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Yttrium: Compounds, Production and Applications : Compounds, Production and Applications [1 ed.]
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Copyright © 2010. Nova Science Publishers, Incorporated. All rights reserved. Yttrium: Compounds, Production and Applications : Compounds, Production and Applications, edited by Bradley D. Volkerts, Nova Science Publishers,

Copyright © 2010. Nova Science Publishers, Incorporated. All rights reserved. Yttrium: Compounds, Production and Applications : Compounds, Production and Applications, edited by Bradley D. Volkerts, Nova Science Publishers,

MATERIALS SCIENCE AND TECHNOLOGIES

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YTTRIUM: COMPOUNDS, PRODUCTION AND APPLICATIONS

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Yttrium: Compounds, Production and Applications : Compounds, Production and Applications, edited by Bradley D. Volkerts, Nova Science

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Yttrium: Compounds, Production and Applications : Compounds, Production and Applications, edited by Bradley D. Volkerts, Nova Science

MATERIALS SCIENCE AND TECHNOLOGIES

YTTRIUM: COMPOUNDS, PRODUCTION AND APPLICATIONS

BRADLEY D. VOLKERTS

Copyright © 2010. Nova Science Publishers, Incorporated. All rights reserved.

EDITOR

Nova Science Publishers, Inc. New York

Yttrium: Compounds, Production and Applications : Compounds, Production and Applications, edited by Bradley D. Volkerts, Nova Science

Copyright © 2011 by Nova Science Publishers, Inc. All rights reserved. No part of this book may be reproduced, stored in a retrieval system or transmitted in any form or by any means: electronic, electrostatic, magnetic, tape, mechanical photocopying, recording or otherwise without the written permission of the Publisher. For permission to use material from this book please contact us: Telephone 631-231-7269; Fax 631-231-8175 Web Site: http://www.novapublishers.com NOTICE TO THE READER The Publisher has taken reasonable care in the preparation of this book, but makes no expressed or implied warranty of any kind and assumes no responsibility for any errors or omissions. No liability is assumed for incidental or consequential damages in connection with or arising out of information contained in this book. The Publisher shall not be liable for any special, consequential, or exemplary damages resulting, in whole or in part, from the readers’ use of, or reliance upon, this material. Any parts of this book based on government reports are so indicated and copyright is claimed for those parts to the extent applicable to compilations of such works.

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Independent verification should be sought for any data, advice or recommendations contained in this book. In addition, no responsibility is assumed by the publisher for any injury and/or damage to persons or property arising from any methods, products, instructions, ideas or otherwise contained in this publication. This publication is designed to provide accurate and authoritative information with regard to the subject matter covered herein. It is sold with the clear understanding that the Publisher is not engaged in rendering legal or any other professional services. If legal or any other expert assistance is required, the services of a competent person should be sought. FROM A DECLARATION OF PARTICIPANTS JOINTLY ADOPTED BY A COMMITTEE OF THE AMERICAN BAR ASSOCIATION AND A COMMITTEE OF PUBLISHERS. Additional color graphics may be available in the e-book version of this book.

LIBRARY OF CONGRESS CATALOGING-IN-PUBLICATION DATA Yttrium : compounds, production, and applications / [edited by] Bradley D. Volkerts. p. cm. Includes index. ISBN 978-1-61761-145-2 (e-book) 1. Yttrium. I. Volkerts, Bradley D. QD181.Y1Y78 2009 546'.403--dc22 2010026199

Published by Nova Science Publishers, Inc. † New York

Yttrium: Compounds, Production and Applications : Compounds, Production and Applications, edited by Bradley D. Volkerts, Nova Science

CONTENTS Preface Chapter 1

Nd:YAG Laser Treatment for Different Vascular Lesions Ekrem Civas, Berna Aksoy and Hasan Mete Aksoy

Chapter 2

Yttrium in Pigments and Phosphors Vicente Rives

Chapter 3

Microwave Properties and Applications of Yttrium Iron Garnet (YIG) Films: Current State of Art and Perspectives I.V. Zavislyak and M.A. Popov

Chapter 4

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vii 

Bismuth-Substituted Yttrium Iron Garnet Nanoparticles: Preparation and Applications R.Y. Hong,, Y.M. Wang, L.S. Wang, Y.J. Wu and H.Z. Li Yttrium Application for Spallation Neutron Energy Spectrum Reconstruction S. Kilim, M. Bielewicz, B. Słowiński, E. Strugalska-Gola, M. Szuta and A. Wojciechowski

Chapter 6

Yttrium Applications for Heat-Resisting Alloys Tadaaki Amano

Chapter 7

Influence of Annealing on Yttrium Dopant Distribution in CeriaBased Nanoparticles Shao-Ju Shih, Guoqiang Li, Chun-Kuo Huang and Konstantin B. Borisenko

Chapter 8

Yttrium Phosphanides – A Surprisingly Scarce Substance Class Matthias Westerhausen, Rainer Kränzle, Sven Krieck and Nico Ueberschaar

Chapter 9

Physics and Engineering Aspects of Electronic Conduction in Yttrium Dihydride M. Sakai and O. Nakamura

Index

Yttrium: Compounds, Production and Applications : Compounds, Production and Applications, edited by Bradley D. Volkerts, Nova Science

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127

155

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PREFACE Yttrium is a silvery-metallic transition metal chemically similar to the lanthanoids and has historically been classified as a rare earth element. The most important use of yttrium is in making phosphors, such as the red ones used in television cathode ray tube displays and in LEDs. Other uses include the production of electrodes, electrolytes, electronic filters, lasers and superconductors; various medical applications; and as traces in various materials to enhance their properties. Yttrium has no known biological role, but exposure to yttrium compounds can cause lung disease in humans. This book presents topical research in the study of Yttrium, including Yttrium in pigments and phosphors; Microwave properties and applications of Yttrium iron garnet films; and the physics and engineering aspects of electronic conduction in Yttrium dihydride. Nd:YAG laser has recently been used widely for vascular applications. It has become the chosen treatment for vascular lesions with a different character. In Chapter 1, the aim is to present basic vascular and tissue interactions in the Nd:YAG laser treatment of vascular lesions and to prepare a guide for clinical use. Lesion diameter, color, depth and pressure make the basis for the choice of laser parameters. When the literature is reviewed, it is evident that lasers have been used increasingly as an alternative to surgical methods in the treatment of congenital and acquired vascular lesions. Clinical use of Nd:YAG laser presents a wide range of options to the practicing physician in the treatment of different vascular lesions from easy to difficult. Despite its low abundance in the Earth (ca. 31 ppm of the Earth’s crust, making it the 28th most abundant element), yttrium-containing oxides have found many applications in recent years. It is a component of many of the so-called high temperature superconductors with a structure derived from the perovskite one. Their use in pigments as a colour-producer or as a colour-enhancer in different crystalline structures has deserved also much attention. It should be recalled that different colours can be obtained by simply switching the structure of the solid. Yttrium is also used in many optical devices involved in luminiscence processes, originated by itself of upon interaction with other elements (rare earth elements, mainly). In addition, due to the relatively low toxicity of yttrium and the rare earth elements, attempts are being made to substitute first row transition elements in conventional ceramic pigments by these ions. In Chapter 2 the authors review the structures, properties and applications of different families of compounds where yttrium has been incorporated pursuing these applications. Different synthetic routes to these compounds are also discussed.

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In the first part of Chapter 3, the overview of magnetic and crystallographic properties of truly remarkable material in the family of microwave ferrites – YIG (yttrium-iron garnet) is given. A detailed insight of complex 20 magnetic sublattice single crystal structure of that material is presented and advantages of yttrium-containing garnet over materials with other rare-earth ions are emphasized. Next, a cheaper and more practically feasible form of YIG, namely, magnetic films are discussed. Two most common types – liquid-phase epitaxial (LPE) and laser-pulse deposited (LPD) films are reviewed, including structural properties, relaxation characteristics and advanced theoretical anisotropy models. Further, various experimental microwave methods for YIG magnetic parameters testing, including original ones are considered. Special attention is devoted to measurements of dipole-exchange spin waves relaxation characteristics using radiospectroscopic and parametric pumping techniques. Finally, main properties of dipole-exchange spin-wave excitations in YIG films are discussed in two simplified cases: dipole (non-exchange magnetostatic) and pure exchange approximation. Second part is devoted to recent developments in YIG films-based metamaterials, including 1D and 2D magnon crystals; composite YIG-piezoelectric and YIG-ferroelectric structures and their possible applications; spin wave based negative refractive index metamaterials. Third part presents comprehensive review of current and perspective microwave applications of YIG films. It includes state-of-the-art for traditional YIG devices (tunable resonators, filters, circulators); original development work regarding magnetostatic surface wave (MSSW) filters and multichannel filters; and various nonlinear devices like selective limiters, signal-to-noise enhancers and devices in which signal processing in a ferrite films is carried out with the help of parametric pumping. Last but not least, a chaotic microwave signals generators are also examined. Yttrium iron garnet (YIG) has received much attention due to it applications in magnetooptical (MO) devices such as circulators, isolators and phase shifters. Bismuth-substituted yttrium iron garnet (Bi-YIG), in particular, has been proved to possess stronger Faraday rotation effect that YIG. This property makes the Bi-YIG nanoparticles much more promising for the applications in MO devices. Chapter 4 briefly introduces YIG and Bi-YIG, and then mainly discusses the synthesis of Bi-YIG nanoparticles. Several characterization methods will be introduced, such as thermogravimetric analysis, differential thermo-analysis, transmission electron microscopy, scanning electron microscopy, X-ray diffraction, ultraviolet-visible absorption spectra, Faraday rotation measurement, etc. The slices of Bi-YIG/PMMA magneto-optical materials were prepared by in situ bulk polymerization. The applications of the as-prepared materials will be mentioned at the end of the chapter. In Chapter 5, a method of spallation neutron energy spectrum determination is shown. The method is based on Yttrium-89 activation measurements and threshold reaction yields comparison. Yttrium is a very good activation detector as its only one isotope, Y89 naturally occurs. Irradiated with high energy neutrons it undergoes three main reactions Y89(n,xn), where x = 2, 3, and 4. Combining the three isotope production equations in one, more general with combined the three reaction cross section in one as well one gets one generalized integral equation. It is Volterra’s integral equation of the first kind. Solving it one gets an analytical expression for spallation neutron energy spectrum. The cross section analytical formula is

