex splaying the calices (arrows) but with a normal outline of the renal surface (arrowhead).

Duplex systems are a common finding, with a reported incidence of 0.8%. Duplications range from a split renal pelvis to a complete duplication, with two separate ureters and two bladder ostia. The ureters often fuse somewhere distal to the renal pelvis to form one ureter (▶ Fig. 13.8). Duplicated systems are more often associated with urinary obstruction or vesicoureteral reflux. In the absence of complications, such as recurrent or atypical urinary tract infections or dilatation, a duplex system may be regarded as a normal variant and does not require further work-up or treatment. The normal waveform of the renal artery on pulsed Doppler sonography is shown in ▶ Fig. 13.9. Both peak systolic velocity and the resistive index (RI) of a normal kidney are age-dependent. Peak velocity in the main renal artery varies from 30 to 50 cm per second in the neonate to 100 to 110 cm per second in the adolescent. An RI up to 0.85 is normal in a neonate and

Fig. 13.5 Interrenuncular septa are cortical fusion defects seen as a hyperechoic line (arrow) extending from the renal surface to the medulla with no associated cortical thinning.

Fig. 13.7 Compound calices. Small, nonexpansile, hypoechoic areas can be seen in the upper and lower poles of the kidney (arrows). These occur when multiple papillae drain into one calyx.

decreases to less than 0.7 during the first year of life. The renal arteries course posterior to the renal veins and reach the renal hilum, where they branch to form segmental arteries. It is not uncommon to have accessory polar arteries to the kidney; therefore, Doppler curves must be obtained in all segments of the kidney.

13.1.2 Ureters Nondilated ureters can be difficult to assess throughout their entire length; however, even normal ureters can often be visualized behind the bladder in children (▶ Fig. 13.10). The ureters should be thin-walled and have a maximum diameter of 5 mm. Normal peristalsis of the ureters and the presence of a urine jet from the ureter ostia within the bladder are useful parameters for the evaluation of ureteral function and patency.

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Kidneys

Fig. 13.8 Duplications of the collecting system are relatively common and range from a split renal pelvis (arrows) to two separate ureters inserting into the bladder. An uncomplicated renal duplication is often an incidental finding.

Fig. 13.9 Normal waveform on pulsed Doppler sonography of the kidney.

13.2 Congenital Anomalies of the Kidney and the Urinary Tract Congenital anomalies of the kidney and urinary tract cover a broad range of disorders (see box Congenital anomalies of the kidney and urinary tract (p. 457)) that result from the following abnormal renal developmental processes: ● Malformation of the renal parenchyma resulting in failure of normal nephron development, as seen in renal agenesis, renal dysplasia, and multicystic dysplasia; ● Abnormalities of embryonic migration of the kidneys, as seen in renal ectopia (e.g., pelvic kidney) and fusion anomalies, such as horseshoe kidney; ● Abnormalities of the developing urinary collecting system, as seen in duplicate collecting systems, posterior urethral valves, and ureteropelvic junction obstruction.

Fig. 13.10 Normal ureters can often be seen behind the bladder in children (arrows). The caliber varies with peristalsis and the ureter may collapse, but it should not exceed 5 mm in diameter.

13.1.3 Bladder The bladder can be properly assessed only when the bladder is full; therefore, proper hydration and filling of the bladder before the scan are important. The bladder wall is smooth, and the musculature at the trigone is slightly thicker than in the rest of the bladder. The bladder wall thickness should not exceed 3 mm when the bladder is full and 5 mm when it is empty. Bladder emptying and residual urine should be correlated with the patient’s sex, age, and bladder volume before micturition.

456

Although in many cases congenital anomalies of the kidney and urinary tract occur in the context of multiple-organ malformation syndromes, most cases are nonsyndromic. Defects can be bilateral or unilateral. The inheritance pattern may be variable, and different congenital anomalies of the kidney and urinary tract may be present in the same patient or in different members of the same pedigree. The main ultrasound feature is dilatation of the urinary tract (see box Role of ultrasound in the assessment of a dilated urinary tract (p. 457)). Prenatal imaging is useful to select patients for postnatal work-up. Bladder and urethral pathologies and multicystic kidneys are described in later sections of this chapter.

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Kidneys

Fig. 13.11 Fifteen-year-old boy with mild chronic renal failure due to renal hypodysplasia associated with maturity onset diabetes of the young. Inhomogeneous hyperechogenicity with loss of the normal corticomedullary differentiation and reduced renal size. A few small simple cysts are seen in the outer cortex (arrow).

Congenital anomalies of the kidney and urinary tract ● ● ● ● ● ● ● ● ●

Aplastic–hypoplastic kidney Multicystic kidney Ureteropelvic junction obstruction Ureterovesical junction obstruction Ureterovesical reflux Duplex systems Ectopic ureter Bladder and urethra anomalies Horseshoe kidney

Role of ultrasound in the assessment of a dilated urinary tract ● ● ●

● ●

Detection of dilated urinary tract segments Grading of hydronephrosis Evaluation of the nature of an obstacle (stenosis, stone, fungus ball, tumor) Evaluation of the renal parenchyma (thickness, structure) Identification of complications (hydropyonephrosis, urine extravasation, others)

13.2.2 Ureteropelvic Junction Stenosis Ureteropelvic junction stenosis is the most common type of obstruction of the upper urinary tract in childhood. It is often bilateral and may differ in degree between the two kidneys; it is frequently demonstrated in prenatal US scans. The stenosis may be intrinsic or due to external compression, often as the result of a supernumerary renal artery. US features are often specific, with dilatation of the pelvicaliceal system in which the renal pelvis is more enlarged than the calices and in which a clear “stop” is seen at the ureteropelvic junction (▶ Fig. 13.13) without dilatation of the ureter. In case of a suspected crossing vessel on color Doppler US (▶ Fig. 13.14), a more detailed anatomical study by means of magnetic resonance (MR) angiography is often necessary to plan the surgical approach in terms of risk and scheduled time in the operating theater.

13.2.3 Ureterovesical Junction Stenosis Ureterovesical junction stenosis is a defect of the ureterovesical junction, usually unilateral. It is also associated with vesicoureteral reflux (VUR) and urinary tract infections (UTI). The whole collecting system on the affected side is dilated, with the lower part more markedly affected than the upper. It is sometimes possible to visualize the premural stenotic ureteral tract (▶ Fig. 13.15). The ureter is often abnormally dilated and tortuous, and uroepithelial thickening can be seen (▶ Fig. 13.16).

13.2.1 Renal Hypodysplasia

13.2.4 Ureterovesical Reflux

Although the term dysplasia is based on a histologic evaluation, it is often used to define cases with abnormal renal parenchymal structure—unilateral or bilateral, diffuse or focal—associated with a reduction of the kidney size. It is characterized by inhomogeneous hyperechoic parenchyma with less evident or absent corticomedullary differentiation. A common finding is the presence of isolated cysts, usually small (diameter < 1 cm) in the outer, often subcapsular, cortex (▶ Fig. 13.11 and ▶ Fig. 13.12).

Ureterovesical reflux is a consequence of dysfunction in the ureterovesical junction. It is the most common urological anomaly associated with recurrent UTI in childhood and may cause renal scarring leading to reflux nephropathy (▶ Fig. 13.17). US can show various degrees of hydroureteronephrosis, which tends to increase during crying, micturition, or other maneuvers that increase abdominal pressure. Thickened uroepithelium is often seen in reflux systems.

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Kidneys

Fig. 13.12 Abnormal renal parenchymal echogenicity with small cortical, subcapsular, and exophytic cysts in a 4-year-old boy with a prenatal diagnosis of renal hypoplasia (renal function is normal).

Fig. 13.13 Three-month-old boy with prenatal finding of mild left renal pelvic dilatation. Severe pelvicaliceal dilatation with “rat tail appearance” of the ureteropelvic junction, suggestive of focal stenosis.

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Kidneys

Fig. 13.14a–c Eight-month-old girl with neonatal finding of renal pelvic dilatation. a Moderately dilated right renal pelvis with a suspected crossing vessel at the ureteropelvic junction (white arrow). b Coronal magnetic resonance balanced fast field echo image shows the relationship between the vessel and the ureteropelvic junction (white arrow). c Laparoscopy confirms the crossing vessel (white arrow) at the ureteropelvic junction (black arrow).

Fig. 13.15a,b Severe right hydronephrosis in a 3-month-old boy (a) due to distal ureteral stenosis (b). Note the difference in the ureteral caliber proximal and distal to the ureteral stricture (white arrow).

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Kidneys

Fig. 13.16 Bilateral thickening of the ureteral walls in a 10-month-old boy with bilateral stenotic megaureter.

Fig. 13.17a,b Examples of “reflux nephropathy” in two boys, 4 and 3 years old, with recurrent pyelonephritis associated with severe ureterovesical reflux: renal parenchymal thinning with asymmetric renal sizes (a), inhomogeneous hyperechogenicity, and dilated, “corticalized” calices with indented contours (b).

It may be possible to diagnose VUR on color Doppler US when backward flow of urine toward the ureter and the pelvis is detected (▶ Fig. 13.18). However, normal US findings do not exclude the presence of VUR, even if it is moderate or severe. Patients with UTI must be selected for further work-up for VUR with voiding cystourethrography (VCUG) based on the clinical presentation of the infection, the patient’s age and family history, and the US findings (see section on UTI). Severe and early antenatal VUR in male fetuses is often associated with highdegree renal dysplasia, which can lead to progressive loss of renal function.

13.2.5 Duplicate Collecting System Fig. 13.18 Five-year-old child with recurrent urinary tract infections. Enlargement of the right intramural ureteral tract, with evidence of ureteral reflux on color Doppler.

460

This is a quite common, often bilateral, urologic anomaly. Duplicate collecting systems (also known as duplex collecting systems) can be defined as renal units containing two pyelocaliceal systems. The US feature is the presence of a midrenal parenchymal septum dividing the two moieties. Indirect US findings are increased renal size (elongated “bread stick” appearance) and contour notches (▶ Fig. 13.19).

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Fig. 13.19 Incidental finding of a complete right mesorenal septum (arrow) in a 6-year-old girl (abdominal ultrasound scan performed for abdominal pain) that identifies two separate renal pelvic systems.

Fig. 13.20 Two-year-old boy with recurrent urinary tract infections. Evidence of a left vesical papilla with two separate ureteral orifices in complete ureteropelvic duplication (white arrow).

The collecting systems may fuse anywhere along their course to form a single ureter, or they may empty separately into the bladder (▶ Fig. 13.20). Dilatation of one or both ureters is a frequent finding. VUR is common, involving the lower collecting system, while ureterocele is commonly associated with the upper pole ureter (▶ Fig. 13.21). Ureterocele is a cystic dilatation of the intravesical submucosal ureter that changes in size with ureteral peristalsis/ micturition. US shows an echogenic membrane arising from the bladder wall. This membrane is more or less rounded, owing to differences in internal tension (▶ Fig. 13.22). Ureteroceles may have an ectopic orifice in the bladder neck or urethra (▶ Fig. 13.23 and ▶ Fig. 13.24). Ectopic ureters and ureteroceles may also be encountered within a single excretory system.

13.2.6 Horseshoe Kidney This anomaly is included in a group of so-called fusion anomalies, in which the two kidneys are fused in early embryonic life. Fusion anomalies of the kidneys can generally be grouped into two categories: (1) horseshoe kidney and its variants; and (2) cross-fused ectopy. Horseshoe kidney is the most common fusion anomaly. It consists of two distinct functioning kidneys on each side of the midline, connected at the lower poles by an isthmus of functioning renal parenchyma or by fibrous tissue that crosses the midline of the body. Horseshoe kidneys are usually ptotic, meaning that the distance between the posteroinferior pilaster of the diaphragm and the upper renal pole is 3 cm or more. The isthmus is located in front of the inferior cava vein, aorta, and rachis (▶ Fig. 13.25 a). VUR and/or ureteropelvic junction stenosis is more frequently seen in this anomaly (▶ Fig. 13.25 b).

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Kidneys

Fig. 13.21a,b Three-day-old girl with prenatal finding of left renal pelvis dilatation. a Two separate and dilated renal pelvises (white arrow, upper pole; black arrow, lower pole), with a dilated and tortuous ureter connected to the upper pole. b The ureter ends in an intravesical ureterocele (white arrow).

Fig. 13.22 Transverse suprapubic ultrasound scan in a 3-month-old boy who had an episode of pyelonephritis. A dilated right distal ureter prolapses into the bladder (intravesical ureterocele).

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Fig. 13.23a,b Six-month-old boy with recurrent urinary tract infections. a Left ureter, mildly dilated, ends at the level of the bladder neck. b Sagittal maximum intensity projection (MIP) reconstruction of a hydrographic highly T2-weighted magnetic resonance image confirms the ectopic infravesical end of the ureter (white arrow).

Fig. 13.24 One-year-old boy with recurrent episodes of acute urinary retention. Ectopic ureter and ureterocele in the context of a single excretory system. Midsagittal suprapubic scan shows the ectopic end of the ureter with the ureterocele, which prolapses into the urethra.

Fig. 13.25a,b Acute left renal colic in a 7-year-old boy. Parenchymal renal isthmus due to fusion of the lower kidney poles (horseshoe kidney) in an axial median ultrasound scan at the level of the transverse umbilical line. a Renal parenchymal bridge (arrows) over the rachis and aorta. b Severe left hydronephrosis due to pyeloureteral junction stenosis.

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Kidneys

Fig. 13.27 One-year-old boy with urinary tract infection. Twinkle artifact (or scintillation artifact) behind a strongly reflecting interface at the lower pole of the kidney confirms the diagnosis of renal stone (arrow).

Fig. 13.26 Eighteen-month-old boy with macrohematuria. Midrenal highly reflective structure with acoustic shadowing is diagnostic of renal stone (arrow).

Horseshoe kidney is generally distinguished from cross-fused ectopia, in which the two fused kidneys lie on one side of the spine and the ureter of the crossed kidney crosses the midline to enter the bladder on the opposite side. Therefore, the presence of a ureter behind the bladder and the absence of an ipsilateral kidney combined with an elongated contralateral kidney is highly suggestive of cross-fused ectopia.

13.3 Urolithiasis and Nephrocalcinosis Urolithiasis is the presence of stones in the urinary collecting system. It is the result of a complex interaction between the environment (stone-promoting and stone-inhibiting factors) and heredity (▶ Table 13.2). The prevalence of urinary stones varies by region, being more frequent in the Far and Middle East and less common in North America and Europe (1–5 cases per 10,000 children). Unlike infectious stones, which are found mainly in infants and young children, calcium stones increase in incidence from the age of 5 years. Uric acid stones are very rare in childhood. The classic adult presentation of sudden acute flank pain is uncommon in pediatric urolithiasis. Hematuria (gross or microscopic) is found in 33 to 90% of children and occurs equally across age groups. UTI is frequently the presenting sign of urolithiasis in preschool-age children. Table 13.2 Balance between stone-promoting and stone-inhibiting factors Promotes stone

Inhibits stone

Urinary volume

Low

High

pH/citrate

Lowa

Higha

Bacteria

Infected urine

Sterile urine

Stone-forming elements

Concentratedb

Dilute

aStruvite

stones are an exception because they require an alkaline pH in order to form. bIn the case of hypercalciuria, hyperuricuria, hyperoxaluria, and cystinuria.

464

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●

Diagnostic steps include the following: Obtaining a thorough patient and family history; Performing urinary, blood, and whenever possible stone analysis to identify metabolic abnormalities; Imaging the urinary tract.

In suspected cases of urolithiasis in children, US is always the first and most often the only imaging study required to exclude or confirm renal stones. Sonographically, a calculus within the collecting system appears as a highly reflective structure that may (usually if > 5 mm in diameter) or may not show acoustic shadowing (▶ Fig. 13.26). A twinkle artifact, which is an artifact occurring behind a highly reflective structure such as a urinary tract stone, may aid stone detection, especially if the stone lacks a strong echo or discrete shadowing. The artifact appears as a rapidly fluctuating mixture of Doppler signals (red and blue pixels) that imitate turbulent flow. However, the Doppler spectrum is absolutely flat, a finding that is characteristic of noise (▶ Fig. 13.27). US of the urinary tract must rule out stasis or an obstruction caused either by a stone or by congenital or acquired abnormalities of the urinary tract (▶ Fig. 13.28 and ▶ Fig. 13.29). The typical stone location is within the renal pelvis and/or the renal calices or the ureter, and less often within the bladder. Struvite stones (magnesium ammonium phosphate in a complex with calcium phosphate) and sometimes cystine stones frequently tend to branch and enlarge, often filling the renal calices and assuming a “stag horn” appearance (▶ Fig. 13.30). The most common ureteral calcifications are stones that migrate down from the kidney (▶ Fig. 13.31) or stones that form locally, primarily in a distal ureteral dilatation (stenotic megaureter; ▶ Fig. 13.32). These stones typically become impacted at anatomical sites of narrowing and are especially difficult to detect when they overlie bony structures such as the sacrum. Detection of a ureteral stone via US is difficult; however, the stone may cause obstruction (hydroureter or hydronephrosis) and may be suspected even if not directly visualized. Non contrast-enhanced, low-dose computed tomography (CT) is more effective than intravenous urography in precisely identifying ureteral stones, and virtually all urinary calculi are

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Kidneys

Fig. 13.28a,b Four-year-old girl with moderate hydronephrosis due to a calculus at the pyeloureteral junction (arrow, a). Note the positive twinkle artifact (b).

Fig. 13.29a–c Three-year-old girl with macrohematuria. a Moderate pelvic dilatation due to intrinsic pyeloureteral obstruction with (b) multiple stones in the lower caliceal group, confirmed (c) on preoperative uro-computed tomography, urographic phase.

visible on CT. However, because of the need for sedation in younger children and the radiation dose, spiral CT is rarely used for detecting urinary tract stones. Low-dose, non contrastenhanced CT may be indicated, particularly in older children, when a renal stone is strongly suspected and US is negative.

Tips from the Pro ●

●

Air in the collecting system may be misinterpreted as urolithiasis. However, shadowing is poorly defined in the case of air; by contrast, it is well defined in urolithiasis. Vesical intramural bulging at the ureterovesical junction secondary to the endoscopic treatment of ureterovesical reflux may sometimes be confused with a stone! Look carefully at the patient’s clinical history (▶ Fig. 13.33)!

Fig. 13.30 Four-year-old girl with gross hematuria. A pelvic stone with a “stag horn” appearance and lower and upper pole caliectasis.

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Fig. 13.31 Twelve-year-old girl with right renal colic. A small stone is located in the distal third of the ureter (arrow), with dilatation of the upper urinary tract.

Fig. 13.32 One-year-old boy with stenotic megaureter and a stone in the distal portion of the ureter. A twinkle artifact sign confirms the diagnosis. Note the ureteral jet flow, which confirms the patency of the distal ureter.

Fig. 13.33 Six-year-old girl endoscopically treated for left ureterovesical reflux. Calcified intramural vesical bulge.

Nephrocalcinosis is microscopic calcification in the tubules, tubular epithelium, or interstitial tissue of the kidney. It typically involves the medullary portion of the kidney (▶ Fig. 13.34). The echogenic pattern may vary according to the underlying tubulopathy, particularly in the initial phase (see box Classification of tubulopathies according to the section of the tubular system involved (p. 467)). This is because different tubular segments may be selectively involved, resulting in different US patterns (▶ Fig. 13.35).

Fig. 13.34 Six-month-old boy with severe growth failure and a clinical diagnosis of metabolic acidosis. Diffuse increase in outer medullary echogenicity, with inversion of the normal corticomedullary differentiation, as a result of renal tubular acidosis.

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Fig. 13.35a,b Two different patterns of medullary hyperechogenicity. a Outer medullary hyperechogenicity and intramedullary echogenic spots in a case of hypercalciuria associated with proximal tubular acidosis in a 6-month-old boy. b Diffuse medullary hyperechogenicity in a 2-year-old girl with distal tubular acidosis.

For the detection and monitoring of nephrocalcinosis, highresolution US is the optimal imaging method. In a variety of metabolic diseases, urolithiasis and nephrocalcinosis occur together (▶ Fig. 13.36). Medullary nephrocalcinosis is distinguished from both cortical (e.g., in acute cortical necrosis, chronic glomerulonephritis, and chronic graft rejection) and diffuse nephrocalcinosis. Unlike that of urolithiasis, the clinical presentation of nephrocalcinosis is often asymptomatic, especially during infancy. Thanks to the routine use of US in premature infants and in children at risk, a large number of conditions are now recognized to be associated with nephrocalcinosis.

Tips from the Pro Fig. 13.36 Fifteen-year-old boy with chronic renal failure and recurrent nephrolithiasis. Diffuse medullary nephrocalcinosis associated with lithiasis (arrow) at the lower caliceal group. Midrenal cystlike image in the medulla (arrowhead) represents an obstructive hydrotubule due to intratubular calcium deposits. Mild pyelocaliceal dilatation coexists.

Classification of tubulopathies according to the section of the tubular system involved Proximal tubules ● ● ● ● ●

Fanconi syndrome Aminoaciduria Dent syndrome Proximal tubular acidosis Idiopathic hypercalciuria

Loop of Henle ● ●

Idiopathic hypercalciuria Bartter syndrome

Distal and collecting tubules ● ● ●

Gitelman syndrome Liddle syndrome Distal tubular acidosis

●

Uromodulin deposits within the renal calices in newborns may resemble nephrocalcinosis (▶ Fig. 13.4; ▶ Fig. 13.37). These deposits, however, disappear within 1 to 2 weeks, and follow-up will show completely normal kidneys.

13.4 Kidney Cysts and Cystic Nephropathies Many renal disorders in childhood are characterized by the presence of cysts. A cyst is a dilatation that can involve different segments of the intrarenal collecting system, from glomeruli (Bowman capsules) to distal collecting tubules. The continuity with the nephron may or may not be lost. A cyst is lined by a single layer of flattened epithelium and contains clear serous fluid. There is no communication between the cyst and the collecting system (▶ Fig. 13.38). Cystic diseases of the kidney include a heterogeneous group of disorders that may be inherited or sporadic, unilateral or bilateral, and symptomatic at birth or detected later in life. Genetically determined cystic disorders are listed in box Classification of genetically determined renal cystic diseases (p. 468). Renal cysts are also present in many pathologies

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Fig. 13.37a,b Four-day-old preterm infant with hyperechogenicity of the inner medulla (a) related to uromodulin deposits within the renal calices. In the same child at 1 month of age, these deposits disappeared, and the kidneys appeared to be completely normal (b).

Classification of genetically determined renal cystic diseases Uromodulin-associated nephropathies (uromodulin renal luminal tubular transfer defects) ● ●

Medullary cystic kidney disease Familial juvenile hereditary nephritis

Ciliopathies (alterations of the cilia or centrosome proteins) ●

● ●

Fig. 13.38 Incidental finding of a large left mesorenal simple cyst in a 3-year-old girl.

(▶ Fig. 13.39) and syndromes characterized by dysmorphology or dysfunction of several organs, usually associated with various degrees of renal hypodysplasia. Acquired cysts usually appear in advanced stages of chronic renal failure.

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Autosomal-dominant/autosomal-recessive polycystic kidney disease Nephronophthisis glomerulocystic kidney disease

Congenital Anomalies of the Kidney and Urinary Tract (CAKUT) alterations in the prenatal developmental process of the kidney and the urinary tracts ● ●

Multicystic kidney disease Renal cystic hypodysplasia

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Fig. 13.39 Multiple large renal cysts and thin hyperechoic renal tissue between the cysts in a 5-year-old boy with tuberous sclerosis.

13.5 Autosomal-Dominant Polycystic Kidney Disease

Fig. 13.40 Eleven-year-old boy with a father and grandmother affected by polycystic kidney disease. Right kidney with a mesorenal dorsal cyst and a large exophytic lower pole cyst. The renal parenchyma has a normal structure.

US is the main modality used for imaging cystic kidney disease. MR and CT are complementary techniques in selected cases. Advanced software and transducers with excellent tissue penetration and spatial resolution (multiple-frequency electronic and broadband convex and linear sensors) enable the detection of very small cysts, up to 2 mm in diameter. The cysts are usually smooth with thin walls unless there are complications (e.g., bleeding, inflammation, abscesses, tumor proliferation). A characteristic sonographic sign is posterior enhancement, which is due to lack of attenuation of the US beam when it crosses the cyst. Lateral acoustic shadows due to interactions of the US beam with the cyst walls are also seen. In some cases, it is important, but sometimes not easy, to exclude a communication with the pyelocaliceal system. The detailed information gained from US, when combined with clinical data, often leads to a definitive diagnosis. ▶ Table 13.3 lists the diagnostic possibilities based on the location of cysts and kidney size.

Autosomal-dominant polycystic kidney disease (ADPKD) is one of the most common genetic pathologies, with an incidence of 1 in 1,000 live newborns. This condition is associated with renal failure in half of patients by the age of 50 years. Sometimes, it is also clinically evident in children, leading to end-stage renal failure in childhood. Clinical signs include hypertension, hematuria, and lumbar pain. ADPKD is typically bilateral, but the kidneys may be of different sizes in the early stage of the disease. The increase in renal volume is usually less than in the recessive form, and the kidney size may sometimes be within normal range. The usual findings are multiple cysts that are ubiquitous, particularly in the cortex, and more often subcapsular, with possible exophytic growth and distortion of the profile of the kidney (▶ Fig. 13.40). The renal parenchyma surrounding the cysts is often normal or may display slightly increased echogenicity (▶ Fig. 13.41). Liver involvement is the most common extrarenal manifestation of ADPKD. The development of liver cysts increases with advancing age; liver cysts are rare in childhood but may occur.

Table 13.3 Different renal pathologies suggested by the parenchymal location of cysts and kidney size Cortical cysts

Medullary cysts

Renal size decreased

Cystic hypodysplasia

Nephronophthisisa

Renal size unchanged

Glomerulocystic kidney disease

Nephronophthisisb/ medullary sponge kidney disease

Renal size increased

Autosomal-dominant polycystic kidney diseasec

Autosomal-recessive polycystic kidney diseased

aAdvanced

renal failure. renal failure. cUbiquitous cysts, mainly cortical. dUbiquitous cysts, mainly medullary. bEarly

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Fig. 13.41a,b Four-year-old boy with a family history of polycystic kidney disease. A few bilateral cortical simple cysts are present with substantially normal parenchyma (a, b). Note one cyst (arrow, b) with multiple luminal septa; this must be regarded as a cystic agglomerate.

Fig. 13.42 Autosomal-recessive polycystic kidney disease in a 6-month-old girl. Diffuse inhomogeneous multifocal renal parenchymal hyperechogenicity, with multiple small fusiform cysts.

13.5.1 Autosomal-Recessive Polycystic Kidney Disease Autosomal-recessive polycystic kidney disease (ARPKD) has an incidence of 1 in 20,000 live newborns. It is sometimes a cause of intrauterine death. It may be diagnosed at birth, in which case the baby usually has severe renal failure, or later in life. There is bilateral renal involvement with a marked increase in renal volume. Sometimes, the kidneys occupy most of the intra-abdominal space. The disease is characterized by inhomogeneous, multifocal, increased parenchymal echogenicity, particularly involving the medulla (▶ Fig. 13.42), with typical sparing of the external cortex. This results in the appearance of a linear hypoechogenic subcapsular rim that is not seen in ADPKD. The cysts occur as a result of dilatation of the tubules in the medulla (collecting tubules). They are fusiform and usually less than 1 cm in diameter (▶ Fig. 13.43 and ▶ Fig. 13.44). Hepatic complications occur in a significant proportion of children with ARPKD, with biliary dilatation and portal fibrosis.

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The liver involvement and renal involvement in ARPKD tend to be inverse, and children older than 1 year of age often present with portal hypertension rather than impaired renal function.

Tips from the Pro ●

●

●

In the prenatal and neonatal periods, both the dominant and recessive types of polycystic kidney disease may present as large, diffusely hyperechoic kidneys, and distinct cysts may not be seen in the initial phase. In ARPKD, twinkle artifacts (▶ Fig. 13.43 b) may be related to the presence of multiple small adjacent cysts throughout the medulla. “Not everything that twinkles is stones.” The entire abdomen must always be included in the US examination to look for associated hepatic cysts in ADPKD, and for dilated biliary ducts and signs of portal hypertension in ARPKD.

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Fig. 13.43a–c Two cases of autosomal-recessive polycystic kidney disease (ARPKD). A 10-year-old patient with ARPKD: multifocal medullary hyperechogenicity and microcysts at the corticomedullary junction, with sparing of the cortex (a). Twinkle artifacts are due to the highly reflecting cystic interfaces (b). In another patient with ARPKD (a 6-year-old girl), fusiform medullary cysts due to dilatation of the collecting tubules are clearly evident (arrow, c).

Fig. 13.44 Unusual case of a right kidney with stigmata of autosomal-recessive polycystic kidney disease and a left kidney that appears normal in a 7-year-old girl (ultrasound examination done for abdominal pain).

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Fig. 13.45a,b Eight-year-old girl with advanced renal failure due to nephronophthisis. Inhomogeneous increase in renal parenchymal echogenicity, with lack of the normal corticomedullary differentiation (a). Presence of small medullary cysts (arrow, b).

Fig. 13.46 Regular size and structure of the right kidney in a 2-year-old girl with left multicystic kidney and large cysts.

13.5.2 Nephronophthisis Nephronophthisis is a rare form of tubulointerstitial nephropathy in which small cysts are present in the medulla or at the corticomedullary junction; it progresses to end-stage renal failure in all cases. On US, the kidneys are of normal size in the early stage of renal failure and become small in end-stage renal failure. There is a progressive increase in parenchymal echogenicity, with reduction and subsequent loss of corticomedullary differentiation. Initially, medullary cysts may not be evident; in advanced stages of renal failure, however, small cysts (< 1 cm) may be evident (▶ Fig. 13.45).

13.5.3 Glomerulocystic Disease Glomerulocystic disease is a very rare autosomal-dominant genetic nephropathy characterized by dilatation of the Bowman spaces. The renal size can vary. US findings are nonspecific. Sometimes, there are subcapsular cortical cysts of small

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size, surrounded by heterogeneously hyperechoic parenchyma. There may be associated caliceal deformity.

13.5.4 Medullary Sponge Kidney Disease The pathogenesis of this form is unclear. The diagnosis is based on the urographic sign of medullary radial “striation” due to the presence of contrast medium in the dilated collecting tubules. US findings include medullary hyperechogenicity due to nephrocalcinosis and inversion of the normal corticomedullary differentiation; renal stones may be present. Renal involvement may also be only focal and/or partial.

13.5.5 Multicystic Kidney Disease Multicystic kidney disease is always a unilateral pathology (▶ Fig. 13.46). The affected kidney is nonfunctioning, with the

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Fig. 13.47 Four-year-old boy with a prenatal diagnosis of left multicystic kidney. Multiple cysts, heterogeneous in size and randomly located, with hyperechoic renal tissue among the cysts.

Fig. 13.48 Example of a complicated cyst: presence of a vascularized intracystic septum (arrow).

renal parenchyma completely replaced by multiple cysts; no normal renal parenchyma can be seen between the cysts. These are heterogeneous in size, randomly located, and separated by hyperechoic septa or soft tissue (▶ Fig. 13.47). A “pseudohydronephrotic” variant may be observed in which there is communication between the outlying cysts and the central one, simulating a dilated pyelocaliceal system. This condition sometimes requires a complementary MR urographic study for a definitive diagnosis. The multicystic kidney gradually involutes, while the other kidney is usually normal in structure and morphology and becomes hypertrophic to compensate. However, US follow-up, including the contralateral normal kidney, is advised to monitor the involution of the multicystic kidney and the growth of the contralateral kidney. It is reported that a decline in renal function in patients with multicystic kidney disease is possibly related to a certain degree of renal dysplasia in the contralateral kidney. There is no current literature to support the routine surgical removal of a multicystic kidney.

13.5.6 Simple Cysts Most simple kidney cysts are incidental findings (▶ Fig. 13.38). They can be located in various sites of the kidney. They are

spheroid or ovoid cavities with smooth, thin walls, posterior enhancement of echoes, and lateral acoustic hypoechoic shadows. They may compress the intrarenal collecting system, causing various degrees of caliceal or pelvic dilatation. Most simple kidney cysts are found incidentally, during imaging tests done for other reasons (▶ Fig. 13.39). In childhood, simple isolated renal cysts have to be examined at least once a year to evaluate their growth and to exclude more complex pathologies that may become evident as the child grows.

13.5.7 Complicated Cysts Renal cysts are defined as complex cysts in the following cases: ● Intracystic septa with a thickness of more than 1 mm and Doppler flow within the septa (▶ Fig. 13.48); ● Calcifications of the wall or the intracystic septa; ● Rupture of the cyst; ● Intracystic hemorrhage (▶ Fig. 13.49); ● Infection or abscess formation. In complicated cysts, MR or CT is often performed, particularly during the surgical work-up. Differential diagnoses with cystic renal tumors should also be considered.

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Kidneys corticomedullary differentiation (▶ Fig. 13.50 and ▶ Fig. 13.51) and cause enlargement of the kidney.

Wilms Tumor

Fig. 13.49 Ten-year-old boy with macrohematuria after right-sided trauma. Volume increase and hyperechoic contents in a right upper pole kidney cyst due to posttraumatic bleeding. The renal parenchyma is compressed at the periphery of the cyst.

13.6 Renal Tumors Renal tumors are rare in childhood, and they can be incidental findings when a patient is seeking medical attention for other reasons. Some malignant tumors may become very large before they become clinically evident (Wilms tumors are a typical example) because the patients often remain asymptomatic for a long time. The US features of most tumors are nonspecific, and the final diagnosis is always based on histopathology. The main role of US is to identify the presence of a tumor, to determine the organ of origin (which may be difficult when extensive tumor masses are present), and to assess possible complications that require immediate intervention. US is also used for planning and performing a biopsy. US is the first modality of choice in most radiologic examinations in children and is usually the first diagnostic step for renal tumors, so all radiologists should know a few things about how, when, and where to look for renal tumors.

The most common malignant abdominal tumor in children is Wilms tumor, also known as nephroblastoma (▶ Fig. 13.52). It accounts for approximately 90% of malignant renal tumors in childhood. The worldwide prevalence is around 1 in 10,000 children before the age of 15 years, and in up to 6% of cases, the tumors are bilateral: synchronous bilateral if they occur simultaneously and metachronous bilateral if they appear at different times. Practically all (> 99%) bilateral cases are preceded by nephroblastomatosis (▶ Fig. 13.50). Eighty percent of Wilms tumors are diagnosed before 5 years of age. The tumor usually presents as an asymptomatic abdominal mass that is sometimes very large, occupying a considerable part of the intra-abdominal space. However, the tumor may also be small and well defined, usually at the upper pole of the kidney. Wilms tumor may also present with hematuria and abdominal pain, especially when there is intratumoral hemorrhage (▶ Fig. 13.53), which may occur spontaneously or following a minor or major trauma. Ten percent of affected children have congenital anomalies (see box Anomalies associated with Wilms tumor (p. 474)), and 1 to 2% of cases are familial. Studies have suggested that Wilms tumor is slightly more frequent among people of African origin and rare among eastern Asians. Today, children with Wilms tumor generally have a good prognosis; survival rates are between 60 and 80%, even with the more unfavorable histologic subtypes.

Anomalies associated with Wilms tumor ●

● ● ● ● ● ●

13.6.1 Malignant Tumors Nephroblastomatosis Embryologically, the kidneys are fully developed around 36 weeks of gestation. In about 1% of infants, embryologic tissue persists. The presence of these nephrogenic remnants is called nephroblastomatosis. They may resolve spontaneously but may also undergo malignant transformation into Wilms tumors (▶ Fig. 13.50), especially in a genetically susceptible child. The location of these remnants in the kidney depends on the stage at which nephrogenesis is interrupted. The lesions are divided into perilobar remnants, which typically lie in the peripheral cortex or columns of Bertin, and interlobar remnants. The latter are less frequent but more likely to transform into neoplasia. Nephroblastomatosis can be very difficult to detect with US alone but in a perilobar location may reduce the

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Wilms tumor, aniridia, genitourinary abnormalities, mental retardation (WAGR)a Denys–Drash syndromea Beckwith–Wiedemann syndrome Trisomy 18 Neurofibromatosis Multicystic dysplastic kidneys aIt has been suggested that children with this condition have a 50% chance of developing Wilms tumor, and it is recommended that they be sonographically screened every 3 to 4 months until 5–7 years of age.

US shows a well demarcated mass with inhomogeneous echogenicity: both cystic hypoechoic and hyperechoic areas due to necrosis and fat deposits (▶ Fig. 13.54). Nine percent of Wilms tumors are calcified. Sometimes, there is a hypoechogenic capsule. It is crucial to use a linear high-frequency probe for optimal visualization of the parenchyma. When a large tumor mass is present, it may be difficult to determine whether the tumor arises from the kidney. One characteristic sign that may help to differentiate a Wilms tumor from an extrarenal mass is the socalled lobster claw sign, in which the renal parenchyma resembles a claw that grasps the tumor (▶ Fig. 13.55; Staging of Wilms tumor (p. 476)).

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Fig. 13.50a,b a Perilobar nephrogenic rests in the left renal cortex, seen as hypovascularized, hyperechogenic areas (arrows) with reduced corticomedullary differentiation. b Corresponding coronal contrast-enhanced computed tomographic scan showing nephrogenic remnants in the left kidney (arrow) and a Wilms tumor in the right kidney (asterisk). (Images courtesy of Dr. Yvonne Simrén, Department of Pediatric Radiology, Sahlgrenska University Hospital, Göteborg, Sweden.)

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Staging of Wilms tumor ● ● ●

● ●

Stage I Tumor limited to kidney, completely resected Stage II Tumor not limited to kidney but fully resected Stage III Tumor not completely resected, confined to abdomen Stage IV Metastatic spread to lung, liver, bone, or brain Stage V Bilateral tumor

Thrombosis in the renal vein and inferior vena cava is relatively common, and the tumor itself may invade these structures (▶ Fig. 13.56). Although these tumors often are contained within a pseudocapsule, they may be invasive and extend through the renal capsule into mesentery and omentum. Metastases are typically seen in the liver and lungs (see box). Fig. 13.51 Diffuse nephroblastomatosis in the right kidney of 4-yearold girl. Reduced corticomedullary differentiation and an overall enlarged kidney. (Images courtesy of Dr. Yvonne Simrén, Department of Pediatric Radiology, Sahlgrenska University Hospital, Göteborg, Sweden.)

Tips from the Pro ●

Always check for thrombosis in the renal vein and inferior vena cava. Always scrutinize the contralateral kidney, and use a high-frequency linear probe.

Fig. 13.52a,b a Ultrasound of a large left-sided Wilms tumor in which the renal parenchyma (arrow) is left as a thin rim around the tumor mass (arrowhead). b As shown on the corresponding T2-weighted magnetic resonance image, these tumors typically become large (asterisk) before detection.

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Fig. 13.53 Large left-sided Wilms tumor with acute intratumoral hemorrhage showing as anechoic dark fluid (arrow) and surrounding solid tumor (asterisks). These patients may present with acute abdominal pain, with or without preceding trauma.

Clear Cell Carcinoma Clear cell carcinoma is the most common type of renal cell carcinoma; however, it is still rare in children and accounts for between 2 and 6% of renal neoplasms in childhood. The overall peak age is 1 to 4 years, but clear cell carcinoma may be found in younger children. Other types include papillary renal cell carcinoma, chromophobe renal cell carcinoma, and duct renal cell carcinoma. The tumor usually originates in the renal medulla. Von Hippel-Lindau disease and tuberous sclerosis are two known risk factors for this type of neoplasm. These tumors may show calcifications in about 25% of cases. They typically infiltrate the medulla and sometimes the renal pelvis. Metastases are found primarily in the skeleton, but also in lymph nodes, brain, liver, and lungs. Vascular thrombus is a very rare complication but has been reported. The tumors are highly malignant, and the prognosis is generally poor. The findings on US are similar to those in small Wilms tumors (▶ Fig. 13.57), but skeletal metastasis is a clue that suggests this diagnosis.

Renal Cell Carcinoma Renal cell carcinoma is a rare tumor in children but may be seen, especially in the form of a malignancy secondary to immunosuppression after chemotherapy and/or radiation. Children with tuberous sclerosis, Beckwith–Wiedemann syndrome, or urogenital malformations are at increased risk for developing this neoplasm. Boys are affected twice as often as girls and are usually 10 years of age or older. Patients present with abdominal flank pain, abdominal mass, and hematuria. The masses may invade the retroperitoneum, renal vein, and inferior caval vein. Metastases are found in lymph nodes, liver, and lung. The US findings are similar to those seen in Wilms tumor, but if the child is 10 years of age or older, renal cell carcinoma is a more likely diagnosis.

Rhabdoid Tumor Rhabdoid tumors typically occur in young infants. The peak age at diagnosis is around 18 months, and there is a slight male predominance. This tumor is highly aggressive and has the poorest

Fig. 13.54 Heterogeneous Wilms tumor with cystic hypoechoic areas (arrowhead) and hyperechoic areas with fatty infiltration (arrow).

prognosis of all pediatric renal tumors. Patients present with abdominal mass, hematuria, fever, hypertension, and hypercalcemia. Metastases are found in the central nervous system (CNS), and the CNS lesions sometimes become clinically evident before the renal masses are detected. Like all other renal tumors, rhabdoid tumors cannot be distinguished from Wilms tumors by US alone. The margins may be diffuse, and the capsule is thick. Calcification may be seen. Local invasion of adjacent structures and vessels is relatively common.

Lymphoma The kidneys usually do not contain lymphoid tissue, so lymphomatoid involvement of the kidneys occurs from hematogenous spread, usually of a non-Hodgkin (especially Burkitt) lymphoma. Other variants are very rare. It has been reported that as many as 62% of patients with non-Hodgkin lymphoma have renal involvement at autopsy, but in only 3 to 8% was this evident at imaging. Usually, symptoms appear at a very late stage, and patients may then present with flank pain, hematuria, palpable mass, and weight loss. Because of diffuse infiltration, lymphoma may be very difficult to discover on US, and global enlargement of the kidney may be the only sign. However, cases have been described of subcortical masses exhibiting any echogenicity.

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Fig. 13.55a,b a “Lobster claw” sign, in which the renal parenchyma (arrows) encircles the infiltrating tumor (asterisk). b The corresponding contrast-enhanced computed tomographic scan shows the same picture: enhancing renal parenchyma (arrows) with a tumor of low attenuation (asterisk) in the upper pole.

13.6.2 Benign Tumors Mesoblastic Nephroma (Renal Hamartoma) This is the most common kidney tumor in infants, typically presenting in the first 6 months of life as a palpable abdominal mass. It has a slight male predominance. The tumors are usually unilateral, may be detected prenatally, and are considered benign, although they have been known to metastasize. Mesoblastic nephromas differ from Wilms tumors in that they usually infiltrate the renal parenchyma and sinus, lack a surrounding capsule, and do not infiltrate the vascular tree.

Multilocular Cystic Nephroma Multilocular cystic nephroma is a rare benign type of renal tumor that contains multiple cysts separated by septa. Multilocular cystic nephromas typically affect boys younger than 2 years of age and adult women. They usually present as a painless abdominal mass (▶ Fig. 13.58). Imaging alone cannot differentiate this mass from a Wilms tumor, but the multiple cystic areas are a diagnostic clue.

Angiomyolipoma (Renal Hamartoma) Angiomyolipomas are most frequently seen in children with tuberous sclerosis. They consist of fat, smooth muscle, and vessels. The vascular pattern is sometimes distinct, characterized by large, dilated vessels. The lesions are usually small and bilateral, and usually asymptomatic. They may become large, and with increased size there is a higher risk for fatal hemorrhage from vessels in which aneurysms may form. Therefore, tumors larger than 4 cm should be embolized or resected. In extreme cases, the tumors may become locally aggressive and invade tissue such as lymph nodes and the inferior caval vein. When US examinations reveal hyperechoic lesions in the renal cortex in patients with tuberous sclerosis, angiomyolipoma is the most likely diagnosis (▶ Fig. 13.59).

Metanephric Adenoma

Fig. 13.56a,b a Thrombus in the right renal vein (arrow) and adjacent heterogeneous tumor (asterisk) in the right kidney. b Thrombus in the inferior vena cava (asterisk). (Images courtesy of Dr. Bjarne Smevik, Department of Pediatric Radiology, Oslo University Hospital, Norway.)

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This tumor can occur at any age, is unilateral, and has a slight female preponderance. Patients present with pain, flank mass, hematoma, hypercalcemia, and hypertension. On US, the tumor is a well defined, solid, and hypervascularized renal mass.

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Fig. 13.57a–c a Renal cell carcinoma in the right kidney, located at the upper pole, seen as a heterogeneous solid mass. b Same tumor as in a with color Doppler. Doppler signal in the tumor differs from that in the healthy kidney. c Corresponding contrast-enhanced coronal computed tomographic scan of the tumor shown in a and b in the upper pole of the right kidney, situated in close proximity to the liver but with no obvious infiltration of adjacent structures. Note the small rim of contrast in the periphery of the tumor.

Fig. 13.58a,b a Cystic nephroma in a 2-year-old boy presenting with an asymptomatic abdominal mass. These tumors typically show multiple cysts and intertwining septal areas. The left picture was taken with a curved probe (8 MHz) and the right with a high-frequency linear probe (12 MHz). (Image courtesy of Dr. Eiríkur Gunnlaugsson, Department of Pediatric Radiology, Oslo University Hospital, Norway.) b Corresponding contrastenhanced axial computed tomographic scan of the same patient as in a.

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Fig. 13.59a,b Small angiomyolipomas in the right kidney (arrows, a, b), seen as hyperechoic masses. Note the small cortical cysts (arrowheads, a), which are a frequent finding in patients with tuberous sclerosis.

13.7 Urinary Tract Infection UTI is common in childhood, with a lifetime prevalence of 2 to 8%. The risk for recurrent UTI is 12 to 30% in the first year after the initial infection. Patients with upper UTI are at risk for developing renal scars. Escherichia coli causes 60 to 90% of all UTIs in childhood. Non-E. coli infections are seen more frequently in patients who have renal malformations or renal calculi, who have undergone bladder catheterization, or who have had repeated treatments of UTI with antibiotics. Clinical tests have attained a relatively high level of diagnostic accuracy, thus reducing the role of imaging in diagnosing UTI. Several guidelines have been published during the last decade with suggested imaging algorithms for children who have UTI, based on the age of the patient and the clinical presentation of the infection. The guidelines of the National Institute for Health and Clinical Excellence, United Kingdom, for the management of UTI in childhood (www.nice.org.uk/CG054) are among the most frequently used (▶ Table 13.4). Routine imaging is not recommended to diagnose and localize UTI in children. However, in younger patients, both diagnosing UTI and differentiating infection in the lower from that in the upper urinary tract can be difficult based on clinical and laboratory findings alone. Comprehensive US with added amplitude-coded color Doppler sonography has a high sensitivity for renal involvement in UTI and is the main modality of choice when the clinical assessment is inconclusive (▶ Fig. 13.60). US is ideal to diagnose obstruction of the urinary tract and should also be used for the assessment of acute complications of UTI, such as a renal abscess (▶ Fig. 13.61). Growth impairment resulting from renal scarring should be assessed by comprehensive measurement of the kidney in three planes; however, US is not sensitive for renal scars as such, and dimercaptosuccinic acid (DMSA) scan remains the modality of choice for the detection of parenchymal loss. The main aim of the radiology work-up in children with UTI is to depict underlying conditions that could make the patient more susceptible to renal damage caused by the infection, such as signs of atypical disease and unidentified malformations with or without obstruction. US should always be the first modality of choice in this assessment; it may be entirely diagnostic or can be used to tailor further investigations in cases of more complex malformations (▶ Fig. 13.62).

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The sonographic signs of acute pyelonephritis include focal or generalized nephromegaly due to edema, focal or generalized increased echogenicity, and reduced corticomedullary differentiation (▶ Fig. 13.60 a). Amplitude-coded color Doppler sonography shows focal perfusion defects within the kidney (▶ Fig. 13.60 b). In pyelonephritis, the renal pelvis typically shows slightly thickened and echogenic uroepithelium. A mildly increased anteroposterior diameter of the renal pelvis may be seen. This is normally due to hypotonia of the muscle wall caused by the inflammation (▶ Fig. 13.60 c). Increased echogenicity of the perirenal fat may be seen, and sometimes there is a sliver of free fluid surrounding the renal pelvis. The urine may be echogenic because of pyuria (▶ Fig. 13.62).

