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108 Pages·2014·2.08 MB·English
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Tracheal Structure Characterization using Geometric and Appearance Models for E(cid:14)cient Assessment of Stenosis in Videobronchoscopy A dissertation submitted by Carles S(cid:19)anchez Ramos at Universitat Aut(cid:18)onoma de Barcelona to ful(cid:12)l the degree of Doctor of Philosophy. Bellaterra, November 9, 2014 Director Dr. F.Javier S(cid:19)anchez Pujadas Dept. Ci(cid:18)encies de la Computaci(cid:19)o & Centre de Visi(cid:19)o per Computador Universitat Aut(cid:18)onoma de Barcelona Co-director Dra. Debora Gil Resina Dept. Ci(cid:18)encies de la Computaci(cid:19)o & Centre de Visi(cid:19)o per Computador Universitat Aut(cid:18)onoma de Barcelona Co-director Dr. Jorge Bernal del Nozal Dept. Ci(cid:18)encies de la Computaci(cid:19)o & Centre de Visi(cid:19)o per Computador Universitat Aut(cid:18)onoma de Barcelona Thesis Dr. Laura Igual committee Universitat de Barcelona Barcelona, Spain Dr. Fernando Vilarin~o Universitat Aut(cid:19)onoma de Barcelona Bellaterra, Spain Dr. Joaquim de Ciurana Universitat de Girona Girona, Spain This document was typeset by the author using LATEX2ε. TheresearchdescribedinthisbookwascarriedoutattheComputerVisionCenter,Univer- sitat Aut(cid:18)onoma de Barcelona. Copyright⃝c 2014byCarlesS(cid:19)anchezRamos. Allrightsreserved. Nopartofthispublication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the author. ISBN: 978-84-940530-7-8 Printed by Ediciones Gr(cid:19)a(cid:12)cas Rey, S.L. Dedicat a la familia i amics per ser-hi sempre Acknowledgements I would like to thank the supervisors Javier Sanchez and Debora Gil for their help and guidance throughout this Master Thesis. I would also thank the help of Jorge Bernal and all the people of CVC for their support. Finally, I would like to thank Toni Rosell from the Bellvitge hospital for their knowledge that helped me to understand the problem. Thank you! You're the best! i ii Abstract Recent advances in the optics of endoscopic devices have increased their use for minimal invasive diagnostic and intervention procedures. Among all endoscopic procedures (which include exploration of patient internal organs from mouth to anus), bronchoscopy is one of the most frequents with around 261 millions of procedures per year. Although the use of bronchoscopy is spread among clinical facilities it presents some drawbacks, being the visual inspection for the acquisition and assessment of anatomical measurements the most prevalentofthem. Oneofthebasicinterventionsimpliestoobtainthepercentageofairway obstruction,whichisknownasstenosis. Errorsinthismeasurementhaveadirectimpactin thetreatmentthepatientwillbeprescribed. Thereforeanobjectivecomputationoftracheal stenosis in bronchoscopy videos would constitute a breakthrough for this non-invasive tech- nique and a reduction in operation cost for the public health service due to the decrease in interventions because of bad visual measurements. The calculation of the degree of stenosis isbasedonthecomparisonoftheregiondelimitedbythelumeninanobstructedframeand theregiondelimitedbythe(cid:12)rstvisibleringinahealthyframe. Inordertoobtainagoodde- limitationoftheseregionsareliablecharacterizationoftheneededtrachealstructures: rings and luminal area is needed. We propose in this thesis a parametric strategy for the extrac- tionof lumen andtrachealringsregions based onmodels oftheir geometry and appearance that guide a deformable model. In order to ensure a systematic applicability we present a statisticalframeworktoselecttheoptimalparametersofourmethod. Wehavevalidatedour method in two ways: accuracy of the anatomical structures extraction and comparison of the performance of our automatic method over manually annotated stenosis. Experiments reportresultswithininter-observervariabilityforbothqualitymetrics. Theperformanceof ourmethodiscomparabletotheoneprovidedbycliniciansanditscomputationtimeallows for a on-line implementation in the operating room. iii iv Resum Elsaventatgesrecentsenles(cid:18)optiquesdelsdispositiusendoscopishanfetquehihagiuncreix- ementenelseuusperadiagnosticsiintervencionsnoivasives. Dinsdetotselsprocediments endoscopics (els cuals s'incloeix l'exploraci(cid:19)o dels organs interns del pacient des de el nas al anus), la broncoscopia es un dels mes frequ(cid:127)ents amb 261 millions d'intervencions a l'any. Encara que el seu us s'exten per per la majoria de les cliniques presenta alguns problemes o inconvenients com per exemple el m(cid:19)es important de tots: el mesurament de forma visual delesestructuresanot(cid:18)omiques. Unadelesintervencionsm(cid:19)esb(cid:18)asiquesimplical'obtenci(cid:19)odel percentatge d'obtrucci(cid:19)o anomenat estenosis. Enrrors en aquesta mesura tenen un impacte directealtractamentdelpacient,pertant,unmesuramentobjectiudelesestenosistraqueals envideosdebroncosc(cid:18)opiaconstituiriaunaropturaenlautilitzaci(cid:19)od'aquestat(cid:18)ecnicanoinva- sivaiunareducci(cid:19)oenelcostdelesoperacionsperlasanitatpu(cid:19)blicaperundecreixementen lesoperacionsrepetidespermesuramentsvisualserrornis. Elc(cid:18)alculdelgraud'estenosisesta basatenlacomparaci(cid:19)odelaregi(cid:19)odelimitadaperl<arealuminal(enunframepatol(cid:18)ogic)amb laregi(cid:19)odelimitadaperelprimeranellvisiblederefer(cid:18)encia(enunframesa). Peraconseguir tenirunabonadelimitaci(cid:19)od'aquestesregions,unabonade(cid:12)nici(cid:19)odelesestructurestraqueals (anells i lumen) es necess(cid:18)aria. En aquesta tesis proposem una estrategia param(cid:18)etrica per a l'extracci(cid:19)o de les estructures traqueals necessaries per al c(cid:18)alcul de l'estenosis. Per assegurar unaaplicabilitatdelsistemapresentemunprotocolestad(cid:19)(cid:16)sticperseleccionarelspar(cid:18)ametres m(cid:19)es(cid:18)optims. Elsexperimentsdemostrenqueelnostrem(cid:18)etodeest(cid:18)adinsdelavariabilitatdels metges, per tant el rendiment es comparable a un metge amb la particularitat que el temps de computaci(cid:19)o permet una implementacio(cid:19) on-line en el moment del diagn(cid:18)ostic. v vi

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tion of lumen and tracheal rings regions based on models of their geometry and appearance that guide having an idea on which is the reflection between the incidence light and trachea surface. Regarding for χi = 360i/ Nθ a uniform sampling of the interval [0, 360] of step hθ = 360/ Nθ and sx t
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