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Preface

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based on Fermi gas model of atomic nucleus and Niels Bohr idea of nuclear reaction through compound nucleus. The method has been applied for spallation neutron spectra determination on “Energy plus Transmutation” U/Pb assembly irradiated with 1.6 and 2.52 GeV deuterons. The assembly is a lead cylindrical target (8.4 cm diameter, 45.6 cm length) with natural uranium blanket (206.4 kg). The lead target was irradiated with JINR Dubna NUCLOTRON. “Energy plus Transmutation” is also the name of an international project, 12 countries take part in. The method is still in a phase of development. It could be applicable in nuclear waste (actinides, fission products) transmutation with high energy neutrons. The neutron energy spectrum is a very important parameter there. The improvement in high temperature oxidation resistance of heat-resisting alloys as a result of small additions of yttrium has been well known for many years. Two effects may be attributed largely to the improvement: first, the mass gain is reduced; secondly, the adherence of surface oxide is enhanced. Although varying hypotheses and explanations have been proposed, the mechanism of the beneficial addition of yttrium remains unexplained. In Chapter 6, yttrium-added Cr2O3-forming Ni-20Cr, Ni-20Cr-1Si and Y2O3-coated Ni-20Cr-1Si alloys were studied in oxygen for 18ks at 1473 and 1573K, and then yttrium-added Al2O3forming Fe-20Cr-4Al and Fe-20Cr-4Al-Pt alloys were studied in oxidizing atmospheres (oxygen, oxygen-water vapor) for 18ks at 1473, 1573 and 1673K, by mass gain measurements, amount of spalled oxide, observation of surface appearance, XRD, SEM, EPMA and TEM. Yttrium-added and Y2O3-coated Cr2O3-forming Ni-20Cr-1Si alloys decreased in mass gain, and yttrium-added and Y2O3-coated Ni-20Cr-1Si alloys showed excellent oxidation resistance. Yttrium-added Al2O3-forming Fe-20Cr-4Al and Fe-20Cr-4AlPt alloys decreased in mass gain, and mass gain of yttrium-added Fe-20Cr-4Al-Pt alloy showed the smallest value for 18ks at 1473K in oxygen. Yttrium-added Fe-20Cr-4Al alloys showed good oxide adherence after oxidation at 1673K in oxygen. However, oxide scales on these alloys often spalled after oxidation at 1673K in oxygen-water vapor. Yttrium is one of the most widely used dopants (e.g. in yttrium-doped ceria (YDC) and yttria-stabilized zirconia) for improving performance of solid electrolytes utilized in solidoxide fuel cells (SOFC). It is well-established that oxygen ion conductivity is a function of yttrium concentration in the electrolytes and detailed knowledge about factors influencing such concentration distribution is important. In Chapter 7, the authors examine the change in distribution of yttrium concentration after annealing in YDC particles. The geometry and morphology of YDC particles, synthesized by spray pyrolysis, were characterized by transmission electron microscopy (TEM), and the distribution of yttrium was investigated by X-ray energy-dispersive spectroscopy (XEDS) considering electron interaction volume and geometry of the particle in the XEDS profile analysis. In addition, relative concentrations of Ce (III) ions, which are thought to be proportional to the concentrations of oxygen vacancies in the YDC particles, were examined using X-ray photoelectron spectroscopy (XPS) to correlate with yttrium concentration distributions. It was found that in the as-prepared hollow spherical particles the concentration of the yttrium increases linearly from the inner surface towards the outer surface. After annealing the distribution of yttrium becomes non-linear with the dopant migrating to the inner and outer surfaces of the particle. The concentration of Ce(III) ions decreases upon annealing, following the change in the dopant concentration gradient, mostly due to increase in the size of the crystallites in the particles.

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Yttrium represents an intermediate between typical s-block metals (alkali and alkaline earth metals) and transition metals (d block elements). On the one hand it exhibits no significant redox activity (s-block behaviour) with a common oxidation state of +3 but Y3+ represents a hard and strong Lewis acid which results in an extreme air and moisture sensitivity and its chemistry can also involve degradation of Lewis bases. On the other hand, the d-orbital contribution (transition metal behaviour) shows an important influence on molecular structures even though ionic contributions should dominate the bonding situation. An intermediate behaviour can also be expected for the synthesis of organometallic yttrium compounds. Straight-forward strategies such as metallation reactions (e.g., of H-acidic hydrocarbons with YR3), salt metathesis reactions [such as, e. g., of AR or AeR2 (A = alkali metal, Ae = alkaline earth metal) with YCl3], or direct synthesis (such as, e.g., of Y metal with R-I) pose severe challenges due to various side-reactions other than ether degradation and a low reactivity of the metal itself. Screening the literature for yttrium phosphanides leads to the surprising fact that a very limited number of publications deals with this topic. Reasons for this finding will be discussed here. However, it is not intended to cover the literature excessively. Yttrium represents an intermediate between typical s-block metals (alkali and alkaline earth metals) and transition metals (d block elements). On the one hand it exhibits no significant redox activity (s-block behaviour) with a common oxidation state of +3 but Y3+ represents a hard and strong Lewis acid which results in an extreme air and moisture sensitivity and its chemistry can also involve degradation of Lewis bases. On the other hand, the d-orbital contribution (transition metal behaviour) shows an important influence on molecular structures even though ionic contributions should dominate the bonding situation. An intermediate behaviour can also be expected for the synthesis of organometallic yttrium compounds. Straight-forward strategies such as metallation reactions (e.g., of H-acidic hydrocarbons with YR3), salt metathesis reactions [such as, e. g., of AR or AeR2 (A = alkali metal, Ae = alkaline earth metal) with YCl3], or direct synthesis (such as, e.g., of Y metal with R-I) pose severe challenges due to various side-reactions other than ether degradation and a low reactivity of the metal itself. Screening the literature for yttrium phosphanides leads to the surprising fact that a very limited number of publications deals with this topic. Reasons for this finding will be discussed in Chapter 8. However, it is not intended to cover the literature excessively. One of the simplest compounds of yttrium (Y) is probably YH2, since it contains hydrogen (H), the simplest atom, and its crystal structure is the CaF2 type in which Y occupies fcc lattice sites and H occupies all the tetrahedral sites, i.e., interstitial sites surrounded by four Y atoms. Despite these chemical and structural simplicities, the Hall coefficient (one of the most important quantities in transport characteristics) was not definitively reported until 2007, approximately 50 years after the first report of the Hall coefficient of Y, the host metal of yttrium hydride. Chapter 9, the authors examine the electrical and optical properties of YH2. The authors’ study will reveal that YH2 is an exotic metal with several peculiar characteristics that make the Hall coefficient measurement very difficult. Their measurements imply that both electrons and holes contribute to the electronic conduction of this material, and that they both have approximately the same carrier density and mobility, so that the Hall coefficient of YH2 becomes extremely small compared to those of conventional metals. Furthermore, an approximately linear correlation exists between the Hall coefficient and the specific resistivity, as these quantities vary with the H-defect density in YH2. Several future

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applications of YH2, including switchable mirrors, hydrogen gas sensors, cold cathode lamps are discussed. A spintronics application taking advantage of the peculiar characteristics of YH2 is proposed.

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In: Yttrium: Compounds, Production and Applications ISBN: 978-1-61728-928-6 Editor: B.D. Volkerts © 2011 Nova Science Publishers, Inc.

Chapter 1

ND:YAG LASER TREATMENT FOR DIFFERENT VASCULAR LESIONS Ekrem Civas1, Berna Aksoy*,2 and Hasan Mete Aksoy 1

Civas Clinic, Ugur Mumcu cad. No: 61/6 Ankara, Turkey Private Konak Hospital, Dermatology Clinic, Yenisehir mah. Donmez sok, No: 53 Izmit, Kocaeli, Turkey 3 Private Konak Hospital, Plastic and Reconstructive Surgery Clinic, Yenisehir mah. Donmez sok, No: 53 Izmit, Kocaeli, Turkey 2

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ABSTRACT Nd:YAG laser has recently been used widely for vascular applications. It has become the chosen treatment for vascular lesions with a different character. In this chapter, the aim is to present basic vascular and tissue interactions in the Nd:YAG laser treatment of vascular lesions and to prepare a guide for clinical use. Lesion diameter, color, depth and pressure make the basis for the choice of laser parameters. When the literature is reviewed, it is evident that lasers have been used increasingly as an alternative to surgical methods in the treatment of congenital and acquired vascular lesions. Clinical use of Nd:YAG laser presents a wide range of options to the practicing physician in the treatment of different vascular lesions from easy to difficult.

1. INTRODUCTION Vascular lesions are a common problem that every physician faces, and they represent a significant treatment challenge at times. Vascular lesions can objectively be a source of bleeding, pain or itch [1]. Furthermore, they are a source of embarrassment, shame, decreased self-esteem, depression, social isolation, difficulty in making personal relationships or comments from other people [1]. It has been shown that even minor and seemingly clinically *

E-mail address: [email protected], [email protected]. Tel: +902623187070/1143 Fax: +902623115544, Corresponding author: Berna Aksoy, Ozel Konak Hastanesi, Yenisehir mah. Donmez sok. No: 53 Izmit, Kocaeli, TURKEY.