Table 13.4 Summary of the National Institute for Health and Clinical Excellence (NICE) guidelines recommended algorithm for children with urinary tract infection Age

Responds well to treatment within 48 hours

Atypical UTIa

Recurrent UTIb

< 6 months

Ultrasoundc

Ultrasound, DMSA scan, VCUG

Ultrasound, DMSA scan, VCUG

6 months–3 years

None

Ultrasound and DMSA scand

Ultrasound and DMSA scand

> 3 years

None

Ultrasound

Ultrasound and DMSA scan

Abbreviations: DMSA, dimercaptosuccinic acid; UTI, urinary tract infection; VCUG, voiding cystourethrography. aAtypical UTI: non-Escherichia coli UTI, seriously ill, poor urine flow, abdominal or bladder mass, raised creatinine, septicemia, failure to respond to treatment with suitable antibiotics within 48 hours. bRecurrent UTI: two or more episodes of UTI with acute pyelonephritis/ upper urinary tract infection or one episode of UTI with acute pyelonephritis/upper urinary tract infection plus one or more episodes of UTI with cystitis/lower urinary tract infection or three or more episodes of UTI with cystitis/lower urinary tract infection. cIf ultrasound is abnormal, consider VCUG. dConsider VCUG if dilatation on ultrasound, poor urine flow, non-E. coli infection, family history of vesicoureteral reflux.

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Fig. 13.61 A renal abscess is seen as a fluid-filled structure within the kidney, with or without internal echoes. The absence of Doppler signal within the lesion combined with clinical signs of infection will facilitate the differentiation of a renal abscess from other expansive processes within the kidney.

13.8 Renovascular Disease 13.8.1 Renal Artery Stenosis

Fig. 13.60a–c a The sonographic features of pyelonephritis include generalized or focal swelling of the kidney, seen as a wedge-shaped hyperechoic area within the kidney with reduced corticomedullary differentiation (arrows). b Corresponding focal perfusion defects, best seen with amplitude-coded Doppler sonography, are visible (arrows). c Hypotonia of the renal pelvis due to mild pelvic dilatation (arrow) caused by inflammation is often found together with slightly thickened and echogenic uroepithelium (arrowhead).

Renovascular disease is uncommon in children and accounts for approximately 5 to 10% of all cases of childhood hypertension. Unlike in the adult population, renovascular hypertension in childhood is rarely related to atherosclerosis; it is most commonly caused by fibromuscular dysplasia, syndromes (most often neurofibromatosis type 1), vasculitis, trauma, tumor, or thrombus, particularly from umbilical artery catheters. One to two percent of renal transplant recipients develop renal artery stenosis at the renal allograft (see section on renal transplantation). US is often the initial examination in the assessment of renovascular disease in children. It is regarded as a baseline examination and will tailor further work-up in combination with the clinical and laboratory assessment. The examination should include meticulous color and spectral Doppler examination of the renal arteries. Both extrarenal and intrarenal arteries should be assessed. Signs of renal artery stenosis include reduced peak systolic velocity distal to the stenosis and increased acceleration time (< 70 milliseconds). Aliasing at the site of the stenosis in the renal artery caused by turbulent flow may be seen on a successful examination of the extrarenal vessel (▶ Fig. 13.63). Visualization of the entire length of the renal arteries is preferred but may be impossible in an uncooperative child. Therefore, the most important sign of renal artery stenosis in children is the slow upstroke arterial waveform on pulsed Doppler examination of the intrarenal arteries, the so-called pulsus tardus et parvus pattern (▶ Fig. 13.64). Children with hypertension and any of the above-mentioned sonographic signs of renal artery stenosis should be referred for further work-up. MR angiography involves no radiation exposure, so this technique can be ideal in children. However, MR angiography, even with intravenous gadolinium contrast, has a

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Fig. 13.63 In renal artery stenosis, there will be turbulent flow around the stenotic area within the vessel. This may be seen as aliasing on color Doppler ultrasound (arrow).

artery stenosis may be absent and the parvus tardus effect masked if the renal vessels are noncompliant. Angiography is therefore indicated with a normal US examination if the child is symptomatic, has very high blood pressure or risk factors for renovascular disease, and the blood pressure is not controlled with two or more antihypertensive drugs.

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Fig. 13.62a,b Ultrasound has a high sensitivity in the assessment of obstruction and may reveal malformations of the urinary tract. This duplex kidney has hyperechoic pus in an infected, dilated upper moiety. The lower moiety is also dilated but shows anechoic urine (a). The obstruction is caused by a dilated ureterocele with pus prolapsing into the bladder from the upper ureter (asterisk, b). The large ureterocele compromises flow from the lower ureter ostium, causing obstruction of the lower moiety, as well.

relatively low spatial resolution and a tendency to overdiagnose stenosis in small arteries. Furthermore, the technique has not been properly evaluated for the assessment of renal artery stenosis in children. CT angiography has a better spatial resolution than does MR angiography and is often a preferred technique in suspected renal artery stenosis. The ability to detect relevant stenosis in small arteries on CT angiography is questionable, and the technique has the disadvantage of a high radiation dose. Digital subtraction angiography remains the gold standard for this diagnosis and offers a potential therapeutic intervention in the same session. The reported sensitivity of US in detecting or suspecting renal artery stenosis is variable, and the sonographic signs of renal

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If a child is unable to hold his or her breath, pulsed Doppler traces may still be obtained by keeping the cursor still and obtaining the Doppler traces as the artery moves in and out of the “gate” with respiration. Clinically significant renal artery stenosis may occur in a polar artery. Therefore, Doppler traces should be obtained both in the middle part and in the upper and lower poles of the kidney.

13.8.2 Renal Vein Thrombosis Renal vein thrombosis is rare in childhood and most often occurs in the neonatal period. Risk factors for neonatal renal vein thrombosis include asphyxia, maternal diabetes mellitus, dehydration, congenital renal malformations, and infection. There is a male predominance, 70% of cases are unilateral, and it occurs more frequently on the left side. In the neonate, renal vein thrombosis usually starts in the arcuate and intralobular small veins and spreads into the larger renal veins and, in 40% of cases, into the inferior vena cava. In older children, the thrombus arises in the larger veins and spreads retrograde into the smaller veins of the kidney. The main clinical features of renal vein thrombosis are hematuria, thrombocytopenia, and flank pain, but only approximately 20% of patients present with all three main symptoms.

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Fig. 13.64a,b The slow upstroke, pulsus tardus et parvus pattern, is suggestive of renal artery stenosis.

Fig. 13.65 Ultrasound features in the acute phase of renal vein thrombosis include nephromegaly, loss of corticomedullary differentiation, and hyperechoic streaks within the inter- and intralobar veins (arrow).

US is the modality of choice in suspected cases of renal vein thrombosis and has by large replaced renal venography in establishing the diagnosis. The sonographic features of renal vein thrombosis vary with its stage and severity. Initially, there is nephromegaly with increased echogenicity of the renal parenchyma and loss of corticomedullary differentiation. Hyperechoic intermedullary streaks radiating from the renal hilum are a characteristic sonographic feature of renal vein thrombosis. The streaks represent blood clots in the interlobular vessels (▶ Fig. 13.65). The nephromegaly usually increases during the first week after presentation, and edema and hemorrhage may cause heterogeneous echogenicity (▶ Fig. 13.66). The kidney will eventually shrink, and there may be calcification of the renal parenchyma and/or the renal vein. The findings on duplex and color Doppler examination in the initial phase include a severely increased RI, often with reversed diastolic flow and absent flow in the renal vein (▶ Fig. 13.67). The clots in the intrarenal vessels will retract, and collateral veins will form in the renal hilum; therefore, intrarenal venous flow may be seen in the later stages of renal vein thrombosis (▶ Fig. 13.68). Particularly when it occurs on the left side, renal vein thrombosis is associated with adrenal hemorrhage because the left adrenal vein drains directly into the left renal vein. Adrenal hemorrhage is hyperechoic in the acute phase but rapidly liquefies and usually becomes anechoic (▶ Fig. 13.69). The hemorrhage most often involves the entire adrenal gland, but occasionally only one limb is affected.

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Fig. 13.66 The sonographic features of renal vein thrombosis change over time. Within the first week after presentation, the nephromegaly increases, and there is a more heterogeneous parenchyma, typically with patchy hyperechoic areas and loss of corticomedullary differentiation. (Courtesy of Ingegerd Aagenæs, Oslo University Hospital, Norway.)

Fig. 13.67 In the acute phase of renal vein thrombosis, there is no venous flow in the renal hilum. The congestion of blood within the kidney causes a high resistive index, and the diastolic arterial flow may be reversed.

Fig. 13.68 In the later stages of renal vein thrombosis, tortuous venous collaterals may form in the renal hilum that give rise to venous flow on color Doppler sonography.

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Fig. 13.69 Adrenal hemorrhage is an associated finding in renal vein thrombosis, particularly on the left side, and is most often seen as a hypo- or anechoic mass at the upper pole of the kidney (asterisk). Note also the thrombus in the small intrarenal veins (arrow).

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13.9 Parenchymal Nephropathy

Fig. 13.70 Ten-year-old boy with the rapid onset of acute postinfectious glomerulonephritis and hematuria. Enlarged kidneys with increased cortical echogenicity that is particularly evident at the corticomedullary junction.

The term parenchymal nephropathy defines different forms of diffuse or focal renal tissue damage due to genetic or metabolic defects, toxic injuries, or acquired immune-mediated diseases. This damage may involve the glomeruli, tubules, and/or interstitium and vessels. The most typical appearance of renal parenchymal diseases on gray-scale US is a diffuse increase in the echogenicity of the parenchyma of both kidneys, with increased or reduced echogenicity of the renal pyramids (▶ Fig. 13.70). Color and power Doppler analysis of intrarenal flow may reveal an increase in the RI value (> 0.7; ▶ Fig. 13.71). However, even though color Doppler US enables morphological and functional evaluation of the renal parenchyma, it has low specificity and sensitivity (▶ Fig. 13.72) in defining parenchymal nephropathies. Therefore, the role of US is to distinguish the different parenchymal nephropathies according to the broad classes of renal failure (prerenal, postrenal, or renal). In

Fig. 13.71 Congenital nephrotic syndrome in a 4-month-old girl with heavy proteinuria and diffuse edema. Note the increased intrarenal resistive index (arcuate arteries).

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Fig. 13.72 Mild chronic renal failure in a 13-yearold girl with histologically severe lupus nephritis. Diffuse corticomedullary hyperechogenicity.

Fig. 13.73a,b Fourteen-year-old boy with moderate chronic renal failure due to focal segmental glomerulosclerosis. a Reduction of renal size, diffuse altered parenchymal echogenicity, loss of normal corticomedullary differentiation. b Evidence of small acquired cortical cysts (white arrow).

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Fig. 13.74 Seven-year-old boy with acute renal failure due to membranoproliferative glomerulonephritis. Increase in renal size with diffuse parenchymal hyperechogenicity.

Fig. 13.75 Acute nephrotic syndrome and renal failure in a 14-year-old boy with lupus nephritis. Large kidneys with cortical hyperechogenicity.

“prerenal” acute renal failure, there are usually no US-detectable abnormalities, except for renal parenchymal hyperechogenicity in the case of severe renal hypoperfusion. Some US patterns associated with the different forms of parenchymal nephropathy are summarized below.

13.9.1 Glomerular Nephropathies These are the most common forms of renal injury and are often due to primary or secondary immunologic pathologies. They present with macrohematuria, proteinuria, renal failure, and hypertension. The common, but nonspecific, US signs include increased cortical echogenicity and corticomedullary differentiation, with echogenicity that may be analogous to that of the liver and spleen (▶ Fig. 13.70, ▶ Fig. 13.71, ▶ Fig. 13.72, ▶ Fig. 13.73, ▶ Fig. 13.74, ▶ Fig. 13.75, ▶ Fig. 13.76, ▶ Fig. 13.77). In the most serious proteinuric forms, it is possible to find a relatively thin hypoechoic subcapsular linear rim

due to edema (▶ Fig. 13.78). Another finding may be thickening of the renal pelvic walls. Doppler US is usually within the normal range (RI, 0.50–0.70) except for cases with greater inflammatory involvement (▶ Fig. 13.71).

13.9.2 Tubular Nephropathies Acute tubular necrosis is clinically characterized by acute renal failure resulting from tubule cell death due to prolonged renal ischemia, nephrotoxins, or sepsis. US is often inconclusive, but increased cortical echogenicity is commonly observed. Color Doppler shows a reduction in the parenchymal color signal and, sometimes, hypoechoic areas with reduced perfusion due to infarctions. Tubular nephropathies are quite rare and caused by genetic tubular defects. Symptoms are variable and depend on the tubular tract affected (e.g., isolated hypercalciuria, Fanconi syndrome).

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Fig. 13.76 Genetically diagnosed Alport syndrome in an 11-year-old boy with mild chronic renal failure and heavy proteinuria. Large kidneys with an almost homogeneous increase in cortical echogenicity.

Fig. 13.77 Comparable echogenicity between the liver and the kidney due to increased renal parenchymal echogenicity in a 12-year-old girl with acute glomerulonephritis.

Fig. 13.78 Congenital nephrotic syndrome in a 4-month-old girl with heavy proteinuria and diffuse peripheral edema. Cortical hyperechogenicity with a hypoechoic subcapsular rim. Note the perirenal ascites.

Nonspecific US findings are an increase in medullary echogenicity up to the inversion of the normal corticomedullary differentiation and/or multiple hyperechoic spots (▶ Fig. 13.79).

13.9.3 Interstitial Nephropathies Interstitial nephropathies are uncommon and often due to drug toxicity or to immunologic causes. Mild renal failure and mild proteinuria are the most frequent clinical findings. The US scan can be normal or may reveal a mild increase in parenchymal echogenicity. In the case of severe interstitial inflammation, the intrarenal RI may be increased (> 0.70).

Fig. 13.79 Distal renal tubular acidosis with hypercalciuria in a 6month-old girl with failure to thrive. Medullary nephrocalcinosis and perimedullary hyperechogenicity.

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Fig. 13.80 Two-year-old girl with acute renal failure due to hemolytic-uremic syndrome. Enlarged kidneys with intense cortical hyperechogenicity.

Fig. 13.81 Follow-up sonography in a 7-year-old boy with previous severe renal thrombotic microangiopathy (and severe acute renal failure at the onset of the disease). Normal-sizesd kidneys with residual mild increase in cortical echogenicity.

13.9.4 Vascular Nephropathies The involvement of small intrarenal vessels is rare in childhood. Gray-scale US is usually normal or reveals a mild increase in corticomedullary echogenicity. Color Doppler may reveal an increased intrarenal RI (> 0.70) or focal areas with poor or nondetectable vascular signals. In hemolytic-uremic syndrome, marked cortical hyperechogenicity is always present in the acute phase (▶ Fig. 13.80). US color Doppler may serve as a prognostic tool (▶ Fig. 13.81). In the acute phase, the intrarenal RI is higher

than normal (> 0.70), and the arterial diastolic flow is very often abolished. Color Doppler abnormalities may precede the clinical onset of acute renal failure, whereas their disappearance is a prelude to functional improvement.

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In parenchymal nephropathies, the diagnostic role of US is limited and US findings are nonspecific. A definitive diagnosis requires clinical and often histologic data.

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Fig. 13.82a,b Ultrasound has relatively low sensitivity for renal trauma but may be used to exclude major trauma. These images show a grade IV laceration of the left kidney (arrows) with a surrounding intracapsular hematoma (asterisks), initially shown by ultrasound (a) and later confirmed by computed tomography (b).

13.10 Renal Trauma

Fig. 13.83a,b Gray-scale sonography has relatively low sensitivity for renal trauma. a The renal laceration can be seen only as a subtle irregularity of the renal cortex with a slightly reduced echogenicity of the underlying parenchyma (arrow). b When color Doppler is applied, the renal laceration can be seen clearly, and its extension into the renal parenchyma can be determined. (Courtesy of Ingmar Gassner.)

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Children are more susceptible than adults to renal damage following blunt trauma because they have larger organs compared to total body volume, less perirenal fat tissue, and overall weaker anatomical protection. Blunt abdominal trauma accounts for the majority of injuries to the urinary tract in childhood, and of those, more than half affect the kidneys. Overall, the kidney is the third most commonly injured internal organ in children. Parenchymal damage usually results from direct impact, whereas injuries to the vascular tree and collecting system are more likely to come from deceleration. Hematuria may or may not be seen in renal damage. The degree of hematuria does not necessarily correlate with the severity of renal damage, but all patients who present with macroscopic hematuria following trauma need to be carefully assessed radiologically. US can, if carried out by a trained, experienced professional, help exclude major renal damage (▶ Fig. 13.82). Minor injuries are very difficult to detect. Therefore, it has been suggested that US may be the first choice in imaging when it comes to minor trauma, and that CT should be performed if the US examination is inconclusive or the patient presents with symptoms that do not correspond to the imaging results. The US examination, including color Doppler US, must be meticulously carried out. Renal lacerations can be difficult to detect on gray-scale sonography alone (▶ Fig. 13.83). The extent of renal damage is also more easily depicted when color Doppler is applied (▶ Fig. 13.84). The sensitivity of contrast-enhanced US is much higher, even for minor renal trauma, than that of conventional US, including Doppler examination. To date, however, the only US contrast agent available in Europe (SonoVue, Bracco Imaging) is not yet approved for children; therefore, it has to be used “off label” with written consent from the child’s legal guardians. US, including color Doppler US, also plays a major role in the follow-up of patients with proven grade III or higher renal trauma. Renal hemorrhages are often self-limiting because of the strong renal capsule. However, if a hematoma becomes large, the venous and subsequent arterial flow to the kidney may become compromised because of the high pressure within

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Fig. 13.84a–c The application of color Doppler sonography helps to determine the extent of renal trauma. a On gray-scale sonography, a hematoma is seen around the lower pole of the left kidney (arrows), and the underlying renal parenchyma looks relatively normal. b Color Doppler sonography reveals normal perfusion of the upper pole of the kidney and severely impaired blood supply to the lower pole. c Computed tomographic examination confirms the sonographic findings (arrow). (Courtesy of Ingmar Gassner.)

the capsule, requiring decompression of the kidney. Therefore, a hematoma must be followed closely, and the renal flow and RI must be measured. Compression of the kidney parenchyma by a subcapsular hematoma may also result in hypertension, the so-called Page kidney. The compression decreases blood flow to the kidney, which triggers excess secretion of the hormone renin; this, in turn, produces hypertension (▶ Fig. 13.85). The ESPR (European Society of Pediatric Radiology) uroradiology task force group has published suggested imaging algorithms for children with suspected mild to moderate renal trauma and for patients with severe trauma (▶ Fig. 13.86 a, b).

13.10.1 Renal Trauma Grading According to the American Association for the Surgery of Trauma (AAST), renal trauma is graded as follows: ● Grade I: contusion or nonenlarging subcapsular hematoma; ● Grade II: superficial laceration < 1 cm in depth, does not involve the collecting system, nonexpanding perirenal hematoma; ● Grade III: laceration > 1 cm without extension into the renal pelvis or collecting system, no evidence of urine extravasation; ● Grade IV: laceration extends to renal pelvis or urinary extravasation; ● Grade V: shattered kidney; devascularization of the kidney due to hilar injury. CT is still considered the gold standard as the first-line imaging tool in trauma to the urinary tract, and it should be offered to all hemodynamically stable patients in whom severe renal damage is considered a risk.

13.11 Pediatric Renal Transplantation 13.11.1 Early Postoperative Assessment The purpose of color Doppler US in the early follow-up of pediatric patients with renal transplants is to confirm vascular patency and peripheral parenchymal perfusion. It is also important to evaluate parenchymal abnormalities, dilatation of the collecting system, the position of drains and stents, and perirenal collections (i.e., hematoma, urinoma, lymphocele, and abscess). A transient mild degree of pelvicaliceal dilatation can be seen in the immediate postoperative period (▶ Fig. 13.87).

13.11.2 Differential Diagnosis of Early Graft Dysfunction Nephrologic Complications Causing Early Graft Dysfunction Nephrologic complications include acute tubular necrosis, acute rejection, nephrotoxicity, and UTI with acute pyelonephritis. The US features of acute tubular necrosis, acute rejection, and nephrotoxicity are nonspecific and include renal enlargement with thickening and heterogeneity of the renal cortex, loss of corticomedullary differentiation, relative hypoechogenicity of the renal pyramids in relation to the more hyperechoic cortex, and thickening of the walls of the collecting system. Acute rejection should be suspected when there is decreased diastolic flow with an RI higher than 0.9, but this sign is nonspecific. The distinction between acute tubular necrosis, acute rejection, and

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Fig. 13.85a,b a Initial ultrasound of a case of suspected renal trauma shows a thin, hardly visible subcapsular hematoma, confirmed by computed tomography (CT; arrows). A couple of days later, the child developed hypertension with an accumulation of perirenal blood, and subsequent development of a Page kidney was suspected. b Follow-up ultrasound (US) shows an increased subcapsular hematoma compressing the renal parenchyma, which was confirmed by CT (arrows). US is usually sufficient to confirm the diagnosis in the right clinical setting.

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Fig. 13.86a,b Suggested imaging algorithms by the ESPR (European Society for Paediatric Radiology) uroradiology task force in major (a) and minor (b) urinary tract trauma. (Source: ESPR uroradiology task force and ESUR paediatric working group: imaging recommendations in paediatric uroradiology, part IV: Minutes of the ESPR uroradiology task force mini-symposium on childhood renal hypertension and imaging of renal trauma in children. Riccabona M, Lobo ML, Papadopoulou F, et al. Pediatr Radiol 2011;41(7):939–944.)

Fig. 13.87 Ten-year-old boy scanned on the 7th day after renal transplantation. Mild-degree pelvic dilatation should be considered a normal finding in the early postoperative period.

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Fig. 13.88a,b Acute vascular rejection findings in two male patients with transplants. a Thickening of the walls of the pelvis. b Heterogeneity of the renal cortex, less evidence of corticomedullary differentiation, and decreased diastolic flow with a higher resistive index.

drug nephrotoxicity cannot be made on the basis of radiologic findings alone, and renal biopsy remains the diagnostic gold standard (▶ Fig. 13.88).

Surgical Complications Causing Early Graft Dysfunction Peri-transplant fluid collections can easily be seen on US. Further imaging or imaging-guided aspiration is often necessary to distinguish between the different causes and types of collections. Some sonographic features may, however, give clues to the diagnosis. Lymphoceles are collections of lymphatic fluid that lack an epithelial lining; they are caused by injury to the lymphatic structures in the hilum of the donor kidney. Lymphoceles normally occur 4 to 8 weeks after surgery. If small, lymphoceles are usually asymptomatic; however, they can be of considerable size and may obstruct the transplant ureter and/or compress the iliac vein, causing leg swelling or thrombosis of the iliac and, in some cases, the renal vein (▶ Fig. 13.89 and ▶ Fig. 13.90). US typically shows a fluid collection inferior and medial to the transplant; such collections often contain septa and produce low-level echoes. Acute hematoma (▶ Fig. 13.91) can be caused by bleeding from small vessels in the renal hilum, or lacerations of the renal artery distal to an anastomosis that may not have been noticed during surgery. Days later, hemorrhage can occur from a mycotic aneurysm or perianastomotic infection. On color Doppler US, echogenicity varies with time from hyperechoic in the acute phase to inhomogeneous as clot lysis occurs. Abscesses are most often seen in patients treated with peritoneal dialysis. Abscess formation can also occur following pyelonephritis secondary to infection of a perinephric collection, or they can be surgical complications. Color Doppler US typically shows a fluid collection with a more or less well-defined capsule-like wall and internal echoes. Urinomas are caused by urine leaks following ureteral ischemia secondary to disruption of the blood supply at the time of procurement or bench preparation, or to technical problems involving the ureterovesical anastomosis. Urinoma may also be

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a consequence of a focal renal infarct involving the collecting system, with subsequent leakage of urine. Antegrade pyelography or contrast-enhanced MR urography can be used to detect the urine leak and confirm the urinoma around the kidney. Radionuclide imaging will demonstrate an extravesical collection.

Vascular Complications Graft artery thrombosis is an early postoperative complication seen within the first 2 days. Renal artery thrombosis presents as a sudden cessation of urine output, graft site pain, and a rise in plasma creatinine. Color Doppler US shows no flow or very pulsatile venous flow in the kidney. Contrast-enhanced MR angiography/contrast-enhanced CT angiography or renal arteriography depicts no flow in the kidney and an absent nephrogram. Occlusion of segmental arteries may also occur and will present on US as focal hypo- to hyperechoic areas delineating the infarction and a segmental loss of flow, which is particularly well depicted by color Doppler US and power Doppler (▶ Fig. 13.92). Contrast-enhanced MR angiography may confirm the diagnosis, and the infarcted area will present as a photopenic area on a DMSA scan. Renal vein thrombosis presents with severe graft tenderness, swelling, and hematuria. Color Doppler US shows a swollen and initially hypoechoic graft, often with hyperechoic intermedullary streaks representing clots in the arcuate vessels. The Doppler curve resembles that of severe acute rejection, with a sharp upstroke in the systolic waves and no, or reversed, diastolic flow; the RI is also markedly elevated. However, in renal vein thrombosis there is no flow in the renal vein. Color Doppler US is usually sufficient for the diagnosis. MR angiography/venousphase angiography can be used to confirm the US findings or to make the diagnosis when the US results are equivocal. Renal artery stenosis in the early post-transplant phase is most often caused by technical problems during surgery. Patients with acute renal artery stenosis present with severe hypertension, loss of renal function, and a bruit over the graft. Kinking of the artery of the transplanted kidney may be a cause of graft dysfunction and may present with aliasing and

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Fig. 13.89 Mild pyelocaliceal dilatation secondary to ureteral compression in a 10-year-old boy with a peri-transplant lymphocele (arrows) around the lower pole of the kidney.

increased systolic peak velocity, mimicking a high-grade renal artery stenosis on color Doppler US, particularly if only parts of the vessel are visible (▶ Fig. 13.93). Arteriovenous fistulas and pseudoaneurysms commonly occur as complications of transplant biopsies. On color Doppler US, an arteriovenous fistula is seen as a vascular-colored mosaic pattern (aliasing) caused by the fast and turbulent shunt flow. The feeding artery has a high flow velocity and a low RI, while the draining vein exhibits arterialization of the venous waveform. A mild arteriovenous fistula may be obscured by the normal color Doppler US signal within the kidney. Additional scanning with high pulse repetition frequency (PRF) settings is therefore needed (▶ Fig. 13.94). A pseudoaneurysm is seen as a cystiform fluid collection that may mimic a cyst on gray-scale US. On color Doppler US, large lesions show turbulent flow, while small lesions show bidirectional jets of forward and reverse flow. Renal angiography is used to confirm the diagnosis and for embolization if the lesion is clinically significant.

ureterovesical anastomosis, ureteral necrosis due to ischemia, hematoma of the ureteral wall, ureteral kinking, or external compression. Patients present with rising plasma creatinine, change in urine output, and graft pain. Color Doppler US may reveal hydronephrosis and obstruction secondary to collections. Color Doppler US often shows a high RI (> 0.75). It is important to know that other causes of a raised RI can coexist with pelvicaliceal dilatation; therefore, these findings are nonspecific. A retrograde or antegrade pyelogram via a percutaneous nephrostomy drain can confirm the diagnosis and is often used in suspected acute obstruction. Acute, nondilated obstructions will be depicted by this technique. Another reliable, noninvasive method of diagnosing obstruction is to assess progressive dilatation of the collecting system on serial US following furosemide administration (“diuresis US”; ▶ Fig. 13.95).

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Urinary Tract Obstruction Ureteral obstruction can occur in the early postoperative phase and is caused by blood clots, ureteral edema, a tight

Bear in mind that low-grade hydronephrosis is not unusual, particularly early after a transplant, and that the absence of collecting system dilatation does not exclude an obstruction, especially if the patient is oliguric or anuric.

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Fig. 13.90a–d a Moderate hydroureteronephrosis in a 14-year-old girl with a septate lymphocele (white arrow, b) along the medial profile of her transplanted kidney. c Heavily T2-weighted coronal TSE (turbo spin echo) image shows in detail the relationship of the lymphocele (black arrow) with the ureter and the bladder (arrowhead); the bladder is compressed and dislocated. d Maximum intensity projection of the coronal urographic GRE (gradient recalled echo) 3D T1-weighted sequence confirms compression of the lymphocele (noncontrasted; arrow) on the urinary tract, with moderate upper hydroureteronephrosis.

13.11.3 Differential Diagnosis of Long-Term Graft Dysfunction and Imaging Aspects Long-term complications in pediatric renal transplantation include graft dysfunction, renovascular disorders, obstruction, infection, and secondary malignancies.

The features of a renal transplant with chronic allograft dysfunction include a thin, sometimes slightly hyperechoic renal cortex, mild hydronephrosis, and loss of corticomedullary differentiation. There are no specific findings in either acute or chronic allograft dysfunction, and the diagnosis is made histologically. Therefore, imaging techniques other than color Doppler US are used only to rule out other causes of graft dysfunction, such as obstruction, sequelae of chronic UTI, or reflux nephropathy.

Graft Dysfunction Acute rejection can occur at any time after transplant. Color Doppler US findings are nonspecific. Therefore, if the graft shows altered echogenicity, particularly with an increase in size and swelling in combination with raised creatinine in the absence of UTI, a graft biopsy should be performed.

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Obstruction Obstruction after the early postoperative phase is normally caused by ureteral stricture or kinking of the ureter, infection, or external compression by fluid collections (normally lymphoceles) or lymphatic tissue in the case of post-transplant

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Fig. 13.92 Loss of flow at the lower pole of a transplanted kidney on the first scan following transplant (within the first 24 hours) during routine follow-up. The aliasing effect at the upper pole is due to lowering of the pulse repetition frequency (PRF) and an increase in color gain.

Fig. 13.91 Resolving perirenal hematoma in a 10-year-old child with a transplant and a reduced post-transplant hematocrit (arrows).

Fig. 13.93a–c a, b Kinking of the renal artery of a transplanted kidney with aliasing and increased systolic peak velocity mimicking high-grade renal artery stenosis on color Doppler ultrasound. c The intraparenchymal resistive index is within normal limits (0.65).

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Fig. 13.94a–c Arteriovenous fistula as a complication of a transplant biopsy in a 14-year-old boy. a Color Doppler ultrasound demonstrates a vascularcolored mosaic pattern caused by the fast and turbulent shunt flow. b The feeding artery has a high flow velocity and a low resistive index. c The draining vein exhibits arterialization of the venous waveform.

lymphoproliferative disorder. The ureter should also be carefully assessed in order to rule out ureteral tumors or renal calculi. Obstruction is often asymptomatic and may be found incidentally on color Doppler US. VUR may also cause the diameter of the collecting system to increase, and US before and after voiding, with evaluation of the emptying of the collecting system after bladder emptying, must be performed; contrastenhanced voiding urosonography may be an option as an alternative to VCUG.

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Transplant Pyelonephritis Graft infections can occur at any time after transplant. Color Doppler US findings include graft swelling, focal areas of reduced flow, increased urothelial thickening, and hydronephrosis (see section on UTI). Sometimes, debris can be seen in the urine as floating hyperechoic dots. Graft infections may be clinically silent, and UTI must always be ruled out when the abovementioned features are picked up as incidental findings on color Doppler US. Although in some cases color Doppler US may reveal post-pyelonephritis scars (▶ Fig. 13.96), a DMSA scan 3 to 6 months after confirmed acute pyelonephritis is advised in order to assess renal scarring.

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Fig. 13.95a–c a, b Moderate to severe hydroureteronephrosis in a 5-year-old boy with a transplant. Note (b) the dilatation of the ureter with increased urothelial thickness (white arrow) and the abrupt reduction in ureteral caliber (black arrow) in the distal third due to ureteral ischemia. c A stent was placed in order to resolve the hydronephrosis.

Fig. 13.96 Fourteen-year-old boy with a transplant, ureterovesical reflux, and recurrent pyelonephritis. A focal area of parenchymal thinning with inhomogeneous echo structure (white arrow) and distorted and corticalized calices (black arrow) are suggestive of a renal scar.

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Fig. 13.97a,b Post-transplant lymphoproliferative disease in a 14-year-old boy. Multiple hypoechoic intraparenchymal nodules evidencedon a routine follow-up ultrasound scan (a) and confirmed on a contrast-enhanced computed tomographic scan (b), which depicts multiple hypodense nodules.

Renovascular Disorders In the long-term follow-up of renal transplants, the most common renovascular complications include arteriovenous fistulas or pseudoaneurysms from graft biopsies and renal artery stenosis. Careful assessment by color Doppler US, as detailed above, must be performed in order to detect intrarenal arteriovenous fistulas and pseudoaneurysms. Extrarenal arteriovenous fistulas or pseudoaneurysms are rare and are caused by surgery or infection rather than biopsy. Color Doppler US shows variable sensitivity and specificity in detecting renal artery stenosis. Color Doppler US shows a high-velocity systolic peak flow (> 200 cm/s) and turbulent flow at the stenosis, and distally the typical pulsus tardus pattern with a delayed systolic upstroke on spectral analysis. MR angiography may be used in selected cases if color Doppler US is not conclusive, but these patients will normally be referred directly for renal angiography, which is the gold standard in confirming and potentially treating renal artery stenosis. Digital subtraction angiography should therefore be performed in hypertensive patients with color Doppler US findings suspicious for renal artery stenosis, and in all patients with severe hypertension regardless of their US findings. With regard to this issue, the role and potential of CT angiography and/or MR angiography in pediatric renal transplantation is controversial and still under discussion.

Post-transplant Lymphoproliferative Disorder and Secondary Malignancies The most common radiologic manifestations of post-transplant lymphoproliferative disorder (PTLD) are lymphadenopathy and hepatosplenomegaly. However, the disorder can affect any of the solid organs and hollow viscera. PTLD can also affect the graft parenchyma; in this case, it will present as one or more hypoechoic areas within the kidney (▶ Fig. 13.97). Careful assessment of the abdomen, including the native kidney, liver, spleen, mesenteric lymph nodes, and renal transplant, is advisable in order to detect PTLD and other secondary malignancies; this approach should be applied in every color Doppler

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US follow-up examination of pediatric patients with renal transplants.

13.12 Bladder and Urethra 13.12.1 Congenital Bladder Anomalies Bladder duplication is a rare anomaly and is almost always associated with urethral/vaginal duplications. Bladder diverticula are herniations of the bladder mucosa through fibers of the detrusor muscle. Most childhood diverticula are secondary to and associated with reflux, neurogenic bladder, and pathologic urethra, but congenital diverticula can occur. Secondary diverticula tend to be multiple and associated with a trabeculated bladder; by contrast, congenital diverticula are solitary and often larger. Congenital diverticula are described in association with Menkes syndrome, cutis laxa, Williams syndrome, and Ehlers–Danlos syndrome. Clinical symptoms of diverticula are UTI, incontinence, and/ or urine retention. Giant bladder diverticula are rare causes of bladder outlet obstruction in children. Complementary VCUG is an important tool for investigating bladder outlet obstruction. The relationship between the diverticula and ureters varies, with the ureters either running through the wall of the diverticulum and opening directly into the bladder or opening into the diverticulum. On sonography, diverticula appear as round or oval anechoic fluid collections arising from the bladder base or around the ureteral orifice (▶ Fig. 13.98). In cases of acquired diverticula, thickened and trabeculated bladder walls are usually present. A dilated distal ureter secondary to ureterovesical compression or reflux may be seen (▶ Fig. 13.99). Ureteroceles (see also section 13.2 on congenital anomalies of the kidney and urinary tract (p. 456)) are cystic dilatations of the intravesical segment of the ureter. A ureterocele may be as small as 1 cm, or it may fill the entire bladder and prolapse through the urethra. On US, it appears as a cystic intravesical mass, contiguous with a dilated ureter and arising from a normally positioned ureteral orifice near the lateral margin of the trigone (▶ Fig. 13.100). The wall of the ureterocele is visualized

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Fig. 13.98 Multiple bladder diverticula in a 2-year-old child with Menkes syndrome.

as a rounded echogenic structure located near the lateral margin of the trigone. On real-time US, partial or complete collapse of a simple ureterocele secondary to ureteric peristalsis may be observed. The most common type of neurogenic bladder is associated with a meningocele, myelomeningocele, or sacral agenesis. Acquired cases are less common and include those associated with traumatic paraplegia or encephalitis/meningitis. Persistent dysfunctional voiding is the main cause of UTIs. Concomitant VUR accounts for the recurrence of pyelonephritis, which often leads to chronic renal failure. The various US findings include urinary tract dilatation, renal parenchyma “scarring,” and bladder wall anomalies, such as irregular wall thickening, often with small diverticula (▶ Fig. 13.99). Postvoiding images are useful in evaluating bladder emptying, which is usually incomplete in these patients.

Fig. 13.99 Hypertonic-type neurogenic bladder in a 14-year-old girl (myelomeningocele) with pseudodiverticula and irregular thickening of the bladder wall.

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13.12.2 Urethral Anomalies

Fig. 13.100 Five-year-old boy with macrohematuria. Ultrasound reveals a linear, rounded echogenic structure located near the lateral margin of the trigone, which is suggestive of ureterocele.

Urethral anomalies, including posterior or anterior valves, duplication, partial or total agenesis, and stricture, are causes of bladder outlet obstruction. Congenital posterior urethral valve is the most common obstructive lesion in male infants. If severe, it can cause highdegree obstructive renal failure. Ultrasound examination of the lower abdomen and perineum may show global or partial urethral dilatation, and it may be difficult to directly demonstrate urethral valves. VCUG can do this better than US. However, US can reveal all the consequences of severe posterior urethral valve: hydroureteronephrosis, reduced renal size or focal decrease in the thickness of the renal parenchyma, and bladder wall thickening, with frequent findings of pseudodiverticula (▶ Fig. 13.101). US can also provide functional information, such as the presence of residual urine in the bladder and various degrees of upper urinary tract dilatation before and after voiding.

Fig. 13.101a,b Fourteen-year-old boy with chronic renal failure due to posterior urethral valves with severe obstructive uropathy. a Bilateral hydroureteronephrosis, b Gross thickening of the bladder walls and deep pseudodiverticula.

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Fig. 13.102a–d Two cases of simple and complicated urachal cysts. a An uncomplicated urachal cyst appears as a collection of simple fluid localized in the midline of the anterior abdominal wall and contiguous with the bladder dome. b, c An infected urachal cyst presents with echogenic material inside (b, longitudinal scan; c, transverse scan) and local hypervascularization (d).

Syringocele can appear as an echogenic line in the middle of the proximal urethra lumen.

13.12.3 Utricle Prostatic utricle cysts are remnants of the müllerian duct system that persist in the midline between the bladder and the rectum; these cysts are usually associated with hypospadias. On sonography, they appear as anechoic or hypoechoic tubular structures posterior and caudal to the bladder base.

13.12.4 Urachal Anomalies The urachus develops from the superior portion of the urogenital sinus and connects the dome of the bladder to the allantoic duct during fetal life. It is located behind the abdominal wall and anterior to the peritoneum in the space of Retzius. Antenatally, the urachus is obliterated and becomes a vestigial structure known as the medial umbilical ligament. In the absence of

complete obliteration, the urachus persists as either a patent urachus, urachal cyst, urachal sinus, or urachal diverticulum. A persistent urachus frequently coexists with a congenital lower urinary tract obstruction, such as posterior urethral valve. It may also coexist with ventral abdominal wall defects, like omphalocele or occasionally prune belly syndrome. A patent urachus results in an open channel between the bladder and the umbilicus. On longitudinal US, it appears as a tubular connection between the anterosuperior aspect of the bladder and the umbilicus. Patency is better assessed with a linear high-frequency transducer because of the superficial location of the urachus. A urachal cyst forms when both the umbilical and vesical ends of the urachal lumen close, while an intervening portion remains patent and filled with fluid. Urachal cysts usually remain obscure until complicated by infection or bleeding (▶ Fig. 13.102). An uncomplicated urachal cyst appears as a collection of simple fluid localized in the midline of the anterior abdominal wall between the umbilicus and the pubis and often

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Fig. 13.103 Stone in the bladder neck in a 12-year-old boy with macrohematuria and dysuria.

contiguous with the bladder dome. A urachal cyst may become infected and display features of mixed echogenicity and thickening of the urachal wall. A urachal sinus is a noncommunicating dilatation of the urachus at the umbilical end. On US, it appears as a thickened tubular structure along the midline below the umbilicus. A urachal diverticulum is a similar deformity that communicates with the anterosuperior aspect of the bladder. It frequently coexists with congenital obstruction of the lower urinary tract. On US, it manifests as an extraluminally protruding, fluid-filled sac that does not communicate with the umbilicus.

13.12.5 Calculi Calculi in the bladder are usually associated with a predisposing factor (e.g., infection by urea-splitting organisms, bladder exstrophy, bladder augmentation, urinary stasis) or rarely with intraluminal foreign bodies. The symptoms may be related to infection or acute bladder neck obstruction (▶ Fig. 13.103). Bladder calculi are classically highly echogenic with an acoustic shadow and twinkling artifacts, and they usually shift to the dependent portion of the bladder as the patient changes position (▶ Fig. 13.104).

13.12.6 Infection Cystitis may be caused by infection (bacterial, viral, fungal) or drugs (chemotherapy). Its typical clinical presentation is one of dysuria and hematuria. Imaging is normally not required to make this diagnosis. The most common findings are diffuse

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bladder thickening and echogenic debris or a fluid–fluid level within the bladder lumen (▶ Fig. 13.105). In cystitis cystica, sonography may show a region of focal, broad-based, and irregular thickening of the trigone, which in many cases may protrude into the bladder lumen, mimicking a rhabdomyosarcoma.

13.12.7 Neoplasm Malignant Lesions Bladder tumors are rare and often malignant. Rhabdomyosarcoma is the most common neoplasm of the lower urinary tract in childhood. It typically involves the bladder or prostate and often presents with symptoms of urinary obstruction, including urinary frequency, stranguria, acute urinary retention, and hematuria. Tumors of the bladder usually occur in a botryoid form and grow intraluminally (▶ Fig. 13.106), whereas prostatic rhabdomyosarcoma tends to present as a solid mass (▶ Fig. 13.107). Sonographically, rhabdomyosarcoma appears as a polypoid mass projecting into the anechoic bladder lumen and, less commonly, as irregular bladder wall thickening.

Benign Lesions Benign bladder lesions are rare in childhood. They include neurofibroma, hemangioma, pheochromocytoma, transitional cell papilloma, and leiomyoma. Congenital urethral polyps are the most frequent benign urethral tumors, arising from a long stalk near the verumontanum. On sonography, they appear as echogenic polypoid masses projecting from the bladder neck into the bladder lumen. They may cause acute bladder neck obstruction (▶ Fig. 13.108).

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Fig. 13.104a,b Eighteen-month-old boy with recurrent urinary tract infections. Large, mobile intraluminal bladder stone (a, supine position of the patient; b, patient on left flank).

Fig. 13.105 Three-month-old girl with fever and urinary tract infection. Severe hypoechoic bladder wall thickening is due to diffuse edema.

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13.13 Contrast-Enhanced Cystosonography

Fig. 13.106 Three-year-old girl with urinary frequency. Ultrasound reveals inhomogeneous bladder wall thickening and a large intraluminal echogenic mass (botryoid-type rhabdomyosarcoma).

VUR is the most common urinary tract abnormality in children and causes recurrent episodes of UTI. It is traditionally diagnosed with VCUG or radionuclide cystography. VCUG and radionuclide cystography involve the use of ionizing radiation and contrast; therefore, enhanced voiding US has been introduced as an alternative technique in children. In this US technique, an echo-enhancing contrast agent is introduced slowly into the bladder through a catheter. VUR is diagnosed when the reflux of echoes from the bladder to the ureter, renal pelvis, and calices is seen, or when color signals are seen in the urinary tract (see box Contrast-enhanced cystosonography: procedure protocol (p. 508)).

Fig. 13.107a–d Three-month-old boy with acute urinary retention. a Ultrasound shows a large, homogeneous, echogenic infravesical mass in the prostate region that dislocates the urethral catheter posteriorly, confirmed on voiding cystourethrography (b). Magnetic resonance imaging confirms the prostatic origin of the mass (sagittal T2-weighted image, c) with homogeneous contrast enhancement (sagittal T1-weighted fat saturation after contrast, d).

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Fig. 13.108a–d a Oval hyperechoic image at the bladder neck (white arrow) in a 3-year-old boy with recurrent episodes of acute vesical retention. b This is confirmed on voiding cystourethrography (black arrow). Macroscopic appearance of the urethral papilloma (c) and ultrasound finding of the bladder neck after removal of the papilloma (d).

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Contrast-enhanced cystosonography: procedure protocol ● ● ●

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●

Fig. 13.109 Recurrence of symptomatic urinary tract infections in a 12-month-old girl. First diagnosis of second-degree vesicoureteral reflux (mild dilatation of the renal pelvis with normal anatomy of the bottom of the calices).

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Bladder catheter placement (feeding tube, 8–6 charriere) Evaluation of residual urine Baseline urinary tract ultrasound examination with empty bladder (technical data: second harmonics, wideband-frequency electronic convex probes, dedicated software for contrast-enhanced ultrasound, low mechanical index) Patient recumbent on left side (which allows front and back scans without mobilization), more rarely in supine decubitus position (patients with a transplant and small children) Mild bladder distention with saline (to verify correct catheter placement and bladder walls) Instillation of SonoVue (Bracco Imaging) second-generation ultrasound contrast agent at a concentration of 8 μL of sulfur hexafluoride per mL in the microbubbles in 0.5-mL boluses (infusion of 1 mL usually enough) into the bladder Continue infusion until spontaneous urination in smaller children or urinary urgency in older ones (in the event of spontaneous output of low volume urine, refill bladder 3 or 4 times) Study during micturation (with closed catheter, and, if possible without catheter)

Fig. 13.110a,b Contrast-enhanced cystosonography control after endoscopic treatment in a 5-year-old boy with bilateral severe ureterovesical reflux. a Persistence of right third-degree ureterovesical reflux (dilated renal pelvis with rounding of calices; white arrow). b Comparison with gray scale image.

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Fig. 13.111 Contrast-enhanced urethrosonography in a 6-year-old boy with urinary tract infections 1 year after posterior urethral valve resection. Minus in proximal urethra (arrow) suggest persistence of urethral valves.

The morphological signs (dilated or nondilated ureter, renal pelvis, and calices) contribute to VUR assessment. The grading of VUR (▶ Fig. 13.109 and ▶ Fig. 13.110) is based on voiding US findings, which makes this system comparable with the most frequently used radiographic system of VUR grading. Many studies have demonstrated the diagnostic adequacy of contrastenhanced cystosonography (CSG) versus VCUG. Limits of the technique are as follows: ● Operator dependency; ● Movement of the patient; ● Anatomical obstacles (e.g., severe scoliosis); ● Difficulties in detecting a transient ureterovesical reflux in one collecting system while the other one is being examined. However, in our experience, CSG is a valid alternative to VCUG, without radiation exposure, in the following conditions: ● First diagnosis in female patients; ● VUR follow-up; ● VUR diagnosis in megaureters and/or ureteroceles; ● VUR diagnosis in transplanted kidneys. The urethra is more difficult to assess on CSG; therefore, this is not recommended as the first diagnostic tool in male patients. Nevertheless, it may provide, if technically possible, an adequate depiction of the urethra. ▶ Fig. 13.111 shows a longitudinal urethral scan with a linear probe through a transperineal plane during micturition.

