Externally-Navigated-Bronchoscopy-Using-2-D-Motion

IEEETRANSACTIONSONMEDICALIMAGING,VOL.32,NO.10,OCTOBER20131745ExternallyNavigatedBronchoscopyUsing2-DMotionSensors:DynamicPhantomValidationXiongbiaoLuo*,Member,IEEE,TakayukiKitasaka,andKensakuMori,Member,IEEEAbstract—Thepaperpresentsanewendoscopemotiontrackingmethodthatisbasedonanovelexternalendoscopetrackingdeviceandourmodifiedstochasticoptimizationmethodforboostingendoscopynavigation.Wedesignedanoveltrackingprototypewherea2-Dmotionsensorwasintroducedtodirectlymeasuretheinsertion–retreatlinearmotionandalsotherotationoftheendoscope.Withourdevelopedstochasticoptimizationmethod,whichembedstraceableparticleswarmoptimizationintheCondensationalgorithm,afullsixdegrees-of-freedomendo-scopepose(positionandorientation)canberecoveredfrom2-Dmotionsensormeasurements.Experimentswereperformedonadynamicbronchialphantomwithmaximalsimulatedrespiratorymotionaround24.0mm.Theexperimentalresultsdemonstratethatourproposedmethodprovidesapromisingendoscopemotiontrackingapproachwithmoreeffectiveandrobustperformancethanseveralcurrentavailabletrackingtechniques.Theaveragetrackingaccuracyofthepositionimprovedfrom6.5to3.3mm,whichfurtherapproachestheclinicalrequirementof2.0mminpractice.IndexTerms—Condensationalgorithm,endoscopy,navigatedbronchoscopy,opticalmousesenor,particleswarmoptimization,stochasticoptimizationmethods,three-dimensional(3-D)motiontracking,two-dimensional(2-D)motionsensor.I.INTRODUCTIONLUNGandbronchuscancersaretheleadingcausesofcancerdeathsworldwide[1],withanestimated1608800newcasesand1378400deathsin2008accountingforabout14%ofallcancerdiagnosesandabout25%ofallcancerdeaths.Toreducetheincidenceratesandthemortalityoflungandbronchuscancers,earlydiagnosisisgreatlyneededtoallowformoreeffectivetreatmentinthepreliminarystagesofthesediseases.Forearlydetectionandtreatmentofsuchcancers,ManuscriptreceivedApril08,2013;revisedMay08,2013;acceptedMay08,2013.DateofcurrentversionOctober02,2013.ThisworkwassupportedinpartbytheCenterofExcellenceproject“Developmentofhigh-precisionbed-sidedevicesforearlymetastaticcancerdiagnosisandsurgery”(01-D-D0806)fundedbyAichiPrefecture,JSPSKakenhi“Modality-seamlessnavigationforendoscopicdiagnosisandsurgeryassistancebasedonmulti-modalityimagefusion”(25242047),and“Computationalanatomyforcomputer-aideddiag-nosisandtherapy:Frontiersofmedicalimagesciences”(21103006)fundedbyaGrant-in-AidforScientificResearchonInnovativeAreas,MEXT,Japan.Asteriskindicatescorrespondingauthor.*X.LuoiswiththeInformationandCommunicationsHeadquarters,NagoyaUniversity,Nagoya,Aichi464-8603Japan(e-mail:[e-mail]).K.MoriiswiththeInformationandCommunicationsHeadquarters,NagoyaUniversity,Nagoya,Aichi464-8603Japan(e-mail:[e-mail]).T.KitasakaiswiththeFacultyofInformationScience,AichiInstituteofTechnology,Toyota,Aichi470-03Japan(e-mail:[e-mail]).Colorversionsofoneormoreofthefiguresinthispaperareavailableonlineat:1)apreoperativeimagingexamination,whichisanoninvasivespecialized3-Dscanofapatient’schest,e.g.,usingcomputedtomography(CT)andmagneticresonanceimaging(MRI)scanners,toinitiallyanalyzepulmonaryabnormalitiesand2)intra-operative/interventionalbronchoscopy,whichisaminimallyinvasivemedicalprocedureusingabronchoscopetodirectlyinspecttheairwaysandperformingatransbronchiallungbiopsy(TBLB)tosamplecancerousorsuspicioustissues.Theformerhelpsphysiciansidentifythelocationsofsuspiciouslesionsbeforebronchoscopicinterventions.Thelatterplaysdifferentimportantrolesinthediagnosis,treatment,andstagingoflungcancer.Unfortunately,thesuccessofinterventionalbronchoscopydependsheavilyonthepositionandtheorienta-tiontrackingofthebronchoscopeinoperatingandexaminationrooms.Bycombiningrecenttechnologicaladvancesinaugmentedorvirtualreality,real-timeendoscopicimaging,andminiaturizedtransducerorsensortechniques,interventionalbronchoscopyhasnotonlysignificantlyimproveditsabilitytolocalizetargetregions,tosamplediagnostictissues,andtoprohibitunnec-essarysurgicalinterventionsindiagnosisandstagingoflungcancerbutalsonowpermitstherapeuticprocedurestoremoveairwaydisordersforpatientswithcentralairwayobstructionsandtotreatearlydetectedpulmonarydiseases[14],[23].Eventhoughsignificantprogressandimprovementhavebeenachievedduringthelastdecade,interventionalbronchoscopyremainssomewhatlimitedsimplyduetotheincreasedclinicalapplicationsofbronchoscopicprocedurestodiagnoseandtreatpulmonarydiseases.Onemainreasonisthatitisstillchal-lengingtoaccuratelyandrobustlylocalizethebronchoscopeinairwaytrees.Withoutanyinformationabouttheaccuratelocationofthebronchoscopeinsideairwaytrees,itcannotguaranteetherelativepositionofthetargetregions,suchasbronchiallesions,pulmonarynodules,masses,infiltrates,orlymphnodesduringbronchoscopicinterventions.Currentstate-of-the-artdevelopmentsininterventionalbron-choscopyarefoundinvirtualbronchoscopyandnavigatedbron-choscopytechniquesthatincreasedclinicalapplicationsforin-terventionstodetectandtreatl