Yttrium: Compounds, Production and Applications : Compounds, Production and Applications, edited by Bradley D. Volkerts, Nova Science

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Ekrem Civas, Berna Aksoy and Hasan Mete Aksoy

insignificant vascular lesions (i.e. vascular spider nevus or cherry angioma) causes significant psychological distress that could be effectively decreased following laser treatment [1]. Neodymium doped:yttrium-aluminum-garnet (Nd:YAG) laser is a widely used laser system in dermatology. Neodymium (Nd3+) ions are implanted into a host crystal of YAG and are the source of laser radiation in Nd:YAG systems. Nd:YAG lasers may be operated in either pulsed or continuous wave mode. Nd:YAG laser has recently been used widely for the vascular applications and it has become the lone treatment for vascular lesions with a different character. Selective photothermolysis and thermal relaxation time lay the foundation for laser and tissue interactions. Lesion diameter, color, depth and pressure make the basis for the choice of laser parameters. Lasers have been used increasingly as an alternative to surgical methods in the treatment of congenital and acquired vascular lesions. Clinical use of Nd:YAG laser includes considerable practical variations and presents a wide range of options to the practicing physician. Nd:YAG laser has became widely used in the treatment of different vascular lesions successfully. In this chapter, the aim is to present basic vascular and tissue interactions in the Nd:YAG laser treatment of vascular lesions and to prepare a guide to the clinical use. Additionally, a review of the published work about Nd:YAG vascular applications will be presented in this chapter so that readers can receive a full guide by sticking to a single reference.

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2. HISTORY OF ND:YAG LASER FOR THE TREATMENT OF VASCULAR LESIONS Nd:YAG laser was first developed in 1961 by Johnson [2] and first used in dermatology by Goldman in 1973 [3]. Goldman used and reported his experiences with Nd:YAG laser in the treatment of tattoo, port-wine stain and cutaneous malignancies [3]. Leon Goldman was a chief pioneer in cutaneous laser surgery history and he deserves special mention [4]. He made various laser applications first to his own skin and observed the results [4]. Afterwards, he expanded this practice to patient treatments and later encouraged other clinicians to become active in this field [4]. Earlier Nd:YAG laser systems were very large, relatively immobile, expensive and would generate powers as high as 100 W [4]. They were not as popular as argon lasers in the vascular lesion treatment in the 70s and 80s [4]. The first studies of Nd:YAG laser treatment for different vascular lesions was reported in 1986 with promising results [5,6]. After the proposal of selective photothermolysis theory in 1983 [7] and investing the depth of coagulation and importance of cooling the skin surface during irradiation with Nd:YAG laser in 1986 [5], Nd:YAG laser systems became more and more popular in the treatment of cutaneous vascular lesions. At the beginning, use of Nd:YAG laser systems was limited to deep laser coagulation of tissue, large vascular malformations and hemangiomas. Rosenfeld et al. [8] studied earlier Nd:YAG laser systems in the treatment of various cutaneous vascular lesions and found them to be highly effective in 1988. After this time, various studies were performed to examine the effectiveness of Nd:YAG laser systems in various vascular lesions. After the beginning of the 21st century, newer Nd:YAG laser systems were found to be more and more efficacious in the treatment of small caliber vessels with fewer complications. The authors have shown recently that the Nd:YAG laser system is effective in various vascular lesions as a sole treatment choice [9].

Yttrium: Compounds, Production and Applications : Compounds, Production and Applications, edited by Bradley D. Volkerts, Nova Science

Nd:YAG Laser L Treatmeent for Different Vascular Lesions

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3. PRINCIPLES R OF VASCU ULAR LASE ER The basic action a principlle of intense pulse p light (IPL) and lasers is based on thhe selective phhotothermolyssis principle and a was first described inn 1983 by Annderson and Parrish P [7]. Light behaves in four ways when it is faaced with a baarrier: reflection, transmissiion, scatter annd absorption (Figure 3.1). Each exposurre results in vaarying degreess of all four innteractions. Laser - tissue in nteractions aree based on lighht source (wavvelength, spott size, pulse duuration and fluence) and tisssue characteriistics. The ideal laaser – tissue innteraction resuults in: sufficieent light to reaach the target, light to o be absorbed by the targeteed chromophorre, absorb bed light to be converted intoo heat, temperrature rise in thhe target to bee sufficient to provide the deesired effect, minimal heating off the surroundding tissue to prevent the development d of adverse effectss (Figure 3.2). There are 3 chromophorres that could be targeted inn the tissue; melanin m (hair,, epidermal piigment and pigmented p lesiions), hemogllobin (vasculaar structures and a malformaations) and w water (epiderm mis and dermiss). The primaary aim of thee selective phootothermolysiis is just to prroduce selectiive damage only to the tarrget tissue by using minim mal light energgy [7]. The ulltimate goal of o the vasculaar laser treatm ment is the heeating of the vessel wall thhrough the abbsorption of laser l energy by b hemoglobin [10]. In coonclusion, sellective vascullar damage coould be produ uced by vessell wall necrosis and minimaal perivascularr collagen dam mage along w coagulatio with on. It is just possible p to achhieve this goaal by choosingg the correct wavelength w annd light param meters, approprriate cooling and a appropriatte operational technique in appropriate a paatient and in appropriate a lession.

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1. 2. 3. 4. 5.

Fiigure 3.1. Theree are four types of laser - tissuee interactions.

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Ekrem Civas, Berna Aksoy A and Haasan Mete Akssoy

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Fiigure 3.2. The ideal laser-tissuee interaction.

A laser pu ulse with a puulse duration that t is nearly equal to or shorter s than the t thermal reelaxation timee (TRT) of thhe target tissuue and with an a adequate fluence f causees selective phhotocoagulativ ve damage inn the target tisssue [7,10]. The T absorptionn by the targeet tissue is reelated mostly to the selecteed wavelengthh [7]. As the absorption a of light increasees in target tissue, the transsmission rate decreases andd this results in i the maximuum damage inn the target mage in the tissue along wiith minimum damage in thhe surroundingg tissues [7]. Thermal dam taarget tissue iss additionally related to the pulse durattion and energgy level alonng with the prrevious correcct choice of thee wavelength [7]. The major factor acting in i selectivity is i the TRT of the target andd surrounding tissues [7]. TRT is the tim me duration passed for a targget (irradiatedd by laser eneergy and with a resulting w increaasing the tempperature of teemperature risse) to decreasee its temperatture by 50% without suurrounding tisssues [7,10]. Thermal T relaxation is closelly related to the t mass [7]. Substances w a bigger mass with m heat slow wly and keepss their thermaal energy for a prolonged time [7]. In coontrary, materrials with a smaller s mass heat and release the therm mal energy much m more quuickly [7]. For this reason TRT T of vascullar lesions deppends largely on the size off the vessel [111,12]. Altern native techniqques to enhannce selectivityy include epiddermal coolinng, carefull deelivery of add ditional passes to allow the skin s to cool beetween pulses or the use of diascopy d to bllanch superficcial capillaries to allow deepper penetrationn of laser enerrgy [10]. Oxyhemog globin that is thhe primary chhromophore foor vascular laseer applications is present inn red blood ceells in the vesssels. It has thhe maximum peak of absorrptions: 418, 542 (alpha peeak) and 577 nm n (beta peakk) (Figure 3.3) [7,11,13]. Thhese peaks are especially effficient laser w wavelengths fo or the treatmennt of small suuperficial vesseels located onn the face and neck [14]. The darker vesssels contain increased i conccentrations off deoxygenatedd hemoglobinn compared w red telang with giectasias that contain moree oxygenated hemoglobin [14]. [ Leg telaangiectasias annd venulectassias are usuallly located deeper and conntain more deeoxygenated hemoglobin h [114]. This cond dition moves the absorptioon curve towaards longer waavelengths, frrom 800 to 12200 nm [14]]. Oxyhemoglobin and deeoxygenated hemoglobin have a broadd band of abbsorption from m 800 to 11000 nm (Figure 3.3) [14-17]. It has been shhown that the longer the

Yttrium: Compounds, Production and Applications : Compounds, Production and Applications, edited by Bradley D. Volkerts, Nova Science

Nd:YAG Laser L Treatmeent for Different Vascular Lesions

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wavelength of the w t laser, the deeper d its peneetration into thhe skin [7,15]. Dermal transsmission of 10064 nm wavelength due to the less scatteer allows the Nd:YAG laseer beam to pennetrate into thhe depth of deermal blood vessels v accomppanied with weaker w melaniin absorption [15,17,18]. Foor this reason n it is prudent that Nd:YAG G laser with a longer waveleength is approoppriate for thhe treatment of o deeper locatted vascular leesions with a higher peak of o absorption [19]. Also, thhe 1064 nm Nd:YAG laser have h been com mbined with lower wavelenngth lasers or broad b band IP PLs to increasee the effectiveeness and patieent satisfaction in the treatm ment of smalleer sized and brrighter colored d telangiectasiias [14].

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Fiigure 3.3. Absorption spectrum m for hemoglobiin, melanin andd water.