Recommended Readings Al-Ghwery S, Al-Asmari A. Multicystic dysplastic kidney: conservative management and follow-up. Ren Fail 2005; 27: 189–192 Avni FE, Garel C, Cassart M, D’Haene N, Hall M, Riccabona M. Imaging and classification of congenital cystic renal diseases. AJR Am J Roentgenol 2012; 198: 1004– 1013 Avni FE, Hall M. Renal cystic diseases in children: new concepts. Pediatr Radiol 2010; 40: 939–946 Benz-Bohm G, Hoppe B. Urolithiasis and nephrocalcinosis. In: Fotter R, ed. Pediatric Uroradiology. 2nd ed. Berlin, Heidelberg, Germany: Springer-Verlag; 2008

Berrocal T, López-Pereira P, Arjonilla A, Gutiérrez J. Anomalies of the distal ureter, bladder, and urethra in children: embryologic, radiologic, and pathologic features. Radiographics 2002; 22: 1139–1164 Bhatt S, MacLennan G, Dogra V. Renal pseudotumors. AJR Am J Roentgenol 2007; 188: 1380–1387 Bosio M, Manzoni GA. Detection of posterior urethral valves with voiding cystourethrosonography with echo contrast. J Urol 2002; 168: 1711–1715, discussion 1715 Brandão LR, Simpson EA, Lau KK. Neonatal renal vein thrombosis. Semin Fetal Neonatal Med 2011; 16: 323–328 Chang SJ, Chiang IN, Hsieh CH, Lin CD, Yang SS. Age- and gender-specific nomograms for single and dual post-void residual urine in healthy children. Neurourol Urodyn 2013; 32: 1014–1018 Chavhan GB, Parra DA, Mann A, Navarro OM. Normal Doppler spectral waveforms of major pediatric vessels: specific patterns. Radiographics 2008; 28: 691–706 Chow L, Sommer FG, Huang J, Li KC. Power Doppler imaging and resistance index measurement in the evaluation of acute renal transplant rejection. J Clin Ultrasound 2001; 29: 483–490 Cosgrove DO, Chan KE. Renal transplants: what ultrasound can and cannot do. Ultrasound Q 2008; 24: 77–87, quiz 141–142 Daneman A, Navarro OM, Somers GR, Mohanta A, Jarrín JR, Traubici J. Renal pyramids: focused sonography of normal and pathologic processes. Radiographics 2010; 30: 1287–1307 Darge K, Troeger J, Duetting T et al. Reflux in young patients: comparison of voiding US of the bladder and retrovesical space with echo enhancement versus voiding cystourethrography for diagnosis. Radiology 1999; 210: 201–207 Elsaify WM. Neonatal renal vein thrombosis: grey-scale and Doppler ultrasonic features. Abdom Imaging 2009; 34: 413–418 Faizah M, Kanaheswari Y, Thambidorai C, Zulfiqar M. Echocontrast cystosonography versus micturating cystourethrography in the detection of vesicoureteric reflux. Biomed Imaging Interv J 2011; 7: e7 Gnessin E, Chertin L, Chertin B. Current management of paediatric urolithiasis. Pediatr Surg Int 2012; 28: 659–665 Grimsby GM, Ritchey ML. Pediatric urologic oncology. Pediatr Clin North Am 2012; 59: 947–959 Hellström M, Hjälmås K, Jacobsson B, Jodal U, Odén A. Normal ureteral diameter in infancy and childhood. Acta Radiol Diagn (Stockh) 1985; 26: 433–439 Hoppe B, Kemper MJ. Diagnostic examination of the child with urolithiasis or nephrocalcinosis. Pediatr Nephrol 2010; 25: 403–413 Impellizzeri P, Borruto FA, Scalfari G et al. Natural history of non-operative treatment for renal injuries in children. Minerva Pediatr 2012; 64: 319–323 Khati NJ, Hill MC, Kimmel PL. The role of ultrasound in renal insufficiency: the essentials. Ultrasound Q 2005; 21: 227–244 Kuzmić AC, Brkljacić B, Ivanković D, Galesić K. Doppler sonographic renal resistance index in healthy children. Eur Radiol 2000; 10: 1644–1648 Lee JY, Kim SH, Cho JY, Han D. Color and power Doppler twinkling artifacts from urinary stones: clinical observations and phantom studies. AJR Am J Roentgenol 2001; 176: 1441–1445 Lowe LH, Isuani BH, Heller RM et al. Pediatric renal masses: Wilms tumor and beyond. Radiographics 2000; 20: 1585–1603 Marks SD, Gordon I, Tullus K. Imaging in childhood urinary tract infections: time to reduce investigations. Pediatr Nephrol 2008; 23: 9–17 Mindell HJ, Cochran ST. Current perspectives in the diagnosis and treatment of urinary stone disease. AJR Am J Roentgenol 1994; 163: 1314–1315 Moghazi S, Jones E, Schroepple J et al. Correlation of renal histopathology with sonographic findings. Kidney Int 2005; 67: 1515–1520 Piaggio G, Degl’ Innocenti ML, Tomà P, Calevo MG, Perfumo F. Cystosonography and voiding cystourethrography in the diagnosis of vesicoureteral reflux. Pediatr Nephrol 2003; 18: 18–22 Prabahar MR, Udayakumar R, Rose J et al. Prediction of tubulo-interstitial injury by Doppler ultrasound in glomerular diseases: value of resistive and atrophic indices. J Assoc Physicians India 2008; 56: 21–26 Privett JT, Jeans WD, Roylance J. The incidence and importance of renal duplication. Clin Radiol 1976; 27: 521–530 Rajiah P, Lim YY, Taylor P. Renal transplant imaging and complications. Abdom Imaging 2006; 31: 735–746 Reed B, Nobakht E, Dadgar S et al. Renal ultrasonographic evaluation in children at risk of autosomal dominant polycystic kidney disease. Am J Kidney Dis 2010; 56: 50–56 Richter-Rodier M, Lange AE, Hinken B et al. Ultrasound screening strategies for the diagnosis of congenital anomalies of the kidney and urinary tract. Ultraschall Med 2012; 33: E333–E338

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Kidneys Riccabona M, Avni FE, Damasio MB et al. ESPR Uroradiology Task Force and ESUR Pediatric Working Group—Imaging recommendations in paediatric uroradiology, part V: childhood cystic kidney disease, childhood renal transplantation and contrast-enhanced ultrasonography in children. Pediatr Radiol 2012; 42: 1275–1283 Riccabona M, Lobo ML, Papadopoulou F et al. ESPR uroradiology task force and ESUR paediatric working group: imaging recommendations in paediatric uroradiology, part IV: Minutes of the ESPR uroradiology task force mini-symposium on imaging in childhood renal hypertension and imaging of renal trauma in children. Pediatr Radiol 2011; 41: 939–944 Riccabona M, Mache CJ, Lindbichler F. Echo-enhanced color Doppler cystosonography of vesicoureteral reflux in children. Improvement by stimulated acoustic emission. Acta Radiol 2003; 44: 18–23 Saadeh SA, Mattoo TK. Managing urinary tract infections. Pediatr Nephrol 2011; 26: 1967–1976 Sadowski EA, Fain SB, Alford SK et al. Assessment of acute renal transplant rejection with blood oxygen level-dependent MR imaging: initial experience. Radiology 2005; 236: 911–919 Shroff R, Rees L. The post-transplant lymphoproliferative disorder-a literature review. Pediatr Nephrol 2004; 19: 369–377

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Steinhart JM, Kuhn JP, Eisenberg B, Vaughan RL, Maggioli AJ, Cozza TF. Ultrasound screening of healthy infants for urinary tract abnormalities. Pediatrics 1988; 82: 609–614 Sugiura T, Wada A. Resistive index predicts renal prognosis in chronic kidney disease. Nephrol Dial Transplant 2009; 24: 2780–2785 Suita S, Nagasaki A. Urachal remnants. Semin Pediatr Surg 1996; 5: 107–115 Sanna-Cherchi S, Ravani P, Corbani V et al. Renal outcome in patients with congenital anomalies of the kidney and urinary tract. Kidney Int 2009; 76: 528–533 Sweeney WE, Jr, Avner ED. Diagnosis and management of childhood polycystic kidney disease. Pediatr Nephrol 2011; 26: 675–692 Thompson PA, Chintagumpala M. Renal and hepatic tumors in the neonatal period. Semin Fetal Neonatal Med 2012; 17: 216–221 Toka HR, Toka O, Hariri A, Nguyen HT. Congenital anomalies of kidney and urinary tract. Semin Nephrol 2010; 30: 374–386 Tsuchiya M, Hayashida M, Yanagihara T et al. Ultrasound screening for renal and urinary tract anomalies in healthy infants. Pediatr Int 2003; 45: 617–623 Tullus K, Roebuck DJ, McLaren CA, Marks SD. Imaging in the evaluation of renovascular disease. Pediatr Nephrol 2010; 25: 1049–1056 Vester U, Kranz B, Hoyer PF. The diagnostic value of ultrasound in cystic kidney diseases. Pediatr Nephrol 2010; 25: 231–240

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Chapter 14 Adrenal Glands

14.1

Embryology of the Adrenal Glands

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14.2

Normal Anatomy

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14.3

Normal Sonographic Appearance

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14.4

Normal Variants

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14.5

Pathology

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14 Adrenal Glands Claire Gowdy and Annie Paterson Ultrasound (US) is the primary imaging modality employed to evaluate the abdomen in infants and children. With respect to adrenal pathology, a palpable mass may be confirmed as having an adrenal origin, or an adrenal lesion may be actively searched for in a child who presents with a hypertensive or metabolic crisis, an endocrinopathy, or neurologic symptoms and signs. Asymptomatic adrenal masses may be detected when the abdomen is being examined for some other reason. The radiologist must describe any mass lesion identified, determine whether an abnormality is unilateral or bilateral, and document any further intra-abdominal foci of disease. Many acquired forms of adrenal pathology appear similar on US, and more detailed anatomical information and tissue characterization with computed tomography (CT) or magnetic resonance (MR) imaging is often required. Radioactive isotope examinations with iodine I 123 metaiodobenzylguanidine (123IMIBG) and/or technetium Tc 99 m methylene diphosphonate (99mTc-MDP), and functional studies with fluorodeoxyglucose F 18 positron emission tomography (18F-FDG-PET), are employed in those children with known or suspected adrenal malignant disease. Correlating the imaging findings with the available clinical and biochemical information is crucial in the context of adrenal disease.

Tips from the Pro ●

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The majority of incidentally detected adrenal masses in children is malignant, and with the exception of small lesions detected in infants younger than 3 months of age, in whom judicious observation may be employed, all should be resected.

The histologic and functional development of the adrenal glands continues throughout infancy, with the cortical zona glomerulosa, zona fasciculata, and zona reticularis fully differentiated by 3 years of age. Aldosterone, produced in the outermost zona glomerulosa layer of the cortex, plays an important role in salt–water balance as part of the renin–angiotensin– aldosterone system. A complex negative feedback mechanism of the hypothalamic–pituitary–adrenal axis regulates adrenal cortical endocrine function postnatally. Cortisol production predominates in the zona fasciculata (middle layer), with adrenal androgens arising in the inner zona reticularis.

14.2 Normal Anatomy The adrenal glands are paired retroperitoneal organs that lie within the Gerota fascia in close relation to the kidneys. On the right side, the adrenal lies posterior to the inferior vena cava (IVC) and superomedial to the upper pole of the right kidney. The left adrenal lies more anteriorly and inferiorly to the kidney than does the right adrenal. Immediately adjacent to the left adrenal are the aorta medially and the pancreas and splenic vein anteriorly. The right adrenal has a pyramidal shape; the contour of the left-sided gland is slightly flatter and is described as semilunar in shape. The glands have a rich arterial supply from the superior, middle, and inferior adrenal arteries. Respectively, these paired vessels arise from the inferior phrenic artery (a branch of the descending aorta), the abdominal aorta, and the ipsilateral main or upper pole renal artery. Usually, each gland is drained by a single vein that emerges from the hilum. On the right side, the vein communicates with the posterior aspect of the IVC, whereas the left-sided vein unites with the left renal vein.

14.1 Embryology of the Adrenal Glands

14.3 Normal Sonographic Appearance

The adrenal glands are composed of a separate outer cortex and an inner medulla, which have different embryologic origins and postnatal functions. The fetal (primitive) cortex develops from the coelomic mesoderm of the urogenital ridge on the posterior abdominal wall during the fifth gestational week. In the seventh week, these cells are surrounded by additional mesothelial tissue as the adult cortex is formed. This mass of cortical cells separates from the adjacent mesothelial tissue in the eighth week and becomes enveloped in connective tissue. The adrenal medulla is formed later, when chromaffin cells derived from the sympathetic ganglia of the neural crest invade the medial aspect of the cortex. The central location of the medullary cells is achieved by the 18th week. At birth, the adrenal glands are large relative to the kidneys, but there is rapid postnatal involution of the fetal cortex, so that by 2 weeks of age, the adrenals have lost more than 30% of their birth weight.

The normal neonatal adrenal is clearly identified with US. The histologically distinct cortex is viewed as a thick, echo-poor outer layer that surrounds a thinner echo-bright vascular core of medullary tissue (▶ Fig. 14.1). The combination of a relatively large size (the neonatal adrenal is about one-third as long as the adjacent kidney) and a lack of retroperitoneal fat aids visualization. With age, the layered appearance of the gland is lost, and a normal adrenal in an older child and adult is seen merely as an echogenic “triangle” atop the kidney below (▶ Fig. 14.2 and ▶ Fig. 14.3).

Tips from the Pro ●

A high-frequency, 6.0- to 8.0-MHz probe is used to evaluate the neonatal adrenal gland. The use of a linear transducer can further enhance the images.

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Adrenal Glands

Fig. 14.1 Normal neonatal adrenal gland. Sagittal image shows the echo-poor cortex and bright vascular medulla. Note the large size of the gland relative to the adjacent kidney.

Fig. 14.2 Normal adrenal gland in a 9-year-old girl (arrow). The cortex and medulla are indistinguishable, and the gland resembles an inverted triangle on top of the adjacent kidney.

Fig. 14.3 Normal adrenal gland in a 15-year-old boy (arrow). The cortex and medulla cannot be seen separately, and the gland is small in relation to the size of the kidney lying below.

14.4 Normal Variants Congenital anomalies of the adrenal glands are uncommon and are usually diagnosed incidentally or during renal sonography in infants with other medical or surgical problems. The variant most frequently visualized by a pediatric sonographer is the “lying down” adrenal, encountered when the adjacent kidney is ptotic or absent (▶ Fig. 14.4). Midline fusion of the adrenal glands (“horseshoe” adrenal) is well documented, but rare (▶ Fig. 14.5). The sonographic

Fig. 14.4 The “lying down” adrenal gland (arrow), seen with ipsilateral renal agenesis. (Image courtesy of Dr. A. Healey, Alder Hey Hospital, Liverpool, UK.)

architecture is maintained, along with gland function. The majority of cases is seen in infants with asplenia (Ivemark syndrome). If fragments of adrenal tissue break off during development, then cortical rests or true accessory adrenal glands (cortical and medullary components) develop, depending upon the timing of the event during gestation. Accessory adrenal tissue may be found around the celiac axis, close to the normal location of the

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Adrenal Glands The sonographic appearance depends upon the age and size of the hematoma. Early on, the mass may be iso- or hyperechoic in comparison with the surrounding tissues (▶ Fig. 14.6a). Gradual liquefaction and shrinkage occur over the following weeks (▶ Fig. 14.6b–d). By 3 months of age, most adrenal hemorrhages have resorbed completely or have calcified. In the latter case, the hemorrhage is echo-bright and may have posterior acoustic shadowing. The differential diagnosis for a neonatal adrenal mass includes congenital neuroblastoma (▶ Fig. 14.7a), simple adrenal cyst (▶ Fig. 14.7b), obstructed upper moiety of a duplex kidney (▶ Fig. 14.7c), and enteric duplication cyst (▶ Fig. 14.7d).

Tips from the Pro ●

Fig. 14.5 Horseshoe adrenal gland shown on T2-weighted axial magnetic resonance image. The adrenal limbs in this case unite posterior to the aorta and inferior vena cava (arrow). The normal architecture of the glands is preserved. (Image courtesy of Professor U. V. Willi, Johns Hopkins Hospital, Baltimore, MD, USA.)

gland. Descent of cortical tissue into the lower abdomen and pelvis at the time of gonadal migration explains descriptions of adrenal tissue within the uterus, broad ligament, ovary, inguinal canal, and scrotum. Accessory adrenal tissue may be hormonally active and become hypertrophic under the influence of adrenocorticotropic hormone (ACTH), most notably in patients with undertreated congenital adrenal hyperplasia. Testicular adrenal rests are seen in the majority of male patients with this condition and are reported as well defined, hypoechoic, intratesticular lesions. They may be bilateral and are often impalpable (▶ Fig. 16.27).

Tips from the Pro ●

Do not confuse a normal neonatal adrenal gland for a dysplastic kidney in cases of renal agenesis or ptosis.

Differentiating an adrenal hemorrhage from a congenital neuroblastoma is difficult. Nevertheless, the following features suggest malignancy rather than hemorrhage: antenatal detection of the mass, foci of calcification seen on initial assessment, internal vascularity by color Doppler, and gradual evolution to a more complex-appearing mass.

14.5.2 Adrenal Hemorrhage in the Older Child Adrenal hemorrhage is well recognized in children following blunt abdominal trauma. It is more commonly identified on the right side and is observed in conjunction with injuries to ipsilateral solid organs and the lower chest. Spinal trauma and diaphragmatic rupture are also documented with adrenal hemorrhage. The diagnosis is usually incidentally noted during CT examination of a severely injured child. Hemorrhage into a preexisting tumor is known to occur, particularly with hypervascular lesions such as pheochromocytoma, angiomyolipoma, myelolipoma, and hemangioma. Adrenal hemorrhage in children receiving extracorporeal membrane oxygenation (ECMO) therapy and secondary to renal vein thrombosis is also recognized.

Tips from the Pro ●

14.5 Pathology 14.5.1 Neonatal Adrenal Hemorrhage Neonatal adrenal hemorrhage is seen in association with birth trauma, perinatal asphyxia, and septicemia. Less commonly, hemorrhage may be found in babies with bleeding diatheses. The cause is not known, but increased adrenal arterial flow or elevated venous pressures likely contribute. Unilateral hemorrhage contained within the gland is generally asymptomatic, but extracapsular extension can progress to severe hypovolemia and even death. Anemia, jaundice, and abdominal and scrotal masses are all reported. Adrenal insufficiency is a theoretical possibility when there is bilateral extensive hemorrhage.

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When an adrenal hematoma is identified in an older child with no documented history of trauma, nonaccidental injury should be considered in the differential diagnosis (▶ Fig. 14.8).

14.5.3 Adrenal Cysts Adrenal cysts are often found incidentally when the abdomen is imaged for some other reason. They are subclassified into endothelial, epithelial, and pseudocyst types; the latter are more common and are due to hemorrhage, infarction, tumor, or dysplasia. Multiple microcysts or macrocysts can be found in some patients with Beckwith–Wiedemann syndrome.

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Fig. 14.6a–d Adrenal hemorrhages in four different infants, all at different stages of evolution. a Acute hemorrhage appears as a solid homogeneous mass (between calipers). (Image courtesy of Dr. K. McHugh, Great Ormond Street Hospital, London, UK.) b With time, hemorrhage has a more heterogeneous appearance, with both solid and liquid components. (Image courtesy of Dr. K. Halliday, Queen’s Medical Centre, Nottingham, UK.) c Eventually, the mass liquefies completely; at this stage, the hemorrhage is most likely to be confused with an obstructed upper moiety in an ipsilateral duplex kidney. d Large liquefied hematoma, with marked compression of the upper pole of the adjacent kidney. (Image courtesy of Dr. A. Healey, Alder Hey Hospital, Liverpool, UK.)

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Fig. 14.7a–d Differential diagnoses to be considered in newborns with adrenal mass lesions. a Echo-bright congenital neuroblastoma. b Well-defined, echo-poor adrenal cyst. (Image courtesy of Dr. A. Healey, Alder Hey Hospital, Liverpool, UK.) c Obstructed upper moiety of a duplex kidney. d Enteric duplication cyst; note the “gut signature” of the layered cyst wall. (Image courtesy of Dr. J. M. Somers, Nottingham City Hospital, Nottingham, UK.)

Fig. 14.8 Axial computed tomographic source image. Right-sided adrenal hemorrhage; the low-attenuation hematoma separates the limbs of the adrenal gland. A hemoperitoneum and periportal edema are also shown. This 2-year-old girl was the victim of a nonaccidental injury and was brought unconscious to the emergency department. (Reproduced from Paterson A. Adrenal pathology in childhood: a spectrum of disease. Eur Radiol 2002;12(10):2491–2508)

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Fig. 14.10 Adrenal abscess. Pretreatment image of a mixed-echogenicity adrenal abscess in a newborn infant. (Image courtesy of Professor E. F. Avni, Erasme Hospital, Brussels, Belgium.)

14.5.4 Adrenal Abscesses

Fig. 14.9a,b Congenital adrenal cyst. a Transverse view from an antenatal ultrasound examination showing a unilocular cystic lesion within the adrenal gland (arrow). b The lesion was subsequently confirmed postnatally (arrow), when it had decreased in size. (Images courtesy of Professor E. F. Avni, Erasme Hospital, Brussels, Belgium.)

Endothelial cysts include lymphangioma and hemangioma. Epithelial cysts include congenital cysts and those that arise secondary to infection with parasites such as Echinococcus (hydatid disease). Hemorrhage and infection may complicate an adrenal cyst. At sonography, cysts may be unilateral or bilateral, single or multiple, simple or complex (▶ Fig. 14.9). Occasionally, their walls may show thin rims of calcification. The clinical history is very important in distinguishing between the subtypes.

Adrenal abscesses are rare. An abscess may develop as a primary lesion following hematogenous seeding of bacteria into a structurally normal gland or may complicate preexisting adrenal hemorrhage. Infection with both Gram-negative and Grampositive organisms has been reported. The presenting signs are pyrexia, irritability, abdominal distention, and vomiting. Prompt diagnosis is necessary. US can help to localize the source of the infection within the adrenal gland, where a complex mass containing debris-laden fluid and septa is observed (▶ Fig. 14.10). The abscess(es) must be drained, and a percutaneous approach is preferred (▶ Fig. 14.11).

14.5.5 Congenital Adrenal Hyperplasia Congenital adrenal hyperplasia is associated with a group of enzyme deficiencies, most inherited in an autosomal-recessive manner, in which normal steroid synthesis by the adrenal cortex is impaired. Deficiency of 21-hydroxylase is the most common cause of congenital adrenal hyperplasia, accounting for 90% of cases, and is confirmed by elevated serum levels of the precursor 17-hydroxyprogesterone. The adrenal cortex cannot synthesize cortisol efficiently, and this is associated with excessive production of ACTH by the pituitary gland. The result is overproduction of cortisol precursors, some of which are diverted to sex hormone biosynthesis. The excess androgens cause virilization, leading to ambiguous genitalia in female

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Fig. 14.11 Adrenal abscess. The image shows a pigtail catheter in situ following drainage of a large abscess. (Image courtesy of Dr. A. Healey, Alder Hey Hospital, Liverpool, UK.)

newborns and rapid postnatal growth in both sexes. A concomitant deficiency of aldosterone leads to the salt-losing crisis, in which infants present with hypovolemic shock and failure to thrive. The adrenal glands in children with congenital adrenal hyperplasia may be enlarged. The adrenal gland may retain the typical y or v shape, and the internal architecture is preserved. An enlarged gland can be measured, according to Sivit et al, as an adrenal limb greater than 4 mm in width and greater than 20 mm in length. The cerebriform pattern (see also ▶ Fig. 15.25) is a characteristic finding whereby the wrinkled surface of the gland resembles the brain gyri and contrasts with the usually smooth surface of the neonatal gland (▶ Fig. 14.12).

Tips from the Pro ●

Sonography is useful to examine the pelvic organs in a virilized female neonate. The uterus may appear normal in outline but lacks an endometrial stripe.

14.5.6 Adrenal Hyperplasia in Older Patients An endogenous or exogenous excess of ACTH can lead to adrenal hyperplasia, which is seen as bilateral diffuse or nodular glandular enlargement at imaging. The glands tend to retain a relatively normal outline and may be better appreciated by CT or MR imaging. Pituitary imaging is also required in this situation. Primary pigmented nodular adrenal hyperplasia and ACTHindependent macronodular adrenal hyperplasia are rare causes of Cushing syndrome. US will not be adequate to view the adrenal changes in the former, in which tiny nodules 2 to 5 mm in diameter are present bilaterally. In macronodular disease, there is striking bilateral glandular enlargement, and the glands have an undulating contour.

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Fig. 14.12a,b Congenital adrenal hyperplasia. Sagittal (a) and transverse (b) ultrasound images show an enlarged gland with a “wrinkled” cortex, the so-called cerebriform pattern. (Images courtesy of Dr. H. Bray, BC Children’s Hospital, Vancouver, Canada.)

14.5.7 Adrenal Hypoplasia Congenital adrenal hypoplasia is rare and can be secondary to a deficiency of pituitary ACTH synthesis and release. This may occur either in isolation or as part of a more generalized problem such as end-organ resistance to ACTH or primary failure of adrenal gland development (an X-linked disorder). Adrenal destruction secondary to autoimmune disease, metabolic conditions (including adrenoleukodystrophy and Zellweger syndrome), infection, infarction, and malignancy presents as adrenal failure later in life. The diagnosis of primary or secondary adrenal hypofunction is made biochemically. Medical geneticists may be able to pinpoint the precise underlying defect.

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Adrenal Glands Table 14.1 Descriptions of new INRG tumor stages (Brisse et al., 2011)

Fig. 14.13 Congenital adrenal hypoplasia in a neonate who presented with hypoglycemia and seizures. Sagittal image of the right adrenal gland (arrow) shows a small gland with loss of the expected corticomedullary differentiation. The infant was diagnosed with panhypopituitarism.

Tips from the Pro ●

Do not forget to evaluate the adrenal glands in neonates who present with hypoglycemic collapse or seizures. Small glands with absence of the normal architecture may signal adrenal hypoplasia and direct further endocrinologic evaluation (▶ Fig. 14.13).

Tumor Stage

Description

L1

Localized tumor not involving vital structures, as defined by the list of IDRFs, and confined to one body compartment

L2

Loco-regional tumor with presence of one or more IDRFs

M

Distant metastatic disease (except stage MS tumor)

MS

Metastatic disease in children younger than 18 months, with metastases confined to skin, liver, and/or bone marrow

adjacent organs and vessels, and assess metastatic spread to lymph nodes or liver. Adrenal tumors are heterogeneous, vascular, and hyperechoic relative to liver. These solid, well-defined tumors do not possess a capsule. Anechoic, cystic areas of hemorrhage and/or necrosis are often present. Focal echogenic areas of calcification are seen in 30%. Very fine calcification may cause a more diffuse increased echogenicity (▶ Fig. 14.14, ▶ Fig. 14.15, ▶ Fig. 14.16, ▶ Fig. 14.17, ▶ Fig. 14.18, ▶ Fig. 14.19, ▶ Fig. 14.20, ▶ Fig. 14.21, ▶ Fig. 14.22, ▶ Fig. 14.23, ▶ Fig. 14.24, ▶ Fig. 14.25). US is a valuable tool for tumor surveillance because there is the risk for the development of a secondary malignancy (▶ Fig. 14.26).

Tips from the Pro ●

14.5.8 Medullary Tumors: Neurogenic Tumors Neuroblastic tumors account for 10% of childhood tumors, are the most common solid extracranial tumors in childhood, and cause 15% of childhood cancer deaths. Neuroblastic tumors comprise neuroblastoma, ganglioneuroblastoma, and ganglioneuroma. These tumors arise from the sympathetic nervous system, and 40% involve the medulla of the adrenal gland. Ganglioneuroma is the most benign form and occurs in older children. Ganglioneuroblastoma has intermediate malignant potential. Neuroblastoma is a malignant tumor; the median age of children at presentation is 22 months. The spectrum of clinical behavior of neuroblastic tumors varies widely. They may be classified as high-, intermediate-, or low-risk entities, with some maturing/regressing while others progress despite treatment. The International Neuroblastoma Staging System (INSS) is used to classify disease (▶ Table 14.1). The International Neuroblastoma Risk Group (INRG) has described image-defined risk factors that allow the standardization of neuroblastoma staging (▶ Table 14.2). Children often present with abdominal distention or pain, and 50% will have metastatic spread at the time of diagnosis. US is used to localize the tumor, define the relationship with

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Neuroblastic tumors appear similar on imaging, and it is not possible to discriminate between the various types with imaging alone. US will allow the visualization of different movements between adjacent structures, which are lost when tumor has invaded the adjacent organ. Vascular tumor thrombus may be seen but is less common than in Wilms tumor. US is useful not only as a screening modality in patients with a suspected adrenal tumor but also in the post-treatment period (▶ Fig. 14.27).

Table 14.2 Description of the Image Defined Risk Factors (IDRFs) for the abdomen and pelvis (Brisse et al., 2011) Anatomic Region

Description

Abdomen and pelvis

Tumor infiltrating porta hepatis and/or hepatoduodenal ligament Tumor encasing branches of superior mesenteric artery at mesenteric root Tumor encasing origin of celiac axis and/or origin of superior mesenteric artery Tumor invading one or both renal pedicles Tumor encasing aorta and/or vena cava Tumor encasing iliac vessels Pelvic tumor crossing sciatic notch

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Adrenal Glands US may localize a tumor to one or both adrenal glands; most are well defined and relatively small, measuring less than 5 cm in diameter (▶ Fig. 14.28). Larger masses are more heterogeneous, with features of central necrosis, hemorrhage, and calcification. Malignant pheochromocytomas can be diagnosed confidently only when invasive disease or metastases are documented. Distant spread of disease is typically to lymph nodes, lung, liver, and bone. Surgical resection remains the principal treatment, but lifelong blood pressure surveillance and monitoring for the development of metachronous tumors are necessary.

Tips from the Pro ●

The diagnosis of a pheochromocytoma is made biochemically, with image localization of the tumor a secondary event.

14.5.10 Adrenal Cortical Tumors Fig. 14.14 A mixed-echogenicity neuroblastoma involving one limb of the right adrenal gland. The other limb shows the normal hypoechoic cortex and hyperechoic central medulla. (Image courtesy of Dr. H. Bray, BC Children’s Hospital, Vancouver, Canada.)

14.5.9 Medullary Tumors: Pheochromocytoma Pheochromocytoma is an intra-adrenal paraganglioma tumor that arises from the medullary catecholamine-producing cells. In contrast to adult pheochromocytomas, those diagnosed in children are more frequently familial than sporadic; von Hippel–Lindau syndrome, multiple endocrine neoplasia types 2A, 2B, and 2C, mitochondrial succinate dehydrogenase enzyme defects, Beckwith–Wiedemann syndrome, and phakomatoses are all associated with paraganglioma development. Genetic testing is mandatory in all children in whom apparently sporadic tumors are diagnosed. In contradistinction to adult tumors, pediatric pheochromocytomas are more likely to be extra-adrenal, bilateral, or multifocal. The clinical presentation is variable, and tumors may be asymptomatic. Symptoms, when present, are due either to the endocrine activity of the tumor or to mass effect from local tumor or distant metastases. Paroxysmal or sustained release of catecholamines may cause hypertension, which can be malignant. Sweating, weight loss, heat intolerance, nausea and vomiting, polyuria, anxiety, and behavioral disturbances are all documented.

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Adrenal cortical tumors—adenomas and carcinomas—constitute fewer than 0.5% of all childhood neoplasms. Younger female children (< 5 years of age) are far more likely to have malignant disease. A proportion of children with an adrenal cortical tumor will have a familial predisposition; Li–Fraumeni syndrome (▶ Fig. 14.29), Beckwith–Wiedemann syndrome, hemihypertrophy syndrome, multiple endocrine neoplasia type 1, congenital adrenal hyperplasia, and Carney complex are all associated with adrenal cortical tumors. More than 90% of adrenal cortical tumors are functionally active, with iso- or heterosexual pseudo-precocious puberty; Cushing or Conn syndrome is the clinical and biochemical result. Virilization is the most typical presentation of a carcinoma, and Cushing syndrome is the archetypal finding with a hormonally active adrenal adenoma (▶ Fig. 14.30). A palpable abdominal mass or pain may be the diagnostic feature of a carcinoma. Most carcinomas are large and lobulated at diagnosis, measuring more than 5 cm in diameter. On US, they tend to have a heterogeneous echotexture that is secondary to intralesional hemorrhage, necrosis, and calcifications (▶ Fig. 14.31 and ▶ Fig. 14.32). Doppler is helpful to determine if there is any associated IVC invasion (▶ Fig. 14.33). Adenomas may be encapsulated, with more regular margins, and they tend to be smaller. Should the adenoma have a high fat content, it will be echogenic. Calcification is not usually a feature of adenomas. Lipid-rich adenomas in older adolescents may be diagnosed (as in adults) with techniques such as chemical shift MR imaging, in which there is signal loss on out-ofphase T1-weighted images. The mainstay of treatment is surgical excision; children with a malignant adrenocortical tumor who are younger than 2 years

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Adrenal Glands

Fig. 14.15a–c Right suprarenal solid mass in a neonate. a The tumor shows generalized increased echogenicity and a well-defined margin. It is causing a local mass effect, displacing the right kidney inferiorly and compressing the inferior vena cava (IVC). b Color Doppler demonstrates internal vascularity within the tumor. The IVC is compressed by the large retroperitoneal mass. The upper pole of the right kidney demonstrates normal flow with color Doppler. c Coronal reformat from a contrast-enhanced computed tomographic scan demonstrates the inferior displacement of the right kidney and anteromedial displacement of the IVC by the right adrenal neuroblastoma. The lumen of the IVC is narrowed but remains patent (arrow). Congenital neuroblastoma occurs within the neonatal period and is the most common malignancy in this age group. (Images courtesy of Dr. H. Nadel, BC Children’s Hospital, Vancouver, Canada.)

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Fig. 14.16a,b A right suprarenal mass with a well defined margin, which causes local mass effect on the liver. a The echogenicity is heterogeneous, with hypoechoic areas due to tumor necrosis or hemorrhage: International Neuroblastoma Staging System (INSS) stage 1. b There is internal vascular architecture within this neuroblastoma, as demonstrated with color Doppler. (Images courtesy of Dr. H. Nadel, BC Children’s Hospital, Vancouver, British Columbia, Canada.)

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Fig. 14.18 This large, solid right adrenal neuroblastoma has no capsule and an indistinct lobulated margin, and it contacts the adjacent liver with loss of a clear plane between the adjacent structures. (Image courtesy of Dr. H. Nadel, BC Children’s Hospital, Vancouver, Canada.)

Fig. 14.17a,b a This neuroblastoma shows loss of a clear plane between the liver and the tumor (arrow). b Contrast-enhanced computed tomography is often a part of the initial staging to delineate vascular involvement and assess for metastatic spread. The tumor has a clear margin from the liver and kidney on this study. Magnetic resonance imaging is an alternative for cross-sectional imaging. (Images courtesy of Dr. H. Nadel, BC Children’s Hospital, Vancouver, Canada.)

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Fig. 14.19a,b Ganglioneuroblastoma arising from the left adrenal gland. a The tumor is well-defined and predominantly hypoechoic on ultrasound. There is internal hyperechoic calcification and also some posterior acoustic shadowing. b Coronal T1-weighted magnetic resonance (MR) image of the same patient shows a well-defined tumor with homogeneous signal intensity greater than that of the liver (arrow). MR imaging can also be used as part of the staging process at diagnosis to define lymphadenopathy and hepatic metastases. (Images courtesy of Dr. H. Bray, BC Children’s Hospital, Vancouver, Canada.)

Fig. 14.20 This neuroblastoma is predominantly hyperechoic with numerous well defined anechoic cystic structures corresponding to necrosis: International Neuroblastoma Staging System (INSS) stage 4. The tumor crosses the midline. (Image courtesy of Dr. H. Nadel, BC Children’s Hospital, Vancouver, Canada.)

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Fig. 14.21 Cystic neuroblastoma is well documented. This tumor contains internal septa with a solid hyperechoic component superiorly. (Image courtesy of Dr. H. Bray, BC Children’s Hospital, Vancouver, Canada.)

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Adrenal Glands

Fig. 14.22a,b Infant presenting with abdominal distention. Physical examination showed hypertension and a hemoglobin level of 5 g/dL. Abdominal ultrasound revealed bilateral multicystic adrenal mass lesions (a) on the right and (b) on the left side. Urinary dopamine levels were markedly elevated. Biopsies confirmed neuroblastoma.

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Fig. 14.24 Sagittal ultrasound shows a mixed-echogenicity primary adrenal tumor with a rim of calcification in an infant. (Image courtesy of Dr. J. M. Somers, Nottingham City Hospital, Nottingham, UK.)

Fig. 14.23a,b a This neuroblastoma contains hyperechoic punctate and curvilinear echoes due to calcification, seen in up to one-third of cases. Posterior acoustic shadowing may or may not be present. b Coronal reformat from a contrast-enhanced computed tomographic examination clearly shows the calcification within a low-attenuation solid mass arising in the right suprarenal region, extending across the midline, displacing the right kidney, and surrounding both renal arteries at their origin from the aorta. The inferior vena cava is encased by tumor and cannot be defined separately from the mass. (Images courtesy of Dr. H. Bray, BC Children’s Hospital, Vancouver, Canada.)

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Fig. 14.25a–c a This neuroblastoma in a 9-month-old child is a small right adrenal neuroblastoma (arrow) with metastatic spread to the liver, visible as numerous hyperechoic foci. The prognosis is good, with a 75 to 90% 3-year survival. b Axial slice from a contrast-enhanced computed tomographic scan illustrates the heterogeneous low-attenuation right adrenal primary tumor (arrow) with multiple low-attenuation foci of metastatic disease within the liver. c Iodine I 123 metaiodobenzylguanidine (123I-MIBG) study is a part of the staging process at diagnosis and surveillance. The majority of neuroblastoma tumors shows avid uptake of the radioactive tracer. This case shows tracer within a large left adrenal neuroblastoma and metastatic disease within the liver, consistent with INSS 4S disease. Bone disease may also be evident on the 123I-MIBG study; however, a technetium Tc 99 m methyl diphosphonate (99mTc-MDP) bone scan is usually also performed at diagnosis to look for bone metastases. (Images courtesy of Dr. H. Nadel, BC Children’s Hospital, Vancouver, Canada.)

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Fig. 14.27 Small residual adrenal mass in an infant treated successfully for advanced neuroblastoma. The mass is heterogeneous with tiny flecks of echo-bright calcification.

of age and whose tumor weighs less than 200 g have a better outcome. Resection is curative for those with adenomas.

Tips from the Pro ●

Imaging can rarely distinguish between a benign and a malignant adrenal tumor mass, but the latter can be inferred if the mass is large (> 5 cm) or is seen to encase or invade adjacent structures, and of course if there is evidence of distant metastatic disease.

14.5.11 Other Adrenal Tumors Further histologic subtypes of both benign and malignant adrenal tumors are exceptionally rare in the pediatric age group. Many cannot be distinguished on radiologic grounds alone, and histologic analysis is necessary for diagnosis.

Lipomatous Tumors

Fig. 14.26a,b Embryonal rhabdomyosarcoma that developed within a treated, mature neuroblastoma under surveillance, confirmed histologically. a Heterogeneous, rounded mass lesion arising at the site of the previous neuroblastoma. b There is avid uptake within the rhabdomyosarcoma, seen on a fused fluorodeoxyglucose F 18 positron emission tomography/computed tomography (18F-FDG-PET/CT) image. (Reprinted with kind permission of Springer Science + Business Media from Mann GS, Byrne AT, Nadel HR, Bray H. Embryonal rhabdomyosarcoma as a second malignancy following multimodal therapy for advanced-stage neuroblastoma. Pediatr Radiol 2008;38 (9):1017–1020.)

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This group includes myelolipoma, angiomyolipoma, teratoma, and lipoma. All are benign lesions. Myelolipomas are more common in older patients, and when small they are asymptomatic. Hematopoietic bone-marrow and mature adipose cells are found within them in variable proportions (▶ Fig. 14.34). Patients with poorly controlled congenital adrenal hyperplasia have an increased incidence of these lesions. Spontaneous hemorrhage and mechanical compression of adjacent structures are two possible causes of symptomatic tumors. The adrenal gland is a rare location for an extragonadal teratomas. In the few cases reported in the literature, most are mature and benign. Symptoms when present may be vague: nonspecific back pain or abdominal distention. However, torsion or leakage of intralesional contents can result in an acute abdomen. At US, these tumors contain both cystic and solid elements, with adipose tissue being echo-bright.

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Adrenal Glands

Fig. 14.29 Small, right-sided adrenal mass lesion discovered in a 7-month-old girl with Li–Fraumeni syndrome who presented with precocious puberty.

Fig. 14.28a,b Pheochromocytoma in a 16-year-old girl with hypertension and elevated urinary catecholamines. a Ultrasound shows a small, well-defined, left-sided hypoechoic lesion. AO, aorta; LK, left kidney; SPL, spleen. b The lesion is of increased signal intensity on the T2-weighted magnetic resonance image. (Images courtesy of Dr. H. Bray, BC Children’s Hospital, Vancouver, Canada.)

Fig. 14.30a,b Adrenal adenoma in a 14-year-old girl who presented with Cushing syndrome. a Ultrasound shows a well-defined, homogeneous, right-sided adrenal mass. b The corresponding axial source computed tomographic scan showing the ovoid lesion to enhance less than the adjacent liver.

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Fig. 14.31a–c Adrenal carcinoma in a 5-month-old infant. a Abdominal radiograph shows large, left-sided mass lesion with a peripheral rim of calcification (arrows). b Ultrasound examination shows a heterogeneous tumor mass, with linear echo-bright areas of calcification and mixed echogenic and echo-poor regions, suggesting associated tumoral hemorrhage and necrosis. c Coronal reformat from a contrast-enhance computed tomographic examination again demonstrates the marked tumor heterogeneity and calcifications.

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Cavernous Hemangiomas and Lymphangiomas These are benign lesions that may be discovered incidentally or during evaluation of the abdomen should they be large enough to cause a mass effect. Intralesional hemorrhage may lead to a more acute presentation. US can locate a lesion within the adrenal gland. The appearance in the adrenal is similar to that elsewhere in the body (▶ Fig. 14.35).

Rarer Adrenal Malignancies It is often not possible to distinguish between any of these tumors when using any of the available imaging modalities (▶ Fig. 14.36). Extrarenal rhabdoid tumor, peripheral primitive neuroectodermal tumor, and secondary non-Hodgkin lymphoma will be seen as unilateral or bilateral solid masses of variable size that generally have a heterogeneous echotexture. Central necrosis and invasion of adjacent vessels and organs may all be detectable by US.

14.5.12 Miscellaneous Adrenal Masses Hemolytic anemia and myeloproliferative disorders may result in extramedullary hematopoiesis. It is extremely rare to find this in the adrenal gland, and the sonographic appearances are nonspecific; a well-defined mass of intermediate echogenicity is seen. The past medical history of the patient may be of assistance, but oftentimes biopsy is still required. Juxta-diaphragmatic pulmonary sequestrations are not adrenal masses, but they may be mistaken for them at imaging (▶ Fig. 14.37). The identification of a feeding systemic arterial vessel may help to differentiate these from other lesions.

14.5.13 Wolman Disease

Fig. 14.32a,b Left-sided adrenal carcinoma. a Mixed-echogenicity mass lesion suggesting tumor hemorrhage and necrosis at ultrasound. b Coronal T1-weighted magnetic resonance image confirming the adrenal lesion; areas of high signal in the primary tumor represent methemoglobin and intralesional hemorrhage. There is also a large metastatic deposit in the right lobe of the liver (arrow).

Wolman disease is a rare autosomal-recessive metabolic disorder characterized by the deposition of triglycerides and cholesterol esters in the liver, spleen, lymph nodes, small bowel, and adrenal cortex. There is a deficiency of the lysosomal enzyme acid lipase. Presentation is within months of birth, with steatorrhea, vomiting, abdominal distention, and failure to thrive. Hepatosplenomegaly and lymphadenopathy are seen. The imaging findings are characteristic, with bilateral adrenal enlargement and dense calcification (▶ Fig. 14.38). Thickening of the wall of the small bowel and an enlarged liver and spleen may also be seen with US.

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Fig. 14.33a–c Adrenal carcinoma. a Well defined, right-sided adrenal mass of intermediate echogenicity. b Central flow is demonstrated on color Doppler. c Extension into the adjacent inferior vena cava (arrow) is shown on a transverse image.

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Fig. 14.34 Adrenal myelolipoma (between calipers) discovered incidentally. The echo-bright areas represent the lipomatous elements, the echo-poor regions the myeloid component. (Image courtesy of Dr. S. J. Gillespie, Royal Victoria Hospital, Belfast, Northern Ireland.)

Fig. 14.36 Axial computed tomographic source image showing a large, heterogeneous right adrenal mass lesion that is directly invading the inferior vena cava (white arrow). The patient was a 16-year-old girl with an extrarenal rhabdoid tumor. (Reprinted with permission of Elsevier from Baslassy C, Navarro OM, Daneman A. Adrenal masses in children. Radiol Clin N Am 2001;49:711–727)

Fig. 14.35 Adrenal lymphangioma. Oblique image showing a multiloculate, fluid-filled adrenal mass; the right kidney is flattened and lies more posteriorly. The imaging characteristics of this lesion within the adrenal gland are identical to those found elsewhere within the body.

Fig. 14.37 Left-sided suprarenal mass in a 5-day-old girl, which had been documented on antenatal imaging. There is an echogenic mass (between cursors) lying posterior to the flattened adrenal gland (white arrow). The diagnosis is intra-abdominal extralobar pulmonary sequestration. (Reprinted with permission of Elsevier from Baslassy C, Navarro OM, Daneman A. Adrenal masses in children. Radiol Clin N Am 2001;49:711–727)

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Adrenal Glands

Fig. 14.38a,b Wolman disease. This infant presented to the emergency department with intractable vomiting and failure to gain weight. a Sagittal ultrasound shows a densely calcified right-sided adrenal gland. b Coned plain radiograph showing the upper abdomen. The heavily calcified adrenal glands are arrowed. (Reproduced from Paterson A. Adrenal pathology in childhood: a spectrum of disease. Eur Radiol 2002;12(10):2491–2508.)

