Tracheal Structure Characterization using Geometric and Appearance Models for Efficient ...

108 Pages·2014·2.08 MB·English

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!
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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.
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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.
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