There are various v laser systems s that haave been usedd for the vascuular lesion treaatment. The most commonlly used laser systems m s for thhe vascular leesion treatmennt are 532 nm m frequency dooubled Nd:YA AG lasers, puulsed dye lassers (585-595 nm) and 1064 nm Nd:YA AG lasers. H Hemoglobin ab bsorbs the shorrter two peakss of wavelengtth much moree strongly thann the longer 10064 nm wavellength (Figuree 3.3). If we ree-plot the dataa on the figuree 3.3, we see the t ratio of heemoglobin to o melanin abssorption. Thee hemoglobinn and melaninn shares the maximum abbsorption spectrum at the shorter waveelengths [7]. In the treatm ments with theese shorter w wavelengths, melanin m presennt as epidermaal pigment com mpetes with thhe hemoglobinn during the trreatment [7]. However, wee should proteect and sparee the epiderm mal pigment duuring laser trreatments. As the wavelenngth gets biggger, the absorrption and scattering coeffficients are coonsiderably lo ower with the reduction of o ratio of melanin m to bloood absorption and this prrovides the greatest g selecctivity during the laser trreatment of vascular v lesioons [7,20]. A Although it seeems to be the ideal wavelenngth of treatm ment at the first hemoglobin absorption peeaks located in i 500 to 600 nm range, heemoglobin andd melanin havve no competiition at the seecond hemoglobin absorptioon peak locateed around the 1064 nm wavvelength and this t has the cllinical advantaages that will be b mentioned later. The fluencce-response cuurve of Nd:Y YAG laser treatment for vaascular lesionns like port w wine stains is very v steep andd several phennomena cause it [18,21]. Met-hemoglobinn (met-Hb) foorms by the paartial oxidation of oxyhemooglobin and heemoglobin whhen blood is heated to 50 - 54°C [21]. Optical O absorp rption of met-Hb is much higher than that of hem moglobin or

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oxyhemoglobin in the near infrared spectrum of 1064 nm [18,21]. Absorption of blood at 1064 nm increases by a factor of about 3 when blood is photocoagulated by 1064 nm Nd:YAG laser pulses [12,18,21]. This phenomenon could be explained by partial conversion of oxyhemoglobin to met-Hb [18,21]. Photocoagulation of human blood results in increase of absorption by 2 to 10 times and increase of scattering by 2 to 4 times in the wavelengths ranged from 500 to 1100 nm [18]. Also chromophores concentrate by the loss of water from the blood by the formation of a coagulum in the vessel lumen [18]. Additionally, optical scattering also increases in thermally coagulated blood [18]. It has been shown that fluences greater than minimum purpura dose (MPD) (i.e. threshold fluence for subtle and immediate purpura) result in a significant increase of absorption during 1064 nm Nd:YAG laser treatment in humans [18]. Another important parameter that affects laser treatment of vascular lesions is the volume fraction of dermis occupied by the vessels to be treated [18]. This volume fraction ranges from less than 0.05 in pink port wine stains to about 0.25 in dark, purple and hypertrophic port wine stains [18]. During laser irradiation, both factors predict the total energy absorbed per unit dermal volume which is relevant to the bulk heating of the dermis; peak temperature and the collective density of targeted vessels [18]. The importance of bulk dermal heating is greater for Nd:YAG laser than for a PDL as 1064 nm light penetrates into the dermis deeper than the 595 nm light [18]. MPD was found to differ among patients and with vascular lesion color [18]. For example, MPD for pink port wine stains was found to range from 90 to 250 J/cm2 and for purple port wine stains it was found to range from 40 to 60 J/cm2 [18].

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4. SELECTING PARAMETERS There are several factors that have to be taken into consideration when treating a vascular lesion with laser; patient’s skin color, lesion depth and diameter, wavelength of the laser, pulse duration and spot size. The wavelength used should reach the desired depth to treat the lesion and the configuration should meet the treatment parameters. After selecting the wavelength, it is necessary to select the correct pulse duration, spot size and fluence parameters for the vascular lesion to be treated [16]. It is wise to remember that fixed parameters can not be used to treat different vascular lesions [16].

4.1. Wavelength Wavelength is the primary factor determining the penetration of laser energy [7]. Wavelength is measured as nanometers (nm). The depth of penetration is determined by the wavelength of the laser beam as seen in Figure 4.1.1 [22]. Depth of penetration increases as the wavelength gets bigger over the range that is absorbed by melanin and hemoglobin [7]. More scattering is seen with shorter wavelengths [7]. Lasers with a short wavelength have shallow penetration and high hemoglobin and melanin absorption (Figure 4.1.2) [7]. So it is evident why lasers with a short wavelength had a wide use in small and shallow vessels e.g. fine facial telangiectasia. As the wavelength gets bigger, the lasser beam reaches deeper targets and requires higher fluences for efficacy [7,10]. Nd:YAG laser with a wavelength of 1064 nm is able to penetrate deeper into the vessels and carries minimal risk of epidermal

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daamage [23]. This T near infrrared wavelenngth also allow ws darker skin types to bee treated as deecreased interraction of thhis wavelength with melannin results inn minimal risks to the eppidermis like epidermal disruption d andd pigmentaryy irregularities (“epidermaal bypass”) [116,17,23-25]. In this sectionn, we will nott discuss the other o wavelenggths as we wiill use only onne wavelengtth; 1064 nm Nd:YAG lasser, in the discussion d of selecting thee treatment paarameters of vascular v lesionns.

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Fiigure 4.1.1. Waavelength and vaascular lesion innteraction.

Fiigure 4.1.2. Sho ort wavelength lasers l have a shhallow penetratiion depth.

4.2. Pulse Du uration Pulse durattion is the lenggth of time forr each pulse too be emitted from f the laser source and measured as milliseconds m m (m ms) [16]. The primary p criterrion to determ mine the pulse duration is thhe diameter of o the vascullar lesion to be treated [10,16]. An additional crriterion for deetermining thee pulse duratiion is the voluume of indiviidual vessels within a vasccular lesion [116]. While sho orter pulse duurations are apppropriate forr the treatmennt of small diaameter and loower volumed d vessels, longer pulse durrations are apppropriate for the treatmennt of larger diiameter vessells with higher volume [16,226]. Although pulse durationns differ accorrding to the

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manufacturers of Nd:YAG lasers, m l pulse duration d capaccity of differennt Nd:YAG laasers range frrom 0.1 to 600 0 ms. Pulse durattion does not affect a the amoount of the ligght delivered (fluence) ( and the t thermal daamage [12]. Iff the desired response r can not n be obtaineed, the responsse in small vessels could bee improved by y a small decrrease in pulsee duration [26]. The pulse durations d shouuld be long ennough to inflicct thermal dam mage to endotthelial cells buut short enouggh not to causee extensive peerivascular daamage that is the reason off scarring [111,26]. Longer pulse duratioon causes a sllower heating of the vessel and a leads to suufficient damaage to vessel wall w to cause coagulation c annd prevent vesssel rupture [111,26]. The puulse durations should be seleected as short as possible foor efficiently heating h the taarget but theyy should be seelected as longg as possible to provide m minimal heatin ng of the epiddermis [26]. Puulse durationss vary accordiing to differennt vascular sttructures (Figu ure 4.2).

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Fiigure 4.2. Pulsee durations needd to be varied acccording to diffferent vascular structures. s

While the largest vesseels (3-4 mm blue b reticularr veins) respoond better to the lowest fluences of 90--100 J/cm2 at 40 to 50 ms pulse durationns, the smalleest vessels (0.225 mm red teelangiectasias)) respond bettter to fluences higher thaan 140 J/cm2 at 10 to 155 ms pulse duurations [15]. Pulse durationns of 50-100 ms m match the TRT T of vessells with a diam meter of 1 to 4 mm and sparee the epidermiis in all skin phototypes [277]. The laser surgeon s should remember that pulse duraations that aree too short succh as those deelivered by thee pulsed dye laser l or the freequency doublled Q-switchedd Nd:YAG lassers tend to caause violent mechanical m e effects such as a poor coaguulation, intravvascular cavittations and veessel rupture resulting in purpura and inntracutaneous hematomas [77,10,16,26,28]]. Contrary too this, pulse durations d thatt are too longg than the TR RT of the targget structure lead l to the diiffusion of mo ore heat outsidde the target during d the expposure and maay cause accum mulation of innterstitial fluid d by excessivee coagulation and result in swelling and unwanted u dam mage to the suurrounding tisssues [7,10,166,26]. Similarlly, dense paccking of pulsees, rapid appllications of coonsecutive pu ulses and highh laser light inntensity causee excessive coollateral therm mal damage arround the vessel treated [166]. Thus ideal pulse duration appears too be necessarily equal to TRT [28]. Wheen treating a homogenous h v vascular lesionn, the chosen pulse p durationn should be d a given treatment sesssion [16]. Geenerally smalleer and darker red vessels keept constant during reequire higher fluences and shorter pulsee durations buut larger vessels require loonger pulse

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durations [26,29-31]. For a given fixed fluence setting, epidermal side effects like hyperpigmentation could be effectively decreased by increasing pulse duration [26,32].