Recommended Readings Aljabri KS, Bokhari SA, Alkeraithi M. Adrenal hemangioma in a 19-year-old female. Ann Saudi Med 2011; 31: 421–423 Arena F, Romeo C, Manganaro A et al. Bilateral neonatal adrenal abscess. Report of two cases and review of the literature. Pediatr Med Chir 2003; 25: 185–189 Avni EF, Rypens F, Smet MH, Galetty E. Sonographic demonstration of congenital adrenal hyperplasia in the neonate: the cerebriform pattern. Pediatr Radiol 1993; 23: 88–90 Balassy C, Navarro OM, Daneman A. Adrenal masses in children. Radiol Clin North Am 2011; 49: 711–727, vi Barwick TD, Malhotra A, Webb JAW, Savage MO, Reznek RH. Embryology of the adrenal glands and its relevance to diagnostic imaging. Clin Radiol 2005; 60: 953–959 Brisse HJ, McCarville MB, Granata C et al. International Neuroblastoma Risk Group Project. Guidelines for imaging and staging of neuroblastic tumors: consensus report from the International Neuroblastoma Risk Group Project. Radiology 2011; 261: 243–257 Calhoun SK, Murphy RC, Shariati N, Jacir N, Bergman K. Extramedullary hematopoiesis in a child with hereditary spherocytosis: an uncommon cause of an adrenal mass. Pediatr Radiol 2001; 31: 879–881 Cobanoglu U, Yaris N, Cay A. Adrenal myelolipoma in a child. Pediatr Surg Int 2005; 21: 500–502 Coulter CL. Fetal adrenal development: insight gained from adrenal tumors. Trends Endocrinol Metab 2005; 16: 235–242

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Daneman A, Navarro O, Haller JO. The adrenal and retroperitoneum. In: Slovis TL, ed. Caffey’s Pediatric Diagnostic Imaging. Philadelphia, PA: Mosby Elsevier; 2008:2214–2233 Daneman D, Daneman A. Diagnostic imaging of the thyroid and adrenal glands in childhood. Endocrinol Metab Clin North Am 2005; 34: 745–768, xi Delfino M, Elia J, Imbrogno N et al. Testicular adrenal rest tumors in patients with congenital adrenal hyperplasia: prevalence and sonographic, hormonal, and seminal characteristics. J Ultrasound Med 2012; 31: 383–388 Demirel N, Baş AY, Zenciroğlu A, Taşci-Yildiz Y. Adrenal bleeding in neonates: report of 37 cases. Turk J Pediatr 2011; 53: 43–47 Ellis CL, Banerjee P, Carney E, Sharma R, Netto GJ. Adrenal lymphangioma: clinicopathologic and immunohistochemical characteristics of a rare lesion. Hum Pathol 2011; 42: 1013–1018 Eo H, Kim JH, Jang KM et al. Comparison of clinico-radiological features between congenital cystic neuroblastoma and neonatal adrenal hemorrhagic pseudocyst. Korean J Radiol 2011; 12: 52–58 Ferraz-de-Souza B, Achermann JC. Disorders of adrenal development. Endocr Dev 2008; 13: 19–32 German-Mena E, Zibari GB, Levine SN. Adrenal myelolipomas in patients with congenital adrenal hyperplasia: review of the literature and a case report. Endocr Pract 2011; 17: 441–447 Havekes B, Romijn JA, Eisenhofer G, Adams K, Pacak K. Update on pediatric pheochromocytoma. Pediatr Nephrol 2009; 24: 943–950 Hoffman CK, Filly RA, Callen PW. The “lying down” adrenal sign: a sonographic indicator of renal agenesis or ectopia in fetuses and neonates. J Ultrasound Med 1992; 11: 533–536 Karagiannis A, Mikhailidis DP, Athyros VG, Harsoulis F. Pheochromocytoma: an update on genetics and management. Endocr Relat Cancer 2007; 14: 935–956 Li Y, Zhong Z, Zhao X. Primary mature teratoma presenting as an adrenal tumor in a child. Urology 2011; 78: 689–691 Lonergan GJ, Schwab CM, Suarez ES, Carlson CL. Neuroblastoma, ganglioneuroblastoma, and ganglioneuroma: radiologic-pathologic correlation. Radiographics 2002; 22: 911–934 Low G, Dhliwayo H, Lomas DJ. Adrenal neoplasms. Clin Radiol 2012; 67: 988–1000 Magiakou MA, Chrousos GP. Cushing’s syndrome in children and adolescents: current diagnostic and therapeutic strategies. J Endocrinol Invest 2002; 25: 181–194 Mitty HA. Embryology, anatomy, and anomalies of the adrenal gland. Semin Roentgenol 1988; 23: 271–279 Moore KL, Dalley AF II, Agur AMR. Clinically Oriented Anatomy. 6th ed. Baltimore, MD: Lippincott Williams & Wilkins; 2009 Nimkin K, Teeger S, Wallach MT, DuVally JC, Spevak MR, Kleinman PK. Adrenal hemorrhage in abused children: imaging and postmortem findings. AJR Am J Roentgenol 1994; 162: 661–663 Paterson A. Adrenal pathology in childhood: a spectrum of disease. Eur Radiol 2002; 12: 2491–2508 Porcaro AB, Novella G, Antoniolli SZ, Martignoni G, Brunelli M, Curti P. Adrenal extramedullary hematopoiesis: report on a pediatric case and update of the literature. Int Urol Nephrol 2001; 33: 601–603 Pradeep PV, Mishra AK, Aggarwal V, Bhargav PRK, Gupta SK, Agarwal A. Adrenal cysts: an institutional experience. World J Surg 2006; 30: 1817–1820 Ratnavel N, Farrer K, Sharland M, Chakraborty R. Neonatal adrenal abscess revisited: the importance of raised inflammatory markers. Ann Trop Paediatr 2005; 25: 63–66 Ribeiro RC, Michalkiewicz EL, Figueiredo BC et al. Adrenocortical tumors in children. Braz J Med Biol Res 2000; 33: 1225–1234 Ribeiro RC, Pinto EM, Zambetti GP, Rodriguez-Galindo C. The International Pediatric Adrenocortical Tumor Registry initiative: contributions to clinical, biological, and treatment advances in pediatric adrenocortical tumors. Mol Cell Endocrinol 2012; 351: 37–43 Rockall AG, Babar SA, Sohaib SAA et al. CT and MR imaging of the adrenal glands in ACTH-independent Cushing syndrome. Radiographics 2004; 24: 435–452 Roupakias S, Papoutsakis M, Mitsakou P. Blunt adrenal gland trauma in the pediatric population. Asian J Surg 2011; 34: 103–110 Sethuraman C, Parker MJ, Quarrel O et al. Bilateral absence of adrenal glands: a case series that expands the spectrum of associations and highlights the difficulties in prenatal diagnosis. Fetal Pediatr Pathol 2011; 30: 137–143 Sivit CJ, Hung W, Taylor GA, Catena LM, Brown-Jones C, Kushner DC. Sonography in neonatal congenital adrenal hyperplasia. AJR Am J Roentgenol 1991; 156: 141–143 Willi UV. The adrenal glands. In: Carty H, Brunelle F, Stringer DA, Kao C-S, eds. Imaging Children. Edinburgh, UK: Churchill Livingstone Elsevier; 2005:975–996 Yang DH, Goo HW. Horseshoe adrenal gland in right atrial isomerism and asplenia. Pediatr Radiol 2008; 38: 815 Zenker M, Schindler C, Kändler C, Hümmer HP, Rupprecht T, Ries M. A macrosomic newborn with a cystic adrenal mass. Eur J Pediatr 1999; 158: 261–263

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Chapter 15

15.1

Normal Anatomy and Variants

536

15.2

Pathology

538

Sonography of the Female Genital Tract

15

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15 Sonography of the Female Genital Tract Willemijn Klein The female genital tract consists of the vagina, cervix, uterus, and ovaries. Pathology of the female genital tract in children is uncommon or often not yet apparent, and therefore an ultrasound (US) examination of this area is rarely requested. If requests are made in our university hospital, the examination in neonates is mostly for large ovarian cysts or ambiguous genitals, in young girls mostly for tumors, and in teenagers for tumors and amenorrhea. US views of these structures are optimal when obtained through a filled or half-full bladder, which provides an acoustic window and pushes the air-filled bowels aside. If necessary, this can be accomplished in neonates by retrograde filling through a catheter. In neonates and small children, a linear high-frequency probe (4–12 MHz) gives high-resolution images; in larger children and adolescents, a curved array probe is used (3–6 MHz). In the case of congenital anomalies, magnetic resonance (MR) imaging provides a better delineation of the anatomy than does US. Some of these anomalies are shown only with MR images.

15.1 Normal Anatomy and Variants In the first days after birth, the uterus and ovaries of female neonates are remarkably prominent because of stimulation by maternal hormones. The cervix is equal in size to the fundus or slightly larger (▶ Fig. 15.1). The myometrium is thick, and the endometrial lining is visible (▶ Fig. 15.2). The ovarian follicles of the neonate may be large (▶ Fig. 15.3). After a few days, the size decreases and remains small for the next years. There will be a slow growth of these organs in relation to age and weight. During these years, the endometrium is usually not apparent and the follicles are small (up to 1 cm; ▶ Fig. 15.4). In the prepubertal years (usually from 9 years on), the uterus and ovaries increase in size more rapidly. The fundus grows larger than the cervix, which will cause a pear-shaped appearance (▶ Fig. 15.5). At puberty, the female genital tract will reach adult values, and the endometrium will be visible as an echogenic lining that varies with the phases of the menstrual cycle (▶ Fig. 15.6).

Fig. 15.1a,b Normal large uterus and cervix in a female neonate several hours after birth. a Sagittal ultrasound. b Transverse ultrasound. White arrow, uterus with echogenic endometrium; open arrow, bladder; arrowhead, rectum.

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Sonography of the Female Genital Tract

Fig. 15.2 This transverse ultrasound shows the normal uterus in a female neonate. The uterus is large because of stimulation by maternal hormones. The myometrium is thickened. The echogenic lining in the cavum is the endometrium (arrow).

Fig. 15.3 Fifteen-day-old neonatal girl with an asymptomatic large ovarian cyst. Open arrow, ovarian cyst; white arrowhead, bladder; open arrowhead, uterus.

Fig. 15.4 Normal uterus in a 10-year-old girl. The uterus is small, and the endometrium is not visible. White arrow, uterus; open arrow, vagina.

Fig. 15.5 Normal aspect of the uterus in a healthy postmenarchal 14-year-old girl. The myometrium is thickened. The free fluid in the cavum of Douglas is physiologic. In this case, the endometrium is not visible. Visibility depends on the cycle stage. White arrow, uterus; open arrow, vagina; white arrowhead, free fluid.

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Sonography of the Female Genital Tract

Fig. 15.6a,b Normal aspect of the uterus of a 14-year-old girl. a Transverse image. The uterus (white arrow) has an echogenic endometrium. The right ovary has a small cyst (open arrow). b Sagittal image.

15.1.1 Normal Measurements Normal values for the uterus and ovaries are shown in ▶ Table 15.1. The volumes were calculated with the formula for an ellipsoid: length × width × height × 0.523.

15.2 Pathology 15.2.1 Congenital Anomalies Congenital anomalies of the female genital tract are the result of abnormalities in the development of the paramesonephric (Müllerian) ducts, and to a much lesser degree the mesonephric (Wolffian) ducts, urogenital sinus, and/or cloaca. The upper

Table 15.1 Uterine and ovarian volumes Age

Number of healthy girls

Uterus, mL (SD)

Number of healthy girls

Ovary, mL (SD)

0–1 month

15

3.4 (1.2)

6

0.5 (0.4)

3 months

7

0.9 (0.2)

4

0.4 (0.1)

1 year

19

1.0 (0.2)

6

0.5 (0.2)

3 years

26

1.0 (0.3)

17

0.7 (0.4)

5 years

26

1.0 (0.3)

13

0.7 (0.5)

7 years

28

0.9 (0.3)

15

0.8 (0.6)

9 years

18

1.3 (0.4)

12

0.6 (0.4)

11 years

16

1.9 (0.9)

10

1.3 (1.0)

13 years

8

11.0 (10.5)

8

3.7 (2.1)

15 years

15

21.2 (13.5)

9

6.7 (4.8)

Source: Van Rijn RR, Robben S. Normal values. In: Van Rijn RR, Blickman JG, eds. Differential Diagnosis in Pediatric Imaging. New York, NY: Thieme Medical Publishers; 2011:625–660.

538

parts of the paramesonephric ducts form the fallopian tubes. The lower parts fuse in the midline in a process called lateral fusion. They form the uterus and upper part of the vagina (Müllerian tubercle). The lower part of the vagina develops from the urogenital sinus. The lower part is separated from the upper part by the hymen, which thins and perforates in the perinatal period. The close relation of the paramesonephros with the mesonephros and metanephros makes a combination of genital and urinary tract anomalies likely. Therefore, during a US examination of the female genital tract in search of congenital anomalies, one should always visualize the kidneys and bladder as well. The reverse is also true; when a congenital renal anomaly, such as a horseshoe kidney, multicystic kidney, or duplex system, is detected, the uterus should be visualized as well because in approximately 10% of cases there will also be an abnormal formation of the genitals.

Müllerian Duct Anomalies In considering the embryologic development of the female genital tract (▶ Fig. 15.7), congenital malformations in this area can be classified as follows: 1. Müllerian agenesis, in which there is a defect in the caudal portion of the Müllerian ducts; 2. Disorders of lateral fusion, in which the fusion of the two Müllerian ducts is incomplete; and 3. Disorders of vertical fusion, caused by malfusion between the Müllerian tubercle and urogenital sinus. First category: In Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome, the vagina (or proximal two-thirds) is absent, in combination with absence or abnormalities of the uterus and frequently abnormalities of the urinary tract. In addition, the ovaries may be absent, malformed, or in a high location (maldescensus). The presentation is usually in pubertal girls with

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Sonography of the Female Genital Tract

Fig. 15.7 Drawing of the embryologic development of the female genital system. The paramesonephric ducts (Müllerian ducts; arrow) fuse caudad to cephalad to form the proximal vagina and uterus. The unfused cephalic parts become the fallopian tubes. The caudal end comes in contact with the urogenital sinus (yellow; arrowhead). The vagina is formed partly by the urogenital sinus and partly by the paramesonephric ducts.

primary amenorrhea. MR imaging is needed to clearly visualize the rudimentary uterus and ovaries (▶ Fig. 15.8, ▶ Fig. 15.9, ▶ Fig. 15.10). There is an association with renal anomalies, and skeletal abnormalities may also occur. Second category: When correct lateral fusion of the Müllerian ducts fails to occur, there will be a septate, bicornuate, didelphys, or unicornuate uterus (▶ Fig. 15.11, ▶ Fig. 15.12, ▶ Fig. 15.13, ▶ Fig. 15.14, ▶ Fig. 15.15, ▶ Fig. 15.16). A minor fusion defect is a vertical septum in the vagina (▶ Fig. 15.17). Girls with these defects will often be asymptomatic until reproductive age (▶ Fig. 15.18). MR imaging is a better imaging modality than US to delineate the exact anatomy of these disorders. Third category: Disorders of vertical fusion are imperforate hymen, transverse vaginal septum, and atresia of the cervix or vagina. Vertical defects may be obstructive, and therefore symptoms occur at an earlier age. Symptoms of hydrocolpos may develop after birth because of the accumulation of genital secretions. However, symptoms usually occur at puberty with cyclic abdominal pain without menstruation. Vertical fusion defects are associated with lateral fusion defects. Rarely, there is a triad of uterus didelphys, obstructed hemivagina, and ipsilateral renal agenesis, the Herlyn-Werner-Wunderlich syndrome (▶ Fig. 15.19 and ▶ Fig. 15.20).

Tips from the Pro ●

When a congenital anomaly of the kidneys is seen, visualize the female genital system as well to detect additional congenital anomalies.

Fig. 15.8a–c Hypoplastic vagina in a teenage girl with MayerRokitansky-Küster (MRK) syndrome. She came to the hospital with primary amenorrhea. a Image showing the hypoplastic uterus behind the filled bladder (arrow). b Magnetic resonance image sagittal T2 sequence nicely depicts the hypoplastic vagina (arrow), which was not found on ultrasound. c The hypoplastic uterus (arrow).

539

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Sonography of the Female Genital Tract

15.2.2 Cloacal Malformation Cloacal malformation is a complex congenital malformation characterized by one common outflow of the urinary, genital, and intestinal tracts into the urogenital sinus. This occurs only in phenotypic girls. In a mild form, incomplete cloaca, a urogenital sinus is associated with an adjacent, anteriorly placed anus. In the more severe forms, there are different cloacal endings of the rectum and bladder/urethra into the vagina or urogenital sinus. Associated anomalies are Müllerian duct defects, renal tract abnormalities, spinal cord abnormalities, and skeletal (pelvic) abnormalities. US will be one of the first steps in the diagnostic work-up of these patients, preferably done soon after birth. An abdominal mass in these baby girls is usually a hydro(metro)colpos filled with urine or meconium (▶ Fig. 15.21). The combination of urine and meconium in the rectum and colon may calcify. The first US should include the pelvic structures, kidneys, and spinal canal because of associated anomalies. Further imaging of the pelvis is necessary to plan operations. This used to be a fluoroscopic study (genitography); however, nowadays (3D) MR imaging or computed tomography (CT) is preferred in specialized centers (▶ Fig. 15.22 and ▶ Fig. 15.23).

Disorders of Sexual Development

Fig. 15.9a,b Hypoplastic uterus and hypoplastic proximal vagina in a girl with primary amenorrhea. The hypoplastic vagina and uterus are consistent with Mayer-Rokitansky-Küster (MRK) syndrome. She had normal ovaries (not visible in these images). a Sagittal magnetic resonance (MR) image T2 sequence showing the hypoplastic uterus (white arrow) and proximal vagina (open arrow). b Transverse MR image T2 sequence shows the hypoplastic uterus (white arrow).

540

A neonate with cryptorchidism, labioscrotal fold fusion, clitoromegaly, epispadias, or hypospadias can have a disorder of sexual development (also called intersex state or ambiguous genitals), such as pseudo- or true hermaphroditism or gonadal dysgenesis. The diagnostic work-up should take place in the first days after birth to determine the true sex of the neonate and the possible treatments. US should determine the presence of a uterus and the type and position of the gonads (testes, ovaries, or both). In true hermaphroditism, there may be one testis and one ovary, or a combination with tissue that has a testicular echostructure and follicles, called an ovotestis (▶ Fig. 15.24). Patients with gonadal dysgenesis will have streak gonads (i.e., dysfunctional gonads without germ cells). During the US examination, the adrenals must be imaged because most female (XX) intersex neonates have masculinized external genitals. This is caused by congenital adrenal hyperplasia or adrenogenital syndrome, in which the adrenals are enlarged and typically have a cerebriform aspect (▶ Fig. 15.25 and ▶ Fig. 15.26). In boys with ambiguous genitals, a diagnosis will be reached in only 50% of cases (▶ Fig. 15.27). Male pseudohermaphroditism (46,XY) may have a female phenotype with undervirilization due to androgen insensitivity. In congenital adrenal hyperplasia syndrome, the XY neonate has a female phenotype and will present at puberty with amenorrhea. US can show the testes in the inguinal canal or in the abdomen. Inconclusive US examinations can be repeated, followed by MR imaging and ultimately laparoscopy. Intra-abdominal testes are highly likely to undergo cystic, premalignant, and malignant changes.

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Sonography of the Female Genital Tract

Fig. 15.10a–e Five-year-old girl with abdominal pain. a On ultrasound, a lymphangioma is seen in the right upper abdomen (open arrow). b In the left inguinal region, there is some free fluid (open arrow) and also a small uterus (white arrowhead). c Magnetic resonance (MR) image T2 space sequence nicely depicts the lymphangioma (open arrow). d During the MR imaging procedure, the girl was crying constantly, which provoked the bilateral inguinal hernias (open arrows). e Image shows the bilateral inguinal hernias (open arrows), as well as the hypoplastic uterus. At surgery, the lymphangioma was removed completely. The hypoplastic uterus was confirmed. The inguinal hernias both contained normal ovaries; the ovaries were placed intra-abdominally and the herniations closed. This girl had familial Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome.

541

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Sonography of the Female Genital Tract

Fig. 15.11 Ultrasonography of a 15-year-old girl with stomach pain, in whom a uterus didelphys was found coincidentally. RT, right uterus (white arrow); LT, left uterus (open arrow). (Courtesy of Professor Rebecca Stein-Wexler, UC Davis Children’s Hospital, Sacramento, CA USA.)

Fig. 15.12 A young girl underwent an ultrasound examination for a urinary tract infection. Coincidentally, a uterus didelphys was found. UT, uterus.

Fig. 15.14 Young woman with primary infertility, caused by a uterus didelphys. She had a normal vagina. This transverse magnetic resonance image shows the two uteri (arrows).

Fig. 15.13 This girl was born with a cloacal malformation (see also ▶ Fig. 15.21). Ultrasound of the uterus didelphys (arrows) at the age of 18 months.

542

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Sonography of the Female Genital Tract

Fig. 15.15a–d Girl with primary amenorrhea and monthly abdominal pain lasting 3 days. Hydrometrocolpos was relieved before magnetic resonance imaging. a Uterus didelphys (arrows). b Two cervices (arrows). c Two vaginas. The right vagina is aplastic (white arrow) and the left vagina is mostly aplastic, with 4 cm hypoplastic (open arrow). d Coronal view of the uterus didelphys and bicollis with blood products in both sides, consistent with hydrometrocolpos (arrows). This girl also had a congenital trachea abnormality and normal kidneys.

543

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Sonography of the Female Genital Tract

Fig. 15.17 Teenager with an asymptomatic septum in the uterus and vagina (open arrowheads).

Fig. 15.16 Young woman with primary infertility. A hysterosalpingogram shows a septate uterus.

Fig. 15.18a,b a A young woman found to have a uterus didelphys (not previously known) and a pregnancy in the right uterine horn (white arrow). The left uterus also has stimulated endometrium (open arrow). b There are two vaginas (white arrows). A premature delivery was performed at 28 weeks via cesarean section because of the abnormal genital tract anatomy.

544

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Sonography of the Female Genital Tract

Fig. 15.19a–c Fifteen-year-old girl with painful menstruation and normal blood loss. Magnetic resonance (MR) imaging showed a right renal agenesis (not shown), as well as a uterus didelphys with right-sided obstruction of the vagina and hematometrocolpos. This triad of findings is called the HerlynWerner-Wunderlich syndrome. a Coronal MR image shows the uterus didelphys, with a right (white arrow) and a left uterus (open arrow). b Coronal MR image shows the obstructed right vagina (white arrow) and open left vagina (open arrow). c Transverse MR image showing the obstructed right-sided hematocolpos (white arrow) and the left uterus (open arrow).

545

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Sonography of the Female Genital Tract

Fig. 15.20a,b Twelve-year-old girl with abdominal pain. a Ultrasound shows a hydrometrocolpos. This was caused by a transverse septum. b Magnetic resonance image shows blood products in the hydrometrocolpos.

546

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Sonography of the Female Genital Tract

Fig. 15.21a–d Neonatal girl born at 35 weeks. Prenatally, a large abdominal cyst was found. Postnatally, she had respiratory insufficiency caused by the abdominal swelling. At physical examination, she was found to have anal atresia and no urethra. The prenatal cyst appeared to be a hydrocolpos in this girl with a cloacal malformation. a First radiograph after birth showing the large abdominal mass (white arrows), which was a hydrocolpos. The intestines are pushed to the upper abdomen. b Ultrasound of the abdominal swelling shows a lesion with a fluid–fluid level. The uterus was found on top of this swelling. This was the hydrocolpos. c The second ultrasound, obtained on day 1 after catheterization of the hydrocolpos, showing the bladder (white arrow), uterus (open arrow), vagina with fluid (white arrowhead), and vaginal catheter (open arrowhead). d A suprapubic catheter was positioned in the vaginal pouch. The catheter was filled with contrast in this enema study, which shows filling of the common channel of vagina and urethra (cloaca; white arrow) during micturition, or overflow, with retrograde filling of the uterus didelphys (open arrow; see also ▶ Fig. 15.13).

547

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Sonography of the Female Genital Tract

Fig. 15.22a–c Neonatal girl born with a cloaca with anal atresia. a The ultrasound images show a uterus didelphys (arrows). b The two vaginas are separated by a septum. c A contrast enema via the distal stoma of the colon (white arrow) shows contrast overflow to the two vaginas (open arrow) through a rectovaginal fistula.

548

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Sonography of the Female Genital Tract

Fig. 15.23a,b Neonatal girl born with a cloacal malformation. a The enema study combines rectography, genitography, and micturition cystography. Single-outlet flow (white arrow), rectum (open arrow), vagina with impression of the cervix (white arrowhead), bladder (open arrowhead), and ureteral reflux at both sides (indented white arrow). b Same anatomy in a magnetic resonance T2-weighted image. Single-outlet trajectory (white arrow), rectum (open arrow), uterus (white arrowhead), bladder (open arrowhead), and the marker for the normal anus position (indented white arrow). (Courtesy of Dr. M. Thomeer, Erasmus Medical Center, Rotterdam, The Netherlands.)

Fig. 15.24a,b This baby was born with disorder of sexual development. a Ultrasound on day 1 shows a normal uterus (white arrow) and an apparently normal ovary (within measurements). Open arrow indicates the rectum. The adrenals (not shown) were normal. The karyogram was 46,XX, a girl. However, she returned at the age of 2 months with inguinal swelling. b Image shows inguinal testis-like structures, perhaps an ovotestis (between measurements). Surgery was performed. Pathology confirmed the diagnosis of ovotestis on both sides, therefore true hermaphroditism.

549

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Sonography of the Female Genital Tract

Fig. 15.25a–d This neonate was born with ambiguous external genitals. On day 1, an ultrasound of the urogenital system was obtained. The uterus and adnexa were normal; however, the adrenal glands were enlarged and cerebriform. Further tests confirmed the diagnosis of adrenogenital syndrome in a female neonate. a Ambiguous external genitalia. The midline structure could be either a small penis or clitoromegaly. There is no scrotum, and no testes were palpable. (Published with parental consent.) b The urethra is embedded in a phallus-like structure (arrow). c There are a normal uterus (white arrow) and adnexa with a cyst (open arrow). d Ultrasound shows normal kidneys. The adrenal glands (white arrow) are abnormally large and cerebriform, compatible with the diagnosis of adrenogenital syndrome.

550

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Sonography of the Female Genital Tract

Fig. 15.26a,b This neonate was born with ambiguous genitals: a large clitoris and partial fusion of the labia. On day 1, an abdominal ultrasound was obtained. a Uterus (white arrow) behind the bladder, normal aspect. Ovaries were also found. The urethra is phallus-like. b Normal adrenal glands (arrow: right adrenal gland) were seen. The karyogram was normal and there was no adrenogenital syndrome. This was a girl with a large clitoris, within the without further pathology.

Fig. 15.27 This baby was born with anal atresia, labia-like external organs, and a small phallus. Disorder of sex development was in the differential diagnosis. Ultrasound on day 1 shows testes in the labia-like structures. This was a bifid scrotum in a boy with 46, XY. The kidneys and adrenals were normal.

Be aware that a disorder of sexual development may also present at a later age—for instance with an inguinal hernia in girls, delayed puberty, or virilization of girls at puberty. Phenotypic girls with male pseudohermaphroditism can present with primary amenorrhea. There is an association with urinary tract anomalies, and therefore the kidneys and ureters should be included in US imaging. Further imaging may include fluoroscopic genitography to assess the urethra, vagina, and fistulas, and MR imaging to assess the internal gonads and genitalia.

Fig. 15.28 Fetal ultrasound showing a large ovarian cyst (white arrow). The open arrow indicates the urinary bladder. (Courtesy of Dr. M. Bekker, gynecologist, Radboud University Medical Center, Nijmegen, The Netherlands.)

15.2.3 Ovarian Tumors Adnexal masses in girls are uncommon. Patients may be asymptomatic or have nonspecific complaints, which can result in a delayed correct diagnosis. US is the imaging modality of choice. It should give information on the size of the lesion, internal characteristics (cystic, solid, calcified), and presence of flow. MR imaging can give further details on the extent, involved organs, and contents for the differential diagnosis and surgical planning. However, CT may be preferred to MR imaging when the situation is acute or when sedation for MR imaging is unwished for. CT is also used for the staging of malignant disease.

551

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Sonography of the Female Genital Tract

Fig. 15.29 This girl was born at 26 weeks, 4 days. She had a minipuberty, and a large ovarian cyst of 4.5 cm (arrow) was found on ultrasound. This cyst was punctured to prevent torsion.

The difference between benign and malignant lesions is not always clear on imaging. There are some clues for malignancy: solid lesions (as opposed to cystic or heterogeneous) and a size larger than 8 cm. Also, a mass or precocious puberty and elevated tumor markers are indicative of malignancy. The origin of ovarian tumors may be germ cells (teratoma, dysgerminoma, yolk sac tumor, choriocarcinoma, mixed varieties); epithelial cells (cystadenoma and cystadenocarcinoma); or stromal cells (granulosa–theca cell tumor, fibroma, thecoma, Sertoli–Leydig cell tumor, and undifferentiated sex cord stromal tumor). Other tumors that may (rarely) be situated in the ovary are small cell carcinoma, hemangioma, metastasis of colon carcinoma, Burkitt lymphoma, rhabdomyosarcoma, Wilms tumor, neuroblastoma, and retinoblastoma.

Benign Ovarian Tumors An ovarian cyst (> 3 cm) is the most common adnexal abnormality in female neonates and girls. Pain, torsion, rupture, and hemorrhage will bring these patients to the doctor’s attention and treatment. With the widespread use of prenatal US, ovarian cysts are frequently detected, and the number of neonates born with a known ovarian cyst has increased (▶ Fig. 15.28). There is no consensus on the best diagnostic and therapeutic regimen. This also depends on the sonographic aspect of the cyst. Simple cysts are anechoic (▶ Fig. 15.29). Complex cysts have septa, strands, debris with a fluid–fluid level, or a blood clot that resembles a solid part (▶ Fig. 15.30, ▶ Fig. 15.31, ▶ Fig. 15.32). Asymptomatic simple lesions with a diameter of less than 2.5 cm on postnatal US need no follow-up. Simple lesions with a

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Fig. 15.30 An abdominal cyst had been found prenatally in this neonatal girl. Follow-up after birth showed a cyst with debris, diagnosed as an ovarian cyst with hemorrhage. During the following month, the cyst did not decrease in size but remained asymptomatic. At 9 months, it had decreased in size. Probably a prenatal ovarian torsion.

diameter of more than 2.5 cm are followed with US to confirm involution and exclude cystic neoplasm. In some clinics, cysts larger than 5 cm are aspirated; in other hospitals, they are removed. Complex cysts are associated with ovarian torsion. Recently, some authors have advocated a conservative approach in newborns with complex cysts. Most of these cysts involute over time, but on follow-up the affected ovary is either absent or atrophic. If a fluid–fluid level is detected, a dependent echogenic layer with an anechoic superficial layer is seen in hemorrhagic cysts, whereas a dependent anechoic layer with an echogenic superficial layer is typical of a dermoid cyst. The floating echogenic layer is fat. Dermoid cysts (also called mature teratomas) comprise two-thirds of pediatric ovarian neoplasms. These lesions contain all three primitive cell lines (endoderm, mesoderm, and ectoderm). The diagnostic content of fat and calcifications may not always be very clear on US, and therefore MR imaging or CT is frequently needed. In most cases, there is a large cystic component and a solid nodule (the dermoid plug, Rokitansky nodule, or “tip of the iceberg”; ▶ Fig. 15.33, ▶ Fig. 15.34, ▶ Fig. 15.35, ▶ Fig. 15.36). Mucinous and serous cystadenomas are large cystic lesions with septa. They may have solid components. These are very rare in children.

Malignant Ovarian Tumors Immature teratomas are less differentiated than mature teratomas; however, on imaging the level of malignancy may not always be clear. They may be larger with more solid compo-

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Sonography of the Female Genital Tract

Fig. 15.31a–c Neonatal girl with the prenatal diagnosis of a large ovarian cyst. a Ultrasound on day 1 shows a cyst with a 4.7-cm diameter and a fluid– fluid layer, consistent with hemorrhage. The cyst was asymptomatic, and the treatment was conservative. b Ultrasound at 2 months shows organization of the hemorrhage within the cyst, now with a diameter of 3.6 cm. c At age 6 months, the cyst had decreased to 2.6 cm. The white arrow indicates the uterus. The calipers indicate the contralateral ovary.

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Fig. 15.32a–d Another neonatal girl with the prenatal diagnosis of an ovarian cyst, with, however, a solid component. Therefore, the differential diagnosis included teratoma. a Ultrasound on day 1 shows the cyst with a diameter of 4.8 cm. The solid component shows no calcification and no vascularization. Therefore, it was diagnosed as an ovarian cyst with an organized hemorrhagic component. The lesion was asymptomatic, and the treatment was conservative with ultrasound follow-up. b Ultrasound on day 1 showing the relation of the complicated cyst (open arrowhead) to the bladder (white arrow), uterus (open arrow), and rectum (white arrowhead). c On ultrasound after 5 weeks, the cyst diameter has decreased to 4.5 cm. The white arrow indicates the left kidney. d At the age of 2 months, the cyst has decreased in size, and the contents seem to merge.

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Sonography of the Female Genital Tract

Fig. 15.33a,b Eight-year-old girl with some abdominal pain. On ultrasound, a lesion was found in her right adnexa. a The lesion shows calcification (white arrow) within the solid component (Rokitansky nodule). b No vascularization. The lesion turned out to be a mature teratoma of the right adnexa.

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Sonography of the Female Genital Tract

Fig. 15.34a–d Fourteen-year-old girl who came to the hospital with a swollen left leg. The diagnosis was thrombosis of the left iliac vein with compression of the inferior caval vein caused by a large cystic lesion. a Ultrasound (US) shows the small, solid, septate compartments of the large cystic lesion (white arrow). b US shows the relation of the cystic lesion (white arrow) to the uterus (open arrow): not connected. On US, the ovaries are not identified. c Magnetic resonance imaging, fat-saturated sequence, performed after the US examination shows the solid compartment with some lipid structures (white arrow), suggestive of a Rokitansky nodule of a teratoma. d Nice view of the size of the cyst (white arrow) above the uterus (open arrow). The girl’s classmates teased her about her big belly and looking pregnant; however, it was not until the thrombosis developed that she visited a doctor. Surgery was performed, and a teratoma of the left ovary was removed.

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Sonography of the Female Genital Tract

Fig. 15.35a–c Nine-year-old girl seen by a pediatrician with vomiting and backache after micturition. At physical examination, a swelling in the abdomen was found. a Ultrasound shows a cystic mass with a small solid component with calcification. b The mass is apical to the uterus (white arrow), probably originating from an ovary. c Magnetic resonance image of the same lesion. This was a teratoma.

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Sonography of the Female Genital Tract

Fig. 15.36 Another image of a teratoma of the left ovary that nicely shows the dental elements in the Rokitansky nodule (white arrow).

nents. Dysgerminomas are the least differentiated type. These tumors are solid, lobulated masses with enhancing fibrovascular septa (▶ Fig. 15.37, ▶ Fig. 15.38, ▶ Fig. 15.39). They may occur in combination with other germ cell tumors, especially in cases of gonadal dysgenesis. Malignant stromal cell tumors are granulosa cell tumors and Sertoli–Leydig cell tumors. Granulosa cell tumors produces hormones and cause pubertal symptoms. The tumors are multicystic, almost spongelike, with solid components, and they may have hemorrhagic products. However, the appearance varies widely (▶ Fig. 15.40). Sertoli–Leydig cell tumors usually are asymptomatic but may be associated with virilization due to male hormone production. They are usually solid, but these tumors also may vary widely in appearance. Small-cell carcinoma of the ovary is rare and often lethal. This tumor affects girls and young women and may be familial. Patients may present with hypercalcemia and abdominal pain and swelling. The tumor is usually solid and tends to spread intra-abdominally. Other tumors affecting the uterus and vagina in girls are rhabdomyosarcoma (▶ Fig. 15.41 and ▶ Fig. 15.42) and primitive neuroectodermal tumor (PNET).

Fig. 15.37a–c Eleven-year-old girl sent to our university hospital with a tumor in the lower abdomen. The ultrasound examination shows a solid lesion with heterogeneous tissue (a). Furthermore, there are two solid lesions in the liver (arrow, b) and a 5-cm lesion in the spleen that is not anechoic (c). This turned out to be a dysgerminoma with liver metastases; the spleen lesion was an echogenic cyst.

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Sonography of the Female Genital Tract

Fig. 15.38a–d Fourteen-year-old girl seen at our university hospital with a nontender swelling in her belly. Ultrasound shows a solid swelling with some small cysts above her bladder (a), some tiny calcifications (b), and little vascularity (c). At the aortic bifurcation, there are two enlarged lymph nodes (d). (continued)

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Sonography of the Female Genital Tract and leukocytosis. Therefore, the differential diagnosis includes appendicitis. The initial imaging in children is US. The most common finding is enlargement of the ovary and a rounded edematous aspect, in combination with free fluid (▶ Fig. 15.43, ▶ Fig. 15.44, ▶ Fig. 15.45). Hemorrhage can give a more heterogeneous appearance. Also suggestive is the presence of multiple small peripheral follicles within the ovary. A mass can be found, such as a large cyst or a teratoma. Doppler US may show decreased or absent venous and/or arterial flow within the ovary; however, this does not have a good correlation with nonviability. Also, the demonstration of normal flow does not exclude torsion. A whirl sign of the vascular pedicle may be demonstrated in torsion. In ovarian torsion, the mass is usually located in the midline above the bladder. In addition, CT and MR imaging can show abnormal ovarian enhancement (▶ Fig. 15.46).

15.2.5 Pelvic Inflammatory Disease In older girls, pelvic inflammatory disease should be included among potential causes of acute lower abdominal pain. Sexually active girls and adolescents have a disproportionate risk for acquiring sexually transmitted diseases, probably caused by risky behavior and low levels of antibodies for these diseases. The diagnosis of pelvic infection is usually made clinically, based on a combination of pelvic pain, fever, and a foul discharge. US is rarely needed. However, when the symptoms are nonspecific or are not responding to therapy, US can help to distinguish among pelvic inflammatory disease, appendicitis, urinary tract infection, and complications of a hemorrhagic luteal cyst. In pelvic inflammatory disease, the organisms (most commonly Neisseria gonorrhoeae, Chlamydia trachomatis, and endogenous anaerobic organisms) infect the fallopian tubes and ovaries by an ascending path, causing pyosalpinx. Peritoneal spillage can occur with infections of the ovaries, leading to tubo-ovarian abscess formation. A pelvic mass may be present. The sequelae of pelvic inflammatory disease can be chronic pelvic pain, adhesions, and tubal occlusions causing infertility or ectopic pregnancy (▶ Fig. 15.47 and ▶ Fig. 15.48). Fig. 15.38e (continued) MRI of the lesion, which turned out to be a dysgerminoma. The white arrow indicates the retroperitoneal pathological lymph nodes.

15.2.4 Ovarian Torsion An ovarian torsion is a partial or complete rotation of the ovarian vascular pedicle on its long axis and usually involves both the ovary and the fallopian tube. Therefore, the term adnexal torsion is preferred. The torsion initially compromises the venous flow, which results in congestion and edema. This is followed by arterial flow compromise, causing ischemia and necrosis. It may ultimately lead to peritonitis. Torsion has an association with adnexal mass or (dermoid) cyst, but in about half of the cases, there is no lead point. Adnexal torsion can occur at any age, but the peak incidence is in the neonatal period and in puberty. The symptoms of adnexal torsion are similar to those of any acute abdomen: pain, nausea, pyrexia,

560

15.2.6 Amenorrhea Primary amenorrhea is defined as the absence of menarche by the age of 16, either with or without secondary sexual development. In cases of primary amenorrhea without impuberism, the most frequent cause is an obstructive Müllerian anomaly: an imperforate hymen or rarely a transverse vaginal septum (▶ Fig. 15.20). These patients present with cyclic abdominal pain and hemato(metro)colpos. Another cause is MRKH syndrome, with hypoplastic uterus and vagina (▶ Fig. 15.8). Rarely, it is caused by male pseudohermaphroditism. Primary amenorrhea with impuberism is usually caused by a delay of puberty. US of the uterus will show early signs of puberty. Rarely, it will show no signs of early puberty, and the cause can be found in the ovaries (dysgenesis, Turner syndrome), hypothalamus, or pineal gland. Secondary amenorrhea is commonly caused by pregnancy, also in young girls, which should never be forgotten! This may

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Sonography of the Female Genital Tract

Fig. 15.39a–c Girl nearly 2 years old with a lesion on her left buttock, found after a fall in the playground. However, the lesion persisted for weeks, and the girl was brought to a doctor. a Ultrasound (US) shows a heterogeneous lesion. The deeper borders are not found. Unfortunately, the girl was so unwilling to undergo a US examination that no images were obtained from the abdominal side. b Magnetic resonance (MR) imaging under total anesthesia followed. There was a large tumor in close relation to the uterus (white arrow). c This MR image shows the small part that was seen on physical examination and US (white arrow). This turned out to be a malignant yolk sac tumor, a dysgerminoma.

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Sonography of the Female Genital Tract

Fig. 15.40a–d Seven-year-old girl with symptoms of puberty: mammary growth and pubic hair growth. The levels of estradiol and testosterone were elevated. a, b Ultrasound showed a mostly solid tumor of the left adnexa (white arrows) and a stimulated endometrium (open arrow). c T2-weighted transverse magnetic resonance (MR) image showing the solid lesion with some cysts, some of which have a fluid–fluid level (arrow). d T1 fat-saturated MR image after intravenous contrast injection showing the enhancing tumor (arrow). This was a juvenile granulosa cell tumor.

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Sonography of the Female Genital Tract

Fig. 15.41a–c a One-year-old girl sent to our university hospital with a vaginal lesion. Elsewhere, it had been diagnosed as a vascular malformation. However, it grew over a 6-month period. b The initial ultrasound in our hospital shows solid filling of the vagina (between white arrows). c Magnetic resonance image showing the enhancing lesion in the wall of the vagina (white arrow) under the uterus (open arrow). This was a vaginal rhabdomyosarcoma. (Published with parental consent.)

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Sonography of the Female Genital Tract

Fig. 15.42a–c Five-year-old girl seen by a pediatrician because of repeated episodes of cystitis, not responsive to antibiotics. a Ultrasound shows a tumor in the bladder. b Sagittal view with the catheter in situ. c Magnetic resonance image shows that the tumor is based in the lower ventral and dorsal bladder wall, as well as the ventral vaginal wall (white arrow). This was a rhabdomyosarcoma.

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Sonography of the Female Genital Tract

Fig. 15.43 Three-year-old girl with a painful, red swelling in the right inguinal region. Ultrasound shows an oval structure with some very small cysts surrounded by some fluid. There is a visible connection with the intra-abdominal structures. At surgery, this turned out to be a necrotic ovarian torsion in an inguinal herniation.

Fig. 15.44 Swollen adnexa with peripheral cysts (between white arrows), compatible with the diagnosis of adnexal torsion.

Fig. 15.45a,b Eight-month-old girl with a sudden painful swelling in the right groin that could not be reduced manually. Ultrasound shows a swollen ovary (a) without flow (b). She was brought to the operating room, where a necrotic ovary was found in the right groin.

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Fig. 15.46a–e Twelve-year-old girl with intermittent abdominal pain. a Ultrasound shows a normal left ovary with a small cyst (white arrow). Next to but separate from this ovary is a very large right ovary. b Abundant vascularization in the lesion/right ovary. c Sagittal overview of the 8-cm lesion apical to the bladder. d Fat-saturated T1 magnetic resonance (MR) image without contrast shows the solid lesion with some small peripheral cysts and inhomogeneous parts, consistent with hemorrhagic changes. e Fat-saturated T1 MR image after contrast injection shows some enhancing parts. This lesion mimics a malignant ovarian tumor but turned out to be an adnexal torsion with a hemorrhagic component.

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Fig. 15.47a,b Adolescent girl with abdominal pain and fever. a Ultrasound shows a prominent uterus and a fluid-filled structure with abundant vascularization. b The same is seen on computed tomography. It was diagnosed as pelvic inflammatory disease with a tubo-ovarian abscess (white arrow).

Fig. 15.48a–c Young woman with abdominal pain related to her menstrual cycle. Ultrasound (a–c) shows multiple cysts in the lower abdomen with sedimentation or fluid–fluid layers. The diagnosis was endometriosis with hemorrhagic cysts.

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Tips from the Pro ●

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Fig. 15.49 Sixteen-month-old girl brought to a pediatric endocrinologist because of growth beyond expectation. The estradiol and growth hormone levels were abnormally high for her age; there was a pubertas praecox. The cause was found on magnetic resonance imaging: a small tuber cinereum hamartoma (white arrow).

be denied by the young mother and her caretakers, and she may present with abdominal mass and pain. Polycystic ovarian syndrome is the most common pathologic cause of secondary amenorrhea. Hyperestrogenic, hyperandrogenic stimulation leads to anovulation. The ovary has multiple small cortical cysts. The patients may present with irregular bleeding, in combination with obesity and hirsutism. Patients with prolonged illness or anorexia nervosa can have delayed puberty or secondary amenorrhea. Their ovaries have cysts of different sizes in no preferential location.

15.2.7 Pubertas Praecox Precocious puberty is defined as complete sexual development, including menarche, before 8 years of age. This can have a central or peripheral cause. Central (true) precocious puberty can be caused by lesions such as tuber cinereum hamartoma (▶ Fig. 15.49) or increased intracranial pressure; however, it is idiopathic in two-thirds of cases. On US, the uterus and ovaries will be enlarged. Follow-up US with hormonal therapy will show a decrease in size. Peripheral precocious puberty (pseudopuberty) is usually caused by autonomous ovarian follicular cysts. US will show a stimulated uterus and a unilateral follicular ovarian cyst. This can be seen in McCune–Albright syndrome. Another cause can be a hormone-producing tumor such as a granulosa cell tumor or Leydig cell tumor.

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US is the first imaging modality of choice in girls with abdominal and especially genital problems. For the female genital tract, a full bladder is the best acoustic window. It may be helpful to fill the rectum with saline as well—for instance, in patients with hypoplastic or unstimulated uterus and ovaries. If the US examination is inconclusive, MR imaging is the preferred imaging modality to clarify the anatomy and pathology of the pelvis and especially the internal genitals because of the high resolution and absence of radiation. The shared embryologic origin of the genital and urologic organs can be recognized in the shared pathologies. Therefore, if pathology is found in the female genital tract, one should always check the kidneys, and vice versa. Also, when a girl has an inguinal herniation, check the urogenital tract.

Recommended Readings Anthony EY, Caserta MP, Singh J, Chen MY. Adnexal masses in female pediatric patients. AJR Am J Roentgenol 2012; 198: W426–W431 Cesca E, Midrio P, Boscolo-Berto R et al. Conservative treatment for complex neonatal ovarian cysts: a long-term follow-up analysis. J Pediatr Surg 2013; 48: 510– 515 Chavhan GB, Parra DA, Oudjhane K, Miller SF, Babyn PS, Pippi Salle FL. Imaging of ambiguous genitalia: classification and diagnostic approach. Radiographics 2008; 28: 1891–1904 Chinchure D, Ong CL, Loh AH, Rajadurai VS. Neonatal ovarian cysts: role of sonography in diagnosing torsion. Ann Acad Med Singapore 2011; 40: 291–295 Duigenan S, Oliva E, Lee SI. Ovarian torsion: diagnostic features on CT and MRI with pathologic correlation. AJR Am J Roentgenol 2012; 198: W122–W131 Epelman M, Chikwava KR, Chauvin N, Servaes S. Imaging of pediatric ovarian neoplasms. Pediatr Radiol 2011; 41: 1085–1099 Fiaschetti V, Taglieri A, Gisone V, Coco I, Simonetti G. Mayer-Rokitansky-KusterHauser syndrome diagnosed by magnetic resonance imaging. Role of imaging to identify and evaluate the uncommon variation in development of the female genital tract. J Radiol Case Rep 2012; 6: 17–24 Garel L, Dubois J, Grignon A, Filiatrault D, Van Vliet G. US of the pediatric female pelvis: a clinical perspective. Radiographics 2001; 21: 1393–1407 Gassner I, Geley TE. Ultrasound of female genital anomalies. Eur Radiol 2004; 14 Suppl 4: L107–L122 Haber HP, Mayer EI. Ultrasound evaluation of uterine and ovarian size from birth to puberty. Pediatr Radiol 1994; 24: 11–13 Jaramillo D, Lebowitz RL, Hendren WH. The cloacal malformation: radiologic findings and imaging recommendations. Radiology 1990; 177: 441–448 Nakhal RS, Hall-Craggs M, Freeman A et al. Evaluation of retained testes in adolescent girls and women with complete androgen insensitivity syndrome. Radiology 2013; 268: 153–160 Oltmann SC, Garcia N, Barber R, Huang R, Hicks B, Fischer A. Can we preoperatively risk stratify ovarian masses for malignancy? J Pediatr Surg 2010; 45: 130–134 Patel MN, Racadio JM, Levitt MA, Bischoff A, Racadio JM, Peña A. Complex cloacal malformations: use of rotational fluoroscopy and 3-D reconstruction in diagnosis and surgical planning. Pediatr Radiol 2012; 42: 355–363 Servaes S, Victoria T, Lovrenski J, Epelman M. Contemporary pediatric gynecologic imaging. Semin Ultrasound CT MR 2010; 31: 116–140 Ziereisen F, Guissard G, Damry N, Avni EF. Sonographic imaging of the paediatric female pelvis. Eur Radiol 2005; 15: 1296–1309

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Chapter 16

16.1

Technique of Scrotal Ultrasound and Normal Ultrasound Anatomy

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Male Genital Tract

16.2

Hydrocele and Indirect Inguinal Hernia

570

16.3

Scrotal Tumors

576

16.4

Testicular Torsion

580

16.5

Epididymitis and Epididymo-orchitis

584

16.6

Idiopathic Scrotal Edema

585

16.7

Testicular Trauma

585

16.8

Cystic Transformation of the Rete Testis (Tubular Ectasia)

587

16.9

Epididymal Cyst

587

16 16.10 Varicocele

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16.11 Bilobed Testicle and Polyorchidism 589 16.12 Undescended Testicle and Retractile Testicle

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16 Male Genital Tract Matteo Baldisserotto Diseases of the genital tract are frequent in boys. Common indications for ultrasonography (US) include acute painful swelling of the scrotum or its contents, painless swelling of the scrotum or groin, and absence of detection of the normal testis on physical examination. In this chapter, diseases of the genital tract in boys and the role of US in the diagnosis of these diseases based on US findings will be discussed.

