الفهرس | Only 14 pages are availabe for public view |
Abstract Recently,automatedanalysisofmedicalimagesbecomesimportantforeasierandfaster clinical diagnosis.Identifyinghumanorgansisthekeycomponentforsuchanalysis, i.e., segmentationoftheanatomicalstructuresfrommedicalimages. Coronary arteriessegmentationinthree-dimensional(3D)imageshasgainedwide interestinoldandrecentscientificresearchandisregardedasafundamentalstepin evaluatingthedegreeofCoronaryArteryDisease(CAD)incardiacclinicaldiagnosis and surgicalplanning.Thus,variousmethodshavebeendevelopedforsegmenting coronaries fromdifferentcardiacimagingmodalities. Previously developedsegmentationmethodsweredesignedinawaythatcanad- dress thechallengingtaskofcoronaryarteries.Thechallengesofcoronarysegmentation can besummarisedinfourpoints:thesmallsizeofcoronaries,structuresattachedto coronaries hassimilarintensityandintensity,shapevariationsalongthevesselsand presence ofcalcifications. The researchproblemofcoronarysegmentationwasdividedintothreeparts.First, enhancing the3Dinputimagesusingvesselenhancementtechniqueswhichmakeit easier todetectandextractcoronaryvesselregionsinnextsteps.Second,recognizing and segmentingcoronariesusingapropersegmentationmethodthatcanhandlethe changesinintensityandgeometryalongcoronaries.Third,usingtheresultedcoronary vesseltreefordetectingandquantifyingstenoses(narrowness). A frameworkforacoronarysegmentation,stenosesdetectionandquantification system isproposedalongwithacomprehensiveoverviewofthestate-of-artcoronary segmentationalgorithms. The proposedcoronarysegmentationframeworkwasdividedintothreemainparts: enhancementandpreprocessing,coronarysegmentation,andstenosesdetectionand quantification.Inenhancement,inputCTAimagesareenhancedbyremovingcalci- fications usingthresholding,makingcoronaryregionsmoreobvioususinghistogram equalization andenhancingvesselregionsusingHessianbasedanalysis.Inputcenter- lines arealsoresampledforbetteraccuracyofsegmentationresultsandsuchresampled centerlinesareusedinavolumetricwrappingstep.Theresultedwrappedvolumeis then usedinthesegmentationstepthatrecognizesandsegmentscoronaryvesselsusing Otsu thresholdingtechnique.Finally,thesegmentedcoronariesarethenusedinafur- ther steptodetectandquantifyvesselstenoses.Thiswasdonebyanalysingtheareaof vesselcross-sectionsalongthewholecoronarytreetodetectstenosesandapplylinear regression tothesecalculatedareastoquantifythedegreeof(stenoses)narrowing. The proposedsystemwastestedandevaluatedon48ComputedTomographyAn- giography(CTA)standarddatasetsofcoronarypatientsatdifferentlevelsofseverity. The evaluationusesthreemetricsforcomparingobtainedsegmentationresultswith the manualsegmentationannotatedbythreeexperiencedobservers.Stenosesdetec- tion andquantificationresultsarealsoquantitativelyevaluatedusingtwoevaluation metrics foreachstepbycomparingobtainedresultstodetectionandquantification previously definedbyphysicians.Furthermoretheresultswerecomparedwithother state-of-art algorithmsshowingthestrengthsandweaknessesoftheproposedsystem. |