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4.3. Spot Size Spot size is the diameter of the laser light beam and usually controlled at the level of the laser handpiece. The principle factor in the determination of a spot size is the depth of the vascular lesion to be treated and the secondary factor is the size of the vessel [16]. The laser operator should consider the deepest part of the vessel when considering the vessel depth, not the closest distance from the epidermis [16]. Small spot sizes (1-4 mm) are appropriate for the treatment of superficial tiny vascular lesions (facial telangiectases, poikiloderma of Civatte or other flat vascular malformations) [16]. Larger spot sizes (bigger than 4 mm) penetrate deeper into the tissue and are appropriate for the treatment of deeply located larger vascular lesions with a bigger diameter (leg telangiectases, tuberous hemangiomas, or hypertrophic port wine stains) [16,31]. Smaller spot sizes result in greater laser light scattering and are not effective enough in treating larger or deeper vessels [16]. Conversely, larger spot sizes result in lesser laser light scattering and deliver greater energy more effectively to the target and photocoagulates it and this results in more swelling [16]. Although a smaller spot size requires higher energies, it reduces the pain and makes the treatment more tolerable [27]. When decreasing the spot size from 6 to 3 and from 3 to 1.5 mm, roughly 1.7 times more fluence is required to get similar immediate reactions in the vessels of the same size [26]. The smallest effective spot size should be used for the safety and comfort [12,26]. Although larger spots achieve superior vessel clearance than smaller spots that are roughly the size of the vessel, using a spot size that is as small as possible reduces the risk of adverse side effects and minimizes the pain experienced during the treatment [12,30]. A larger than needed spot size leads to general dermal heating and smaller spot size leads to greater percentage of incident energy delivered into vessel heating [12,30]. Additionally a larger spot size can increase the scatter of light in the tissues and may increase the proportion of energy absorbed by the extravascular tissues [12]. Thus a spot size in the range of 3 to 10 mm may enhance the specificitiy of the vascular laser treatment [11]. As a guide, it has been recommended that a spot size of about 25% larger than the maximum vessel size of the vascular lesion should be used [12]. The total amount of energy delivered to the tissue depends on the fluence (J/cm2) and the spot size [12,16]. It is important to remember the dramatic increase in delivered energy to tissues upon increasing the spot size [16]. Table 4.3 summarizes the relationship between total energy and the spot size. Table 4.3. The total energy amount changes with the change of spot size in case of the same fluence settings Spot size 3 mm 5 mm 7 mm 10 mm

Total energy delivered X 1 times X 3 times X 5 times X 11 times

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4.4. Fluence Fluence is the amount of laser energy given per unit area of tissue during the laser application [16]. Fluence is expressed as Joules per square centimeters of tissue (J/cm2). Although the basic factor is the color of the vessel to be treated, vessel diameter, vessel depth, spot size and vascular pressure should all be collectively considered in the determination of fluence [16]. Smaller vessels have small amount of chromophore so lesser light absorbancy and smaller spot sizes result in greater light scattering, all of which necessitate a compensatory higher fluence (i.e. greater intensity of light application) [16]. So, fluence should be increased when treating light colored (pink and red), small diametered and high volumed vessels by small spot size [16,26]. Additonally, vessels may vary in their intravascular blood pressure according to their anatomic localization [16]. So, high pressure vessels like the perialar telangiectasias require typically higher fluences than expected by their dimensions [16,28]. On the contrary, fluence should be decreased when treating dark colored (blue to purple), large diametered and flaccid vessels by bigger spot sizes [16,26]. Adjustments in fluence settings should be made based on patient’s skin color, presence of sun exposure, clinical endpoints (vessel clearance, mild to moderate bruising or erythema) and epidermal responses [10]. Darker skinned patients need more fluences to get the same clinical endpoints as melanin acts as a competitive factor for the light energy.

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4.5. Algorithm For the determination of optimum laser parameters bringing about these aforementioned actions, three phases of optical-thermal models of laser-tissue interaction takes place; optical, thermal and tissue denaturation phases [21]. In the first optical phase, the target must selectively absorb the light better than the surrounding tissue [21]. Wavelength choice critically affects this phase (being well absorbed by blood); green or yellow light for superficial vessels and red or infrared wavelength for vessels located deeply in the skin [21]. In the second thermal phase, the TRT is determined for each type of targeted tissue [21]. If the time necessary for heating up the target is well below the TRT, the heat builds up in the target together with temperature and pressure resulting in breakdown or an explosion of the target (thermo-mechanical damage) [21]. If the time used to heat up the target is similar to the TRT, the damage is limited to the target (pure thermal damage) [21]. If the time used to heat up the target is well over its TRT, the heat is transferred from the target to the surrounding tissues resulting in the worst result of nonselective destruction [21]. The last phase of tissue denaturation process determines the final damage and is dependent on the change of the structural components of the treated target tissue [21]. Every tissue reacts differently to a rise in temperature and this changes its optical properties [21]. Optical absorption is generally accepted to increase by a factor of 3 to 4 after this phase [21]. The steeper the increase in temperature, the quicker the tissue is denaturated mainly following arrest of the laser pulse [21]. Indeed this effect continues until the tissue temperature has returned to normal thus more than 50% final damage of the target tissue develops after the laser has been switched off [21].

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Clinically it is far more important to recognize and know the immediate desired clinical skin responses than to memorize various treatment parameters [10]. Treatments should be individualized according to the characteristics of every patient and of every lesion in practice [10,16]. One should use the smallest fluence and smallest spot size that achieves the complete immediate vessel clearance in a particular clinical setting [12,16,26]. If this desired clinical end point is not observed at the lower settings, fluence can be gradually increased by 5 to 10 J/cm2 at a time or the spot size is incrementially increased to obtain a deeper penetration [16]. In some cases, the fluence should be decreased in case of an increase in spot size to prevent epidermal overheating [16]. The laser pulses should be placed in a manner to prevent overlapping of treatment spots [16]. If signs of epidermal damage (i.e., vesiculation or gray discoloration) are observed, fluence should be reduced with or without a decrease in the spot size [16]. Spot size, fluence and pulse duration parameters should be changed according to the regional vascular lesion characteristics to be treated [16,26]. Figure 4.5 shows the relationships of spot size, fluence and pulse duration to the characteristics of a given vascular lesion in the determination of Nd:YAG laser parameters for the treatment of vascular lesions proposed by Groot et al [16]. Although these treatment parameters increase the theoretical risk of blistering and scarring, this risk could be compensated by adequate pre- and postcooling of each treated site [29]. With adequate cooling, larger spot sizes (2-8 mm), moderate fluences (100-350 J/cm2) and extended pulse durations (30-50 ms) treat adequately larger blue vessels (1 to 4 mm diameter) that contain lower oxygenated hemoglobin [33]. Contrary to this, small spot sizes (less than 2 mm), high fluences (350-600 J/cm2) and short pulse durations (15-30 ms) treat adequately small red superficial vessels (less than 1 mm in diameter) that contain high oxyhemoglobin saturation [33].

Figure 4.5. The algorithm of laser parameter selection (adapted from Groot et al. [16]).

In the algorithm proposed by Groot et al. [16] it is important to select parameters sequentially in the order of wavelength, pulse duration, spot size and fluence as each setting relies on the constancy of the previous parameter (Figure 4.5) [16]. The amount of the energy delivered to the tissue can be controlled and should not be extensive when the condition of the

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order of the algorithm is maintained [16]. To achieve this goal, the cooling should be sufficient to prevent inconsistent and adverse results [16]. It is mandatory to start with a small test site with longer pulse duration, smaller spot size and a lower fluence to minimize tissue damage [16].

5. DEFINITION OF VASCULAR PATHOLOGY

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Vascular lesions had been divided into two major categories; namely vascular tumors and vascular malformations, according to the biologic activity of the lesion during the 1996 International Society of the Study of Vascular Anomalies Workshop [22]. Vascular tumors, most of which are hemangiomas, develop and show a rapid growth phase by endothelial proliferation and angiogenesis which later subsides and regresses [22,34]. All types of hemangiomas, namely “strawberry”, “capillary” and “cavernous” hemangiomas are collectively named hemangiomas [22,34]. Clinical differences in appearances of hemangiomas may relate to the depth of the lesion localization in the body [22]. Local or diffuse errors in embryonic capillary, lymphatic, venous, arterial or combined vascular structure with a normal turnover rate of endothelial cells are named vascular malformations [22]. Port wine stain is a capillary vascular malformation [22,34]. Vascular malformations are always congenital, non-regressing and show a growth rate that is proportional to the growth of the child [22,34]. Sometimes they may not be visible at birth and may enlarge by the changes in hemodynamic and hormonal factors [22]. Both types of vascular lesions could be differentiated by pathological, immunohistochemical studies and imaging techniques [22,34]. The detailed discussion of this topic is beyond the scope of this chapter. Classification of vascular lesions according to the Modified Mulliken’s system that has been used in this chapter is presented in Table 5.1 [22]. Table 5.1. Classification of vascular lesions that has been used in this chapter Vascular tumors Hemangiomas Acquired Pyogenic granuloma (Lobular capillary hemangioma)

Vascular malformations High flow vascular malformation Arterial malformation Arteriovenous malformation Arteriovenous fistulas Low flow vascular malformation Capillary malformation Venous malformation Lymphatic malformation Combined vascular malformation Macular stain Vascular ectasia Angiokeratoma

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6. CLINICAL APPLICATIONS Laser treatment of vascular lesions occupies an enormous space in the cosmetic dermatologic applications. Correct treatment starts with a correct diagnosis and a correct treatment choice. The provision of different lasers for the treatment of different vascular lesions was associated with higher laser equipment costs and with a need to increase the treatment costs for the patients in the past. There are about 40.000 babies born with a vascular pathology annually in the U.S.A only [10]. The incidence of vascular malformations in newborns is around 5% [10]. Most of the congenital vascular lesions could not be afforded by the parents in the past due to high aforementioned costs so there were various complications faced in the past. The efficacy of any given vascular laser can be altered by wavelength, energy, spot size, pulse duration and the use of a cutaneous cooling device [11]. The aforementioned Nd:YAG laser system could treat both deeply and superficially located vascular lesions if the pulse duration, spot size and fluence parameters are properly selected. There are various successful reports of its effectiveness in the treatment of both superficial and deep vascular lesions. So 1064 nm Nd:YAG laser system could be an effective alternative alone for the treatment of all cutaneous vascular lesions.

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6.1. Patient Selection It is necessary to choose the suitable patient to obtain an acceptable treatment end point. The operating physician must consider all of these factors; patient age, the relationship of the lesion with other organs, the possibility of spontaneous regression and as the most important factor, the eligibility of the lesion for the treatment by using Nd:YAG laser. An 1064 nm Nd:YAG laser system providing short pulse durations at higher fluence and different spot size settings could be valuable in treating different vascular lesions. Still it is important to remember that short wavelength lasers give better results in the treatment of erythematous and very superficial vascular lesions (for example nevus flammeus) [10]. The major goals of vascular lesion treatment should include: 1. 2. 3. 4. 5.

prevention of life- or function- threatening complications, preventing or treating ulcerated lesions, prevention of disfigurement, avoiding aggressive surgical procedures, Minimizing Psychological Distress.