16.1 Technique of Scrotal Ultrasound and Normal Ultrasound Anatomy The scrotum should be positioned comfortably for a successful US examination. In older children and adolescents, a simple method is to lift the scrotum and close the thighs, thus allowing the thighs to support the scrotum. In younger children, the scrotum and perineal region should be studied in the “frog leg” position. The testicles should be examined with multiple-frequency linear array transducers in transverse and longitudinal planes along their entire length. The spermatic cord and its vessels should also be traced along their entire length up to the deep inguinal ring. Depending on the indication and/or US findings, the study should be extended to include the abdominal cavity. Color Doppler and power Doppler must be included in the assessment, with settings adequate to detect low flow velocities. On US, the testis appears as an elliptical and isoechoic organ with a smooth echotexture (▶ Fig. 16.1). The tunica albuginea is seen as a hyperechoic line covering the surface of the testis. The mediastinum presents as a hyperechoic central linear structure crossing the organ (▶ Fig. 16.1, ▶ Fig. 16.2, ▶ Fig. 16.3, ▶ Fig. 16.4). Testicular volume is calculated with the formula V = L × W × H × 0.52, where V = volume, L = length, W = width, and H = height. The volume should be evaluated according to the patient’s age (▶ Table 16.1). The epididymis appears as an elongated structure with increasing volume from the tail inferiorly to the head superiorly. Its echogenicity is similar to that of the testicle (▶ Fig. 16.1 and ▶ Fig. 16.2). Generally, in the transverse plane, the epididymis is located adjacent to the rear aspect or to the side of the testicle. The spermatic cord consists of the vas deferens, which is visible as a hypoechoic tubular structure (▶ Fig. 16.1 b), together with a network of veins (pampiniform plexus) and arteries.

Tips from the Pro ●

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The US coupling gel should be adequately heated and must be applied in generous amounts.

16.2 Hydrocele and Indirect Inguinal Hernia 16.2.1 Hydrocele A hydrocele is abnormal fluid in the scrotum. This can be classified as a communicating hydrocele or a noncommunicating hydrocele. The processus vaginalis is patent in communicating hydrocele (▶ Fig. 16.5), whereas it is closed in noncommunicating hydrocele. A communicating hydrocele may be associated with an indirect inguinal hernia (▶ Fig. 16.6). Noncommunicating hydrocele is common in newborns and can be quite large. It occurs as a result of the increased production and malabsorption of scrotal fluid. In older children, noncommunicating hydrocele can be observed after viral diseases or after trauma. When a clinical diagnosis of hydrocele has been established, US is requested to assess whether a communication with the peritoneal cavity is present and to exclude an associated hernia. On US, a hydrocele is characterized by different quantities of anechoic fluid surrounding the testis. When the hydrocele is small, only a thin layer of fluid is identified along the spermatic cord ( Video 16.1). In these cases, gentle manual compression of the scrotum displaces the liquid toward the inguinal canal, allowing determination of the patency of the canal ( Videos 16.1 and 16.2). When a hydrocele is massive, it can be challenging to identify the testicle (▶ Fig. 16.6 and ▶ Fig. 16.7). It is important to differentiate communicating hydrocele from noncommunicating hydrocele. The communication with the

Table 16.1 Values for testicular volume Age

Volume (mL) Mean (SD)

1 months

0.30 (0.10)

3 months

0.36 (0.10)

5 months

0.39 (0.10)

7 months

0.32 (0.10)

9 months

0.31 (0.10)

11 months

0.30 (0.10)

2 years

0.31 (0.10)

6 years

0.31 (0.10)

Abbreviation: SD, standard deviation. Source: Created from data within Kuijper EA, van Kooten J, Verbeke JI, van Rooijen, Lambalk CB. Ultrasonographically measured testicular volumes in 0- to 6-year-old boys. Hum Reprod 2008;23(4):792–796, with permission of Oxford University Press. Note: In total, of 344 boys from different ethnic backgrounds were studied. Testicular volume was calculated with the formula length × width × height × 0.523. No differences were found between ethnic groups or between right and left testicles.

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Male Genital Tract

Fig. 16.2a,b a Normal testicle in a newborn boy examined with a 13–4 MHz linear probe. Longitudinal view. RT, testicle; EH, epididymal head; ET, epididymal tail. b The testis in the transverse view demonstrates the mediastinum testis (arrow).

Fig. 16.1a,b a Normal testicle in a newborn boy examined with a 12– 5MHz linear probe. Longitudinal view: testicle, head of the epididymis (arrow), and tail of the epididymis (arrowhead). b Transverse view: testicular mediastinum (arrow) and deferent duct (arrowhead).

Fig. 16.3a,b Color Doppler ultrasound of a normal testicle in a 15-year-old. a Transverse view. The transmediastinal artery (arrowhead), a large branch of the testicular artery, courses through the mediastinum testis to supply the capsular artery (arrow). b Longitudinal view of the mediastinum (arrow).

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Fig. 16.4 Transverse ultrasound image of a normal testicle in a 16year-old demonstrating an oval gonad with a flattened mediastinum (arrow).

Fig. 16.5 Diagram shows a fluid collection (orange) along the spermatic cord communicating with the peritoneal cavity (communicating hydrocele).

Fig. 16.6 Scrotal ultrasound in a newborn boy reveals a large noncommunicating hydrocele with debris causing posterior displacement of the testicle. (a) Transverse view: testicle (arrow). (b) Longitudinal view: testicle (arrow) and epididymal head (arrowhead). Fig. 16.7 (a) Scrotal ultrasound, longitudinal view in a newborn boy reveals a communicating hydrocele (arrows) with a large scrotal hernia containing omental fat (O). (b) Transverse view shows omental fat (O), lateral displaced testicle (T), and an associated hydrocele (arrow).

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Male Genital Tract

Fig. 16.9 Two-year-old boy with an asymptomatic lump in the groin. Ultrasound, longitudinal view, shows a cyst in the spermatic cord, a spermatic cyst (C). E, epididymis; T, testis ( Video 16.9).

peritoneal cavity is usually easily identified in massive communicating hydrocele. However, the hydrocele may be encysted in the spermatic cord (spermatic cyst; ▶ Fig. 16.8, ▶ Fig. 16.9, ▶ Fig. 16.10), with quite characteristic appearances.

16.2.2 Indirect Inguinal Hernia Fig. 16.8 Diagram of an encysted hydrocele (spermatic cord cyst; arrow).

Fig. 16.10 Eight-year-old boy with a painless lump in the groin. Ultrasound, longitudinal view, shows a cyst, a spermatic cyst (arrow). T, testis.

Indirect inguinal hernia occurs when the processus vaginalis remains patent, and consequently, bowel loops, omentum, or mesentery may herniate into the scrotum (▶ Fig. 16.11). Inguinoscrotal hernias are six times more frequent in boys than in girls, and they are more common on the right side and in premature infants. US is useful in the diagnosis of incarcerated scrotal hernias that clinically present as a scrotal “mass.” These irreducible hernias can be classified as obstructive (when the bowel is obstructed), incarcerated (incarcerated by adhesions), or strangulated (when the blood supply of the herniated bowel is compromised). US has an accuracy of 95% for the detection of a hernia. Omental fatty tissue may present as a hyperechoic tubular structure or mass (▶ Fig. 16.7). The bowel may demonstrate peristalsis and can be identified by its contents: air, liquid, and/ Video 16.12a,b,c or echogenic fecal material (▶ Fig. 16.12; ▶ Fig. 16.13, ▶ Fig. 16.14; Video 16.3). When bowel is identified, the assessment of peristalsis is important. The absence of peristalsis may be related to a nonviable bowel. The presence of an akinetic bowel loop inside the scrotum has a sensitivity of 90% and a specificity of 100% for the diagnosis of strangulation (▶ Fig. 16.15). Sometimes, the groin is swollen in the immediate postoperative period. The radiologist can be asked to exclude an acute recurrence of the hernia. Most of the time, the swelling is caused by edema and/or hematoma (▶ Fig. 16.16). Rarely, the hernia persists or recurs after herniotomy. One should look for a bowel loop in the groin that can be followed toward the intraperitoneal bowel. It will often demonstrate peristalsis (▶ Fig. 16.17). Postoperative complications of inguinal hernia repair include seroma, hematoma, abscess, and displacement or “foldings” of the prosthetic mesh. On US, edema and thickening of the subcutaneous tissues of the inguinal region are seen. Seroma,

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Male Genital Tract abscess, and hematoma appear as fluid collections with mixed echogenicity (▶ Fig. 16.15, ▶ Fig. 16.16, ▶ Fig. 16.17). A prosthetic mesh appears as a linear, hyperechoic structure measuring about 2 mm in thickness, with a fine irregular surface and posterior acoustic shadowing. The position and disposal of the prosthetic mesh can also be evaluated during the scan. Following inguinal hernia repair, the patient should be monitored for testicular atrophy as a result of venous or arterial injury/obstruction in the spermatic cord. A hernia may recur in up 17% of operated patients.

Tips from the Pro ●

The best method to investigate a potential inguinal hernia is to ask the child to cough while standing, or to assess the area while the child is crying.

Fig. 16.11 Diagram of an inguinoscrotal hernia with cryptorchidism.

Fig. 16.12a,b One-year-old boy presenting with crying and a firm lump in the groin. a Ultrasound (US) reveals an incarcerated scrotal hernia (arrows) containing bowel loops in the inguinal canal (H) adjacent to the testicle (T). b Color Doppler US demonstrates absence of flow in the herniated bowel loops, which are displacing the spermatic cord vessels. Surgery revealed an incarcerated inguinal hernia containing viable bowel.

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Fig. 16.13 Six-month-old boy presenting with crying, abdominal distention, and a firm lump in the groin. Color Doppler ultrasound shows a large inguinal hernia containing an avascular omental fat mass (F). At surgery, an incarcerated inguinal hernia contained necrotic omental tissue.

Fig. 16.14a,b Newborn boy with a myelomeningocele presenting at physical examination with a large scrotal mass. a Ultrasound reveals a right scrotal hernia containing bowel loops (arrows), the right testis (T) in the peritoneal cavity, and an encysted hydrocele (H). b A left scrotal hernia (arrow) contains loops of small bowel.

Fig. 16.15 One-year-old boy with vomiting, abdominal distention, crying, and a firm lump in the groin. Ultrasound with a curvilinear 6–3 MHz probe demonstrates an incarcerated scrotal hernia containing distended and edematous bowel loops (L) in the inguinal canal adjacent to the testicle (T) and an associated small hydrocele (H). Surgery revealed an incarcerated inguinal hernia containing viable bowel.

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Fig. 16.16a,b A 2-month-old boy with a swollen groin 1 day after herniotomy. Small hydrocele and hemorrhagic remnants of the sac. No recurrence of the hernia. b A 9-month-old boy with a swollen groin 1 day after herniotomy. The testicle is well perfused. There are swollen remnants of the perioneal sac with hemorrhage. (Courtesy of Dr. Erik Beek, Wilhelmina Children’s Hospital, University Medical Centre Utrecht, The Netherlands.)

Fig. 16.17 A 3-month-old boy with a swollen groin a few hours after herniotomy. There is a bowel loop present along the spermatic cord (arrow). The testicle is surrounded by a small hydrocele. Apparently the operation failed to close the canal. (Courtesy of Dr. Erik Beek, Wilhelmina Children’s Hospital, University Medical Centre Utrecht, The Netherlands.)

16.3 Scrotal Tumors 16.3.1 Testicular Tumors Testicular tumors are rare in boys, accounting for 1 to 2% of all pediatric solid tumors. Malignant germ cell tumors, like seminoma and embryonal carcinoma, are rarely present in prepubertal patients. Teratoma is the most common testicular tumor in children and accounts for nearly 50% of prepubertal testicular tumors. Teratomas are mostly benign. They are formed of different germ cells of endoderm, mesoderm, and ectoderm. The average age of patients at presentation is 18 months, but these tumors can occur in the neonatal period. They can cause a rise in the serum alpha1 fetoprotein level. Gonadal stromal cell tumors account for 13% of the total; they include granulosa cell (5%), Leydig cell (4%), Sertoli cell (3%), and mixed gonadal stromal cell (1%) tumors.

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Epidermoid cysts constitute approximately 1% of testicular tumors. They are more common in nonwhite males in the second or third decade of life at the time of diagnosis. Epidermoid cysts are benign intratesticular masses, and unlike mature teratomas, they have no malignant potential. They are composed of keratinizing, stratified, squamous epithelium with a welldefined fibrous wall. Testicular microlithiasis is found in 0.6% of patients undergoing US but is present in about 50% of men with a germ cell tumor. It is much more common in patients without cancer. A meta-analysis of adult studies showed that in men without other risk factors for testicular cancer, the presence of testicular microlithiasis should not lead to further investigations or follow-up studies. Testicular tumors have very different US appearances; these lesions can be cystic, cystic–solid, or solid, and they may conVideo tain calcifications (▶ Fig. 16.18 and ▶ Fig. 16.19; 16.19). Although epidermoid cysts are true cysts, they appear solid on radiologic images. They appear as well-circumscribed, round to slightly oval hypoechoic nodules, which may have laminations. The laminations often give rise to an “onion skin” or ringed appearance, and the nodule may have a hyperechoic wall that is sometimes calcified (▶ Fig. 16.20). Gonadal stromal tumors may present as well-defined hypoechoic nodules (▶ Fig. 16.21). These tumors can be quite large at diagnosis, affecting the entire testicle with associated cystic areas. Yolk sac tumors and choriocarcinomas have variable US presentations; they may be homogeneous or heterogeneous and may contain cystic areas of necrosis and/or calcifications (▶ Fig. 16.22). On US, microlithiasis appears as small nonshadowing hyperechoic foci ranging in diameter from 1 to 3 mm. Testicular microlithiasis is often bilateral (▶ Fig. 16.23).

16.3.2 Secondary Tumors of the Testes Secondary testicular tumor involvement occurs in lymphoma and leukemia. This is more commonly seen in prepubertal boys. Testicular involvement occurs in 4% of patients with lymphoma and 11 to 25% of patients with leukemia. The testis is a frequent site of extramedullary relapse. Neuroblastoma and Wilms tumor can also compromise the testicle secondarily.

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Fig. 16.18a,b Fifteen-year-old boy with a firm testicular mass at physical examination. a Ultrasound (US) reveals a heterogeneous nodule (N) with a cystic area. It invades the scrotum wall (arrow) in a testicle with a small amount of microlithiasis. b Color Doppler US shows neovascular and hypovascular areas. The diagnosis of a testicular seminoma was confirmed at pathology.

Fig. 16.20 Fifteen-year-old boy with asymmetry of the testicles and delayed puberty. In the left testicle, a well-circumscribed tumor of mixed echogenicity is found. Ultrasound suggests an epidermoid cyst, which was confirmed at pathology. (Courtesy of F. J. A. Beek. Wilhelmina Children’s Hospital, University Medical Centre Utrecht, The Netherlands.) Fig. 16.19 Eight-year-old boy with a swollen right testicle. Ultrasound shows a collection of echogenic homogeneous round structures that resemble testicular tissue, some with microlithiasis. These structures did not move freely, apparently surrounded by thick mucus. The testicle itself (not shown) was compressed. Pathology showed a benign monodermal teratoma. (Courtesy of F. J. A. Beek. Wilhelmina Children’s Hospital, University Medical Centre Utrecht, The Netherlands.)

Fig. 16.21 Nineteen-year-old man with a hypoechoic nodule (N) in the right testicle, which proved to be a Leydig cell tumor.

US features of testicular leukemia vary widely; lesions can be unilateral or bilateral, diffuse or focal, and hypoechoic or hyperechoic (▶ Fig. 16.24). The US appearance of testicular lymphoma is also variable and indistinguishable from that of germ cell tumors (▶ Fig. 16.25). Testicular lymphoma usually appears as a discrete hypoechoic lesion, which can compromise the entire testicle. Wilms tumor may cause paratesticular involvement with a clinical scrotal mass (▶ Fig. 16.26). Testicular adrenal rests are a rare cause of a testicular mass. They can be clinically identified in patients with congenital adrenal hyperplasia and rarely in patients with Cushing syndrome. On US, these lesions appear as hypoechoic nodules and heterogeneously hyperechoic masses with shadowing. They are typically multiple, bilateral, and eccentrically located (▶ Fig. 16.27).

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Fig. 16.23 Fourteen-year-old boy with testicular microlithiasis incidentally detected at ultrasound.

Fig. 16.22 Color Doppler ultrasound in a 4-year-old boy shows a tumor that involves the whole testicle, with neovascular, avascular, and cystic areas. The diagnosis of an endodermal sinus tumor, also known as yolk sac tumor, was confirmed at pathology.

16.3.3 Extratesticular Tumors and Masses

Fig. 16.24a,b a Two-year-old boy with a recurrence of acute myeloid leukemia in the right testicle (arrows). b After 2 months of treatment, the normal anatomy was restored. (Courtesy of S. G. F. Robben. Maastricht University Medical Center, Maastricht, The Netherlands.)

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The most frequent malignant extratesticular tumor is a rhabdomyosarcoma originating from the spermatic cord or scrotal tunics. There is a bimodal behavior related to age, with a peak at 2 to 3 years and a second peak in adolescence. Paratesticular structures can give rise to a variety of benign tumors, like lipoma, leiomyoma, hemangioma, and fibroma. However, these are extremely rare. Lipoma is the most common benign neoplasm of the paratesticular tissues and spermatic cord. Scrotal hemangiomas are extremely rare, comprising fewer than 1% of all hemangiomas. On US, a rhabdomyosarcoma appears as a hypo- or hyperechoic solid hypervascular mass (▶ Fig. 16.28). Lipomas have a homogeneous hyperechoic appearance. On interrogation with Doppler, scrotal hemangiomas may present with a lobular pattern of vessels. They can mimic a varicocele at conventional or color Doppler US, but US may be useful in delineating the overall extent of the mass. Fibrous pseudotumors are benign, reactive, nonneoplastic lesions of the spermatic cord, epididymis, and tunica caused by fibroinflammatory reaction. Patients often have a history of trauma or infection. On US, they can mimic rhabdomyosarcoma, and the diagnosis is rarely made before surgical resection. Cellular neurofibroma of the spermatic cord is a rare solid extratesticular mass in adults and children with neurofibromatosis type 1. Ultrasonically, this tumor usually appears as a homogeneous nodule. Meconium periorchitis is a very rare masslike lesion that arises as a result of an inflammatory reaction to meconium within the scrotal sac after a prenatal bowel perforation.

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Fig. 16.25a–c a Seven-year-old boy presenting with a mass in the left testicle. b The mass is hypoechoic and well perfused. c Biopsy showed a non-Hodgkin lymphoma, which was also found in the mediastinum. (Courtesy of Mrs. W. M. Klein, University Medical Center St Radboud, Nijmegen, The Netherlands.)

Fig. 16.26a–c Boy with a Wilms tumor in the right kidney that metastasized to the scrotal wall. a Coronal magnetic resonance image T2 sequence demonstrates a mass in the kidney. b Ultrasound (US) shows an isoechoic scrotal mass. c Color Doppler US shows that the mass is richly vascularized. (Courtesy of R. R. van Rijn, Emma Children’s Hospital, Academic Medical Center of the University of Amsterdam, The Netherlands.)

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16.4 Testicular Torsion Testicular torsion is a surgical emergency, and delayed treatment or a wrong US diagnosis may result in loss of the testicle. Two types of torsion are described: intravaginal (most common) and extravaginal (torsion in the newborn).

16.4.1 Intravaginal Testicular Torsion

Fig. 16.27a,b Ten-year-old boy with congenital adrenal hyperplasia and bilateral testicular adrenal rests. a Transverse ultrasound (US) demonstrates a hypoechoic nodule in the testicles (white arrows). b Color Doppler US reveals a hypervascular lesion (white arrows). (Courtesy of C. G. Bruce, Pontificia Universidad Católica de Chile, Santiago, Chile.)

Intravaginal torsion affects mainly adolescents, but it can be observed in younger children and adults. When the attachment of the tunica vaginalis is too high, the spermatic cord can rotate within it, which can lead to intravaginal twisting (bell clapper deformity). This deformity can be found in up to 17% of normal individuals, and it may be bilateral in 12 to 40% of cases. The viability of the testis and the changes detected by US depend on the time elapsed since the start of the torsion. In general, the rate of testis salvage is greater than 90% if the torsion is detected and treated within 4 hours, and the success rate decreases with longer delay. Detorsion and orchidopexy 24 hours after the onset of torsion result in testicular atrophy in practically 100% of cases. The key to the US diagnosis is identification of the twisted spermatic cord ( Video 16.4). The location of the twist is superior to the testicle, and the twist presents with a snail shell– shaped whirlpool sign, knot, or mass (▶ Fig. 16.29; Video 16.29). This finding is highly sensitive and specific for the diagnosis of testicular torsion. A reduction or absence of flow on color Doppler or power Doppler interrogation has a sensitivity of 76 to 88% (▶ Fig. 16.30). Testicular torsion with heterogeneous parenchymal echotexture and cystic areas indicates late torsion and testicular nonviability. Therefore, at this stage, emergent scrotal exploration may no longer be required (▶ Fig. 16.31 and ▶ Fig. 16.32).

Fig. 16.28a,b Two-year-old boy with a firm mass in the right scrotum. a An extratesticular mass (M) with backward displacement of the right testicle (T) is observed on ultrasound (US). b The mass is hypervascular on color Doppler US. The diagnosis of rhabdomyosarcoma was confirmed at histopathology.

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Fig. 16.30a,b Ten-year-boy with scrotal pain lasting less than 6 hours. a Color Doppler ultrasound (US) and pulsed Doppler US show vessels inside the testicle. b A hyperechoic mass with spiraling vessels is observed in a location cephalic to the testicle on color Doppler US (arrow). Surgery proved that the mass corresponded to the torsed spermatic cord. The testis was viable.

Tips from the Pro ●

Some patients have a redundant spermatic cord with a spiral appearance of the vessels; this can simulate a torsion of the spermatic cord. In these cases, slight compression of the cord with the transducer allows the cord to be extended, which helps exclude torsion.

Fig. 16.29a–c Fifteen-year-boy with scrotal pain lasting less than 6 hours. a Color Doppler ultrasound shows no vessels inside the left testicle, which contains microlithiasis. b A hyperechoic mass containing torsed hypoechoic structures is observed above the testicle, corresponding to a twisted spermatic cord. c Surgery proved that the mass corresponded to the twisted spermatic cord (arrow). T, testicle.

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Fig. 16.31a,b Nine-year-old boy with scrotal pain for more than 24 hours. a Color Doppler ultrasound reveals an avascular and heterogeneous testicle with hyperemia of the peritesticular tissues. b At surgery, a spermatic torsion with a necrotic testicle was found.

Fig. 16.33 A newborn boy with a firm mass in the left scrotum. Power Doppler ultrasound, transverse view, reveals a large avascular left testicle (arrow) with hypoechoic lines radiating from the mediastinum, typical of extravaginal testicle torsion.

Fig. 16.32 Seven-year-old boy with scrotal pain of more than 24 hours’ duration caused by testicular torsion. Color Doppler ultrasound demonstrates an avascular and heterogeneous testicle (T) with hyperemia of the peritesticular tissues. At surgery, a spermatic torsion with a necrotic testicle was found.

16.4.2 Extravaginal Testicular Torsion Extravaginal torsion accounts for about 5% of all cases of torsion. Of these, 70% occur in the prenatal period and 30% after birth. The postnatal form is associated with a high birth weight and/or traumatic delivery. This type of torsion is often caused in the neonatal or prenatal period by deficient fixation of the

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spermatic cord. It occurs because the tunica vaginalis is not yet fixed to the gubernaculum, and therefore the spermatic cord and tunica vaginalis twist as a unit. When such torsion occurs in utero, the testis is usually infarcted. If it happens in the postnatal period, immediate surgical intervention may salvage the testis. The torsion may be bilateral. A complicated pregnancy and vaginal delivery seem to be predisposing factors for extravaginal torsion. On US, the testicular volume is most commonly increased, but it can be normal or reduced with absence of color Doppler flow. The testicular appearances are heterogeneous or hypoechoic. Streaks radiating from the mediastinum may be identified (▶ Fig. 16.33). A peripheral hyperechoic line may be seen, corresponding to severe testicular atrophy (▶ Fig. 16.34). A hydrocele, occasionally with debris, and thickening of the paratesticular structures are described associated findings

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Tips from the Pro ●

Every boy with an impalpable testis should have the inguinal region carefully studied with high-quality equipment. If the cause is severe testicular atrophy, this should be detected. The testicle appears as a small, hyperechoic nodule in the scrotum, and the investigation can be terminated.

16.4.3 Torsion of the Appendix Testis

Fig. 16.34 A newborn boy with an impalpable left testicle. Ultrasound, transverse view, demonstrates an atrophic left testicle related to intrauterine extravaginal torsion (arrow). The right testicle is normal (arrowhead).

Torsion of the appendix testis is the most common cause of acute scrotum in children. The prevalence of torsion of the testicular appendages ranges from 31 to 57% in children with acute scrotum. In these cases, the physical examination of the scrotum is very painful. Identification of the “blue dot” sign is highly specific for torsion of the appendix, although this is seen in only 21% of cases (▶ Fig. 16.35). US has an important role, not only to rule out testicular torsion but also to identify US signs of torsion of the testicular appendix.

Fig. 16.35a–c a Four-year-old boy with scrotal pain for 5 days. a The “blue dot” sign (arrow) was noted only after strong scrotal compression. b Color Doppler ultrasound reveals an enlarged avascular testicular appendix (arrow) in the epididymis–testicular recess and signs of epididymoorchitis. c At surgery, torsion of the testicular appendix was confirmed.

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Fig. 16.36a,b Four-year-old boy with testicular pain of 8 hours’ duration. a Ultrasound (US) demonstrates a hyperechoic twisted testicular appendix (arrow). E, epididymis; T, testicle. b Color Doppler US demonstrates absence of flow in the testicular appendix (arrow) in the epididymis–testicular recess in the longitudinal view. E, epididymis; T, testicle.

Fig. 16.37 Fourteen-year-old boy with a history of appendiceal torsion 3 years previously, presently with scrotal pain. Ultrasound shows a scrotolith (arrowhead) and a small hydrocele.

A torsed appendix testis usually shows up on US as a hyperechoic, isoechoic, or hypoechoic avascular nodule in the upper pole of the testis, measuring over 5 mm. It usually lies medial to the head of the epididymis in the transverse plane and in the recess between the epididymal head and upper testicular pole in the longitudinal plane (▶ Fig. 16.36). When signs of epididymitis are observed, one should scan the head of the epididymis in the transverse plane and look for a torsed testicular appendix medial to it. In a later phase, cystic areas may appear in the appendix, or the appendix testis can become detached and form a scrotolith (▶ Fig. 16.37).

Tips from the Pro ●

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A normal testicular appendix never compresses the tunica albuginea, distinguishing it from a torsed testicular appendix.

Fig. 16.38 Fourteen-year-old boy with right testicular pain for 2 weeks. Transverse view demonstrates a swollen, hypoechoic right vas deferens (arrow) and a normal left vas deferens (arrowhead), suggestive of deferentitis.

16.5 Epididymitis and Epididymo-orchitis Epididymo-orchitis is an important cause of acute scrotum in children, and its prevalence ranges from 14 to 28%. The scrotum may be affected by hematogenous epididymo-orchitis, particularly in cases of sepsis caused by Escherichia coli or Neisseria meningitidis. In younger children, epididymitis may be associated with congenital anomalies of the urogenital tract. If necessary, other imaging modalities should complement the US investigation. There may be bilateral involvement in patients with mumps, and there may also be subclinical involvement of the parotid glands in patients with mumps orchitis and epididymitis. Epididymitis secondary to bacterial infection is an uncommon cause of acute scrotum in children. When observed in patients at this age, it is most often related to torsion of a testicular appendix or trauma.

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Fig. 16.40 Eleven-year-old boy with testicular pain lasting for 3 days. A comparative study shows that the left epididymal head is normal (arrowhead) and the right epididymal head is enlarged and hypervascular (arrow) on color Doppler ultrasound, compatible with epididymitis.

The diagnosis of bacterial epididymitis or epididymo-orchitis should be considered only after testicular torsion or appendix testis torsion has been excluded at US.

16.6 Idiopathic Scrotal Edema

Fig. 16.39a,b Sixteen-year-old boy with testicular pain for 2 weeks. a The epididymal head (EP, arrow) is normal on ultrasound. b The epididymal tail (arrow) is enlarged, hypoechoic, and hypervascular, compatible with epididymitis. T, testicle.

The epididymis is totally or partially enlarged in cases of epididymitis. In cases of ascending contamination of the male genital tract, the vas deferens initially becomes swollen and hypoechoic before involvement of the epididymal tail, the body, and finally the epididymal head (▶ Fig. 16.38 and ▶ Fig. 16.39). When there is an associated orchitis, the testicle becomes swollen and appears hypoechoic or heterogeneous on US. Color Doppler US may reveal increased blood flow in the epididymis and testis (▶ Fig. 16.40), and abscess formation may occur (▶ Fig. 16.41). Other signs, such as a hydrocele with serous fluid or with septa and/or debris and thickening of the scrotal wall, are often found.

Tips from the Pro ●

The diagnosis of bacterial epididymitis or epididymo-orchitis should be considered only after testicular torsion or appendix testis torsion has been excluded at US.

Idiopathic scrotal edema is a self-limiting disease that is characterized by enlargement and diffuse hyperemia of the scrotal wall, which may extend to the abdomen. Idiopathic scrotal edema must be differentiated from cellulitis, which presents with fever and an elevated white blood cell count. Idiopathic scrotal edema may affect one or both sides of the scrotum and may recur in up to 75% of patients. It usually affects children younger than 10 years of age; the mean age of patients at presentation is 6 years. Some etiologic factors are allergies, insect bites, and angioneurotic or Quincke edema. US signs are a marked thickening of the scrotal wall with a striated aspect (▶ Fig. 16.42), a small hydrocele, and inguinal lymphadenopathy. There is increased blood flow of the peritesticular tissues on color Doppler.

16.7 Testicular Trauma Blunt scrotal trauma occurs most commonly among boys from 6 to 12 years old. Typical trauma mechanisms include kicks, falls, sports injuries, and bicycle or car collisions. Testicular trauma may result in simple contusion, testicular hemorrhage, epididymal hemorrhage, testicular fracture, or testicular rupture, which is the most serious of these conditions. US may be used for trauma staging and to rule out testicular rupture. A normal US examination excludes significant testicular injury. Acute bleeding or bruising of the testicular parenchyma usually appears as a hyperechoic area, whereas “old blood” appears as a hypoechoic lesion. Intratesticular hypoechoic areas are seen in cases of testicular fracture. In testicular rupture, the echogenic tunica albuginea is discontinuous. This finding has a sensitivity of 100% and a specificity of 65%. Acute hematocele and chronic testicular mixed collections are seen as

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Fig. 16.41 Fifteen-year-old boy treated for traumatic epididymitis without relief of symptoms. Color Doppler ultrasound demonstrates an enlarged and hyperemic right epididymal tail with a fluid collection, which proved to be an epididymal abscess.

Fig. 16.42a,b Four-year-old boy with idiopathic scrotal edema. a Ultrasound (US) demonstrates scrotal wall thickening (arrows) and small bilateral hydroceles (H). RT, right testicle; LT, left testicle. b Color Doppler US demonstrates a swollen, hyperemic scrotal wall.

hyperechoic and hypoechoic areas confined by the tunica vaginalis (▶ Fig. 16.43 and ▶ Fig. 16.44). The distinction from bacterial epididymitis may be difficult in cases of traumatic epididymitis.

Tips from the Pro ●

Fig. 16.43 Two-year-old boy with scrotal trauma after a fall. Color Doppler ultrasound demonstrates a hematocele (H) with anterior displacement of the testicle (T) and epididymis.

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In scrotal trauma, discontinuity of the tunica albuginea is indicative of testicular rupture, and the patient requires emergency surgery.

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16.8 Cystic Transformation of the Rete Testis (Tubular Ectasia) This condition is caused by partial or complete obliteration of the efferent testicular ducts, causing ectasia and transformation to cystic tubules. The condition is rare in children. It can be associated with epididymal cysts. In cystic transformation of the rete testis, the cysts are located in the mediastinum (▶ Fig. 16.46). These features help to differentiate cystic transformation of the rete testis from cystic testicular tumors.

16.9 Epididymal Cyst

Fig. 16.44 Fifteen-year-old boy with scrotal trauma after a kick. Color Doppler ultrasound demonstrates a hematocele (H) with anterior displacement of the testicle (T) and epididymis (E).

Epididymal cysts are a common finding, with a prevalence of 35% at the age of 15 years. Cysts of the epididymis may have a lymphatic origin or may be related to a spermatocele, which occurs exclusively in postpubescent boys. Many cysts in children regress over time. The cyst is generally located in the head of the epididymis. On US, the cyst appears anechoic with thin and smooth walls (▶ Fig. 16.46). Larger cysts may have septa and may be confused with hydroceles. One US feature helps to differentiate between the two: a cyst displaces the testis, whereas a hydrocele involves the testis.

Fig. 16.45a,b Nineteen-year-old man with cystic dilatation of the rete testis. a Transverse view demonstrates cysts centered in the mediastinum. b Longitudinal view of the cysts.

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16.10 Varicocele A varicocele is an abnormal enlargement of the veins of the pampiniform plexus of the spermatic cord caused by venous reflux. The condition is quite common and presents in adolescents and young adults. Most cases are idiopathic. The vast majority of varicoceles is left-sided. In some patients, a varicocele is related to compression of the renal vein or testicular vein by an intra-abdominal mass. After surgical correction, no significant change in testicular volume occurs, but there is an improvement of the sperm count and hormone levels. On US, the dilated veins appear as anechoic tortuous tubular structures along the spermatic cord. The venous reflux is best demonstrated during the Valsalva maneuver with color and pulsed Doppler (▶ Fig. 16.47; Video 16.47; ▶ Fig. 16.48). A varicocele may affect testicular growth, so testicular volumes must be systematically evaluated by US (▶ Fig. 16.49).

Fig. 16.46 Fourteen-year-old boy with a palpable scrotal mass. Ultrasound demonstrates a cyst (c), probably located in the head of the epididymis (H: small hydrocele).

Fig. 16.47a,b Fifteen-year-old boy referred for ultrasound (US) because of a suspected varicocele. a The pampiniform plexus veins at rest in the longitudinal view. b Venous reflux to the plexus during Valsalva maneuver on color Doppler ultrasound.

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Fig. 16.49a–c Eighteen-year-old man referred for ultrasound (US) because of a reduction in the right testicular size. a US of the left (L) testicle in longitudinal view. b US of the right (R) testicle in longitudinal view. c Color Doppler US shows an intratesticular varicocele with venous reflux during Valsalva maneuver. Fig. 16.48a–c Thirteen-year-old boy with visible varices, grade 2. a The left pampiniform plexus veins at rest in the longitudinal view. b Transverse view of the testicle and pampiniform plexus veins at rest. c Venous reflux to the plexus during Valsalva maneuver on color Doppler ultrasound. (Courtesy of R. R. van Rijn, Emma Children’s Hospital, Academic Medical Center of the University of Amsterdam, The Netherlands.)

Tips from the Pro ●

All patients who during a Valsalva maneuver in a dorsal decubitus position have a normal US appearance of the pampiniform plexus should also be investigated in an upright position.

16.11 Bilobed Testicle and Polyorchidism Bilobed testicle and polyorchidism are rare anomalies. A bilobed testicle is considered a variant of polyorchidism. In a bilobed testicle, the division of the genital ridge is incomplete, resulting in a bilobed appearance. Besides of the risk that a bilobed testicle will be confused with a testicular tumor, these individuals have a greater chance of developing testicular tumors. In a bilobed testis, US demonstrates a deep cleft that divides the testis in two (▶ Fig. 16.50). In polyorchidism, US can demonstrate the supernumerary testis in the scrotum or inguinal canal (▶ Fig. 16.51).

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Fig. 16.51 Six-month-old boy with crossed ectopia of the right testicle. Both testicles are in the left inguinal canal (arrows). (Courtesy of Cristian G. Bruce, MD, Pontificia Universidad Católica de Chile, Santiago., Chile) Fig. 16.50 Two-year-old boy with a deep interpolar cleft (arrow) corresponding to a bilobed testicle at ultrasound.

Fig. 16.52 Two-year-old with a nonpalpable left testicle. Ultrasound detected the left atrophic testicle high in the inguinoscrotal canal (arrows).

16.12 Undescended Testicle and Retractile Testicle An undescended testicle, or cryptorchidism, is the most common birth defect of the male genitalia. It occurs in about 3% of boys and in 30% of premature boys. Approximately 80% of undescended testes descend by the first year of life, and the majority of these within the first 3 months. The testicle may be located in the inguinal canal or in the retroperitoneum between the kidney and internal inguinal ring; it also may be ectopic in the subcutaneous tissue of the thigh, the perineum, the opposite scrotum, or the femoral canal. In retractile testicle, the testicle can be pulled down into the scrotum during physical examination, but it does not stay in the scrotum when released. A retractile testis may cause decreased fertility in the future. At US examination, the undescended testicle is often located in the inguinal canal, and it appears as an ovoid structure with

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Fig. 16.53 Twelve-year-old with a nonpalpable left testicle. Ultrasound detected the testicle (T) high in the inguinoscrotal canal, at the level of the internal inguinal ring (arrow).

a characteristic internal hyperechoic line corresponding to the testicular mediastinum. The testicle may be located in the internal canal (▶ Fig. 16.52). When compressed by the probe, the testicle slides in the inguinal canal. Testicular atrophy may occur (▶ Fig. 16.53). An intra-abdominal testis is located medial to the iliac vessels. Cryptorchidism can cause atrophy of the Video 16.54a,b). The sensitivity of US testicle (▶ Fig. 16.54; for the identification of an inguinal testis is approximately 100%, and for an abdominal testis approximately 50%. In retractile testis, the testis can be observed to move from the inguinal canal into the scrotum and vice versa.

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Male Genital Tract

Fig. 16.54 Three-month-old boy with a nonpalpable right testicle. The right testicle (T) is in a high intra-abdominal position, lateral and caudal to the cecum (C).

Recommended Readings Akbar SA, Sayyed TA, Jafri SZ, Hasteh F, Neill JS. Multimodality imaging of paratesticular neoplasms and their rare mimics. Radiographics 2003; 23: 1461–1476 Aso C, Enríquez G, Fité M et al. Gray-scale and color Doppler sonography of scrotal disorders in children: an update. Radiographics 2005; 25: 1197–1214 Baldisserotto M, de Souza JC, Pertence AP, Dora MD. Color Doppler sonography of normal and torsed testicular appendages in children. AJR Am J Roentgenol 2005; 184: 1287–1292 Chandra RV, Dowling RJ, Ulubasoglu M, Haxhimolla H, Costello AJ. Rational approach to diagnosis and management of blunt scrotal trauma. Urology 2007; 70: 230– 234 Coley BD, Siegel MJ. Male genital tract. In: Siegel MJ, ed. Pediatric Sonography. 3rd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2002:579–624 Coley BD, Siegel MJ. Male genital tract. In: Siegel MJ, ed. Pediatric Sonography. 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2011:554–601 De Carli C, Guerra L, Leonard M. Bilobed testicle in children: diagnosis and management. Can Urol Assoc J 2009; 3: E87–E88 Deurdulian C, Mittelstaedt CA, Chong WK, Fielding JR. US of acute scrotal trauma: optimal technique, imaging findings, and management. Radiographics 2007; 27: 357–369

Hesser U, Rosenborg M, Gierup J, Karpe B, Nyström A, Hedenborg L. Gray-scale sonography in torsion of the testicular appendages. Pediatr Radiol 1993; 23: 529–532 Homayoon K, Suhre CD, Steinhardt GF. Epididymal cysts in children: natural history. J Urol 2004; 171: 1274–1276 Kalfa N, Veyrac C, Baud C, Couture A, Averous M, Galifer RB. Ultrasonography of the spermatic cord in children with testicular torsion: impact on the surgical strategy. J Urol 2004; 172: 1692–1695, discussion 1695 Lee A, Park SJ, Lee HK, Hong HS, Lee BH, Kim DH. Acute idiopathic scrotal edema: ultrasonographic findings at an emergency unit. Eur Radiol 2009; 19: 2075–2080 Luker GD, Siegel MJ. Pediatric testicular tumors: evaluation with gray-scale and color Doppler US. Radiology 1994; 191: 561–564 Martin LC, Share JC, Peters C, Atala A. Hydrocele of the spermatic cord: embryology and ultrasonographic appearance. Pediatr Radiol 1996; 26: 528–530 Mazzu D, Jeffrey RB, Jr, Ralls PW. Lymphoma and leukemia involving the testicles: findings on gray-scale and color Doppler sonography. AJR Am J Roentgenol 1995; 164: 645–647 Mac New HG, Terry NE, Fowler CL. Cystic dysplasia of the rete testis. J Pediatr Surg 2008; 43: 768–770 Nijs SM, Eijsbouts SW, Madern GC, Leyman PM, Lequin MH, Hazebroek FW. Nonpalpable testes: is there a relationship between ultrasonographic and operative findings? Pediatr Radiol 2007; 37: 374–379 Phillips G, Kumari-Subaiya S, Sawitsky A. Ultrasonic evaluation of the scrotum in lymphoproliferative disease. J Ultrasound Med 1987; 6: 169–175 Pohl HG, Shukla AR, Metcalf PD et al. Prepubertal testis tumors: actual prevalence rate of histological types. J Urol 2004; 172: 2370–2372 Rathaus V, Konen O, Shapiro M, Lazar L, Grunebaum M, Werner M. Ultrasound features of spermatic cord hydrocele in children. Br J Radiol 2001; 74: 818–820 Robinson P, Hensor E, Lansdown MJ, Ambrose NS, Chapman AH. Inguinofemoral hernia: accuracy of sonography in patients with indeterminate clinical features. AJR Am J Roentgenol 2006; 187: 1168–1178 Savas M, Yeni E, Ciftci H, Cece H, Topal U, Utangac MM. Polyorchidism: a three-case report and review of the literature. Andrologia 2010; 42: 57–61 Tan IB, Ang KK, Ching BC, Mohan C, Toh CK, Tan MH. Testicular microlithiasis predicts concurrent testicular germ cell tumors and intratubular germ cell neoplasia of unclassified type in adults: a meta-analysis and systematic review. Cancer 2010; 116: 4520–4532 Tasian GE, Copp HL, Baskin LS. Diagnostic imaging in cryptorchidism: utility, indications, and effectiveness. J Pediatr Surg 2011; 46: 2406–2413 Traubici J, Daneman A, Navarro O, Mohanta A, Garcia C. Original report. Testicular torsion in neonates and infants: sonographic features in 30 patients. AJR Am J Roentgenol 2003; 180: 1143–1145 Woodward PJ, Schwab CM, Sesterhenn IA. From the archives of the AFIP: extratesticular scrotal masses: radiologic-pathologic correlation. Radiographics 2003; 23: 215–240 Woodward PJ, Schwab CM, Sesterhenn IA. From the archives of the AFIP: extratesticular scrotal masses: radiologic-pathologic correlation. Radiographics 2003; 23: 215–240 Zaragoza MR, Buckler LB, Parikh MJ. Cystic dysplasia of the testis: an unusual cause of a pediatric scrotal mass. Urology 1996; 47: 244–247

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Chapter 17 Musculoskeletal Ultrasound

17.1

Pediatric Hip

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17.2

Ultrasound of the Musculoskeletal System in the Older Child

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17 Musculoskeletal Ultrasound Jim Carmichael and Karen Rosendahl

17.1 Pediatric Hip Ultrasound (US) has added substantially to the management of hip disorders in newborns and infants, particularly with respect to developmental dysplasia of the hip, and also to the different forms of arthritis.

17.1.1 Normal Development of the Hip The hip joint forms by cleavage after 8 weeks’ gestational age. The fetal period is characterized by further growth and early endochondral ossification of the iliac, ischial, and pubic nuclei. These nuclei subsequently fuse, although separated by a growth zone (the Y-cartilage), to form the bony part of the hip socket. At birth, the shape of the bony socket varies along a continuum, from a smooth, round acetabulum with a well defined lateral edge (85% of all newborns) to a shallow, dysplastic acetabulum (3 to 4% of all newborns). This is best demonstrated on a coronal ultrasound view through the mid acetabulum (Graf standard view; ▶ Fig. 17.1). During the next few months, as the hyaline cartilage ossifies, the socket takes on a more mature shape, provided that the femoral head is stable and well centered. Around 1 to 2% of all newborns require abduction treatment to facilitate the maturation process. This figure rises to 6 to 7% according to the definition used for pathology. The normal femoral head is not strictly spherical, but slightly ovoid. The ossification center is visible sonographically in 3% of all newborns and normally appears radiologically at 3 to 4 months of age, somewhat earlier in girls than in boys. By 8 months of age in girls and 10 months in boys, the ossification

center is visible in nearly 100% of normal hips. Appearance after the age of 10 months is considered pathologic, and conditions such as Meyer dysplasia and multiple epiphyseal dysplasia should be considered in the differential diagnosis. During the first year of life, the sizes of the ossification centers may differ slightly between the two sides. At about 8 to 9 years of age, secondary ossification centers appear at the acetabular margin. Presumably, these centers are of importance for further growth of the acetabulum, and they subsequently fuse with the pelvic bone at about 18 years of age. In adults, the acetabulum covers slightly more than 50% of the femoral head.

17.1.2 Ultrasound Examination for Developmental Dysplasia of the Hip Developmental dysplasia of the hip (DDH) is the most common musculoskeletal disorder in infancy, with a reported prevalence from 0.5 to 4% according to the case definition used, age, ethnicity, and method of ascertainment. The term developmental dysplasia of the hip refers to a spectrum of pathology, ranging from the normal to severely dysplastic hip, with or without coexisting instability, in the newborn to the dysplastic and dislocated hip presenting in later infancy or early childhood. DDH affects both hips in approximately 30 to 40% of the cases; in unilateral disease, the left hip is more often affected than the right. More girls are affected than boys; for DDH presenting in later childhood, the ratio of girls to boys is approximately 5:1. Similarly, DDH detected on ultrasound, based on a modified Graf technique (Rosendahl), is also more common in newborn girls,

Fig. 17.1a,b Coronal (standard) views through the mid acetabulum, showing (a) key features for classification into different hip types and (b) the acetabular cartilage, consisting of an outer, circular fibrocartilaginous rim (arrow) and an inner component of hyaline cartilage (open arrow).

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Fig. 17.2 Ultrasound examination with the baby placed in a special, homemade hip cradle, lateral position, hip slightly flexed.

affecting 5.7% of all girls compared with 1.2% of boys. At skeletal maturity, the prevalence of hip dysplasia is reported at 3 to 19%, again according to the case definition used, age, ethnicity, and method of ascertainment. DDH is the underlying mechanism contributing to nearly one-fourth of hip-joint replacements in adults ages 40 years and younger.

Ultrasound Technique A combined technique for assessing both acetabular morphology and hip stability is advised. Although there is a strong association between hip morphology and stability, morphologically normal hips may be unstable, and vice versa. Hip morphology should be assessed with a Graf coronal (standard) section through the mid acetabulum, whereas hip stability may be assessed with different views (coronal, axial). We examine the child in the lateral position, placed in a special, self-made hip cradle for stabilization (▶ Fig. 17.2). Hip morphology is assessed with the baby’s hip slightly flexed and in a neutral abduction–adduction position to avoid lateralization in cases of instability. The baby’s femur is held with the examiner’s right hand, while the left hand holds the transducer, with the fourth and fifth fingers sliding behind the sacrum to stabilize the pelvis (▶ Fig. 17.2). The transducer, preferably a highfrequency (5–17 MHz as appropriate for the baby’s size) linear probe, is placed along the hip joint, perpendicular to the skin. After the caudal portion of the iliac bone has been identified abutting the Y-cartilage, the transducer is gently rotated until the distal part of the iliac bone parallels the contour of the image (▶ Fig. 17.3a). The resultant image represents the coronal (standard) view (▶ Fig. 17.1). After having secured the standard view with the femoral head centered in the acetabulum, we perform a Barlow-like provocation test with the baby and the examiner’s hands in the same starting position. The few hips that are irreducible are assessed with a dislocated femoral head. The most accurate approach for defining and grouping morphology is to measure the acetabular α-angle, or bony inclination, on a coronal midacetabular view (▶ Fig. 17.3a). The α-angle is the equivalent of the acetabular index on a pelvic radiograph and is based on lines drawn between fixed reference points for increased accuracy. In contrast, the assessment of

femoral head coverage is based on at least one movable reference point, such as the capsule (▶ Fig. 17.3b). In cases of hip instability, which is seen in up to 2% of all newborns, this measurement technique may bias the result significantly. Most hips stabilize during the first couple of weeks; however, instability, although subtle, can be seen up to the age of 3 to 4 months, or even longer. Hip stability is best assessed sonographically because the clinical Barlow–Ortolani tests are relatively inaccurate. Different US techniques have been used, including the Harcke dynamic, multiplanar approach. We prefer to perform the provocation test after the assessment of hip morphology, with the baby in the same lateral position (▶ Fig. 17.2). With the right hand, the baby’s hip is slightly rotated inward while mild pressure is applied along the axis of the femur (i.e., a telescopic movement). If no instability can be elicited, the same maneuver can be repeated three to four times with slightly different degrees of inward rotation. Because a screaming, distressed baby can hinder the detection of an unstable hip, we opt for a babyfriendly environment, including warm US gel and warm hands. In special cases, we even use a pacifier dipped in 50% sucrose or give 1 to 2 mL of 5% glucose per orally, in accordance with routines commonly used for premature babies.

Hip Classification: Morphology and Stability Based on hip morphology and the α-angle, hips are classified as normal (α-angle ≥ 60 degrees), immature (50 degrees ≥ αangle < 60 degrees), or dysplastic (mild, 43 degrees ≥ αangle < 50 degrees; significant, α-angle < 43 degrees), with or without instability (▶ Fig. 17.4). In regard to stability, hips are classified as stable, unstable (but not dislocatable), dislocatable (Barlow +), or dislocated (Ortolani + ; ▶ Fig. 17.5). When a hip is dislocated, traction and abduction are performed to test whether or not the femoral head is reducible (▶ Fig. 17.6). A partly reducible hip with a bright acetabular cartilage often is associated with delayed ossification or a dysplastic acetabulum (▶ Fig. 17.7), although the hyperechogenicity can disappear after reduction of the femoral head (▶ Fig. 17.8). Early surgical intervention to restore containment should be considered in these cases. The results should be reported in a standardized way, including the indications for the examination, the clinical findings (if possible), the US findings for each of the hips separately, and recommendations for further management.

Clinical Validity of the Findings During the last 25 years, the significance of acetabular dysplasia as described by Graf has been examined in a substantial number of studies. At birth, the mean acetabular inclination angle (α-angle) is 62.5 degrees (standard deviation [SD], 5.9) for girls and 65.4 degrees (SD, 5.1) for boys (▶ Fig. 17.9). From population-based studies, we have learned that around 75 to 85% of newborns have morphologically normal hips, 13 to 25% have immature hips, and 2 to 4% have dysplastic hips. One study reports a strong association between hip morphology and stability; only 0.1% of morphologically normal hips are dislocatable, versus 0.6% of immature hips, 62% of slightly dysplastic hips, and almost 100% of severely dysplastic hips. Several studies show that morphologically normal hips tend to remain

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Fig. 17.3a,b a The bony, acetabular inclination is measured by the α-angle, formed between the horizontal baseline and a line connecting the bony acetabular rim and the caudal portion of the iliac bone (cross-hatching). b Femoral head coverage as a measure of acetabular shape: a/b × 100. Values below 47% for boys and 44% for girls are considered pathologic.

Fig. 17.4a–d Rosendahl modification of Graf hip types. a Normal: normal hip with good bony modeling, a sharp bony rim, and narrow covering cartilage roof triangle. b Immature: physiologically immature hip. Dysplastic, mild (c) or significant (d): deficient bony modeling, rounded/flattened bony rim, and displaced cartilage roof. The images were obtained during the first postnatal day in four different newborns.

Fig. 17.5a–d Based on a Barlow maneuver with the newborn in a lateral position, hip stability is classified as follows: (a) stable; (b) unstable, with a gap between the femoral head and the acetabulum (arrow), but not dislocatable; (c) dislocatable, in which the femoral head can be pushed lateral to the baseline (dashed line), Barlow + ; or (d) dislocated, Ortolani + .

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Fig. 17.6a,b a Dislocated hip in a newborn. b On traction and abduction, the femoral head is partly, but not entirely, relocated. Note the remaining gap between the femoral head and the acetabulum (arrow). The cartilage is hyperechoic (open arrow), suggestive of damage.

Fig. 17.7a–c Dislocated and in part reducible hip (a) at 5 weeks of age (note the bright cartilage; arrow) and (b) at 11 weeks. The cartilage has restored normal echogenicity (open arrow). c Radiograph at 6 months of age shows a mildly dysplastic acetabulum.

Fig. 17.8a,b a Ultrasound of a dislocated and in part reducible left hip at 4 weeks. b Radiograph at 11 months showing a dysplastic left acetabulum with a subluxed femoral head.

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Fig. 17.10 Hip effusion in a 6-year-old boy presenting with an acute limp. Ultrasound shows a joint effusion with distention of the capsule (long arrow). The fluid is echo-free, suggestive of a transient synovitis. A, articular cartilage of the femoral head; F, femoral neck; E, femoral epiphysis; IL, iliopsoas muscle; short arrows, anterior and posterior capsule; arrowhead, normal focal prominence at the insertion of the posterior layer of the capsule, near the articular cartilage.

Fig. 17.9 Mean α-angle (standard deviation) for boys and girls separately, in a population-based cohort of 4,055 newborns.

normal with or without coexisting instability and that 97% of sonographically immature hips tend to normalize spontaneously within 3 months; a similar pattern has been observed for mildly dysplastic but stable hips. A recent 6-year follow-up of infants with mildly dysplastic and potentially unstable hips showed no difference in radiographic outcome at 6 years of age between those allocated to initial splintage for 6 weeks and those offered active sonographic surveillance. The delayed acetabular ossification or persistent dysplasia seen in a third of infants from both groups at 1 year of age had completely resolved in all but one of the girls in the treatment group.

Tips from the Pro ●

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A calm baby is crucial for successful ultrasound of the hip. Use sugar if necessary! A correct standard section is key to a correct diagnosis. In newborns, a dislocated hip that is not entirely reducible requires early treatment to reduce or prevent damage to the acetabular cartilage.

17.2 Ultrasound of the Musculoskeletal System in the Older Child 17.2.1 Arthritis Arthritis may result from or be associated with a number of conditions, including connective tissue diseases, trauma, congenital disorders, inflammatory diseases, and hematologic and neoplastic diseases. Here, we will focus on inflammatory disease and juvenile idiopathic arthritis but also comment on some of the other diseases that can be associated with joint symptoms in children.

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Transient Synovitis of the Hip Transient synovitis of the hip is an inflammatory condition of unknown origin that affects children between 2 and 10 years of age. Children typically present with an acute onset of local pain and a limp. The condition is self-limiting, and most patients recover after 1 to 3 weeks without any sequelae. A complicating Perthes disease has been reported in 1 to 2% of cases. Boys are more frequently affected than girls. The history and clinical and laboratory findings may help to rule out the differentials, in particular septic arthritis and trauma. US is the preferred imaging method, showing an anechoic effusion without any significant synovial thickening (▶ Fig. 17.10 and ▶ Fig. 17.11). If the findings are equivocal, US-guided aspiration should be considered. If there is no improvement within 3 weeks, additional imaging is indicated. Radiography can be used to rule out Perthes disease; if the results are normal, magnetic resonance (MR) imaging can be helpful.

Septic Arthritis Septic arthritis is seen more frequently in the pediatric population than in adults. In neonates, extension of a metaphyseal focus of osteomyelitis is a common route of infection, whereas hematogenous spread is more likely in older children. At all ages, there is a great diversity of infecting bacteria, but Staphylococcus and Haemophilus influenzae predominate in infants younger than 2 years of age. The hip is most frequently affected, especially in neonates. The diagnosis is based on joint aspiration, US-guided if possible. On US there is an effusion that often has echogenic material within (▶ Fig. 17.12). The capsule and surrounding tissues can be thickened. If a complicating abscess is suspected, MR imaging should be considered to guide therapy.

Juvenile Idiopathic Arthritis Juvenile idiopathic arthritis (JIA) is a heterogeneous condition encompassing all forms of chronic arthritis of unknown origin

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Fig. 17.11 Hip effusion in a 6-year-old boy. Same patient as in ▶ Fig. 17.10, 3 weeks later. The effusion is smaller and contains small particles (arrow), commonly seen in the resolution stage of a transient synovitis.

Fig. 17.13 Ultrasound of the left hip in a 9-year-old boy with juvenile idiopathic arthritis, showing a distended capsule (arrows) and a small, echogenic effusion. There was no evidence of a septic arthritis.

that has an onset before 16 years of age. It is characterized by chronic synovial inflammation, with a risk for the development of progressive joint destruction and serious functional disability. The reported incidence varies from 0.6 to 1 in 1,000 children, so JIA represents an important cause of acquired disability in children. During the last decade, new and potent therapeutic agents have become available to children with JIA, underscoring the need for accurate monitoring of the therapeutic response in regard to both disease activity and structural damage to the joint, prevention of the latter being considered the gold standard in studies of treatment efficacy. Current classifications, based on clinical criteria, are unsatisfactory because clinical parameters are poor markers of disease activity/progress and joint destruction.

Fig. 17.12 Septic arthritis of the right hip in a 3-year-old girl. Ultrasound shows an echogenic effusion, with significant distention of the capsule, which is thickened.

The role of imaging in JIA is first to diagnose the disease, second to evaluate disease activity, and third to monitor the effect of therapy. There has been a shift from traditional radiography toward newer techniques such as US and MR imaging, without proper evaluation of their accuracy and validity. Joint damage in JIA is traditionally evaluated with radiographic methods of scoring joint space narrowing and erosions; however, these are quite insensitive, in part because of the growing skeleton. Wrist disease has been associated with a more severe course of arthritis and a poorer functional outcome, and the wrist is the only joint for which suitable radiographic measures of disease progression have been reported. Much effort has been expended recently on validating existing scoring systems and devising new ones, of which the adapted versions of the Sharp/van der Heijde score have gained the most widespread acceptance. US is superior to clinical examination in the diagnosis and localization of joint effusion, bursal fluid collection, and synovitis (▶ Fig. 17.13). MR imaging is superior to other modalities in showing subtle cartilage and soft-tissue changes in the early stages of the disease, when radiographs are still normal. Computed tomography (CT) may be of value in visualizing the axial skeleton and sacroiliac joints. Bone scintigraphy may be useful in evaluating disease activity; however, the method is flawed, yielding both false-positive and false-negative results.

Ultrasound Techniques for the Assessment of Joints US is performed with a high-frequency linear transducer (12– 17 MHz), and the child is positioned according to which joint is being examined. The procedure must be tailored to the patient’s complaints and the location of pathology, and it should include a dynamic assessment and Doppler imaging

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Fig. 17.14 Ultrasound of the hip in a healthy 3-year-old girl. Standard anterior oblique view, identified by a horizontal femoral neck (F). The echogenicity of the anterior layer of the capsule (red double arrow) is slightly brighter than that of the posterior layer (white double arrow), a feature that can be seen in approximately one-fifth of normal hips. The line between the two layers represents their interface (arrowhead). C, femoral head cartilage; E, femoral epiphysis; IL, iliopsoas muscle; G, growth plate.

fluid can be seen with the hip in the neutral position, additional images with the hip in internal and external rotation should be obtained. Small effusions will then become visible. Note that on internal rotation, the capsule normally bulges slightly. A second view, including the femoral head and the labrum, should be obtained to evaluate the sphericity of the femoral head and the labrum (▶ Fig. 17.15). (Perthes – slipped capital femoral epiphysis – labral pathology?).

Knee

Fig. 17.15 Ultrasound of the hip in a 10-year-old healthy boy, showing a normal, rounded femoral head (E) and a normal labrum (arrow). ILT, iliopsoas tendon; G, growth plate; A, acetabular corner; C, articular cartilage.

when necessary. Below, we present the commonly used approaches.

Hip With the child supine, hips extended, and in a neutral rotational position, the transducer is placed along the femoral neck to produce the standard view (▶ Fig. 17.14). This includes the femoral head and neck, the capsule with its insertion, and the iliopsoas muscle. The capsule normally parallels the femoral neck from its origin at the outer surface of the labrum to its insertion at the intertrochanteric line. Here, it merges with the periosteum, although some fibers turn back to form an inner layer, inserting at the junction between the articular cartilage and bone. Both the outer and the inner capsular layers are lined with a thin synovial membrane comprising only one to three cell layers. On US, a thin, bright line representing the interface between the two layers can be seen in about 70% of normal hips (▶ Fig. 17.14). Moreover, in normal hips, differentiation between the synovial membrane and the fibrous capsule is impossible. Most often, both capsular layers have similar echogenicity and are isoechoic to the psoas muscle in about half of children and hyperechoic in one-third. In one-fifth of hips, the outer capsular layer is brighter than the inner (▶ Fig. 17.14). The thickness of the joint capsule as measured from its outer contour to the femoral neck is usually 4 to 5 mm, with no significant differences between left and right. A tiny sliver of joint fluid can be seen in approximately 6% of healthy children. If no

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The child is supine, with a slightly flexed knee joint to avoid biasing (e.g., anisotropy) of the quadriceps and patellar tendons. The standard sagittal view includes the patella inferiorly, the quadriceps tendon, and the suprapatellar recess (▶ Fig. 17.16). The recess is an acoustic window into the knee joint. If no fluid is seen on the initial scan, additional views obtained under manual compression (i.e., with a maneuver similar to that used for the “patellar dip” test) will lead a small effusion into the recess. On the other hand, if the recess is distended, graded compression with the transducer will help distinguish an effusion from synovial hypertrophy (▶ Fig. 17.17). Normally, a sliver of anechoic fluid can be found at all ages. An axial view in the popliteal fossa is helpful to exclude a Baker cyst.

Ankle With the child supine and the ankle joint slightly dorsally flexed, the true ankle joint, or talocrural joint, is assessed via the anterior recess. The sagittal standard view includes the distal tibia, the anterior recess, and the dorsal aspect of the talus (▶ Fig. 17.18). Normally, the recess is filled with fat pads, recognized as a triangular hyperechoic area. However, in some children this fat pad can appear relatively irregular, mimicking slivers of fluid. In such cases, additional views in flexion and extension can help differentiate between fluid and normal but irregular fatty tissue. The anterior aspect of the subtalar joint can be assessed by placing the transducer along the lateral aspect of the hindfoot, just below the anterior talofibular ligament. An effusion can be seen in the groove between the calcaneus and the talus (▶ Fig. 17.19). The posterior subtalar joint is best examined by scanning its posterior recess via a sagittal plane along the Achilles tendon/calcaneus.

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Fig. 17.16 Ultrasound of the knee joint in a 7-year-old healthy girl. Anterior sagittal view showing the distal femur (F), patella (P), quadriceps tendon (Q), and a sliver of joint fluid in the suprapatellar recess (arrow) between the suprapatellar (open arrow) and the prefemoral (arrowhead) fat pads.

Fig. 17.17 Ultrasound (US) in a 6-year-old boy presenting with a swollen knee joint, showing a distended suprapatellar recess (arrow). On compression, the distention disappeared, consistent with an echoic effusion suspicious for a septic arthritis. US-guided aspiration confirmed the diagnosis. PC, patellar cartilage.

Fig. 17.18 Sagittal standard view of the true ankle joint, showing the anterior recess filled with fat pads (arrow). T, distal tibia; TN, talar neck.

Fig. 17.19 Anterior subtalar joint in a 6-year-old boy with juvenile idiopathic arthritis. The transducer is placed just below the anterior talofibular ligament. There is an effusion and synovial hypertrophy (arrows). C, calcaneus; T, talus.

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Fig. 17.20 Elbow. Standard sagittal view via the anterior recess shows a normal fat pad (arrow) and an effusion/synovial hypertrophy (open arrow). HC, humeral capitellum; BR, musculus brachialis.

Fig. 17.21 Standard sagittal view of the radiocarpal and midcarpal joints, showing an effusion and synovial hypertrophy in the radiocarpal joint (arrows) and in the midcarpal joint (open arrows). L, os lunatum; R, radius, os lunatum; CAP, os capitatum.

Elbow Effusions of the elbow joint can be assessed via the posterior or the anterior joint recesses with longitudinal views (▶ Fig. 17.20). Small amounts of fluid initially collect in the olecranon fossa posteriorly, best seen when the elbow is slightly flexed. With increasing amounts of fluid, the anterior (coronoid fossa) and posterior (olecranon fossa) fat pads are displaced away from the bone.

Wrist The wrist assessment includes the radioulnar, radiocarpal, and midcarpal joints. The radioulnar joint is assessed via an axial view, whereas the radiocarpal and midcarpal joints are assessed via a midsagittal dorsal view (▶ Fig. 17.21).

Findings

Fig. 17.22a,b Different appearances of ankle pathology. a Eight-yearold girl presenting with a swollen right ankle. Ultrasound shows a large effusion (large arrows) with synovial hypertrophy (small arrows). b Tenyear-old boy with an effusion (open arrow) due to a known reactive arthritis. Note the speckled appearances. T, talus.

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The pathologies include a bulging capsule, an effusion, and synovial thickening (focal or general). An effusion can be black (anechoic), suggestive of a transient synovitis; black with speckles, suggestive of a reactive arthritis of some duration; or gray (echoic), suggestive of a septic arthritis (or of a hemorrhage, particularly in patients with trauma or hemophilia; ▶ Fig. 17.22). Because of overlapping findings, however, a specific diagnosis cannot be made based on the appearances alone. A bulging capsule is consistent with an effusion, synovial hypertrophy, or a combination of the two. A dynamic

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Fig. 17.23a,b Ultrasound of the hip in a 9-year-old boy with juvenile idiopathic arthritis, showing (a) an effusion with a focal synovial thickening (arrow) in the left hip and (b) an effusion with floating echogenic material within in the right hip, suggestive of osteochondromatosis.

Fig. 17.24a,b Axial view via the popliteal fossa, showing a Baker cyst.

examination, with extension and flexion of the joint or manual compression/squeezing, will often allow differentiation between the two because fluid is compressible and synovial hypertrophy is not (▶ Fig. 17.17). Note that mild capsular bulging is normal in the hip joint when an examination is performed with the hip inward rotated. Synovial thickening can be focal, suggestive of a synovial tumor, such as osteochondromatosis (▶ Fig. 17.23) or synovial sarcoma, or general, suggestive of an inflammatory condition such as JIA. In JIA, the synovial thickening often shows a villous pattern (pannus). Color Doppler can show hyperemia, suggestive of active inflammation. Popliteal synovial cysts, also known as Baker cysts, present as swelling in the popliteal fossa due to enlargement of the

gastrocnemius–semimembranosus bursa, which lies between these two muscles on the medial side of the fossa slightly distal to the center crease in the back of the knee. On US, there is an anechoic mass, which may include echogenic debris or septa (▶ Fig. 17.24 and ▶ Fig. 17.25).

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Use standard views to become familiar with the normal appearances of each joint. Do a clinical examination, speak to the patient and caregivers, and perform a tailored US examination according to the child’s complaints.

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Fig. 17.25 A child with known juvenile idiopathic arthritis presenting with an enlarging mass behind the knee. Ultrasound demonstrates a cyst communicating with the joint space between the medial head of the gastrocnemius (arrows) and the semimembranosus tendon (arrowheads).

Fig. 17.26 Composite images offering an extended field of view are very useful. Panorama (Philips Healthcare) setting demonstrating a shin hematoma with central fluid and adjacent inflammatory changes.

17.2.2 Soft-Tissue Masses: Lumps and Bumps Ultrasound Technique The US assessment of soft-tissue lesions in children requires attention to internal structure, consistency, extent, and vascularity. This can be achieved only with meticulous technique and a thorough understanding of image optimization. A properly optimized US assessment can often be diagnostic, with no further imaging needed. US machine presets are often designed for adult patients, which can lead to poor image quality in children. In addition to basic image acquisition, a pediatric radiologist should have a good understanding of the following optimizations.

Frequency, Depth, Probe Type, and Field of View High-frequency transducers (14–17 MHz) are vital for imaging fine structural details within superficial tissues; however, penetration beyond 5 cm of tissue depth will require frequency reduction—often simplified as a “penetration” setting—or a change to a lower-frequency transducer. High-frequency linear transducers have a limited field of view. Beam-steering techniques that allow an extended field for view are very useful—for example, WideSCAN (Philips Healthcare, Andover, MA). Assessment of the full extent of a lesion will often require a lower-frequency curvilinear transducer. Panorama (Philips Healthcare) post processing can provide excellent anatomical overviews (▶ Fig. 17.26) and can overcome the difficulties in spatial positioning often found by referring clinicians. The pediatric radiologist should be ready to use a variety of probes and to switch to lower-frequency and curvilinear transducers as required.

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Frame Rate and Upset Children Higher-resolution settings will lower image frame rates. Below 30 frames per second, this lag will become very noticeable and can impair scanning of moving children. Optimization is required, with many factors involved. Reduction in sector width, depth, and probe frequency and the removal of B-mode persistence settings can all help. Small-footplate, high-frequency transducers (“hockey stick” type) often offer very high frame rates and detail, although at the expense of field of view and penetration.

Dual-Imaging Function This functionality can extremely useful to facilitate comparisons between sides of the body—for example, between an affected hip and the normal opposite side.

Harmonic Imaging Harmonic imaging utilizes the weaker harmonic signal that is generated within the patient. This avoids the primary beam attenuation and artifact that is more important at greater tissue depths. Attenuation and artifact has limited effect when scanning superficial lesions in children, so use of harmonic imaging will weaken signal and degrade image quality. An experienced operator should be aware of these limitations and ensure harmonic imaging is utilized appropriately.

Near Field and Superficial Structures The near field of modern US probes should not require gel standoffs after appropriate frequency, depth, and focus optimization. Nonetheless, a US gel standoff can be very useful to allow demonstration of the spatial location of a lesion (▶ Fig. 17.28).

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Musculoskeletal Ultrasound and in color Doppler imaging has a velocity scale analog. This setting needs to be kept low (minimum of 350 Hz advised) to detect low velocities. It is always used in combination with Doppler gain, and at such levels of sensitivity, caution is needed regarding false-positive results resulting from operator or patient movement. Aliasing is inevitable at these levels, and the operator should be aware of this artifact. Other settings may complicate vascular assessment. Wall filters are designed to remove low-velocity flows and should be turned off. Persistence settings should be used with caution; high settings can help reveal vascularity, but they can be difficult to use with a moving child and can prevent the visualization of vessel pulsatility. Spectral analysis can be useful to assess flow characteristics, but close attention to Doppler settings is again required. The PRF must be adjusted to prevent aliasing. The angle of insonation should be less than 60 degrees to prevent large errors in velocity estimation, and the Doppler sampling gate must be adjusted to the size of the structure being examined.

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Fig. 17.27a,b Harmonic imaging can provide useful information, but cautious use is advised in children. a Dorsal distal radial ultrasound showing qualitatively different images; not all structures are more clearly seen. b Testicular ultrasound with and without harmonic imaging: the lesion is clearly more apparent without harmonics.

Doppler Imaging A full exploration of Doppler imaging is beyond the scope of this text; however, there are some vital aspects that must be understood to allow a confident assessment of vascularity. In general, the aim should be to optimize for maximum Doppler sensitivity to ensure that low-velocity flow is not missed. Once this is achieved, settings can be adjusted to characterize higher velocities to prevent aliasing, sometimes mistaken for turbulent flow. The fundamental difference between color Doppler and power Doppler imaging is that color Doppler involves averaging of the signal, whereas power Doppler involves summation of the signal. This means that color Doppler may average out low or turbulent velocities, resulting in poor signal (▶ Fig. 17.29). Power Doppler will not do this, but as a consequence, it lacks directional information. Accordingly, it is advised that color Doppler be used only when directional information is required. Failure to detect slow flow (e.g., in venous malformations) is the biggest risk when scanning without optimized settings. Several settings need to be optimized for low-flow situations. Most modern machines have a set of preprogrammed optimizations, including filters and pulse repetition frequency (PRF) settings, which should be set to low. The PRF is normally changed by a scale setting. The value is always displayed on the screen

Take a couple of extra minutes to adjust your machine settings. Be aware of your Doppler settings, and adjust them appropriately according to the task. Have a wide variety of US probes available to cover all age groups.

Assessment of Soft-Tissue Masses Imaging referrals for soft-tissue masses in children are common, and parental anxiety about cancer is often high. Difficulties arise for general and specialist radiologists alike when soft-tissue masses do not conform to the expected appearances for common pathologies. The vast majority of referrals will be for simple and benign pathologies; however, the possibility of malignant pathology always remains, no matter how rare. This is further complicated by the fact that definitive imaging characteristics for many of the rarer types of tumor have not been established. In addition, the histopathologic classifications of rarer tumor types are constantly evolving, reflecting increasingly complex immunological and genetic assessments. US offers an excellent means of assessment and in many cases can be definitive if appropriate techniques are used. However, it cannot exist in isolation, and close attention needs to be paid to the clinical history and examination findings. Discussion with the referring clinician will be vital in producing a meaningful differential. Without this, for example, confusion between a common lipoma and a very rare liposarcoma can become reality. Several review articles have been published with suggested diagnostic approaches. A simple summary of the diagnostic approach is as follows: if the ultrasound appearances do not conform to a specific diagnosis, atypical features are present, or the clinical scenario does not fit, then MR imaging should be considered for further assessment in conjunction with specialist

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Fig. 17.28a–c A gel standoff can be used to provide useful anatomical localization, demonstrating (a) the position of glandular tissue behind the nipple, (b) the skin overlying a proximal intercarpal joint, and (c) an association with an infected sinus tract (arrowhead) and skin pimple (arrow).

Fig. 17.29 Curvilinear probe with color Doppler assessment of a peripheral vessel. Because the Doppler signal is weakest when perpendicular to flow, an appearance of absence of flow is possible if a careful assessment is not made.

surgical opinion as necessary. The US examination should characterize the size, internal structure, vascularity, and extent of a lesion, and its precise anatomical site. The role of MR imaging is beyond the scope of this chapter, and comprehensive review articles are recommended for further information.

Infection and Trauma Infection can present as a soft-tissue mass when a subcutaneous abscess or sinus tract develops. Imaging by US is usually definitive in the clinical context. Inflammatory changes in subcutaneous fat and increased vascularity will usually be

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present. A gel standoff can help demonstrate the spatial relation to skin lesions (▶ Fig. 17.28c). A traumatic lesion presenting as a soft-tissue mass will usually represent a hematoma. US will demonstrate fluid, organizing clot, or a combination of the two according to the time since trauma (▶ Fig. 17.26).

Congenital Vascular Lesions The assessment of vascular lesions in children is made complex by varying historical nomenclature. Recent classification by Mulliken and Glowacki is based on endothelial type and is now widely followed. Assessment of these lesions requires careful Doppler analysis, suggestions for which are discussed above.

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Fig. 17.30a,b Six-month-old child with an enlarging discolored arm mass. a Ultrasound demonstrates a well-demarcated solid mass superficial to muscle (arrows). b Doppler scanning demonstrates avid flow within the solid lesion.

Fig. 17.31a,b Eight-year-old child with a leg mass and bluish discoloration. a Ultrasound shows an ill-defined mass with multiple serpiginous channels (arrowheads). b Doppler imaging shows lowvelocity flow, confirming a venous malformation. Note the low-flow optimization: pulse repetition frequency of 661 Hz, high gain, and lowvelocity filter. Flow may be missed without appropriate settings.

The classification system separates hemangiomas from vascular malformations. Vascular malformations are grouped as high- or low-flow lesions. Congenital hemangiomas are distinct tumors consisting of a proliferating cellular mass with prominent vascularity due to pathologic angiogenesis. They follow a pattern of rapid growth with a slow involution phase. The proliferative phase should complete by 9 months of age, and the slower involution may take many years. Hemangiomas are the most common soft-tissue tumor in children (more frequent in girls) and can be multifocal. Most will have a benign course; however, mass effect, ulceration, and coagulopathy are possible complications. US will demonstrate a well-demarcated solid mass with avid vascularity. The presence of a solid mass is a key finding that allows easy differentiation from vascular malformations. Both arterial and venous waveforms may be present, which are distinguishable from those in high-flow lesions by spectral analysis (▶ Fig. 17.30). Vascular malformations consist of dysplastic vascular/lymphatic tissue and are present from birth, although they may not present immediately. Their incidence is equal in the two sexes. US is of use in differentiating the type of vascular malformation and assessing the type of flow involved. The extent of the lesion is usually demonstrated by ultrasound, however MR has a role is assessing deeper structures and macro-vascular supply. High-flow lesions include arteriovenous malformations and fistulas. Low-flow lesions include venous, capillary, lymphatic, or a combination of these elements. Complications include circulatory disturbance leading to heart failure, tissue overgrowth, and coagulopathy.

Arteriovenous malformations are usually clinically apparent, but US will demonstrate defined vascular channels with highvelocity turbulent flow. Capillary malformations are not generally apparent on US, with the vascular abnormality limited to a superficial area of epidermis. Occasionally, skin thickening is identified by US. Venous malformations are often obvious by their clinical characteristics: skin discoloration and change in appearance with gravity, Valsalva, and so on. The malformation will consist of compressible tubular venous structures and venous lakes with septa. Great care is needed to demonstrate flow; minimal pressure will compress the lesion and unprepared Doppler settings will fail to detect low-velocity flow (▶ Fig. 17.31). The dysplastic veins can be mistaken for a multicystic or lobulated mass. The presence of phleboliths is diagnostic; occasionally, radiography is required to demonstrate them. Lymphatic malformations, previously known variously as lymphangiomas or cystic hygromas, have a characteristic appearance: fluid spaces separated by fine septa and no flow. The size of the cysts and fluid spaces can vary, and small cystic components a few millimeters in size are possible (▶ Fig. 17.32a). These lesions are prone to hemorrhage, which causes rapid enlargement; US will detect fluid levels due to intralesional blood products. Lymphangiomatosis is the term for extensive, multifocal lymphatic malformations. Because lymphangiomatosis may present as a solitary lesion, the diagnosis should be considered during assessment, with a low threshold for examination of other areas or MR imaging screening of the body (▶ Fig. 17.32b). Mixed types of vascular lesion occur, and the possibility of associated syndromes should be considered, such as Klippel

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Fig. 17.33a,b A reactive lymph node will appear enlarged and hypoechoic. a In this case, the fatty hilum, ovoid morphology, and vascular pedicle are preserved. b A necrotic node shows central fluid and a lack of vascularity. Note the optimized Doppler settings (pulse repetition frequency of 445 Hz, low filter, and low wall filter) for maximum flow sensitivity.

Fig. 17.32a,b Two-year-old boy with a compressible chest wall mass. a Ultrasound shows a well demarcated multiseptate lesion. No flow was confirmed by optimized Doppler, typical of a lymphatic malformation. In addition, a pleural effusion was seen deep to the lesion, leading to a magnetic resonance imaging examination. b T2 coronal single-shot fat-saturated sequence shows multifocal involvement, in keeping with lymphangiomatosis: in the chest wall, superior mediastinum, and left humerus, and extensive involvement of the peritoneum and retroperitoneum.

Trenaunay syndrome with capillary and venous components and Proteus syndrome with cutaneous and visceral vascular malformations.

Common Nonvascular Soft-Tissue Masses Lymph Nodes US referral for an assessment of lymph node enlargement is common; both normal lymph nodes and enlarged reactive nodes are by far the most frequent findings. Normal nodes should be ovoid, have an echogenic hilum and a vascular

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pedicle, and as a general guide should have a short axis of less than 10 mm, although this varies by anatomical site. Reactive nodes can look unusual and can be indistinguishable from malignant nodes; therefore, the clinical scenario becomes vital in a rational assessment. Abnormal nodes will enlarge, become hypoechoic and rounded, and loose the central hilum and vascular pedicle (▶ Fig. 17.33). In severe infection, nodes can form a necrotic mass to become an abscess, usually appearing as a large inflammatory mass with central cavitation. The more abnormal features a node has, the more likely malignancy becomes, although there is considerable overlap and US cannot exclude malignancy. Follow up scanning can be considered when there is significant doubt.

Lipomas Lipomas are commonly encountered in children. They consist of a mass of mature adipocytes and are usually situated within the superficial fat, although deeper and intramuscular sites are possible. US examination shows an echo-bright and well demarcated fat texture lesion. Lipomas with iso- or hypoechoic appearances can occur (▶ Fig. 17.34). Thin septa are frequently seen, as are heterogeneous components, often best shown on MR imaging. Liposarcomas are extremely rare in children; however, lesions with multiseptate, heterogeneous, or atypical appearances are

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Fig. 17.34a,b Seven-year-old boy presenting with an axillary lump, noticed after trivial trauma. a Ultrasound demonstrates a well-demarcated hyperechoic mass within the subcutaneous fat. There is some internal structure, but no evidence of invasion of the deep muscular layer. Histology indicated a simple lipoma. b Image demonstrates a well-demarcated hypoechoic solid lesion within the subcutaneous fat, again confirmed histologically as a lipoma.

best further assessed with MR imaging. A well-demarcated lesion with homogeneous fat suppression and no enhancing elements indicates a benign lipoma. Lipoblastomas (▶ Fig. 17.35) occur in early childhood; 88% present before 3 years of age, and presentation after 5 years is rare. Lipoblastomas generally have increased vascularity and are well defined with heterogeneous/multiseptate contents. MR imaging will demonstrate multiple septa and enhancing non–fat-containing elements.

Ganglion A ganglion is an encapsulated cystic mass. It may be unilocular, but usually has internal septa or is lobulated. The cyst contains mucinous material with high levels of hyaluronic acid. These lesions were first described by Hippocrates. Most occur incidentally, although there is an occasional history of trauma, and the etiology is uncertain. Ganglia characteristically occur in a periarticular location and may appear to extend toward the synovium of the adjacent joint; however, communication with the synovial space is rare. US may demonstrate internal echoes and should usually be sufficient to make the diagnosis (▶ Fig. 17.36). A multilobulated ganglion can mimic a venous malformation; careful Doppler analysis will rule out flow.

Synovial Cyst Fig. 17.35a,b Three-year-old girl presenting with an enlarging buttock mass. a Ultrasound demonstrates a well-defined but echogenic lesion in the subcutaneous fat, with some mixed internal echoes. b T1 fatsaturated post-contrast axial magnetic resonance imaging demonstrates a well-defined fat-containing lesion with enhancing septa and soft-tissue elements. It displaces but does not invade adjacent structures. Lipoblastoma was confirmed by post-excision histology.

The most common form of synovial cyst is the popliteal (Baker) cyst. Baker cysts differ from ganglion cysts in that they are lined with synovium and communicate with the joint space. The Baker cyst has a characteristic location, arising between the medial head of the gastrocnemius and the semimembranosus tendon. Although most are incidental, synovial cysts are associated with Juvenile Idiopathic Arthritis, and this diagnosis should be considered when assessing the joint. (▶ Fig. 17.25).

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Fig. 17.36a,b Six-year-old child with a slow-growing wrist mass. a Ultrasound demonstrates typical features, with a well-defined lobulated mass (arrow) passing behind the median nerve and radial artery (arrowheads) and the carpus, extending toward the synovium. b Sagittal STIR (short T1 inversion recovery) magnetic resonance imaging demonstrates the well-demarcated fluid containing a lobulated mass, typical of a ganglion cyst.

Fig. 17.37a,b Painless mass in a 3-year-old: granuloma annulare was confirmed on biopsy. Nonspecific imaging features. a Ultrasound shows a heterogeneous, predominantly hypoechoic shin lesion with some vascularity detectable only on optimized settings (pulse repetition frequency of 714 Hz, low wall filter, high persistence, and low-flow optimization). b T1 fat-saturated axial magnetic resonance imaging shows an ill-defined high signal (arrow). No significant enhancement is seen.

Inflammatory Conditions Subcutaneous granuloma annulare is an inflammatory condition in which dermal epithelioid histiocytes form a subcutaneous mass. It occurs in children younger than 5 years of age as a painless, rapidly growing nodule. US demonstrates an ill-defined, heterogeneous, hypoechoic subcutaneous mass with no vascularity. On MR imaging, the mass appears ill defined with intermediate T1 signal and variable T2 signal (▶ Fig. 17.37).

Neurogenic Tumors Neurofibromas are the most common neurogenic tumors. They are benign and can be isolated or associated with neurofibromatosis type 1, in which case they can be multiple or plexiform (i.e., a network of tumors forming a mass along a nerve bundle). Neurofibromas are usually round, well demarcated, and associated with the neurovascular sheath. On US, they appear hypoechoic with a homogeneous texture and some posterior acoustic enhancement. In neurofibromatosis type 1, degeneration into a malignant peripheral nerve sheath tumor can occur, often identified by

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increasing size or pain. This usually occurs in a plexiform neurofibroma. Imaging features of degeneration are increasing size, heterogeneity, and increased vascularity (▶ Fig. 17.38). If these features are present, MR imaging is required for further evaluation, on which increased size, perilesional edema, cystic change, and peripheral enhancement suggest malignant transformation. Imaging with fluorodeoxyglucose F 18 positron emission tomography (18F-FDG-PET) is often needed to help differentiate malignant transformation.

Rare Soft-Tissue Masses with Nonspecific Features A wide range of rare pathology exists in which imaging, in particular US, has little to offer beyond confirming the presence of a tumor and providing basic structural information. Current MR imaging examinations often shed little light on the differential diagnosis of such tumors, and the diagnosis often is made by histology. These rarer diagnoses should be considered if a clinical scenario or the features of a mass do not fit any of the common diagnostic categories. A brief overview of the tumor types is appropriate, although histologic classification systems

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Fig. 17.38a,b Twelve-year-old boy with neurofibromatosis type 1. A calf neurofibroma recently became painful and enlarged. a Ultrasound demonstrates a large mass with avid Doppler flow and cystic changes indicative of malignant degeneration. b Sagittal T1 post-contrast magnetic resonance imaging demonstrates cystic degeneration and avid enhancement. Transformation into a malignant nerve sheath tumor was confirmed on biopsy.

Fig. 17.39a,b Child with a slow-growing wrist mass and some pain. a Ultrasound of the wrist demonstrates a heterogeneous mass (arrow) extending into the joint space and along the ulna. There are no cystic spaces to suggest a ganglion cyst or homogeneous hypoechogenicity to suggest synovium. b T1 fat-saturated coronal magnetic resonance imagingshows a welldemarcated mass (arrow) displacing adjacent structures. Giant cell tumor was confirmed by histology.

Fig. 17.40 Twelve-year-old with a slow-growing tender arm lump. Ultrasound demonstrates a pseudocapsule, hyporeflectivity, and minimal vascularity (note the Doppler settings optimized for low flow: low pulse repetition frequency, low filter). The mass appears deep in the dermis/ muscular layer. Post-excision biopsy confirmed angiomatoid fibrous histiocytoma.

are constantly evolving as a result of advances in genetics and cellular biology.

Fibrohistiocystic Tumors These rare tumors contain fibroblast, myofibroblast, or primitive mesenchymal cells. A malignant tumor in this group is malignant fibrous histiocytoma; more commonly encountered benign forms include: pigmented villonodular synovitis (PVNS) and giant cell tumor of the tendon sheath (GCTTS). PVNS and GCTTS appear to be intra- and extra-articular subtypes of similar tumors, respectively. GCTTS is more common in children, is usually encountered in the hand, and can be extra- or intraarticular. US examination will demonstrate a well-defined solid

mass with extension toward the adjacent joint (if intra-articular; ▶ Fig. 17.39). The solid nature of the mass will help differentiate it from the more common ganglion cyst. MR imaging appearances are variable, but imaging will demonstrate an intermediate-signal solid mass extending into the joint; susceptibility artifact due to hemosiderin deposition is possible. Angiomatoid fibrous histiocytoma has previously been linked with malignant fibrous histiocytoma; however, it should be considered separately because it is a less aggressive, low-grade tumor. It is slow-growing, occurs in later childhood/adolescence, and can be tender. US demonstrates a fibrous pseudocapsule and occasional blood-filled cystic spaces. MR features include fluid levels due to hemorrhage, and variable signal intensity (▶ Fig. 17.40).

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Fibroblastic Tumors

Fig. 17.41 Neonate presenting with a neck mass. Typical ultrasound features of fibromatosis colli: a fusiform mass entirely contained within the sternocleidomastoid muscle (arrowheads) and normal surrounding tissues and nodes. Note displacement of the carotid sheath (arrow).

This classification includes rare mesenchymal tumors that range from benign to malignant, including fibromatosis colli, fibromatosis, and fibrous sarcomas. Because of the variable tumor cellularity and vascularity, the US and MR findings are often nonspecific. Fibromatosis colli is an exception within this group in that the location, imaging features, and clinical history should allow a clear diagnosis. The mass usually becomes apparent at 2 weeks of age in association with torticollis; it initially increases in size before gradually regressing. US shows a fusiform mass within the muscle that is usually hyperechoic to muscle, and most have a hypoechoic rim (▶ Fig. 17.41). Features not in keeping with fibromatosis colli, such as irregularity, local invasion, and lymphadenopathy, should prompt further investigation.

Fig. 17.42a,b Eight-month-old child presenting with an enlarging arm mass. a Ultrasound demonstrates an ill-defined, hyperechoic mass with limited vascularity superficial to the muscular layer. The initial differential included atypical lipoma. b T1weighted post-contrast fat-saturated magnetic resonance imaging reveals an ill-defined enhancing mass within the subcutaneous fat. Post-excision histology confirmed a fibrous hamartoma of infancy.

Fig. 17.43 Five-year-old with a slow-growing painless scalp lump. Ultrasound demonstrates a well-defined hypoechoic lesion with some calcification (arrow) and minimal Doppler flow (note Doppler settings: low pulse repetition frequency, wall filter, and low-flow optimization). Some peripheral hyperechogenicity is seen in the adjacent subcutaneous fat. Post-excision histology confirmed pilomatricoma.

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Musculoskeletal Ultrasound Fibrous hamartoma of infancy (▶ Fig. 17.42) presents a good example of the difficulties encountered with the historical and modern nomenclature of rare tumors; the tumor is not a hamartoma, and an alternative name, subdermal infantile fibromatous tumor, has been suggested. It is rare, and 90% of cases of this tumor present within the first year of life. There is a male predominance. The variable makeup of this tumor is reflected in variable imaging appearances, and clear differentiation from fat-containing tumors is not possible. The diagnosis is made by histology.

Pilomatricoma These tumors arise from the subcutaneous hair cortex cells. They are benign, slow-growing, hard masses that are slightly more common in females. The majority occurs in the head and neck, although about 20% are seen in the extremities. There is frequent calcification, and occasional ossification. Because they often present as small lumps (around 1.5 cm), on US the size and presence of the calcification can be diagnostic (▶ Fig. 17.43). MR can demonstrate a peripherally enhancing capsule, patchy central enhancement, and perilesional edema.

Other Malignant Tumors Presenting as SoftTissue Masses

Fig. 17.44a,b Four-year-old child presenting with a buttock mass. a Ultrasound demonstrates a heterogeneous mass (arrows) that is ill defined with deeper extension. b Subsequent T2 sagittal TSE (turbo spin echo) magnetic resonance imaging reveals a large heterogeneous mass extending into the pelvis (arrow), in keeping with a genitourinary rhabdomyosarcoma.

Occasionally, masses arising from bone or solid organs can present as a peripherally detected lump. US assessment is again useful, to help characterize the lesion and plan subsequent imaging. Rhabdomyosarcoma is the most common soft-tissue sarcoma in children; the median age at diagnosis is 5 years. The most common site is the genitourinary tract, with the extremities involved in 19% of cases. Embryonal, botryoid, and alveolar histologic subtypes exist; the alveolar subtype usually affects the extremities. US (▶ Fig. 17.44a) shows an ill-defined, heterogeneous mass, and the MR (▶ Fig. 17.44b) signal characteristics are nonspecific, with low T1 signal and variable T2 signal. Langerhans cell histiocytosis is a complex multisystem disease caused by accumulations of dendritic cells. It usually presents between the ages of 1 and 3 years. Although often thought of as a disease of the skin or solid organs, presentation as a softtissue mass is not uncommon, in which the mass arises from a bone lesion rather than direct skin involvement. US demonstrates a heterogeneous, hypoechoic solid mass (▶ Fig. 17.45).

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Fig. 17.45a–c Four-year-old child presenting with a neck mass. a Ultrasound demonstrates a large mass with homogeneous hyperechoic tissue extending deep into the neck (arrowhead). Regional lymph nodes are present, but not enlarged (arrows). b A lower-frequency curvilinear probe demonstrates deeper extension by the mass (arrowhead) to involve the skull and allows views of the cerebellum (arrow). c Coronal post-contrast T1weighted magnetic resonance imaging demonstrates involvement of the skull base (arrow). Langerhans cell histiocytosis was confirmed histologically.

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Musculoskeletal Ultrasound Adjacent bone changes may support a diagnosis of Langerhans cell histiocytosis, although these may be present with other aggressive pathology.