Patients should always be carefully examined and searched for unrealistic expectations [19]. The operating physician could use different lasers at different wavelengths in some vascular lesions. For example, beginning the treatments with Nd:YAG laser in port wine stains and continuing later with a shorter wavelength laser after it becomes a lighter colored and superficial vascular lesion and this leads to more acceptable clinical results. In the vascular lesions that are very superficial and light colored (for example salmon patch) the sole and first choice of treatment should be short wavelength laser systems.

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6.2. Preoperative Patient Evaluation, Care and Checklist It is necessary to take medical history and to discuss about the treatment and treatment results with the patient thoroughly before the Nd:YAG laser treatment same as the case in all laser applications. Obtain a thorough medical history of drug usage and learn about: • • • • •

current medications (both routine and occasional use), oral isotretinoin, aspirin, nonsteroid anti-inflammatory drugs, herbs, vitamins and anticoagulants, gold therapy, photosensitizer drugs (Table 6.2). Table 6.2. Frequently used photosensitizer drugs

Antibiotics NSAIDs Diuretics, cardiac drugs Antidiabetics Retinoids Neuroleptics Antifungals Others

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Photosensitizers used in PDT

Doxycycline, tetracycline, ciprofloxacin, ofloxacin, levofloxacin, sulfonamides, lincomycin Ibuprofen, ketoprofen, naproxen, celecoxib Furosemide, hydrochlorothiazide, diltiazem, quinidine, nifedipine, losartan Sulfonylurea group Isotretinoin, acitretin Phenothiazines, chlorprothixene, thiothixene, risperidone Itraconazole, voriconazole Para-aminobenzoic acid (PABA), 5-FU, amiodarone, oral contraceptives, dapson, acetazolamide, amitriptilin, barbiturates, salisilates 5-aminolevulinic acid, Methyl-5-aminolevulinic acid, verteporphyrine, protoporphyrine

Oral isotretinoin treatment should be stopped at least 6 months ago. Aspirin, vitamins and anticoagulant drugs increase the risk of purpura and echymoses. Additionally comsumption of some foods and herbs like cherry or linden tea could serve as an anticoagulant to increase the risk of purpura and echymoses. There is a risk of development of blue to gray discoloration in patients with a history of gold treatment. The laser treatment parameters should be reevaluated by a test pulse in patients with a history of taking photosensitizer drugs (Table 6.2). Also obtain carefull personal medical history to learn about presence of any of the following: • • • • • • • • •

vitiligo, herpes simplex virus exacerbations, coagulopathies, diabetes mellitus, tendency to develop wound infections, tendency to develop keloids or hypetrophic scarring, tattoos, permanent make-up, pacemaker or defibrillator, implants or surgeries in the treatment area.

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The heat and trauma from the laser treatment could induce a flare-up of the preexisting vitiligo. In the case of presence of frequent cutaneous herpes simplex virus infection history in the area to be treated, a pretreatment with an antiviral is indicated. Presence of diabetes could impede the wound healing. The laser treatment should not be performed over tattoos or permanent make-up to prevent oxidation of some pigments and development of dyspigmentation. The Fitzpatrick skin phototype should be determined for each patient. Nd:YAG laser could be used safely for all of the skin phototypes even for dark skin but skin color is important to select the correct energy parameters (look: selecting fluence). The patient should also be interviewed for the presence of any previous treatment experiences for this vascular lesion, if so presence of any difference after that treatment and any complications should be learned. The physician should also explain the treatment aim and the risks of the planned Nd:YAG laser treatment. The patient should understand the aim of obliterating vascular structures by heating the target “hemoglobin” and the low risk of complications due to minimal damage in surrounding structures when appropriate parameters are selected. However, probability of development of burn like vesicles, even if low, should be understood by the patient. Success of the treatment depends on whether patients have realistic expectations or are properly selected [19]. The patients should also be informed that the treatment could last more than a year or 5 sessions such as the treatment of port wine stains.

6.3. Contraindications

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Pregnancy and treatment for any type of cancer are absolute contraindications for Nd:YAG laser treatment. For relative contraindications please look at the previous preoperative patient evaluation part of this chapter.

6.4. Patient Information and Consent Nd:YAG laser treatment of vascular lesions usually needs more than one (3-6) treatment sessions. The time period between consecutive sessions changes from 4 to 6 weeks. After giving the information about treatment details, expected and non-expected results, the informed consent of the patient should be taken. Patients should also be instructed to avoid sun exposure at least for a week following the treatment session [19].

6.5. Role of Cooling Gilchrest et al. [35] was the first to study the effect of cooling in epidermal protection by using ice during argon laser treatment of port wine stains in 1982. Afterwards, cooling became an integral part of the vascular lesion treatments. The theory of selective tissue cooling states that temporal and spatial selective cooling of tissue can provide adequate protection to nontargeted tissues to prevent heat build up and prevent complications such as burns [36]. This theory is complimentary to the theory of selective photothermolysis and affect operational outcome [36]. Skin cooling during the dermal laser therapy is associated

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with not only cooling and protecting the epidermis and preventing collateral dermal damage, but it also reduces the discomfort and pain associated with laser treatment [11,36,37]. In the absence of cooling, development of high temperature of the target following absorption of laser energy could lead to pain or unwanted side effects [36]. Pre-cooling the skin before the laser pulse decreases the pain and post-cooling the skin after the laser pulse protects the epidermis from development of epidermal complications. Longer precooling with darker skin phototype and increased postcooling delay for larger vessels in order to effect full thickness mural denaturation are advisable [38]. Preoperative and postoperative adjunct artificial ice cooling is mandatory in the treatment of many deep vascular lesions as chromophore absorption of light energy is enormous [16]. Skin cooling is especially important in the Nd:YAG laser treatment of port wine stains and leg telangiectasias as high fluences are required to adequately damage these vascular malformations [36,37]. However, there are potential disadvantages of using such a cooling system [11]. Cold induced vasoconstriction or mechanical pressure of the chill tip can cause blanching of the target vessel [11]. This could limit the effectiveness of the vascular laser by decreasing the amount of targeted chromophore within the vessel to be treated [11]. Specifically pre-cooling could prevent the effective treatment of very superficial vessels (pink colored vessels) by this way. Additionally, laser light transmission may decrease if condensation is accumulated on the window of the chill tip [11]. Furthermore the benefits of the chill tip will be lost if the contact of it to the skin is not maintained [11]. There is a learning period of cooling devices and many unwanted adverse effects such as blistering or crusting occur early during this period [11]. Epidermal cooling is achieved mostly with an internal and self contained cooling system that is administered by the handpiece. If the cooling system is not incorporated to the laser system, an external cooling device is needed. Several approaches are present to cool the skin, including water cooled glass chambers for application directly to the skin through which the laser beam is directed (e.g., Chess Chamber, Cool Laser Optics; Photoderm Chiller, ESC; Dermacool Distributors, LLC, Mabetton, GA), cooling coupling gels, pulsed delivery of cryogen spray and refrigerated spray cooling devices (e.g., Dynamic Cooling Device, Candela Corp.) [10,11,37]. Results reported in the literature suggest that cooling helps to secure epidermis and allows use of higher fluences thus leading to more vascular damage and greater degree of clearance per treatment [37,39].

6.6. Post-Operative Care All patients should be advised to expect some degree of redness, swelling and rarely skin peeling after the Nd:YAG laser treatment of vascular lesions. Ice packs could be immediately applied after the Nd:YAG laser treatment of large vessels to decrease the edema formation. The patients should also be advised to use topical antibiotics to prevent any infection in case of development of vesiculation. They could use acetaminophen in case of a need for analgesia [16]. The patients should also be advised to protect the treated area from direct sun exposure and to use sunscreens. Some physicians instruct their patients to use compression stockings (30-40 mmHg pressure) for up to 5 days after treatment of larger leg veins [16]. This may help to reduce the

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Nd:YAG Laser Treatment for Different Vascular Lesions

17

bruising and increase the patient comfort. After the treatment of large vessels, some portions of them may become darker colored, stiff and painful for an extended period of time. This dark coagulum can be removed after 1 to 2 weeks by nicking the vessel with a blade or needle and applying pressure to force it out. The recommended time interval between consecutive treatment sessions is 4 to 6 weeks or longer and depends on the rate of clearance after each treatment session [16]. Larger reticular veins may need up to 3 months to resolve and they should not be re-treated before this time period. The improvement following Nd:YAG laser treatment of vascular lesions has been observed to increase during the follow up from 3 months to 6 months despite the absence of any further treatment sessions [33]. This may be related to the ongoing continued histological effects of collagen remodeling [25].

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6.7. Side Effects Well trained physicians experience very limited complications after performing 1064 nm Nd:YAG laser treatment of vascular lesions with appropriate settings. The side effects that may develop are pain, purpura, bruising, bleeding, hematoma formation, persistent thrombus formation, epidermal textural changes, swelling, discoloration, blisters or scabs, local infection, reactivation of herpes simplex on the face (when the face is treated) or genital (when legs are treated), delayed wound healing, hypo- or hyper-pigmentation and scarring [18,19,21,33,39-42]. Lesion persistence or recurrence could be seen in nonresponders [19]. The risk of development of side effects seems to be correlated with the diameter of the treated vessel and can be reduced by an effective epidermal cooling [27]. The risk is also related to the fluence, spot size and pulse duration [21]. Hyperpigmentation is more frequently seen after development of purpura [26]. Darker skinned patients can experience postinflammatory hyperpigmentation but this complication is transient and its intensity decreases spontaneously with time after the treatment with Nd:YAG laser [39,43]. Another controversy in the use of laser systems in living organisms is whether it causes long term genotoxic effects or not. A recent study reported by Senturk et al [44] implies a risk of laser treatment. Laser energy can modify cellular processes in a dose, wavelength and passage dependent manner in fibroblast cell cultures. Increased cellular DNA damage was seen with higher doses of Nd:YAG than KTP and with increasing number of cell culture passages [44]. It is necessary to evaluate this issue more comprehensively in future studies.