Recommended Readings Ablin DS, Jain K, Howell L, West DC. Ultrasound and MR imaging of fibromatosis colli (sternomastoid tumor of infancy). Pediatr Radiol 1998; 28: 230–233 Benz MR, Czernin J, Dry SM et al. Quantitative F18-fluorodeoxyglucose positron emission tomography accurately characterizes peripheral nerve sheath tumors as malignant or benign. Cancer 2010; 116: 451–458 Brisse H, Orbach D, Klijanienko J, Fréneaux P, Neuenschwander S. Imaging and diagnostic strategy of soft-tissue tumors in children. Eur Radiol 2006; 16: 1147–1164 Brurås KR, Aukland SM, Markestad T, Sera F, Dezateux C, Rosendahl K. Newborns with sonographically dysplastic and potentially unstable hips: 6-year follow-up of an RCT. Pediatrics 2011; 127: e661–e666 Chung EB, Enzinger FM. Benign lipoblastomatosis. An analysis of 35 cases. Cancer 1973; 32: 482–492 Daw NC, Billups CA, Pappo AS et al. Malignant fibrous histiocytoma and other fibrohistiocytic tumors in pediatric patients: the St. Jude Children’s Research Hospital experience. Cancer 2003; 97: 2839–2847 De Maeseneer M, Debaere C, Desprechins B, Osteaux M. Popliteal cysts in children: prevalence, appearance and associated findings at MR imaging. Pediatr Radiol 1999; 29: 605–609 Derlin T, Tornquist K, Münster S et al. Comparative effectiveness of 18F-FDG PET/CT versus whole-body MRI for detection of malignant peripheral nerve sheath tumors in neurofibromatosis type 1. Clin Nucl Med 2013; 38: e19–e25 Dickey GE, Sotelo-Avila C. Fibrous hamartoma of infancy: current review. Pediatr Dev Pathol 1999; 2: 236–243 Dorn U, Hattwich M. Initial experience using routine hip sonography in newborn infants [in German] Wien Klin Wochenschr 1987; 99: 92–95 Dubois J, Garel L. Imaging and therapeutic approach of hemangiomas and vascular malformations in the pediatric age group. Pediatr Radiol 1999; 29: 879–893 Dunn PM, Evans RE, Thearle MJ, Griffiths HE, Witherow PJ. Congenital dislocation of the hip: early and late diagnosis and management compared. Arch Dis Child 1985; 60: 407–414 Engesæter IO, Lehmann T, Laborie LB, Lie SA, Rosendahl K, Engesæter LB. Total hip replacement in young adults with hip dysplasia: age at diagnosis, previous treatment, quality of life, and validation of diagnoses reported to the Norwegian Arthroplasty Register between 1987 and 2007. Acta Orthop 2011; 82: 149–154 Fornage BD, Tassin GB. Sonographic appearances of superficial soft-tissue lipomas. J Clin Ultrasound 1991; 19: 215–220 Gallego Melcón S, Sánchez de Toledo Codina J. Rhabdomyosarcoma: present and future perspectives in diagnosis and treatment. Clin Transl Oncol 2005; 7: 35–41 Gholve PA, Hosalkar HS, Kreiger PA, Dormans JP. Giant cell tumor of tendon sheath: largest single series in children. J Pediatr Orthop 2007; 27: 67–74 Graf R. The diagnosis of congenital hip-joint dislocation by the ultrasonic Combound treatment. Arch Orthop Trauma Surg 1980; 97: 117–133 Harcke HT, Clarke NM, Lee MS, Borns PF, MacEwen GD. Examination of the infant hip with real-time ultrasonography. J Ultrasound Med 1984; 3: 131–137 Harcke HT, Grissom LE. Performing dynamic sonography of the infant hip. AJR Am J Roentgenol 1990; 155: 837–844 Haupt R, Minkov M, Astigarraga I et al. Euro Histio Network. Langerhans cell histiocytosis (LCH): guidelines for diagnosis, clinical work-up, and treatment for patients till the age of 18 years. Pediatr Blood Cancer 2013; 60: 175–184 Inampudi P, Jacobson JA, Fessell DP et al. Soft-tissue lipomas: accuracy of sonography in diagnosis with pathologic correlation. Radiology 2004; 233: 763–767

Laffan EE, Ngan BY, Navarro OM. Pediatric soft-tissue tumors and pseudotumors: MR imaging features with pathologic correlation: part 2. Tumors of fibroblastic/ myofibroblastic, so-called fibrohistiocytic, muscular, lymphomatous, neurogenic, hair matrix, and uncertain origin. Radiographics 2009; 29: e36 Langer R. Ultrasonic investigation of the hip in newborns in the diagnosis of congenital hip dislocation: classification and results of a screening program. Skeletal Radiol 1987; 16: 275–279 Lim HW, Im SA, Lim GY et al. Pilomatricomas in children: imaging characteristics with pathologic correlation. Pediatr Radiol 2007; 37: 549–555 Moholkar S, Sebire NJ, Roebuck DJ. Radiological-pathological correlation in lipoblastoma and lipoblastomatosis. Pediatr Radiol 2006; 36: 851–856 Mulliken JB, Glowacki J. Hemangiomas and vascular malformations in infants and children: a classification based on endothelial characteristics. Plast Reconstr Surg 1982; 69: 412–422 Murphy E, Williams GR. The thyroid and the skeleton. Clin Endocrinol (Oxf) 2004; 61: 285–298 Navarro OM, Laffan EE, Ngan BY. Pediatric soft-tissue tumors and pseudo-tumors: MR imaging features with pathologic correlation: part 1. Imaging approach, pseudotumors, vascular lesions, and adipocytic tumors. Radiographics 2009; 29: 887– 906 Paltiel HJ, Burrows PE, Kozakewich HP, Zurakowski D, Mulliken JB. Soft-tissue vascular anomalies: utility of US for diagnosis. Radiology 2000; 214: 747–754 Pham H, Fessell DP, Femino JE, Sharp S, Jacobson JA, Hayes CW. Sonography and MR imaging of selected benign masses in the ankle and foot. AJR Am J Roentgenol 2003; 180: 99–107 Restrepo R, Oneto J, Lopez K, Kukreja K. Head and neck lymph nodes in children: the spectrum from normal to abnormal. Pediatr Radiol 2009; 39: 836–846 Reynolds DL, Jr, Jacobson JA, Inampudi P, Jamadar DA, Ebrahim FS, Hayes CW. Sonographic characteristics of peripheral nerve sheath tumors. AJR Am J Roentgenol 2004; 182: 741–744 Robben SG, Lequin MH, Diepstraten AF, den Hollander JC, Entius CA, Meradji M. Anterior joint capsule of the normal hip and in children with transient synovitis: US study with anatomic and histologic correlation. Radiology 1999; 210: 499– 507 Rosendahl K, Aslaksen A, Lie RT, Markestad T. Reliability of ultrasound in the early diagnosis of developmental dysplasia of the hip. Pediatr Radiol 1995; 25: 219– 224 Rosendahl K, Dezateux C, Fosse KR et al. Immediate treatment versus sonographic surveillance for mild hip dysplasia in newborns. Pediatrics 2010; 125: e9–e16 Rosendahl K, Markestad T, Lie RT. Congenital dislocation of the hip: a prospective study comparing ultrasound and clinical examination. Acta Paediatr 1992; 81: 177–181 Rosendahl K, Markestad T, Lie RT. Developmental dysplasia of the hip: prevalence based on ultrasound diagnosis. Pediatr Radiol 1996; 26: 635–639 Rosendahl K, Toma P. Ultrasound in the diagnosis of developmental dysplasia of the hip in newborns. The European approach. A review of methods, accuracy and clinical validity. Eur Radiol 2007; 17: 1960–1967 Smith RW, Egger P, Coggon D, Cawley MI, Cooper C. Osteoarthritis of the hip joint and acetabular dysplasia in women. Ann Rheum Dis 1995; 54: 179–181 Szer IS, Klein-Gitelman M, DeNardo BA, McCauley RG. Ultrasonography in the study of prevalence and clinical evolution of popliteal cysts in children with knee effusions. J Rheumatol 1992; 19: 458–462 Tantiwongkosi B, Goske MJ, Steele M. Congenital solid neck mass: a unique presentation of Langerhans cell histiocytosis. Pediatr Radiol 2008; 38: 575–578 Wasa J, Nishida Y, Tsukushi S et al. MRI features in the differentiation of malignant peripheral nerve sheath tumors and neurofibromas. AJR Am J Roentgenol 2010; 194: 1568–1574 Yoshimura N, Campbell L, Hashimoto T et al. Acetabular dysplasia and hip osteoarthritis in Britain and Japan. Br J Rheumatol 1998; 37: 1193–1197

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Chapter 18 Ultrasound-Guided Interventional Procedures: Biopsy and Drainage

18.1

Biopsy

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18.2

Drainage Techniques and Equipment

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18 Ultrasound-Guided Interventional Procedures: Biopsy and Drainage Alex Barnacle and Derek Roebuck Ultrasound (US) guidance is ideal for most interventional procedures in children because it provides high-resolution, realtime imaging without exposure to ionizing radiation. Computed tomography (CT) and magnetic resonance (MR) imaging are rarely required for pediatric interventions; however, CT (or cone beam CT) may be helpful in some complex or difficult procedures, or procedures in the lungs, posterior or middle mediastinum, or bone. The radiologist planning and performing the procedure must have appropriate background knowledge; children are not simply small adults, and errors will occur if all of the factors specific to childhood disease and imaging are not considered. Multidisciplinary team discussions should be routine before most tumor biopsy or drainage procedures, especially when the procedure is complex. Such discussions may need to take into account the relative strengths of an institution, with input from surgery, radiology, and pathology. Several studies have demonstrated that US guidance is safer and more successful than a “blind” approach. This applies to both targeted and nontargeted biopsy procedures. Image guidance during targeted biopsy procedures allows a better evaluation of the lesion and increases the diagnostic yield. Even in nontargeted biopsy procedures, the use of real-time US may be vital in planning a safe approach and identifying local complications immediately. The use of US during drainage procedures usually avoids the need for a fluoroscopic assessment of guidewire or catheter position, thereby eliminating or significantly reducing the radiation dose. High-frequency US probes show the needle tip position in exquisite detail, which may be vital, for example, in small collections or nondilated urinary systems. Possible complications of US-guided biopsy or drainage include hemorrhage, infection, and pneumothorax; air embolism, bile leak, and perforation of hollow viscera are rare but important risks to consider. Percutaneous interventions can cause unsuspected bleeding into the thorax or abdomen, often distant from the site of access. This can lead to delayed recognition of complications postoperatively. It is vital that the medical and nursing teams caring for the child understand exactly what procedure has been performed and are aware of the importance of regular observations, so that any deterioration in the child’s status can be managed immediately. The seeding of malignant cells along a percutaneous biopsy needle track, although very rare, is of particular concern because the consequences can be significant. The incidence of tumor seeding is unknown because it can be difficult to distinguish from local recurrence, particularly when a new tumor develops in the parenchyma of the involved organ rather than in adjacent tissues.

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18.1 Biopsy 18.1.1 Techniques and Equipment Most needle biopsy procedures in children are nontargeted biopsies of the liver, kidney, or spleen, or biopsies of tumors or other soft-tissue masses. Occasionally, targeted biopsies of focal nonmalignant lesions of the liver, spleen, or kidney are requested, such as in patients with fungal disease. The basic principles of biopsy, described below, apply in all cases. The patient should be adequately imaged before the procedure. In cases in which the lesion may be difficult to biopsy, the operator should consider whether there are alternative sites of disease that are simpler to access, such as involved lymph nodes, or fluid that may yield positive cytology or microbiology results on aspiration. Pediatric tumors are often very large at presentation, and much of the lesion may consist of nonviable necrotic tissue or fluid. In such cases, tissue viability must be fully evaluated by contrast-enhanced CT or MR imaging, diffusion-weighted MR imaging, or fluorodeoxyglucose F 18 positron emission tomography (18F-FDG-PET). An on-table assessment of the lesion with US alone may not provide reliable information regarding tissue viability and may lead to a nondiagnostic biopsy. In general, a positive yield is most likely to be obtained from tissue at the margins of a large lesion. In general, nontargeted biopsies of the liver or kidney can be performed in older children and teenagers under sedation alone, but most other biopsies should be performed under general anesthesia. This allows the operator to work at an unhurried pace, with careful attention to detail and without patient movement or anxiety. The operator must discuss patient positioning and paralysis with the anesthesiologist before the procedure. Prone positioning should be avoided when possible because it increases the risk and complexity of the anesthetic technique. When it is desirable to be able to suspend respiration for a short time during a biopsy procedure, an intravenous bolus of propofol may be effective, but when prolonged or repeated “breath-holds” are required, it may be better to use neuromuscular blockade with endotracheal intubation and positive pressure ventilation. Informed consent must be obtained by the operator or by a delegate who is familiar with the benefits and risks of the procedure, its technical aspects, and any relevant alternative options. Acceptable preoperative coagulation parameters differ according to the type of biopsy. In general, superficial soft-tissue lesions in children who are otherwise well can be biopsied without a prior evaluation of the coagulation parameters or platelet count. Before biopsies in the abdominal and thoracic cavities, these parameters should be checked and corrected when necessary. Consideration

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Ultrasound-Guided Interventional Procedures: Biopsy and Drainage Table 18.1 Appropriate needle sizes for different types of biopsy Organ or tissue

Nature of biopsy

Liver

Nontargeted

18

Liver tumor

18

Kidney

Fig. 18.1a,b Coaxial biopsy needle system. a The biopsy system comprises the trocar (A), outer needle (B), and inner biopsy needle (C). b When the biopsy needle is fired, the cutting sleeve advances (arrow) and traps the specimen in the cutting notch.

should be given to maintaining normal levels in the postoperative period if delayed bleeding is considered a risk (e.g., liver biopsy following a bone-marrow transplant). Procedures should be performed in a familiar US machine in a room where the maintenance of sterile conditions can be ensured. Most pediatric biopsies can be performed with a highfrequency linear array transducer; in some cases—for example, in native kidney biopsies in teenagers—a lower-frequency curvilinear array transducer is required. Fine needle aspiration cytology has very few advantages in children, and core needle biopsy is almost always preferred. Various needle types are available, but most operators prefer semiautomated cutting needles (▶ Fig. 18.1). These have a tip that is manually extended under US guidance before the needle is fired, trapping a core of tissue in the cutting notch. Variable throw needles have a cutting notch of adjustable length, and these are very useful for small lesions or those that lie very close to the organ capsule or are adjacent to vital structures. The diameter of the needle selected depends on the nature of the biopsy (▶ Table 18.1). More than one tissue core will be required in most pediatric biopsies. For this reason, coaxial systems are becoming more popular. In these systems, the outer (access) needle is usually 1 gauge larger than the inner (biopsy) needle. There are three main advantages of using a coaxial technique (▶ Fig. 18.2). First, the capsule of the organ or lesion is breached only once, reducing

Needle gauge

Nontargeted

16

Renal tumor

16

Spleen

Nontargeted or focal lesion

18

Other abdominal organs

Bowel

18

Suspected neuroblastoma

14–16

Lung

Focal lesion

18

Soft tissue

Suspected vascular anomaly

16–18

Neuroblastoma or benign tumor

14–16

Other malignant tumor

16

Bone

Soft tissue component

14–16

Lymph node

Confirmation of metastasis from known primary tumor

18

Identification of causative organism in infection

18

Primary diagnosis of lymphoma

14–16

the risk for complications. Second, an unlimited number of cores can be obtained from different parts of the lesion by angling the outer needle. Third, the biopsy track can be blocked at the end of the procedure—for example, by injecting gelatin sponge (as plugs or a slurry) through the outer needle—in order to reduce the risk for bleeding and tumor seeding, although there is little evidence to support that this is effective. To avoid insufficient sampling, it is important to communicate with the pathologist who will examine the biopsy specimen to determine the minimum number of core samples required. A liver biopsy for staging viral hepatitis may require only one core, whereas a biopsy for suspected neuroblastoma may require 10 to 15 cores. Using a coaxial technique in the latter case is clearly mandatory.

Tips from the Pro ●

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Focal renal or splenic lesions may be easier to visualize with the patient’s breath held in inspiration by the anesthesiologist. Filling the bladder with fluid may afford better views of the pelvis. A safe access route to certain lesions—for example, in the adrenal region—may be created by injecting saline to displace adjacent organs. Challenging US-guided biopsies or drainages may be facilitated by using: ○ an angiography room with cone beam CT capability; ○ electromagnetic tracking technology. Combined US- and cone beam CT-guided procedures may be facilitated by using: ○ needle guidance software; ○ image fusion techniques when preprocedural imaging provides information not available with cone beam CT.

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Fig. 18.2a–d Coaxial biopsy of a tumor. a The outer needle has been advanced into the tumor and the trocar removed. b, c The inner (biopsy) needle is advanced into various parts of the tumor. d The tracks of previous needle passes contain air (arrows). (continued)

18.1.2 Tumor Biopsy The most common indications for biopsy in our practice are to assess soft-tissue tumors (suspected neuroblastoma, liver and renal tumors) and lymph nodes or mediastinal masses. Similar principles apply for the biopsy of most of these lesions. The patient should be carefully placed on the operating table, with foam or jelly supports when necessary. US should be used to achieve the optimal position for a safe biopsy. The skin must be prepared and draped to ensure that sterility is maintained throughout the procedure. A sterile US probe cover should always be used.

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Tumor seeding appears to be very rare in children, but one important exception is Wilms tumor (nephroblastoma). Renal tumors should be biopsied via an entirely extraperitoneal approach (▶ Fig. 18.3) to avoid contamination of the peritoneal cavity because intraperitoneal metastasis adversely affects the prognosis. Carcinomas may be more likely to have detectable seeding than the common pediatric tumors. When an adult type of tumor (e.g., a salivary gland mass) is suspected in a child, the management should be discussed at a multidisciplinary team meeting because the standard pediatric approach of core needle biopsy may not be appropriate.

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Ultrasound-Guided Interventional Procedures: Biopsy and Drainage

Fig. 18.2e–g (continued) Coaxial biopsy of a tumor. e Gelatin sponge is injected through the outer needle to improve hemostasis and reduce the chance of needle track seeding of tumor. f The needle is then removed. g The gelatin can be seen as echogenic material distributed along the biopsy track (arrows).

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Ultrasound-Guided Interventional Procedures: Biopsy and Drainage

Fig. 18.3a–c Correct approach for percutaneous biopsy of a renal tumor. a Contrast-enhanced computed tomography shows a tumor arising from the left kidney. The needle should be advanced posterior to the descending colon (arrow) to ensure that the track is extraperitoneal. The dashed lines indicate potential trajectories. b Corresponding transverse ultrasound image shows residual kidney tissue interposed between the tumor and abdominal wall. *, dilated (“trapped”) calyx. c The outer needle (arrow) has been advanced into the tumor through renal tissue. This presumably reduces the risk for tumor seeding, as this kidney will be resected following preoperative chemotherapy.

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Ultrasound-Guided Interventional Procedures: Biopsy and Drainage

Fig. 18.4a,b Native renal biopsy in the lateral position. a The patient lies on a gel pad bolster (B), increasing the separation between the costal margin and iliac crest (arrows). b Coronal ultrasound image shows that the lower pole of the kidney (arrowheads) is now accessible below the costal margin. The arrows indicate ribs.

Tips from the Pro ●

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●

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Insist on adequate preoperative imaging, and examine the images closely to determine which lesion, and which part of that lesion, should be sampled for the best balance between risk and success of the proposed biopsy. A coaxial technique should be used for almost all cases of suspected malignancy. Take more cores than you think will be necessary and sample from numerous different parts of the mass when possible because pediatric tumors are often partly necrotic, and the viable parts may be heterogeneous (e.g., ganglioneuroblastoma) US-guided biopsy of large anterior mediastinal masses is much simpler than using CT, and US allows real-time visualization of the internal thoracic (mammary) arteries and veins, which must be avoided. US-guided biopsy of bone lesions is often possible in cases with cortical destruction and/or periosteal elevation, and it is simpler than using fluoroscopy. Biopsy liver tumors through normal liver parenchyma, but cross only segments that will be resected if surgery is required in order to reduce the chance of peritoneal tumor spread without increasing the risk for intrahepatic recurrence. Contrast-enhanced US may occasionally be useful to increase the conspicuity of certain lesions (e.g., in the liver) for biopsy.

18.1.3 Nontumor Biopsy Nontargeted biopsies are usually indicated for the assessment of renal or hepatic parenchymal disease, but occasionally biopsy of other organs (e.g., the spleen) will be requested. “Blind” biopsy of these organs is now obsolescent and should no longer be taught. Any significant coagulopathy or thrombocytopenia (platelet count < 50–80 nL-1) should be corrected when possible, after discussion with a hematologist if necessary. Although all of these procedures can potentially be performed as day cases, many children’s hospitals still admit patients overnight because of the perceived risk for delayed complications. Biopsy of a native kidney under US guidance is best performed with the patient in the lateral position, with padding under the patient’s opposite side, in order to increase the distance between the ribs and the iliac crest (▶ Fig. 18.4). The prone position can be used if general anesthesia is not required. Two 16-gauge cores are usually sufficient, and for this reason coaxial biopsy is not often used. A pathology technician can check the adequacy of the sample in the operating suite, in case an additional sample is required. Severe complications (i.e., those that require treatment other than analgesia) occur after about 2% of procedures. They include perinephric hematoma, hematuria with clot retention, and arteriovenous fistula. Potential risk factors include vasculitis, lupus nephritis, hypertension, and coagulopathy (even if the coagulation parameters have been corrected by the transfusion of blood products).

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Fig. 18.5a–d Biopsy of a transplanted kidney. a Local anesthetic (arrows) is injected through a hypodermic needle (arrowhead) from the skin to the transplanted kidney, which in this case lies in the right iliac fossa. b The semiautomated biopsy needle (arrow) is inserted through the anesthetized area into the transplanted kidney. c The tip of the needle is advanced, exposing the cutting slot (arrow). d The needle is fired, advancing the cutting sleeve and trapping a core of renal cortex.

Transplanted kidneys are biopsied with the patient in the supine position (▶ Fig. 18.5). Biopsy in the early postoperative period (< 10 days) may be an additional risk factor for complications, which occur after about 3% of procedures overall. Nontargeted biopsy of the native liver is often requested for the evaluation of neonatal cholestasis, hepatitis, certain metabolic diseases, or suspected hemophagocytic lymphohistiocytosis or Langerhans cell histiocytosis. Relative contraindications include ascites and biliary dilatation. The use of a subcostal approach (to either the right or the left lobe) may reduce the risk for complications. Liver transplant biopsies may be performed with a similar technique, as long as consideration is given to the nature of the graft (whole liver, left lobe, or other). Transjugular liver biopsy is sometimes performed—for example, in children with uncorrectable coagulopathy. It is customary in pediatric practice to use US to guide the jugular venous puncture and (in conjunction with fluoroscopy) to guide the biopsy needle to a safe part of the liver parenchyma. The most important complication of liver biopsy is bleeding (intraparenchymal or intraperitoneal), which probably occurs in about 2% of cases. Other potential complications include bile leak or hemobilia,

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pneumothorax, and injury to other organs, such as the duodenum and colon. Following biopsy, the vital signs should be monitored frequently for 4 to 8 hours. Increasing pain in the abdomen, chest, or shoulder and unexplained tachycardia (even without hypotension) are indications for immediate abdominal US to exclude biopsy-related hemorrhage. Routine US following biopsy is not necessary.

Tips from the Pro ●

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When a native kidney is biopsied, the trajectory of the biopsy needle should be planned carefully. ○ Aim to sample cortex. Avoid the central part of the kidney. ○ This may be achieved in transverse, coronal, or oblique planes. ○ It is easiest (and safest) to sample from the lower pole or lateral interpolar cortex. When the liver is biopsied, care should be taken to avoid crossing the fissure for the ligamentum venosum.

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Ultrasound-Guided Interventional Procedures: Biopsy and Drainage

18.2 Drainage Techniques and Equipment The same principles of preprocedural imaging, planning, and consent that were discussed for biopsy apply to drainage procedures. Patients with sepsis are more likely to have deranged coagulation parameters. A multidisciplinary team discussion should be arranged to confirm the goals of drainage. In some cases, particularly when a collection is small, needle aspiration without drain insertion may be both diagnostic and therapeutic. This is less painful and probably safer, and it may avoid the need for general anesthesia. In patients with a large volume of ascitic or pleural fluid, the operator should decide preoperatively how much can safely be drained immediately, to minimize the risk for unpredictable fluid shifts (including pulmonary edema). In such cases, the drain may need to be clamped intermittently postoperatively to allow staged drainage. Patients undergoing drainage of infected collections should be covered with intravenous antibiotics, to minimize the risk for septicemia. Almost all collections can be drained with US guidance alone. A wide range of US transducers should be available, from highfrequency “hockey stick” probes with a small footprint, used for small collections, to 3-MHz probes, used for deep-seated collections in older or larger children. The 8- to 10-MHz sector probes have the advantage of a relatively small footprint yet good penetration, and they are invaluable for renal access in younger children and for intercostal approaches. In most cases, the techniques used are simple and not much equipment is required, so the aspiration or drainage of collections is possible in an intensive care setting. In general, the Seldinger technique is used to access collections for drain insertion. An initial stab incision of the overlying skin and dilation of the subcutaneous tissues with forceps will make subsequent passage of the drain less traumatic. The traditional approach is to use a two-part (trocar) needle, advance a relatively stiff guidewire through the outer needle into the collection, and then advance a series of dilators, followed by a drain, over the guidewire. It is possible to break down internal septa by manipulating a stiff guidewire in the collection, but this technique should be used with caution, particularly in small children, because it increases the risks for bleeding and septicemia. The size of the drain used is usually based on the consistency of the fluid in the collection. The use of locking pigtail drains is strongly advised because the rate of inadvertent removal is lower. The method of drain removal is different for different drain types and must be carefully documented in the patient’s medical records to facilitate tube removal.

Deep pelvic collections are best approached via a transrectal route (▶ Fig. 18.6). The transrectal drain is well tolerated, and there is no cutaneous scar. The transrectal route also avoids inadvertent damage to the bowel and pelvic vessels that may occur with a transabdominal approach. Although the procedure can be performed with a transrectal transducer, in children transabdominal US guidance is usually straightforward. This may involve filling the bladder through a urinary catheter at the start of the procedure. With the patient supine, the trocar needle is advanced into the rectum along the operator’s finger until it abuts the collection. Advancement of the needle and guidewire and insertion of the drain can be guided by real-time US. The alternative, transgluteal approach requires CT guidance and will not be discussed here. Very occasionally, the drainage of deep-seated collections in older children may require CT (or cone beam CT) guidance. Pancreatic collections can be approached via a transgastric route. The gastric wall can be extremely difficult to dilate, and a very stiff guidewire is often required to avoid buckling the drain into the gastric cavity. Indications for the drainage of pseudocysts include infection, pain, significant increase in size, and biliary obstruction. Clinicians involved in the care of patients with pancreatitis should be familiar with the revised Atlanta classification and management strategies. Techniques for nephrostomy placement in children are very similar to those in adults. Infected obstructed kidneys warrant urgent drainage. Causes of obstruction include calculi, blood clots, fungal balls, and anatomical variants such as a pelviureteric junction anomaly. Nephrostomy placement itself is usually slightly easier in children because the kidney is more superficial, and even nondilated systems are well visualized with US. Unilateral nephrostomy is best performed with the patient in a semiprone position, but bilateral nephrostomy requires prone positioning or repositioning of the patient after one side has been drained. Transplant nephrostomy is usually easiest with the patient in the supine position. A single-puncture technique is usually advocated in children (▶ Fig. 18.7).

Tips from the Pro ●

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Nephrostomy can be performed without fluoroscopic guidance, but if an immediate contrast study (“nephrostogram”) is necessary, the procedure should be performed in a room with fluoroscopic facilities. Complex fluid collections do not drain well through percutaneous drains. ○ Fibrinolytic agents can be instilled to try to break down septa and pus. ○ Management of the drain, including fibrinolysis and surveillance imaging, should be controlled jointly by the referring clinical team and the operator.

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Fig. 18.6a–d Transrectal drainage of a pelvic abscess with transabdominal ultrasound guidance and no fluoroscopy. a The abscess (A) lies at the tip of the operator’s finger (arrows), which has been inserted into the rectum. The bladder (B) is full, providing an excellent acoustic window. b An 18-gauge trocar needle is advanced along the operator’s finger with the trocar withdrawn into the blunt outer needle to minimize the risk for rectal injury. When the needle is in position to puncture the abscess, the sharp trocar is advanced, and the two parts are advanced together through the rectal wall. The trocar is then removed so that pus can be aspirated through the outer needle (arrow). c A guidewire, in this case a 75-cm-long stiff Amplatz wire with a 0.97-mm (0.038-in) diameter, is inserted through the needle into the abscess. d A locking pigtail drain is advanced over the guidewire into the abscess.

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Fig. 18.7a,b Transplant nephrostomy. a Color Doppler flow imaging of an obstructed transplant kidney shows the relatively avascular approach to a dilated calyx (c) through overlying cortex. b An appropriate calyx is selected and punctured with a large (18- or 19-gauge) needle (arrows). This allows for the insertion of a relatively large (0.038- or 0.035-inch) stiff guidewire. Following serial dilation of the track, an appropriate sized nephrostomy tube is inserted. The entire procedure can be performed with US guidance alone.

Recommended Readings Abi-Jaoudeh N, Kobeiter H, Xu S, Wood BJ. Image fusion during vascular and nonvascular image-guided procedures. Tech Vasc Interv Radiol 2013; 16: 168–176 Barnacle AM, Roebuck DJ, Racadio JM. Nephro-urology interventions in children. Tech Vasc Interv Radiol 2010; 13: 229–237 Franchi-Abella S, Cahill AM, Barnacle AM, Pariente D, Roebuck DJ. Hepatobiliary intervention in children. Cardiovasc Intervent Radiol 2014; 37: 37–54 Garrett KM, Fuller CE, Santana VM, Shochat SJ, Hoffer FA. Percutaneous biopsy of pediatric solid tumors. Cancer 2005; 104: 644–652 Gervais DA, Brown SD, Connolly SA, Brec SL, Harisinghani MG, Mueller PR. Percutaneous imaging-guided abdominal and pelvic abscess drainage in children. Radiographics 2004; 24: 737–754 Hogan MJ, Hoffer FA. Biopsy and drainage techniques in children. Tech Vasc Interv Radiol 2010; 13: 206–213 Light RW. Pleural controversy: optimal chest tube size for drainage. Respirology 2011; 16: 244–248 Muraca S, Chait PG, Connolly BL, Baskin KM, Temple MJ. US-guided core biopsy of the spleen in children. Radiology 2001; 218: 200–206 Nobili V, Comparcola D, Sartorelli MR et al. Blind and ultrasound-guided percutaneous liver biopsy in children. Pediatr Radiol 2003; 33: 772–775

Olsen JW, Barger RL, Jr, Doshi SK. Moderate sedation: what radiologists need to know. AJR Am J Roentgenol 2013; 201: 941–946 Robertson EG, Baxter G. Tumour seeding following percutaneous needle biopsy: the real story! Clin Radiol 2011; 66: 1007–1014 Roebuck DJ. Genitourinary intervention in children. Pediatr Radiol 2011; 41: 17–26 Sidhu MK, Goske MJ, Coley BJ et al. Image gently, step lightly: increasing radiation dose awareness in pediatric interventions through an international social marketing campaign. J Vasc Interv Radiol 2009; 20: 1115–1119 Sinha MD, Lewis MA, Bradbury MG, Webb NJ. Percutaneous real-time ultrasoundguided renal biopsy by automated biopsy gun in children: safety and complications. J Nephrol 2006; 19: 41–44 Smith TP, McDermott VG, Ayoub DM, Suhocki PV, Stackhouse DJ. Percutaneous transhepatic liver biopsy with tract embolization. Radiology 1996; 198: 769–774 Ward TJ, Goldman RE, Weintraub JL. Electromagnetic navigation with multimodality image fusion for image-guided percutaneous interventions. Tech Vasc Interv Radiol 2013; 16: 177–181 Zaheer A, Singh VK, Qureshi RO, Fishman EK. The revised Atlanta classification for acute pancreatitis: updates in imaging terminology and guidelines. Abdom Imaging 2013; 38: 125–136

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Index 2 22q11.2 deletion syndrome 157

A Abdominal aorta 215, 215, 216 Abdominal aorta thrombosis 215, 216 Abdominal neuroblastoma 215 Abdominal ultrasound, see Intestines and intestinal ultrasound, specific organs and structures Aberrant thymus 157, 158 Abscess – adrenal 517, 517 – breast 204 – chest wall 187, 190 – in renal transplantation 494 – lymph node 134, 135, 135, 187 – pancreatic 446 – pyogenic –– liver 259, 261–263 –– spleen 338 Abusive head trauma 93 Accessory adrenal gland 513 Accessory hepatic vein 246, 248 Accordion sign 394, 398 Acinar adenocarcinoma 441 Acoustic properties of materials and tissues 10 Acute lymphoblastic leukemia 313– 314 Adnexal torsion 560, 565–566 ADPKD, see Autosomal-dominant polycystic kidney disease (ADPKD) Adrenal cortical tumors 520, 529–532 Adrenal glands – abscesses in 517, 517 – accessory 513 – anatomy of 512 – cavernous hemangioma in 531, 533 – congenital adrenal hyperplasia in 517, 518 – cyst in 514, 516–517 – embryology of 512 – extrarenal rhabdoid tumor in 531, 533 – hemolytic anemia and 531 – hemorrhage in –– in older child 514, 516 –– neonatal 514, 515 – in Wolman disease 531, 534 – juxta-diaphragmatic pulmonary sequestration and 531, 533 – lipomatous tumors in 528, 533 – lymphangioma in 531, 533 – myelolipoma in 528, 533 – myeloproliferative disorder and 531 – neuroblastoma in 402–409, 516, 519, 519 – pheochromocytoma in 520, 529 – sonographic appearance of 512, 513 – teratoma in 528 – variants 513, 513, 514 – ”horseshoe” 513, 514 – ”lying down” 513, 513 Adrenal hyperplasia 518 – See also Congenital adrenal hyperplasia (CAH) Adrenal hypoplasia 518, 519

Adrenogenital syndrome 159 AHW, see Anterior horn width (AHW) Aliasing 18, 18 Alobar holoprosencephaly 84 Amenorrhea 539, 560 Amplitude mode 13, 14 Amyloidosis 170 Anal atresia 397, 404 Anesthesia for biopsy 618 Angiomatoid fibrous histiocytoma 611, 611 Angiomyolipoma in kidney 478, 480 Angiosarcoma in spleen 341 Ankle assessment 600, 601 Annular pancreas 426, 426–427 Anorexia nervosa 568 Anterior horn width (AHW) 38, 38–39 Anterior sacral meningocele 99, 104 Anus 397, 404 Aorta abdominal 215, 215, 216 Aortic arch – anomalies 163, 164–168, 170 – double 166, 168, 170 – in mediastinal anatomy 155, 157 – left with aberrant right subclavian artery 164, 164 – right with aberrant left subclavian artery 164, 165–167 Appendicitis 225, 227, 387, 389–390, 392–393 Appendix – abscess 391 – in cystic fibrosis 388 – in hemolytic uremic syndrome 388, 400 – in intestinal ultrasound 387, 388– 393 Appendix testis torsion of 583, 583, 584 Appointment 2 Appointment letter 2 Arachnoid cyst 78 Arteria lusoria 164, 164 Arteriovenous fistula in renal transplantation 495, 499 Arteriovenous malformation (AVM) 194, 197, 607 Arthritis 598, 598, 599–604 – juvenile idiopathic 598, 599 – septic 598, 599 Artifact(s) – aliasing as 18, 18 – defined 17 – enhancement as 17, 17 – flash 19, 19 – in 2D ultrasound 17 – in Doppler ultrasound 18 – mirror 18, 18 – reverberation as 17, 18 – shadowing as 17, 17 – twinkle 464, 464–465, 470 Ascariasis 428 Ascaris lumbricoides 377, 379 Ascensus medullaris 99 Ascites 221, 221, 222–224 Askin tumor 192 Astrocytomas 84 Ataxia telangiectasia 157 Atelectasis 202, 204–205 Attenuation 11, 12

Attitude of staff 2 Atypical mycobacterial infection 134, 135 Atypical teratoid rhabdoid tumors 84 Autoimmune hepatitis type I 277, 281 – See also Hepatitis Autosomal-dominant polycystic kidney disease (ADPKD) 469, 469, 470–474 Autosomal-recessive polycystic kidney disease (ARPKD) 470, 470, 471 AVM, see Arteriovenous malformation (AVM) Axial deformation 19 Axial resolution 16 Azygos vein 155, 157

B Baby changing area 3, 4 Back masses – non skin-covered 98 – skin-covered 98 Baker cyst 609 Banal lymphadenitis 132 Bartonella henselae 132, 133–134, 140 Beckwith-Wiedemann syndrome 440, 446, 474, 520 Benign enlargement of subarachnoid space (BESS) 92, 93–94 Benign small-bowel intussusception 381, 384 – See also Intussusception BESS, see Benign enlargement of subarachnoid space (BESS) Bile sludging 271, 272 Biliary tract, see Common bile duct, Gallbladder – air in 317, 317, 318, 320 – anatomy 246, 247–248 – benign masses of 298, 301 – rhabdomyosarcoma 316 – transducers for 246 Bilobed testicle 589, 590 Biological effects 20 Biopsy – anesthesia for 618 – bone 619 – coaxial systems for 619, 619–621 – complications of 618 – core needle 619 – equipment 618 – fine needle aspiration cytology for 619 – informed consent for 618 – kidney 619, 623, 623 – liver 619, 624 – lung 619 – lymph node 619 – needles for 619, 619 – renal tumor 620 – seeding of malignant cells in 618, 620 – spleen 619 – techniques 618 – tumor 620, 622 Bladder – anatomy 456 – calculi 504 – congenital urethral polyps in 504, 508

– diverticula 500, 501–502 – duplication 500 – in duplicate collecting system 461, 461 – infection 504, 506 – rhabdomyosarcoma 504, 506–507 – tumors 504, 506–508 Blake pouch cyst 78 Bochdalek hernia 208 Bone biopsy 619 Bone tumors of chest 199, 199, 200 Botulinum toxin A for drooling 141, 143 Bowel obstruction 403 – in Hirschsprung disease 409, 411 – in inspissated milk syndrome 404, 406 – in meconium ileus 407, 408, 408– 409 – in meconium peritonitis 408, 409– 410 – in meconium plug syndrome 406, 406 – in meconium pseudocyst 409, 410 Brachiocephalic vein 119, 119, 155, 157 Brain tumors congenital 84, 91–92 Branchial cleft cyst 122, 122, 123 BRCA gene carriers 208 Breast – abscess 204 – carcinoma 208 – congenital anomalies in 202, 205– 206 – cystic lesions in 205, 207–208 – development 185 – in chest anatomy 184, 185 – in gynecomastia 202 – in premature thelarche 202, 205 – inflammation of tissue in 204, 206 – malignant lesions in 208, 208 – metastatic disease in 208 Brightness mode 13, 14 Brucellosis 335, 339 Bucket handle deformity of anus 404 Budd-Chiari syndrome 282, 286–287 Bunny sign 251 Burkitt lymphoma 386 – See also Lymphoma

C CAKUT, see Congenital anomalies of kidney and urinary tract (CAKUT) Calcifying epithelioma of Malherbe 127, 130–131 Candida albicans – in liver 259, 263 – in spleen 202 Candidiasis splenomegaly in 335 Capillary malformations 607 Carney complex 520 Caroli disease 251, 256 Carotid arteries 117, 118, 155, 157 Cat-scratch disease 187 – See also Bartonella henselae Cauda equina 102 Caudal cell mass 98 Caudal regression syndrome 99, 109, 111

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Index Cavernous hemangioma adrenal 531, 533 Cavum septum pellucidum 40 Ceftriaxone 266, 270 Celiac artery 418, 420 Central dot sign 251, 256 Central venous line 119, 119, 120, 177, 177, 178 Cephalohematoma 146, 147, 148 Cerebellar vermis in Dandy-Walker malformation 39 Cerebral structures measurements of 38, 40 Cervical rib 146, 146 Cervix in female genital tract anatomy 475, 536 Changing area 3, 4 Chemotherapy 369 Chest and chest ultrasound, see Breast – advantages of 182 – anatomy in 183, 183, 184–186 – approaches for 182, 182 – arteriovenous malformation in 197 – Askin tumor in 192 – atelectasis in 202, 204–205 – cystic lesions in 205, 207–208 – diaphragm in –– anatomy 186, 186 –– congenital anomalies of 208, 209– 211 –– eventration of 209, 210–211 –– trauma to 211 – diaphragmatic hernia in 208, 209– 210 – diaphragmatic paralysis in 210 – Ewing sarcoma in 199 – extraosseous Ewing sarcoma 192 – fibroadenoma in 207, 207–208 – gynecomastia in 202 – hematoma in 205, 207 – indications for 183 – infantile hemangioma in 192, 196, 196 – infectious lesions in 187, 190 – juvenile papillomatosis in 208 – lung consolidation in 202, 203 – lungs in 184, 184, 185 – lymphadenopathy in 187, 191–192 – lymphoma in 192, 194 – malignant lesions in 208 – mastitis in 204, 206 – noninvoluting congenital hemangioma in 197 – pleura in 184 – pleural fluid collection in 200, 200, 201 – pleural mass in 202, 203 – pleural thickening in 202 – pneumothorax in 202 – Poland syndrome in 187, 259 – premature thelarche in 202, 205 – probe for 182 – rapidly involuting congenital hemangioma in 197 – retroareolar cysts in 205, 207 – rhabdomyosarcoma in 192, 193 – rib abnormalities in 186, 188 – thoracic wall in 183, 183, 184 – trauma in 187, 188–190 – tumors of 192, 192, 193–194 –– in bone 199, 199, 200 – vascular lesions in 192, 194, 196– 199

630

– venous malformations in 197, 197 Chest wall abscess 187, 190 Chiari malformation 78, 82–83 Child-friendly staff 2 Chloroma – in neck 148 – in pancreas 444, 445 Cholangitis – infectious 259, 264–265 – primary sclerosing 271, 273–274 Chole(docho)lithiasis 266, 266, 267– 271 Cholecystitis 259, 264 Choledochal cysts 251, 253–257 Cholestatic diseases 266, 272 Cholesterol polyp in gallbladder 298, 301 Chondrodysplasia punctata 159 Chondrosarcoma 199, 200 Choriocarcinoma in female genital tract 552 Choroid plexus tumors 84 Ciliopathies 468 Cirrhosis 275, 277 Clear cell carcinoma 477, 479 Cloacal malformation 540, 547–549 Clostridium difficile 394, 398–399 Coccyx 102, 103 Colitis, see Enterocolitis – infectious 394 – pseudomembranous 394, 398–399 – ulcerative 394, 395 Colon, see Large bowel Color Doppler 14, 360 Column of Bertin 454 Comet tail artifact 17, 18 Common bile duct – diameter 247 – in pancreatic anatomy 418, 420–421 – transection of in surgery 266, 271 Communication of results 6 Compound imaging 19 Compression graded 360, 362 Congenital abnormalities – in breast 202, 205–206 – in cranial ultrasonography in term infants 78, 80–83, 85–93 – in female genital tract 538, 539–546 – of diaphragm 208, 209–211 – vascular in mediastinum 163, 164, 168–172 Congenital adrenal hyperplasia (CAH) 517, 518, 540 Congenital anomalies of kidney and urinary tract (CAKUT) 468 Congenital brain tumors 84, 91–92 Congenital fibrosarcoma 192 Congenital portosystemic shunts 251, 258–259 Congenital posterior urethral valve 502, 503 Congenital teratoma 84 Congenital urethral polyps 504, 508 Conn syndrome 520 Consent for biopsy 618 Continuous wave Doppler 13 Contrast-enhanced cystosonography (CSG) 493, 506, 508–509 Conus medullaris – ascension of 99 – in spine ultrasound 100 Coronal planes in neonatal cranial ultrasonography 22, 22, 23–26

Corpus callosum (CC) – dysgenesis of 84, 85–87 – measurement of 38, 40 Corrosive esophagitis 162, 163 Cortical dysplasia 84, 88 Couch 5, 5 Coxsackievirus B infection 428 Cranial ultrasonography (cUS) neonatal – advantages of 22 – anatomy in 22, 22, 23–26 – deep gray matter in 31, 31, 32–33 – frontal echodensities in 26, 26–27 – in term infants 70, 71–83, 85–94 – maturational changes in 26 – measurements in 36, 39–40 – periventricular echodensities in 26, 27 – physiologic vs. pathologic echogenic areas in 26 – preterm infant pathology in 39, 41– 69 – timing of 31, 34–37 – transducers for 70 – white matter in 26, 26, 27–29 Crohn disease 428 – in large bowel 393, 394, 394 – in small bowel 373, 373–375 Crying 2 CSG, see Contrast-enhanced cystosonography (CSG) Currarino triad 111, 235, 240 Cushing syndrome 518, 520 Cystadenocarcinoma in female genital tract 552 Cystadenoma in female genital tract 552 Cystic fibrosis – appendix in 388 – gallstones in 266, 267 – intussusception in 382 – liver disease in 275, 278–280 – pancreas in 436, 437–439 Cystic lymphatic malformations 175, 175 Cystic transformation of rete testis 587, 588 Cystitis 504, 506 Cytosarcoma 208

D Dandy-Walker complex 78, 80–81 Dandy-Walker malformation 39, 78, 80 Deep pelvic collections 625, 626 Deformation 19 Deletion syndrome 157 Denys-Drash syndrome 474 Dermoid cyst 123, 123, 124–125 Desk administration 2, 3 Desmoplastic small round cell tumors 230, 230 Developmental dysplasia of hip (DDH) 594, 595–598 Dextrocardia 334 Dialysis peritoneal 225 Diaphragm – congenital anomalies of 208, 209– 211 – eventration of 209, 210–211 – in chest anatomy 186, 186 – trauma to 211 Diaphragmatic hernia 208, 209–210

Diaphragmatic paralysis 210 Diastematomyelia 107, 110 Diastrophic dysplasia 159 Dillinger-Ellison syndrome 441 Diplomyelia 107 Disorders of sulcation and migration 84, 88–89 Distractions 5 Domestic sedation 360, 362 Doppler echo 12 Doppler effect 12, 12 Doppler spectogram 12, 13 Doppler ultrasound – artifacts in 18 – color 14, 360 – continuous wave 13 – in joints 605, 606 – power 15, 15 – pulsed wave 13 Dorsal dermal sinus 107, 108, 109 Dorsal enteric fistula 107 Double aortic arch 166, 168, 170 Douglas pouch fluid in in females 221, 221 Drainage 625, 626–627 – complications of 618 Drooling 141, 143 Dual-imaging function 604 Duplicate collecting system 460, 461– 463 Duplication cyst – in stomach 364, 365 – intestinal 379, 381, 382–385 Dysgerminoma in female genital tract 552, 558, 558–561

E Echinococcus granulosus in liver 259, 263 Echoscopic image construction 13 ECMO, see Extracorporeal membrane oxygenation (ECMO) therapy Ectopic pancreas 426, 428 Ectopic thymus tissue – in mediastinum 157 – in neck 143, 145 Ectopic thyroid gland 137, 137 Ehlers-Danlos syndrome 500 Elastography 19, 19, 20, 275 Elbow assessment 602, 602 Elevational resolution 17, 17 Emla cream 205 Endomesenchymal tract 107 Endoscopic ultrasound of esophagus 360 Enhancement 17, 17 Entamoeba histolytica in liver 259 Enteric duplication cyst 238, 241–242 Enterocolitis, see Colitis – necrotizing 377, 379, 380 – neutropenic 394, 396 Ependymomas 84 Epidermoid cyst 123, 125 – splenic 338, 342 – testicular 577 Epididymal cyst 587, 588 Epididymis 570 Epididymitis 584, 584, 585–586 Epididymo-orchitis 584, 584, 585–586 Epiploic appendagitis 397, 402 Epstein-Barr virus 335 Esophageal achalasia 161, 162

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Index Esophageal atresia 111, 159, 160, 363, 363 Esophageal foreign body 161, 163 Esophagitis corrosive 162, 163 Esophagus – endoscopic ultrasound of 360 – in intestinal ultrasound 360, 361 – in mediastinal anatomy 155, 157, 157 – in mediastinal pathology 159, 160– 163 – tracheoesophageal fistula in 159, 160 Ewing sarcoma – extraosseous 192 – in chest 199 – in liver metastasized 312 Examination 4 Examination room 3, 4–5 Extracorporeal membrane oxygenation (ECMO) therapy 514 Extraosseous Ewing sarcoma 192 Extravaginal testicular torsion 582, 582, 583

F Familial hereditary pancreatitis 428 Familial juvenile hereditary nephritis 468 FAST, see Focused assessment with sonography for trauma (FAST) Fast-flow malformation 197 Fasting 2, 5 Fecalith 227 Female genital tract – adnexal torsion in 560, 565–566 – amenorrhea and 539, 560 – anatomy 536, 536, 537 – cloacal malformation in 540, 547– 549 – congenital anomalies of 538, 539– 546 – granulosa-theca cell tumor in 552, 558, 562 – in pubertas praecox 568, 568 – measurements 538 – Müllerian duct anomalies in 538, 539–546 – ovarian cyst in 551–552, 552, 553– 558 – ovarian torsion in 560, 565–566 – ovarian tumors in 551, 551, 552–564 – pelvic inflammatory disease in 560, 567 – probe for 536 – rhabdomyosarcoma in 558, 563–564 – sexual development disorders in 540, 549–551 – small-cell carcinoma in 558 – teratoma in 552 Fibroadenoma in chest 207, 207–208 Fibroblastic tumors in musculoskeletal ultrasound 612, 612 Fibrohistiocystic tumors in musculoskeletal ultrasound 611, 611 Fibrolamellar carcinoma 302, 309 Fibroma in female genital tract 552 Fibromatosis colli 127, 131, 612, 612 Fibrosarcoma congenital 192 Fibrous hamartoma of infancy 612, 613 Filar cyst 103, 104

Filum terminale – in spinal ultrasound 100, 102, 102 – lipoma of 99, 107 – thickened 111 – tight 99, 111, 112 Fine needle aspiration 619 Flash artifact 19, 19 Focal infarction in preterm infants 64, 67–69 Focal nodular hyperplasia 298, 300– 301 Focused assessment with sonography for trauma (FAST) 225, 226, 287 Foreign body esophageal 161, 163 Forked ribs 186, 188 Foveolar hyperplasia 364, 367–368 Frame rate 604 Frontal echodensities in neonatal cranial ultrasonography 26, 26–27 Fungal infection in liver 259, 263 Fused ribs 186, 188

G Galactoceles 205 Gallbladder, see entries at Chol – benign masses of 298, 301 – cholesterol polyp in 298, 301 – distension of in fasting 246, 246 – hydrops 259 – in preterm infants volume of 247 – volume 247 Gallstones 266, 266, 267–271 Ganglion cell tumors retroperitoneal 235, 236 Ganglion in musculoskeletal ultrasound 609, 610 Ganglioneuroblastoma 175, 176, 192 Ganglioneuroma 175, 176 Gastric volvulus 364, 366 Gastrinoma 441 Gastritis 364 Gastroduodenal artery 418, 420 Gastroesophageal junction 363, 364 Gastroesophageal reflux disease (GERD) 363 Gaucher syndrome 335, 340, 341 GCTTS, see Giant cell tumor of tendon sheath (GCTTS) Genital tract, see Female genital tract, Male genital tract GERD, see Gastroesophageal reflux disease (GERD) Germinal matrix-intraventricular hemorrhage (GMH-IVH) 31, 36, 39, 40– 52, 54–57 Gerota fascia 214 Giant cell tumor of tendon sheath (GCTTS) 611 Glomerular nephropathy 485–487, 487, 488 Glomerulocystic kidney disease 468, 472 GMH-IVH, see Germinal matrix-intraventricular hemorrhage (GMH-IVH) Gonadal stromal cell tumors in male genital tract 577 Graded compression 360, 362 Granulosa-theca cell tumor in female genital tract 552, 558, 562 Graves disease 137, 138 Gray matter deep in neonatal cranial ultrasonography 31, 31, 32–33

Gray matter heterotropias 84 Great vessels in mediastinal anatomy 155, 157 Guidance, see Ultrasound guidance Gynecomastia 202

H Hamartoma – fibrous of infancy 612, 613 – in pancreas 441 – in spleen 340, 341, 349 – mesenchymal of liver 298, 299–300 – renal 478, 480 – tuber cinereum 568, 568 Harmonic imaging 19, 604 Hashimoto thyroiditis 137, 137 Head, see Cranial ultrasonography (cUS) neonatal Head trauma abusive 93 Heart in mediastinal anatomy 155, 157 Hemangioendothelioma in pancreas 441 Hemangioendothelioma in spleen 340, 341, 350 Hemangioma 194 – adrenal cavernous 531, 533 – congenital vs. infantile 295 – in chest 192, 196, 196 – in liver 292, 292, 293–298 – in musculoskeletal ultrasound 607, 607 – in neck 124, 125–130, 140–141 – in spleen 338, 340, 345–346 – noninvoluting 197, 294, 295 – rapidly involuting congenital 197, 295, 295 – scrotal 578 – subglottic 159, 159 Hematoma – chest 205, 207 – in renal transplantation 494, 497 Hematoperitoneum 225, 225, 226–227 Hemihypertrophy syndrome 520 Hemolytic anemia – adrenal gland and 531 – splenomegaly in 339 Hemolytic uremic syndrome 388, 394, 400, 428 Henoch-Schönlein purpura 375, 377, 378, 382, 388, 428 Hepatic arterial flow 249, 251 Hepatic veno-occlusive disease 282, 285 – See also Budd-Chiari syndrome Hepatic venous flow 249, 251 Hepatitis 258, 260, 277, 281 Hepatoblastoma 301, 302–308 Hepatocellular carcinoma 302, 308 Heterotaxy syndrome – defined 332 – with asplenia 335 – with polysplenia 335, 336–337 Hiatal hernia 209 HIE, see Hypoxic-ischemic encephalopathy (HIE) Hip – assessment of 600, 600 – classification 595, 596–597 – developmental dysplasia of 594, 595–598 – in musculoskeletal ultrasound 594, 594, 595–599

– normal development of 594, 594 – transient synovitis of 598, 598, 599 – ultrasound technique for 595, 595, 596 Hirschsprung disease 409, 411 Histoplasmosis 170, 348, 352 Hodgkin disease 136, 174 Holoprosencephaly 84, 87 Horseshoe kidney 461, 463 Human immunodeficiency virus (HIV) infection parotid gland in 140 Hydrocele 570, 572–573 Hydromyelia 107 – See also Syringohydromyelia Hydrops of gallbladder 259 Hygroma colli 126, 129 Hyperlipidemia 428 Hypersplenism recurrent 327 Hypertension portal 275, 279, 281–282 – splenomegaly in 340 Hypertrophic pyloric stenosis 367, 370 Hypoxic-ischemic encephalopathy (HIE) 70, 71, 74–75, 77–79

I Idiopathic scrotal edema 585, 586 Iliac crest 100 Image construction 13, 19 Indirect inguinal hernia 573, 574–576 – in hydrocele 570, 572 Infants, see Preterm infants, Term infants Infectious cholangitis 259, 264–265 Infectious colitis 394 – See also Neutropenic enterocolitis Infectious lesions – in chest 187, 190 – in liver and biliary system 258, 260– 265 Infectious splenomegaly 335, 335, 339 Inferior vena cava 157, 216, 217–219 Inferior vena cava occlusion 216, 218– 219 Inflammatory bowel disease (IBD), see Colitis, Crohn disease Informed consent for biopsy 618 Inguinal hernia indirect 573, 574–576 – in hydrocele 570, 572 Innominate artery in mediastinal anatomy 155, 157 Inspissated milk syndrome 404, 406 Insulinoma 441 Intensive care mediastinal ultrasound in 177, 177, 178 Interhemispheric lipoma 87 Interstitial nephropathies 488 Intestinal duplication cyst 379, 381, 382–384 Intestinal polyps 373, 376–377, 382 Intestines and intestinal ultrasound, see Bowel obstruction, Large bowel, Small bowel, Stomach – appendix in 387, 388–393 – bowel obstruction in 403, 405–411 – color Doppler in 360 – esophagus in 360, 361 – gas in 360 – gastroesophageal junction in 363, 364 – graded compression in 360, 362 – large bowel in 393, 393, 394–402 – rectum in 397, 403

631

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Index – small bowel in 367, 370–387 – stomach in 364, 364, 365–370 – ”gut signature” in 360, 360–361 Intracranial hemorrhage in term infants 70, 71–74 Intraductal papilloma 208 Intradural lipoma 107, 107, 107 Intraparenchymal hemorrhage in term infants 70, 72–74 Intraperitoneal fluid collections 221, 221, 222–227 Intravaginal testicular torsion 580, 581–582 Intraventricular hemorrhage in term infants 69, 70, 71 Intussusception – benign small-bowel 381, 384 – colocolic 381, 386 – contrast and air enema techniques with 382 – ileo-ileal 387 – ileo-ileocolic 381–382 – ileocolic 381–382, 384–387 – on conventional abdominal radiography 382 – pathologic lead points in 382, 385– 386 – reduction of 386, 387 Islet cell tumors 441, 448 Ivemark syndrome 513

J Jejunal atresia 405 JIA, see Juvenile idiopathic arthritis (JIA) Johnson-Blizzard syndrome 440 Joint(s), see Musculoskeletal ultrasound – assessment 599, 600–604 – infection in 606 – trauma 604, 606 Jugular veins 117, 118, 119, 120 Jugulodigastric node 127, 132, 132 Juvenile idiopathic arthritis (JIA) 598, 599 Juvenile papillomatosis 208 Juvenile polyps 394, 401–402 Juxta-diaphragmatic pulmonary sequestrations 531, 533

K Keutel syndrome 159 Kidneys and kidney ultrasound – anatomy of 452, 452, 454–456 – autosomal-dominant polycystic kidney disease in 469, 469, 470–474 – autosomal-recessive polycystic kidney disease in 470, 470, 471 – biopsy 619, 623, 623 – bladder in 456 – clear cell carcinoma in 477, 479 – column of Bertin in 454 – complicated cysts in 473, 473, 474 – compound calices in 454, 455 – cortical fusion defects in 454 – cysts and cystic nephropathies in 467, 468–469 – duplicate collecting system in 460, 461–463 – glomerular nephropathy in 485– 487, 487, 488

632

– glomerulocystic kidney disease in 468, 472 – horseshoe 461, 463 – in Henoch-Schönlein purpura 377, 378 – in renal hypodysplasia 457, 457, 458 – in ureteropelvic junction stenosis 457, 458–459 – in ureterovesical junction stenosis 457, 459–460 – in urolithiasis 464, 464, 465–468 – interstitial nephropathies in 488 – laceration 490, 490 – lymphoma in 477 – medullary sponge kidney disease in 472 – mesoblastic nephroma in 478 – metanephric adenoma in 478 – multicystic kidney disease in 472, 472, 473 – multilocular cystic nephroma in 478, 479 – nephroblastomatosis in 474, 475– 476 – nephrocalcinosis in 466, 466, 467, 467 – nephronophthisis in 468, 472, 472 – parenchymal nephropathy in 485, 485, 486–489 – persistent fetal lobulation in 452, 452 – protein deposits in in neonates 454, 455 – renal artery stenosis in 481, 482– 483 – renal cell carcinoma in 477 – renal vein thrombosis in 482, 483– 484 – renovascular disease in 481, 482– 484 – rhabdoid tumor in 477 – simple cysts in 468–469, 473 – size of 453 – technique for 452, 452 – transplantation of –– abscesses in 494 –– arteriovenous fistula in 495, 499 –– biopsy in 624 –– graft dysfunction in 496 ––– nephrologic complications causing 287, 491 ––– surgical complications causing 494, 496–497 –– hematoma in 494, 497 –– lymphoceles in 494, 496–497 –– post-transplant lymphoproliferative disorder in 500, 501 –– postoperative assessment of 491, 494 –– pseudoaneurysm in 495, 499 –– pyelonephritis in 498, 500 –– renal artery stenosis in 494, 498 –– renal artery thrombosis in 494 –– renal vein thrombosis in 494 –– renovascular disease in 500 –– urinary tract obstruction in 495– 496, 499 –– urinoma in 494 –– vascular complications in 494, 498– 499 – trauma in 490, 490, 491–493 – tubular nephropathies in 487, 488 – tubulopathies in 467

– – – –

tumors in 474, 475–480 ureters in 455, 456 vascular nephropathies in 489, 489 Wilms tumor in 216, 218, 219, 219, 308, 310, 474, 474, 475–476, 476, 477–478 Klinefelter syndrome 204 Klippel Trenaunay syndrome 608 Kwashiorkor 221

L Langerhans cell histiocytosis 170, 199, 340, 354, 613, 614 Large bowel, see Bowel obstruction – Crohn disease in 393, 394, 394 – epiploic appendagitis in 397, 402 – in hemolytic uremic syndrome 394, 400 – in intestinal ultrasound 393, 393, 394–402 – infectious colitis in 394 – juvenile polyps in 394, 401–402 – meconium calcifications in 397, 402 – neutropenic enterocolitis in 394, 396 – nonstratified thickening of with loss of haustral folds 394 – nonstratified thickening of with preservation of haustral folds 394 – pseudomembranous colitis in 394, 398–399 – stratified thickening of 394 – ulcerative colitis in 394, 395 Laryngeal calcification 159 Lateral deformation 19, 20 Lateral resolution 16 Left aortic arch with aberrant right subclavian artery 164, 164 Leiomyoma in spleen 340, 352 Lenticulostriate infarct 67 Lenticulostriate vasculopathy 31, 33 Letter appointment 2 Leukemia 135, 311, 313–314, 369 – See also Chloroma Li-Fraumeni syndrome 520, 529 Linear array transducer 15, 15 Lipoblastoma – in chest wall 192 – peritoneal 231, 231, 232 Lipoblastomatosis 231 Lipoma – in male genital tract 578 – in musculoskeletal ultrasound 608, 609 – in neck 145, 145 – in pancreas 441 – interhemispheric 87 – intradural 107, 107, 107 – of filum terminale 99, 107 Lipomyelocele 106, 106 Lipomyelomeningocele 99, 106, 106 Lisencephaly 84, 89 Liver, see entries at Hepatic – anatomy 246, 246, 247–249 – biopsy 619, 624 – calcifications neonatal 320–321, 321 – fibrolamellar carcinoma in 302, 309 – fungal infection of 259, 263 – hemangioma in 292, 292, 293–298 – hepatitis in 258, 260 – in Budd-Chiari syndrome 282, 286– 287 – in cirrhosis 275, 277

– in cystic fibrosis 275, 278–280 – in focal nodular hyperplasia 298, 300–301 – in nonalcoholic fatty liver disease 275, 275, 276 – in premature infants size of 246 – in situs inversus 334 – infection 258, 260–265 – mesenchymal hamartoma of 298, 299–300 – metastatic disease in 308, 310–314 – parasitic infection of 259, 263 – pyogenic abscess in 259, 261–263 – size of 246–247 – transducers for 246 – trauma 287, 287, 288–291 – tumors 292, 292, 293–301, 303–316 – vasculature 246, 248–249 Lobar holoprosencephaly 84 Lumbosacral junction 99 Lungs – atelectasis in 202, 204–205 – biopsy of 619 – consolidation in 202, 203 – in chest anatomy 184, 184, 185 Lymph node(s) – abscesses 134, 135, 135, 187 – biopsy of 619 – levels 127, 132 – malignant 135, 136 – necrotic 135 – reactive 132 – sonographic and clinical features of 127, 132–133 – supraclavicular 135 Lymphadenitis banal 132 Lymphadenopathy – in chest 187, 191–192 – in mediastinum 170, 173 – in neck 127, 132–136 – mesenteric 219, 220 – retroperitoneal 219, 220 Lymphangiomas – adrenal 531, 533 – in mediastinum 175, 175 – in neck 126, 129–130 – in pancreas 441 – in spleen 341, 347–348 – intra-abdominal 231, 233 Lymphangiomatosis in musculoskeletal ultrasound 607, 608 Lymphatic malformations – cystic 175, 175, 194, 198, 198, 199 – in musculoskeletal ultrasound 607, 608 Lymphoceles in renal transplantation 494, 496–497 Lymphoma – Burkitt 386 – in chest 192, 194 – in kidneys 477 – in mediastinum 174, 174 – in pancreas 444, 444–445 – in spleen 340, 341, 351 – intussusception in 386 – non-Hodgkin 135, 174 – retroperitoneal 231, 233 – splenomegaly in 335

M Male genital tract – anatomy in 570, 570, 571–572

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Index – appendix testis torsion in 583, 583, 584 – bilobed testicle in 589, 590 – cystic transformation of rete testis in 587, 588 – epidermoid cyst in 577 – epididymal cyst in 587, 588 – epididymis in 570 – epididymitis in 584, 584, 585–586 – epididymo-orchitis in 584, 584, 585–586 – fibrous pseudotumors in 578 – gonadal stromal cell tumors in 577 – idiopathic scrotal edema in 585, 586 – indications for ultrasound in 570 – inguinal hernia in indirect 573, 574– 576 –– in hydrocele 570, 572 – lipoma in 578 – mediastinum in 570, 571–572 – polychordism in 589, 590 – retractile testicle in 590, 590, 591 – rhabdomyosarcoma in 578, 580 – scrotal tumors in 576, 577–580 – spermatic cord in 570, 571 – spermatic cyst in 573, 573 – technique with 570 – testicular microlithiasis in 576, 578 – testicular torsion in 580, 581–584 –– extravaginal 582, 582, 583 –– intravaginal 580, 581–582 – testicular trauma in 585, 586–587 – testicular tumors in 576, 577–578 –– secondary 576, 578–580 – testis in 570, 571 – tubular ectasia in 587, 588 – undescended testicle in 590, 590, 591 – varicocele in 588, 588, 589 – vas deferens in 570, 571 – Wilms tumor in 577, 579 Malrotation of small bowel 370, 372, 372 Mammary duct ectasia 205 Mammography 183 Mastitis 204, 206 Mastitis neonatorum 204 Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome 538, 539 McCune-Albright syndrome 568 Meckel diverticulum 377, 379–380, 382, 387, 426 Meckel-Gruber syndrome 446 Meconium calcifications 397, 402 Meconium ileus 407, 408, 408–409 Meconium peritonitis 397, 408, 409– 410 Meconium plug syndrome 406, 406 Meconium pseudocyst 409, 410 Mediastinum and mediastinum ultrasound – aberrant thymus in 157, 158 – anatomy 154, 155–156 – aortic arch in 155, 157 – approaches for 154 – chest radiography of 154 – congenital vascular anomalies in 163, 164, 168–172 – corrosive esophagitis in 162, 163 – cystic lymphatic malformations in 175, 175 – double aortic arch in 166, 168, 170 – ectopic thymus in 157

– – – – – – – –

esophageal achalasia in 161, 162 esophageal atresia in 159, 160 esophageal foreign body in 161, 163 esophagus in 155, 157, 157, 159, 160–163 great vessels in 155, 157 heart in 155, 157 in intensive care 177, 177, 178 in male genital tract anatomy 570,

571–572 – indications for 154 – innominate artery in 155, 157 – left aortic arch with aberrant right subclavian artery in 164, 164 – lymphadenopathy in 170, 173 – lymphoma in 174, 174 – masses in 170, 170, 173–176 – neuroblastoma-ganglioneuroblastoma-ganglioneuroma complex in 175, 176 – pulmonary artery sling in 166, 169 – right aortic arch with aberrant left subclavian artery in 164, 165–167 – subglottic hemangioma in 159, 159 – thymic aplasia in 157, 158 – thymus in 154, 155 – total anomalous pulmonary venous return in 167, 169, 171 – trachea in 155, 157, 159, 159, 160 – tracheobronchial calcification in 159, 160 – tracheoesophageal fistula in 159, 160 – transducer placement in 154 – transducers for 154 Medullary carcinoma thyroid 138, 311 Medullary sponge kidney disease 472 Mega cisterna magna 78 Meningocele 104, 147 – anterior sacral 99, 104 – posterior 104 Mesenchymal hamartoma of liver 298, 299–300 Mesenteric cyst 238, 243 Mesenteric lymphadenopathy 219, 220 Mesenteric lymphoma 231, 233 Mesoblastic nephroma 478 Metabolic syndrome 440 Metanephric adenoma 478 Metastatic disease – in breast 208 – in liver 308, 310–314 – in pancreas 444 – peritoneal 231, 234–236 Middle aortic syndrome 215, 215–216 Midgut volvulus 370, 372, 372 Midline tumors of skull 146, 147 Migration disorders 84, 88–89 Milk curd syndrome 404, 406 Miller-Dieker syndrome 84 Mirror artifacts 18, 18 Mitochondrial succinate dehydrogenase enzyme defects 520 Montgomery cysts 205, 207 Morgagni hernia 209 Motion mode 14, 14, 98, 100 MRKH, see Mayer-Rokitansky-KüsterHauser (MRKH) syndrome Müllerian duct anomalies 538, 539– 546 Multicystic kidney disease 472, 472, 473 Multilocular cystic nephroma 478, 479

Multiple endocrine neoplasia syndrome 138, 140, 520 Musculoskeletal ultrasound – ankle assessment in 600, 601 – arteriovenous malformation in 607 – arthritis in 598, 598, 599–604 – Baker cyst in 609 – capillary malformations in 607 – congenital vascular lesions in 606 – elbow assessment in 602, 602 – fibroblastic tumors in 612, 612 – fibrohistiocystic tumors in 611, 611 – fibrous hamartoma of infancy in 612, 613 – ganglion in 609, 610 – hemangioma in 607, 607 – hip assessment in 600, 600 – hip in 594, 594, 595–599 – joint assessment in 599, 600–604 – juvenile idiopathic arthritis in 598, 599 – Langerhans cell histiocytosis in 613, 614 – lipoma in 608, 609 – lymph nodes in 608, 608 – lymphangiomatosis in 607, 608 – lymphatic malformations in 607, 608 – neurofibroma in 610, 611 – pilomatrixoma in 612, 613 – popliteal cyst in 609 – rhabdomyosarcoma in 613, 613 – septic arthritis in 598, 599 – subcutaneous granuloma annulare in 610, 610 – synovial cyst in 609 – transient synovitis of hip in 598, 598, 599 – vascular malformations in 607 – venous malformation in 607, 607 – wrist assessment in 602, 602 Myelocele 99, 103, 104 Myelocystocele 105, 105 Myelolipoma adrenal 528, 533 Myelomeningocele 99, 103, 104 Myeloproliferative disorder, adrenal gland and 531 Myofibroma 149, 312 Myometrium in female genital tract anatomy 536, 537

N NAFLD, see Nonalcoholic fatty liver disease (NAFLD) Near field 604, 606 Neck and neck ultrasound – anatomy in 116, 116, 117–119 – brachiocephalic vein in 119, 119 – branchial cleft cyst in 122, 122, 123 – carotid arteries in 117, 118 – central line in 119, 119, 120 – cervical rib in 146, 146 – cystic lesions in 120, 121–125 – dermoid cyst in 123, 123, 124–125 – ectopic thymus tissue in 143, 145 – ectopic thyroid gland in 137, 137 – epidermoid cyst in 123, 125 – fibromatosis colli in 127, 131 – hemangiomas in 124, 125–130, 141 – hygroma colli in 126, 129 – indications for 116

– jugular veins in 117, 118, 119, 120 – lipomas in 145, 145 – lymph nodes in 117 –– abscesses 134, 135, 135 –– levels 127, 132 –– –– –– ––

malignant 135, 136 necrotic 135 reactive 132 sonographic and clinical features of 127, 132–133 –– supraclavicular 135 – lymphadenopathy in 127, 132–136 – lymphangiomas in 126, 129–130 – neuroblastoma in 150 – orbital cyst in 123, 124 – paraganglioma in 146, 146 – parotid gland in 116, 116 – pilomatrixoma in 127, 130–131 – retropharyngeal region in 116 – salivary gland stones in 141, 142 – salivary gland tumors in 126, 141, 142 – salivary glands in 116, 138 – subclavian arteries in 117, 118–119 – subclavian veins in 117, 118, 119, 119–120 – sublingual glands in 116, 117 – submandibular gland in 116, 116– 117 – superior caval vein in 119 – thymus in 117, 118 – thyroglossal duct cyst in 120, 121 – thyroid gland in 117, 117–118, 137, 137, 138–140 – thyroid nodules in 138, 138, 139– 140 – thyroiditis in 137, 137, 138 – transducers for 116 – tumors in 127, 131–136 – vascular malformations in 124, 125– 130 – vessel pathology 119, 119, 120 Necrotizing enterocolitis 377, 379, 380 Needles biopsy 619 Neonatal ascites 224 Neonatal bowel obstruction 403, 405– 411 Neonatal cranial ultrasonography, see Cranial ultrasonography (cUS) neonatal Neonatal isoimmune thrombocytopenia 70 Neonatal liver calcifications 320–321, 321 Neonates, see Preterm infants, Term infants Nephroblastomatosis 474, 475–476 Nephrocalcinosis 466, 466, 467, 467 Nephroma – mesoblastic 478 – multilocular cystic 478, 479 Nephronophthisis 468, 472, 472 Nephrostomy placement 625, 627 Nephrotic syndrome 221 Neural groove 98, 99 Neural plate 98, 99 Neural tube 98 Neurinomas in pancreas 441 Neuroblastoma, see Ganglion cell tumors – abdominal 215 – adrenal 402–409, 516, 519, 519 – in chest wall 192

633

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Index – in liver metastasis of 308, 310–311, 313 – in neck 150 – in pancreas 444, 444 – retroperitoneal 219, 311 – splenic displacement by 335, 338 Neuroblastoma-ganglioneuroblastomaganglioneuroma complex 175, 176 Neuroendocrine adenomatosis 441, 443 Neurofibroma in musculoskeletal ultrasound 610, 611 Neurofibromatosis type I 204, 578 Neurogenic tumors of chest wall 192 Neurulation – primary 98 – secondary 98 Neutropenic enterocolitis 394, 396 – See also Infectious colitis Newman-Pick disease 335, 341 NICH, see Noninvoluting congenital hemangioma (NICH) Non-Hodgkin lymphoma 135, 174 – See also Lymphoma Nonalcoholic fatty liver disease (NAFLD) 275, 275, 276 Noninvoluting congenital hemangioma (NICH) 197, 294, 295 Norman-Roberts syndrome 84 Notochord 98, 99 Nyquist-Shannon theorem 13

O Obesity – gallstones in 266, 267 – gynecomastia in 204 – lymphadenopathy imaging and 219 – nonalcoholic fatty liver disease in 275, 275 – pancreas in 440, 448 Occult spinal dysraphism 98, 107, 107, 108–113 Orbital cyst 123, 124 Orthotopic thymus 145 Osteochondroma 200, 200 Osteosarcoma primary 199 Ovarian carcinoma 170 Ovarian cyst 551–552, 552, 553–558 Ovarian follicles in female genital tract anatomy 536, 537 Ovarian small-cell carcinoma 558 Ovarian torsion 560, 565–566 Ovarian tumors 551, 551, 552–564 Ovaries size of 538

P PAIS, see Perinatal arterial ischemic stroke (PAIS) Pampiniform plexus 570 Pancreas and pancreas ultrasound – abscesses in 446 – anatomy 416–417, 417, 418–425 – annular 426, 426–427 – chloroma in 444, 445 – congenital cysts of 446, 447 – cystic lesions in 444 – cystic neoplasms of 446 – developmental anomalies of 426, 426, 427–430 – echogenicity of 421, 424

634

– – – –

gastrinomas in 441 hamartoma in 441 hemangioendoethelioma in 441 in Beckwith-Wiedemann syndrome 440, 446 – in cystic fibrosis 436, 437–439 – in Johnson-Blizzard syndrome 440 – in Shwachman-Diamond syndrome 439, 440 – in situs inversus 428, 430 – indications for 416 – insulinomas in 441 – islet cell tumors in 441, 448 – isthmus of 418, 420 – lipoma in 441 – lymphangioma in 441 – lymphoma in 444, 444–445 – metastatic disease in 444 – neck of 418, 420 – neoplasms 440, 441–448 – neurinoma in 441 – neuroblastoma in 444, 444 – neuroendocrine adenomatosis in 441, 443 – pseudocysts in 444, 446–447 – size of 421, 422 – solid papillary tumor in 441, 442, 448 – tail of 416–417, 418 – technique for 416, 416, 417–419 – uncinate process of 397, 418, 420, 424 Pancreas divisum 426, 426, 428 Pancreatic adenocarcinoma 441 Pancreatic collections 625 Pancreatic duct 416, 418, 421 Pancreatic duct obstruction 434 Pancreatic hypoplasia 428, 429 Pancreatitis – acute 428, 428, 430–434, 448 – chronic 434, 435–437 – familial hereditary 428 – necrotizing 225 Pancreatoblastoma 441, 448 Papillary carcinoma thyroid 138, 139 Papillomatosis juvenile 208 Paraganglioma in neck 146, 146 Paragranuloma 136 Parasitic infection in liver 259, 263 Parenchymal nephropathy 485, 485, 486–489 Parotid gland 116, 116, 138, 140 – See also Salivary glands Parotitis bacterial 140 Patent urachus 503 PCOS, see Polycystic ovarian syndrome (PCOS) Peliosis 340 Pelvic inflammatory disease (PID) 560, 567 Peptic ulcer disease 364 Perianal abscesses 403 Perinatal arterial ischemic stroke (PAIS) in preterm infants 64, 67–69 Perineal fistula 403 Peristalsis in small bowel vs. colon 367 Peritoneal cavity – air in 229, 229, 229, 230 – anatomy of 214, 214 – in males vs. females 214 Peritoneal dialysis 225 Peritoneal fluid 214

– See also Intraperitoneal fluid collections Peritoneal metastases 231, 234–236 Peritoneal tumors 229, 230–236 Peritonitis 225, 227–228 – meconium 397, 408, 409–410 Periventricular echodensities (PVEs) in neonatal cranial ultrasonography 26, 27, 31 Periventricular hemorrhagic infarction (PVHI) 31, 40, 69 Periventricular leukomalacia (PVL) 36, 65 Perthes disease 598 Phakomatoses 84, 90 Phased array transducer 16, 16 Pheochromocytoma 520, 529 Phleboliths 197 PHVD, see Post-hemorrhagic ventricular dilatation (PHVD) Phyllodes tumor 208 PID, see Pelvic inflammatory disease (PID) Piezoelectric effect 15, 15 Pigmented villonodular synovitis (PVNS) 611 Pilomatricoma, see Pilomatrixoma Pilomatrixoma 127, 130–131, 612, 613 Pleomorphic adenoma 141, 142 Pleura in chest anatomy 184 Pleural fluid collection 200, 200, 201 Pleural mass 202, 203 Pleural thickening 202 Plunging ranula 140, 142 PNET, see Primitive neuroectodermal tumors (PNET) Pneumobilia 317, 317, 318 Pneumocystis carinii 170 Pneumoperitoneum 229, 229, 229, 230 Pneumothorax 202 Poland syndrome 187, 259 Polychordism 589, 590 Polycystic ovarian syndrome (PCOS) 568 Polyps, see Intestinal polyps, Juvenile polyps – congenital urethral 504, 508 Popliteal cyst 609 Portal hypertension 275, 279, 281–282 – See also Budd-Chiari syndrome – splenomegaly in 340 Portal vein thrombosis 282, 283–285 – splenomegaly in 335, 340 Portal venous air 317, 318–319 Portal venous flow 249, 249, 250 Portosystemic shunts congenital 251, 258–259 Post-hemorrhagic ventricular dilatation (PHVD) 31, 36, 38, 39–40, 42, 52, 57–60 Post-transplant lymphoproliferative disorder (PTLD) in renal transplantation 500, 501 Posterior fossa abnormalities 78 Posterior triangle 127 Posterior urethral valve congenital 502, 503 Power Doppler 15, 15 Precocious puberty 568, 568 Premature thelarche 202, 205 Preterm infants – cranial pathology in 39, 41–69

– germinal matrix-intraventricular hemorrhage in 31, 36, 39, 40–52, 54–57 – inspissated milk syndrome in 404, 406 – liver size in 246 – perinatal arterial ischemic stroke in 64, 67–69 – post-hemorrhagic ventricular dilatation in 31, 36, 38, 39–40, 42, 52, 57– 58 – splenic length in 331 – white matter injury in 60, 60, 61–66 Primary pigmented nodular adrenal hyperplasia 518 Primary sclerosing cholangitis (PSC) 271, 273–274 Primitive neuroectodermal tumors (PNET) 84, 558 Principles of ultrasound 10 Private room 6 Probes, see Transducers Procedures, see Ultrasound guidance Propagation of ultrasonic waves 10 Prostatic utricle cysts 503 PSC, see Primary sclerosing cholangitis (PSC) Pseudoaneurysm in renal transplantation 495, 499 Pseudoangiomatous stromal hyperplasia 208 Pseudochole(docho)lithiasis 266, 270 Pseudocysts pancreatic 444, 446–447 Pseudomembranous colitis 394, 398– 399 Pseudosinus tract 103, 104 PTLD, see Post-transplant lymphoproliferative disorder (PTLD) Pubertas praecox 568, 568 Pulmonary artery – left 155, 157 – right 155, 157 – sling 166, 169 Pulmonary veins in total anomalous pulmonary venous return 167, 169, 171 Pulsed wave Doppler 13 Pulsus tardus et parvus pattern 481, 483 PVEs, see Periventricular echodensities (PVEs) PVHI, see Periventricular hemorrhagic infarction (PVHI) PVL, see Periventricular leukomalacia (PVL) PVNS, see Pigmented villonodular synovitis (PVNS) Pyelonephritis transplant 498, 500 Pyloric stenosis 367, 370 Pyogenic abscess – in liver 259, 261–263 – in spleen 338

R Radial aplasia 159 Ranula 140, 142 Rapidly involuting congenital hemangioma (RICH) 197, 295, 295 Rectum 397, 403 Recurrent hypersplenism 327 Reflection 10, 11 Refraction 11, 11

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Index Renal agenesis 111 Renal artery 455, 456 Renal artery stenosis 481, 482–483 – in renal transplantation 494, 498 Renal artery thrombosis in renal transplantation 494 Renal cell carcinoma 477 Renal cystic hypodysplasia 468 Renal dysplasia 159 Renal hamartoma 478, 480 Renal hypodysplasia 457, 457, 458 Renal laceration 490, 490 Renal transplantation – abscesses in 494 – arteriovenous fistula in 495, 499 – graft dysfunction in 496 –– nephrologic complications causing 287, 491 –– surgical complications causing 494, 496–497 – hematoma in 494, 497 – lymphoceles in 494, 496–497 – post-transplant lymphoproliferative disorder in 500, 501 – postoperative assessment of 491, 494 – pseudoaneurysm in 495, 499 – pyelonephritis in 498, 500 – renal artery stenosis in 494, 498 – renal artery thrombosis in 494 – renal vein thrombosis in 494 – renovascular disease in 500 – urinary tract obstruction in 495– 496, 499 – urinoma in 494 – vascular complications in 494, 498– 499 Renal trauma 490, 490, 491–493 Renal tumors 474, 475–480 Renal vein thrombosis 482, 483–484 – in renal transplantation 494 Renovascular disease 481, 482–484 – in renal transplantation 500 Resolution 16, 17 Results communication of 6 Rete testis cystic transformation of 587, 588 Retractile testicle 590, 590, 591 Retroareolar cysts 205, 207 Retroperitoneal anatomy 214, 215 Retroperitoneal lymphadenopathy 219, 220 Retroperitoneal lymphoma 231, 233 Retroperitoneal neuroblastoma 219, 311 Retroperitoneal tumors 234, 236–240 Retropharyngeal region 116 Reverberation 17, 18 Reye syndrome 428 Rhabdoid tumor 477 – extrarenal adrenal gland and 531, 533 Rhabdomyosarcoma – biliary tract 316 – bladder 504, 506–507 – chest wall 192, 193 – in female genital tract 558, 563–564 – in male genital tract 578, 580 – in musculoskeletal ultrasound 613, 613 – mediastinum 170 – retroperitoneal 219 Rib(s) – abnormalities 186, 188

– cervical 146, 146 – forked 186, 188 – fused 186, 188 RICH, see Rapidly involuting congenital hemangioma (RICH) Right aortic arch with aberrant left subclavian artery 164, 165–167 Roundworm, see Ascaris lumbricoides

S Sacral dimple 104, 112–113, 113 Sacrococcygeal dimple 98 Sacrococcygeal teratoma 235, 237–240 Safety 20, 20 Salivary gland stones 141, 142 Salivary gland tumors 126, 141, 142 Salivary glands 116, 138 Sarcoidosis 170, 173 Scattering 11 Schizencephaly 84 SCID, see Severe combined immune deficiency syndrome (SCID) Sclerosing angiomatoid nodular transformation in spleen 341 Sclerosing encapsulating peritonitis 225, 228 Scrotal edema idiopathic 585, 586 Scrotal hemangioma 578 Scrotal trauma 585, 586–587 Scrotal tumors 576, 577–580 Scrotum, see Male genital tract Sedation 5, 360, 362, 618 Seldinger technique 625 Semilobar holoprosencephaly 84, 87 Seminoma 170 Septic arthritis 598, 599 Sertoli-Leydig cell tumor in female genital tract 552, 558 Severe combined immune deficiency syndrome (SCID) 157 Sexual development disorders in female genital tract 540, 549–551 Shadowing 17, 17 Shwachman-Diamond syndrome 439, 440 Sialoliths 141, 142 Sialorrhea 141, 143 Sickle cell disease gallstones in 266, 267 Situs inversus 332, 334 – liver and biliary system in 332, 334 – pancreas in 428, 430 Sjörgen disease 140, 141 Small bowel, see Bowel obstruction – Ascaris lumbricoides in 377, 379 – caliber of 367 – contents 367 – Crohn disease in 373, 373–375 – duplication cysts in 379, 381, 382– 385 – folds in 367 – Henoch-Schönlein purpura in 375, 377, 378 – in intestinal ultrasound 367, 370– 387 – intestinal polyps in 373, 376–377 – location of 367 – malrotation/volvulus of 370, 372, 372 – Meckel diverticulum in 377, 379– 380

– necrotizing enterocolitis in 377, 379, 380 – peristalsis in 367 Small-cell carcinoma ovarian 558 Snell’s law 10 Solid papillary tumor (SPT) 441, 442, 448 Spectogram Doppler 12, 13 Spermatic cord – cellular neurofibroma in 578 – hydrocele in 573, 573 – in male genital tract anatomy 570, 571 – in testicular torsion 580, 581 Spermatic cyst 573, 573 Spherocytosis 335, 339 Spinal dysraphism – defined 98 – occult 98 Spine and spinal ultrasound – acoustic window in 98 – caudal regression syndrome in 99, 109, 111 – closed lesions of 98, 107, 107, 108– 113 – diastematomyelia in 107, 110 – – – – – – –

dorsal dermal sinus in 107, 108 embryology of 98, 99 indications for 98 intradural lipoma in 107, 107 last rib in 99, 100 lipomyelocele in 106, 106 lipomyelomeningocele in 99, 106, 106 – lumbosacral junction in scans of 99 – motion mode for 100 – myelocele in 99, 103, 104 – myelocystocele in 105, 105 – myelomeningocele in 99, 103, 104 – non skin-covered back masses in 98, 103, 104 – normal anatomic variants in 102, 103–104 – normal sonographic anatomy in 100, 101–103 – occult lesions of 98, 107, 107, 108– 113 – panoramic view of 99, 100 – sacral dimple in 104, 112–113, 113 – sagittal images of 99 – skin-covered back masses in 98, 104, 105–106 – syringohydromyelia in 107, 109 – tight filum terminale in 111, 112 – transducers for 98 – transverse images of 99–100, 101 – ultrasound technique with 99 Spleen and spleen ultrasound – anatomical considerations with 324, 324 – angiosarcoma in 341 – biopsy 619 – calcification in 340, 348, 352–354 – candidiasis of 202 – displacement of by other pathologic processes 335 – echogenicity in 325, 327 – embryology of 324, 324 – epidermoid cyst in 338, 342 – fungal infection of 202 – hamartoma in 340, 341, 349 – hemangioendothelioma in 340, 341, 350

– hemangioma in 338, 340, 345–346 – hematopoietic activity of 335 – histology of 325 – in heterotaxy syndrome –– defined 332 –– with asplenia 335 –– with polysplenia 335, 336–337 – in Langerhans cell histiocytosis 340, 354 – in preterm infants 331 – in situs inversus 332, 334 – indications for 324 – leiomyoma in 340, 352 – lymphangioma in 341, 347–348 – lymphoma in 340, 341, 351 – pyogenic abscess in 338 – sclerosing angiomatoid nodular transformation in 341 – size of 331, 331, 332 – technique for 324–325, 325, 326 – trauma 348, 355–357 – traumatic cysts in 338, 343 – variants 327, 330–331 – vascularity of 327, 328–329 – wandering 332, 333 – with age 325 Splenic artery 324, 327, 328 Splenic contusion 348 Splenic cysts 335, 341–347 Splenic fusion abnormalities 332 Splenic hematoma 348, 356 Splenic lacerations 348, 356–357 Splenic notch 327, 331 Splenic vein 325, 329 Splenogonadal fusion 332 Splenomegaly generalized 335, 335, 339 Splenorenal fusion 332 Splenunculi 327, 330 Split cord malformation 107 SPT, see Solid papillary tumor (SPT) Staff child-friendly 2 Sternocleidomastoid in fibromatosis colli 127, 131 Stomach – duplication cyst in 364, 365 – food in 364, 364 – in chemotherapy 369 – in foveolar hyperplasia 364, 367– 368 – in gastric volvulus 364, 366 – in gastritis 364 – in intestinal ultrasound 364, 364, 365–370 – in peptic ulcer disease 364 – pyloric stenosis in 367, 370 Struma 138, 139 Subarachnoid hemorrhage 70 Subarachnoid space – benign enlargement of 92, 93–94 – in spinal ultrasound 100 – mean size of 93, 94 Subclavian arteries 117, 118–119, 155, 157 – aberrant left with right aortic arch 164, 165–167 – aberrant right with left aortic arch 164, 164 Subclavian veins 117, 118, 119, 119– 120 Subcutaneous granuloma annulare 610, 610

635

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Index Subdural hematoma in benign enlargement of subarachnoid space 93, 94 Subdural hemorrhage 70 Subglottic hemangioma 159, 159 Sublingual gland obstruction 140, 142 Sublingual glands 116, 117, 140 Submandibular gland 116, 116–117 – See also Salivary glands Submandibular gland stones 141, 142 Submandibular nodes 127 Submental nodes 127 Sucrose 360, 362 Sulcation disorders 84, 88–89 Superior caval vein 119 Superior mesenteric artery (SMA) in midgut volvulus 372, 372 Superior mesenteric vein (SMV) in midgut volvulus 372, 372 Superior vena cava 155, 157 Supraclavicular lymph nodes 135 Synovial cyst 609 Syringocele 503 Syringohydromyelia 107, 109 Syringomyelia 107 Syrup 360, 362

T T cell-related immunodeficiencies 157 Takayasu arteritis 215 Teratoid rhabdoid tumors atypical 84 Teratoma – adrenal 528 – cranial 84 – in female genital tract 552 – in neck 148 Term infants – benign enlargement of subarachnoid space in 92, 93–94 – brain tumors in 84, 91–92 – Chiari malformation in 78, 82–83 – corpus callosum dysgenesis in 84, 85–87 – cranial congenital abnormalities in 78, 80–83, 85–93 – cranial ultrasonography in 70, 71– 83, 85–94 – Dandy-Walker complex in 78, 80–81 – disorders of sulcation and migration in 84, 88–89 – holoprosencephaly in 84, 87 – hypoxic-ischemic encephalopathy in 70, 71, 74–75, 77–79 – intracranial hemorrhage in 70, 71– 74 – intraparenchymal hemorrhage in 70, 72–74 – intraventricular hemorrhage in 69, 70, 71 – liver size in 246 – migration disorders in 84, 88–89 – phakomatoses in 84, 90 – posterior fossa abnormalities in 78 – sulcation disorders in 84, 88–89 – tuberous sclerosis in 84, 90 Testicular microlithiasis 576, 578 Testicular torsion 580, 581–584 – extravaginal 582, 582, 583 – intravaginal 580, 581–582 Testicular trauma 585, 586–587 Testicular tumors 576, 577–578 – secondary 576, 578–580 Testicular volume 570, 570

636

Testis – bilobed 589, 590 – in male genital tract anatomy 570, 571 – retractile 590, 590, 591 – undescended 590, 590, 591 Tethered cord early detection of 98 Thalamo-occipital distance (TOD) 38, 38–39, 42 Thecoma in female genital tract 552 Thelarche premature 202, 205 Thoracic wall in chest anatomy 183, 183, 184 Thorax, see Chest and chest ultrasound Thrombocytopenia neonatal isoimmune 70 Thymic aplasia 157, 158 Thymic hypoplasia 158 Thymopharyngeal duct cysts 143 Thymus 117, 143 – aberrant 157, 158 – as acoustic window 143 – ectopic –– in mediastinum 157 –– in neck 143, 145 – in mediastinum anatomy 154 – in neck anatomy 118 – involution of 154 – orthotopic 145 – size of 154 – with aging 143, 143, 154 Thyroglossal duct 137 Thyroglossal duct cyst 120, 121, 137 Thyroid cyst 138, 138 Thyroid gland 117, 117–118, 137, 137, 138–140 – ectopic 137, 137 Thyroid nodules 138, 138, 139–140 Thyroiditis 137, 137, 138 Tight filum terminale 99, 111, 112 TOD, see Thalamo-occipital distance (TOD) Total anomalous pulmonary venous return 167, 169, 171 Trachea – in mediastinal anatomy 155, 157 – in mediastinal pathology 159, 159, 160 – subglottic hemangioma in 159, 159 Tracheobronchial calcification 159, 160 Tracheoesophageal fistula 159, 160– 161, 363 Transducers 15 – for chest ultrasound 182 – for cranial ultrasound 70 – for female genital tract 536 – for hip 595 – for joint soft tissue masses 604 – for liver and biliary tract 246 – for neck 116 – for spine 98 – linear array 15, 15 – phased array 16, 16 – types of 15 Transient dilatation of central canal 103 Transient synovitis of hip 598, 598, 599 Transplantation renal – abscesses in 494 – arteriovenous fistula in 495, 499 – biopsy in 624 – graft dysfunction in 496 –– nephrologic complications causing 287, 491 –– surgical complications causing 494, 496–497

– hematoma in 494, 497 – lymphoceles in 494, 496–497 – post-transplant lymphoproliferative disorder in 500, 501 – postoperative assessment of 491, 494 – pseudoaneurysm in 495, 499 – pyelonephritis in 498, 500 – renal artery stenosis in 494, 498 – renal artery thrombosis in 494 – renal vein thrombosis in 494 – renovascular disease in 500 – urinary tract obstruction in 495– 496, 499 – urinoma in 494 – vascular complications in 494, 498–499 Transrectal drainage 625, 626 Transverse cerebellar diameter (TCD) 39, 40, 70 Trauma – abusive head 93 – chest 187, 188–190 – diaphragm 211 – focused assessment with sonography for 225, 226, 287 – joint 604, 606 – liver 287, 287, 288–291 – pancreatitis in 428 – renal 490, 490, 491–493 – scrotal 585, 586–587 – spleen 348, 355–357 – testicular 585, 586–587 Triangular cord sign 249, 252 Triple A syndrome 162 Trisomy 18 474 Tuber cinereum hamartoma 568, 568 Tuberculosis 170, 173, 335 Tuberous sclerosis 84, 90 Tubular ectasia 587, 588 Tubular nephropathies 487, 488 Tubulopathies 467 Tumors – biopsy of 620, 622 – bladder 504, 506–508 – brain congenital 84, 91–92 – liver 292, 292, 293–301, 303–316 – neck 127, 131–136 – of chest –– in bone 199, 199, 200 –– in breast 208 – of chest wall 192, 192, 193–194 – of pancreas 440, 441–448 – ovarian 551, 551, 552–564 – peritoneal 229, 230–236 – renal 474, 475–480 – retroperitoneal 234, 236–240 – scrotal 576, 577–580 – seeding of in biopsy 618, 620 – testicular 576, 577–578 –– secondary 576, 578–580 Tunica albuginea 570 Turner syndrome 560 Twinkle artifact 464, 464–465, 470 Typhitis 394, 396 Tyrosinemia type I 277

U Ulcerative colitis 394, 395 Ultrasonic waves – as longitudinal compression waves 10 – attenuation of 11, 12 – frequencies of 10

– propagation of 10 – reflection of 10, 11 – refraction of 11, 11 – scattering of 11 – wavelengths of 10 Ultrasound – biological effects of 20 – history of 10 – principles of 10 Ultrasound guidance – advantages of 618 – in biopsy –– anesthesia for 618 –– bone 619 –– coaxial systems for 619, 619–621 –– complications of 618 –– core needle 619 –– equipment 618 –– fine needle aspiration cytology for 619 –– informed consent for 618 –– kidney 619, 623, 623 –– liver 619, 624 –– lung 619 –– lymph node 619 –– needles for 619, 619 –– renal tumor 620 –– seeding of malignant cells in 618, 620 –– spleen 619 –– techniques 618 –– tumor 620, 622 – in drainage 625, 626–627 Undescended testicle 590, 590, 591 Urachal anomalies 503, 504 Urachal cyst 504 Urachal diverticulum 504 Urachal sinus 504 Urachus patent 503 Ureterocele 461, 462–463, 500, 502 Ureteropelvic junction stenosis 457, 458–459 Ureterovesical junction stenosis 457, 459–460 Ureterovesical reflux 457, 457, 460 – See also Contrast-enhanced cystosonography (CSG) Ureters 455, 456 Urethral anomalies 502, 503 Urethral polyps congenital 504, 508 Urethral valve congenital posterior 502, 503 Urinary bladder, see Bladder Urinary tract infection (UTI) 457, 480, 480, 481–482 Urinary tract obstruction – in renal transplantation 495–496, 499 – in urolithiasis 464, 465 Urinoma in renal transplantation 494 Urolithiasis 464, 464, 465–468 Uromodulin-associated nephropathies 468 Uterus size of 538 UTI, see Urinary tract infection (UTI) Utricle 503

V VACTERL (vertebral abnormalities anal atresia cardiac abnormalities tracheoesophageal fistula and/or esophageal atresia renal agenesis and dysplasia limb defects) 111, 159

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Index Varicocele 588, 588, 589 Vas deferens 570, 571 Vascular anomalies congenital in mediastinum 163, 164, 168–172 Vascular lesions in chest 192, 194, 196–199 Vascular malformations – in musculoskeletal ultrasound 607 – in neck 124, 125–130 Vascular nephropathies 489, 489 Vascular rings 163 Vascular sling – defined 163 – pulmonary artery 166, 169 Venous malformation 194, 197, 197, 607, 607 Ventricular index (VI) 36, 38, 39 Ventricular measurements 36 Ventriculus terminalis 103 Vermis height 40 Vertebral column anomalies categories of 98 – See also Spine Vesicoureteral reflux (VUR) 457, 457, 460 – See also Contrast-enhanced cystosonography (CSG)

VI, see Ventricular index (VI) Viral meningoencephalitis 33 Volvulus – gastric 364, 366 – midgut 370, 372, 372 Von Hippel-Lindau syndrome 520 VUR, see Vesicoureteral reflux (VUR)

W Waiting area 2, 3 Walker-Warburg syndrome 84 Wandering spleen 332, 333 Warfarin embryopathy 159 Warming of gel 5, 5, 360 Watershed pattern 74 Waves, see Ultrasonic waves Wegener granulomatosis 170 Whirlpool sign 372, 372 White matter in neonatal cranial ultrasonography 26, 26, 27–29 White matter injury in preterm infants 60, 60, 61–66 Williams syndrome 500 Wilms tumor 474, 476–478

– anomalies associated with 474 – in liver 308, 310 – inferior vena cava occlusion with 216, 218–219 – nephroblastomatosis and 474, 475 – paratesticular involvement of 577, 579 – retroperitoneal lymphadenopathy and 219 – staging of 476 – tumor seeding with in biopsy 620 Wilms tumor aniridia genitourinary abnormalities mental retardation (WAGR) 474 Wolman disease 531, 534 Wrist assessment 602, 602

X Xiphoid prominent 183, 184

Y Yolk sac tumor – in female genital tract 552 – in male genital tract 576, 578

Z Zellweger syndrome 88 Zuckerkandl fascia 214

“ “Blue dot” sign 583, 583 “Flag-shaped” echogenicity 27 “Gliding sign” 184, 184 “Gut signature” 360, 360–361 “Horseshoe” adrenal gland 513, 514 “Lying down” adrenal gland 513, 513 “Muscular rim sign” 238, 241 “Rat tail appearance” 458 “Seashore sign” 184, 185 “Stag horn” appearance 464, 465 “Thyroid inferno” 137 “Tramline”-like cerebral cortex 75 “Y-configuration” 238, 241–242

637

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