6.8. Histopathological Effects of Nd:YAG Laser Treatment The immediate effects of Nd:YAG laser treatment examined in histopathological sections are intravascular hemorrhage, fragmentation and homogenization of elastic fibers, eosinophilia of smooth muscle cells in the vessel walls of larger dermal vessels and coagulated red blood cells without evident thrombosis in small dermal capillaries [25]. In another study, findings of complete thrombosis in intermediate sized vessels and extensive

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extravasation of red blood cells, bright red coloration of perivascular collagen fibers consistent with fibrin deposition, cytoplasmic vacuolization and swelling with homogenization of chromatin within endothelial cells are observed immediately following laser therapy [31]. The elastic and reticulin fibers are clumped within and surrounding the vessel walls [31]. There are some morphologic damage to the overlying epidermis like eosinophilia of cytoplasm and homogenization of chromatin [31]. These changes are in common for different types of vascular laser treatments [31]. Expression of heat shock protein 70 is increased in the biopsies taken immediately after Nd:YAG laser treatment compared with control and follow-up (3 months) specimens [25]. Intense heat shock protein 70 expression is present in both the epidermis and the muscle cells of dermal vessels [31]. There was no evidence of apoptosis in all immediate or late biopsies [25]. There were elevated levels of TGF-β1 and TGF-β2 receptor levels in the active regions of sclerosis [25]. Pro-collagen I was observed to be expressed predominantly at the dermal epidermal junction [31]. The histologic sections of Nd:YAG laser treated port wine stains at 1.0 and 1.2 MPD have disclosed that 1.2 MPD fluence results in epidermal and diffuse dermal thermal necrosis extending down to the subcutaneous tissue [18]. Dermal microvascular coagulation necrosis with an intravascular coagulum and perivascular collagen denaturation were found to extend 1.95 mm on average from dermoepidermal junction to the deepest damaged vessel [18]. Additionally, when the histopathologic sections of 1 MPD Nd:YAG laser and PDL 595 nm were compared, Nd:YAG laser treated sites showed epidermal necrosis and deeper dermal blood vessel coagulation (2.6 mm vs. 0.95 mm with PDL, i.e. 2.7 times deeper) [18]. At 3 months follow up, large dermal veins show thrombosis, fragmented elastic fibers, extravasated red blood cells and hemosiderin [25]. Small vessels show minimal evidence of thrombosis [25]. Pan-vessel fibrosis was not present in some treated vessels thus it does not correlate distinctly with the closure and vessel integrity interruption which are evidenced by clinical and doppler ultrasound examinations [25]. Additionally, the observation of recanalized thrombosis in some biopsies implies the potential for vessel reappearance after the laser treatment of vascular lesions [25]. The expression of heat shock protein 70 by the vascular cells and surrounding stroma supports the hypothesis of vascular injury is by the induction of heat in the circulating blood [31]. These observations imply that heat shock protein 70 plays a role in clearance of the ectatic vessels and collagen remodeling with decreased incidence of scarring after laser treatment of leg vessels [25]. Thus apoptosis does not play a role in the laser induced vascular injury [25]. The thermally damaged endothelium and perivascular tissues presumably initiate a cascade of inflammation and wound healing process leading to the replacement of vessels by fibrous tissue [26]. The previously proposed role of vessel cavitation with intraluminal steam bubble formation to explain the clinical immediate vessel disappearance has been replaced by perivascular collagen contraction as a result of thermal denaturation and intravascular thrombosis [26]. The ratio of contraction to thrombosis has been shown to increase with increases in pulse duration [26].

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Nd:YAG Laser Treatment for Different Vascular Lesions

19

7. REVIEW OF ARTICLES ON USE OF ND:YAG LASER FOR VASCULAR LESIONS 7.1. Vascular Tumors Vascular tumors are characterized by endothelial proliferation that can cause serious clinical problems like bleeding, ulceration, mass effect and consumptive coagulopathy depending on the localization and size of the lesion [22].

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7.1.1. Hemangiomas Hemangiomas are the most common vascular anomalies of infancy and are true neoplasms [22]. They are present in approximately 1-2% of neonates and 4-12% of term infants by 1 year of age [22]. They are more common in females, light-skinned and premature infants [22]. Congenital hemangiomas are mostly (about 60%) located in the head and neck region [22]. They show a natural course of rapid phase of growth in the first year of life and a phase of involution after 1 year [22,45]. They go through 4 evolutionary stages; early macular stain, actively proliferating, involuting and involuted hemangioma stages [10]. It is controversial whether to treat all hemangiomas owing to their tendency to regress spontaneously [45]. Congenital hemangiomas are usually left on own progress but laser treatment could be performed in proliferating hemangiomas causing serious clinical complications, ulcerated hemangiomas, hemangiomas located in functional and aesthetically important areas like the face and residual discoloration or telangiectasias remaining after involution [22,45]. Interstitial laser therapy was preferred in hemangiomas with life or function threatening behaviour [22]. But it should be kept in mind that the aim of therapy is not the complete removal of a hemangioma but to stop the growth and to initiate regression [45]. The laser treatment should depend on the evolutionary stage of the lesion and distribution pattern of the hemangioma [10]. Localized hemangiomas are associated with improved prognosis than segmental or diffuse lesions associated with structural anomalies [10]. The primary goal of the treatment of infaltile hemangiomas is to prevent or to modify the growth of the hemangioma [10]. As far as the initial macular or slightly elevated hemangiomas are considered, cessation of growth can be achieved in up to 96% of hemangiomas by laser treatment [45]. With the use of Nd:YAG laser systems, cessation of growth and induction of regression have been obtained in up to 70% of exophytic ulcerated and subcutaneous hemangiomas [45]. The second goal of treatment of infantile hemangiomas by lasers is to reduce the pain associated with ulceration [10]. Table 7.1.1 summarizes the studies evaluating the effectiveness of Nd:YAG laser treatment of hemangiomas. The key question in the treatment of congenital hemangiomas is: What is the ideal time to start the Nd:YAG laser treatment? The authors of this chapter recommend that laser treatment should be started as soon as the presence of a hemangioma is confirmed. If there is no risk, it may be wise to wait spontaneous healing until the child is 5 years old. Some other authors advise to wait until 10 years to reduce the risks of the treatment (i.e. scar). The risk of such complications is very low in the hands of experienced laser

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20

Ekrem Civas, Berna Aksoy and Hasan Mete Aksoy

operators and by the use of well configured Nd:YAG laser systems. Additionally these authors neglect the risks of development of both anatomical distortion in the bone and surrounding tissue (hypertrophy) and psychological impairment of child and the whole family. In most of the patients EMLA topical anesthesia along with superficial sedation and external ice cooling is sufficient for the procedure. The larger spot sizes (7-10 mm) are more convenient to use as the lesions generally are located in deeper layers. The intervals should not be shorter than 6 weeks.

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7.1.2. Pyogenic Granulomas Pyogenic granulomas (lobular capillary hemangiomas) are common acquired vascular lesions that are located mostly in the head and neck region and develop in response to a minor trauma most of the time [22,56]. They are eruptive granulomatous vascular lesions and are histologically consistent with features of capillary hemangiomas [10]. They have an inflammatory component with markedly hyperproliferated superficial cutaneous vasculature and always have a central feeding arteriole [10]. They tend to bleed easily and to recur [56]. They are not always easily amenable to laser surgery alone because of varying thickness of these lesions [10]. Diascopy may be used to arrest the flow in the feeding arteriole during the early pulses of laser application to increase the success of laser treatment [10]. Nd:YAG laser treatment was found to be effective in reported 4 cases with giant pyogenic granulomas measuring 0.5 to 3.5 cm in size (Table 7.1.2) [56,57]. After treatment with overlapping shots, immediate pyogenic granuloma necrosis develops and crusting become evident in 2 to 3 days [56]. Postoperative care is minimal as topical treatment with fucidic acid cream or antiseptic mouthwashes were advised for 1 week after each laser treatment [56]. After Nd:YAg laser treatment there were no reported adverse effects other than a burning sensation lasting for a few days that did not require painkillers [56]. The results were excellent with good aesthetic and functional outcome [56]. Table 7.1.2 summarizes the studies evaluating the effectiveness of Nd:YAG laser treatment of pyogenic granulomas.

7.2. Vascular Malformations Vascular malformations are characterized by normal rate of endothelial cell turnover rate and no tendency to regression [22,34]. Vascular malformations exhibit no gender predilection [22,34]. They are present at birth but may not be evident until their growth in proportion with the growth of the individual or in response to hemodynamic changes secondary to trauma or hormonal influence [22,48]. Laser treatment could be performed in vascular malformations depending on the type, localization and size of the lesion [22]. Before laser therapy, diagnostic procedures like ultrasonography, colored doppler ultrasonography, computed tomography and magnetic resonance angiography are necessary to evaluate the vascular malformations and to search whether surgery or sclerotherapy is more promising than laser therapy [45]. Nd:YAG laser systems and especially when they are applied with percutaneous irradiation combined with surface cooling and intralesional application are significantly effective and have promising results in venous malformations [45].

Yttrium: Compounds, Production and Applications : Compounds, Production and Applications, edited by Bradley D. Volkerts, Nova Science

Yttrium: Compounds, Production and Applications : Compounds, Production and Applications, edited by Bradley D. Volkerts, Nova Science Publishers,

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Table 7.1.1. Studies evaluating the effectiveness of Nd:YAG laser treatment of hemangiomas Author (year) Landthaler (1986) [5] Rosenfeld (1988) [8] Clymer (1998) [46] Wacker (1998) [47] Werner (1998) [48] Chang (1999) [49] Pham (2001) [36] Vlachakis (2003) [50] Groot (2003) [16] Ulker (2005) [51] Ulrich (2005) [52] Vesnaver (2006) [53] Scherer (2007) [54] Yang (2009) [55] Civas (2009) [9]

Continuous wave, 100 watt, 1064 nm 1064 nm

1.8 mm

Pulse duration 1.0 sec

Flexible, optic fiber

0.1 sec

Head - neck

1064 nm (Interstitial)

Bare quartz fiber (400-600 μm)

0.3-1.0 sec

1064 nm (Interstitial)

fiber (600 μm)

39

3 head – neck, 1 thigh, 1 intrathora-cic Head - neck

2

Tongue

1

Facial

1064 nm (transcutaneous interstitial) Pulsed, 1064 nm (intralesional) 1064 nm

110 Variable 13

Variable

1

Glans penis

15

Variable

?

Head - neck

?

Face - neck

42

Oral cavity

25

Variable

N

Location

4

Facial

17

?

8 5

Nd:YAG type

Spot size

Fluence 400-1600 J/cm2 20-40 W

Anesthesia Local

N of sessions (interval) 5 (6-8 weeks)

Follow-up

Result

18 months

Effective

1-8 years

Good

110-992 J/cm2

None – Local - Mean 2 (12 weeks) General General 1-5 (average) (6-8 weeks)

33 weeks (average)

Moderate

293 sec

4-8 W

General

1

6 week

0.6 mm

0.2-0.3 sec

General

1-3 (4-6 weeks)

>12 months (mean 3 years)

Bare fiber (600 μm) Optic fiber (600 μm)

30 sec 10 sec

1000-2500 J/cm2 (Variable) 7-10 W

Partial improvement Excellent (in 77%)

General

1

3-20 months

Good

5mm

75-175 ms

80 J/cm2

None

2

6 months

Moderate

1064 nm

?

2-10 sec

35-45 W

General

1 year

Good

Long pulsed, 1064 nm 1060 nm

3-10 mm

0.1-300 ms

?

6 months

Good

Contact probe

3 sec

Max 300 J/cm2 25 W

1-3 (6 months) 1

Local

1

4 weeks

Excellent

Continuous wave, 1064 nm, (percutaneous, intralesional) 1064 nm (transmucosal, intralesional) Long pulsed, 1064 nm Long pulsed, Frequency doubled, 1064 nm Long pulsed, 1064 nm

Flexible quartz fiber (600 μm)

0.2-0.5 sec

600-900 W/cm2

Topical / general

1-3

≤ 8 years

Moderate

Optic fibre 320 μm

125-150 μs

8-12 W/pulse

Local / general

1-3 (3-12 months)

?

Good

600 μm, 5-7 mm Optic fibre, 600 μm

10-100 ms

?

1-5 (4-6 weeks) 1-3

?

Moderate

30-60 ms

75-120 J/cm2 6.5 W/pulse

6-24 months

Good

3-5 mm

10-25 ms

1-5 (6 weeks)

3 months

Good

90-140 J/cm2

Local / general

None / topical

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Table 7.1.2. Studies evaluating the effectiveness of Nd:YAG laser treatment of pyogenic granulomas Author (year) Powell (1994) [57] Bourguignon (2006) [56]

N

Location

Nd:YAG type

Spot size

Pulse duration

Fluence

Anesthesia

1

Gingival

1064 nm

Contact tip

1.0-48.2 sec

22-675 J/cm2

General

3

2 in hand, 1 gingival

1.064 nm, Triple-pulse

10 mm

7.5 ms (delay of 10 ms)

150 J/cm2

Local

N of sessions (interval) 1

1-3 (2 week)

Followup 15 months 1 year

Result Complete excision, No relapse No relapse

Nd:YAG Laser Treatment for Different Vascular Lesions

23

7.2.1. Congenital Vascular Malformations

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7.2.1.1. Port Wine Stain Capillary vascular malformations (Port Wine Stain) occur in 0.3-0.5% of newborns and located frequently in the head and neck region [22]. They are typically flat cutaneous vascular lesions that range in color from pink to purple [22]. They do not disappear but thicken, darken and develop papular and nodular changes with increasing age as a result of erythrostasis [22,42]. They are characterized histologically by normal number of dilated postcapillary venules of the papillary vascular plexus [10]. Before treatment an ophthalmology consultation is mandatory in facial port wine stains involving supraorbital (V1) and infraorbital (V2) branches of trigeminal nerve because of the high incidence of accompanying glaucoma [22]. Only 10% of the typical V1 distribution port wine stains are associated with Sturge-Weber syndrome [22]. Previous attempts of treatment with earlier Nd:YAG laser systems produced higher scar formation and delayed wound healing of 2 to 4 weeks with histopathological observations of deep dermal vascular damage [5]. Later Nd:YAG laser systems were postponed. Frequency doubled 532 nm KTP laser systems re-gained interest in evaluation to treat port wine stains after the beginning of 21st century [39,58-60]. It was concluded from these studies that port wine stains that were resistant to short pulse 585 nm PDL could benefit from further KTP laser treatment [58,59]. Later Ahcan et al [61] observed that the effect of KTP 532 nm laser could be increased despite the reduction of fluence when it was combined with 1064 nm laser light emitted simultaneously. Yang et al [18] compared 1064 nm Nd:YAG laser treatment with the well established standard 595 nm PDL treatment of port wine stains in 2005. They have observed that Nd:YAG 1064 nm treatment results in comparable clinical results with PDL with improved patient satisfaction by its shorter recovery period and purpura duration [18]. However, they have found that Nd:YAG laser treatment is associated with a narrow safety margin [18]. While 1 MPD has resulted in clinical effectiveness, 1.2 MPD fluence has resulted in wide hypertrophic scarring after diffuse and deep thermal dermal and epidermal necrosis [18]. Later KTP and Nd:YAG laser treatments were shown to have a poor effect when applied in test patches for resistant port wine stains along with different laser systems to find out the best laser system [13]. Afterwards the risks of Nd:YAG laser treatment of port wine stains were found to be decreased by bulk skin cooling, non-overlapping placement of consecutive pulses, use of subpurpuric fluences and a small spot size [20]. Nd:YAG laser could also be used for hemostatic cutting in oral operations such as treatment of gingival hyperplasia in Sturge-Weber syndrome [62] Table 7.2.1.1 summarizes the studies evaluating the effectiveness of Nd:YAG laser treatment of port wine stains. The traditional learning was the use of superficial and shorter wavelength lasers in the treatment of port wine stains. Conversely the authors of this chapter have obtained excellent results by the use of well configured Nd:YAG laser equipped with appropriate pulse duration and small spot size variables in the treatment of port wine stains which contain both superficial and deep vascular structures at the same time. The authors achieved approximately 90% amelioration of the port wine stains by additional use of superficial wavelength IPL

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Yttrium: Compounds, Production and Applications : Compounds, Production and Applications, edited by Bradley D. Volkerts, Nova Science Publishers,

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Table 7.2.1.1. Studies evaluating the effectiveness of Nd:YAG laser treatment of port wine stains Author (year) Landthaler (1986) [5] Rosenfeld (1988) [8] Chan (2000) [39]

N

Location

4

Facial

26

?

54

41 head –neck, 13 trunk, limbs

Pham (2001) [36] Chowdhury (2001) [58]

2

Facial

30

21 head – neck 2 trunk 7 extremity

Lorenz (2003) [60]

43

28 head – neck, 5 trunk, 10 extremities

Groot (2003) [16] Woo (2004) [59]

61

Variable

22

15 head – neck, 3 trunk, 4 extremity

Nd:YAG type Continuous wave, 100 watt, 1064 nm 1064 nm

Variable pulse, Frequency doubled, 532 nm 1064 nm, Dynamic cryogen cooling Variable pulse, Frequency doubled, 532 nm Variable pulse, Frequency doubled, 532 nm Long pulsed, 1064 nm Variable pulse, Frequency doubled, 532 nm

Spot size 1.8 mm

Pulse duration 0.5-1.0 sec

Fluence

Anesthesia 2

400-1600 J/cm

Local

N of sessions (interval) 1-5 (6-8 weeks)

Follow-up

Result

18-24 months Effective

Flexible, optic fiber

0.1 sec

20-40 W

None – Local - General

Mean 2 (12 weeks)

1-8 years

Good

2-4 mm

2-10 ms

8-20 J/cm2

?

1-5

?

Fair

5-8 mm

175 ms

80-90 J/cm2

None

1-4

6 months

Moderate

Smartscan device

7-14 ms

18-24 J/cm2

None - Topical (EMLA)

1-4 (2 months)

2 months

Moderate

4 mm

5-50 ms

5.5-15 J/cm2

None - Topical (EMLA)

1

6 weeks

Good

3-10 mm

0.1-300 ms 2-10 ms

Max 300 J/cm2

?

1

6 months

Moderate

7-16 J/cm2

None

1

6 weeks

Poor

3 mm

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Table 7.2.1.1. Continued Author (year)

Nd:YAG type

Spot size

Pulse duration

N of sessions (interval)

Followup

N

Location

Ahcan (2004) [61] Yang (2005) [18]

10

Head - neck

Dual wave-length, 532 + 1064 nm

3 mm

25 ms

6-10 J/cm2

Topical (EMLA)

1

8 weeks

Moderate

16

Long pulsed, 1064 nm

5-7 mm

3-15 ms

0.6-0.8-1.0 MPD

Topical (EMLA)

3 (1 month)

1 month

Moderate

Pence (2005) [42] McGill (2008) [13]

89

12 head – neck, 3 trunk, 2 extremity Head - neck

Frequency doubled, 532 nm

2-6 mm

2-50 ms