医学影像系统原理7 超声

UltrasoundImagingandItsApplicationsMingyueDingDepartmentofBio-medicalEngineering“ImageProcessingandIntelligentcontrol”KeyLaboratoryofEducationMinistry2023/10/82OUTLINES1.Whatisultrasound?2.Historyofthedevelopmentofultrasoundimagingtechnique3.2Dultrasoundimaging4.3Dultrasoundimaging5.3Dultrasoundimagingapplications3WhatisSOUND?SoundisamechanicalwavethatwecanhearAmechanicalwavecanbedescribedby:Amplitude:aWavelength:Frequency:fSoundspeed:Ca4SoundPropagationSpeedSoundcanbetransmittedthroughanymedium-gas,liquid,orsolid.Soundspeedthroughthemediumdependsonthecompressibilityofthemedium.Thespeedsofsomematerialsareshowninthetablebelow.

Soundspeedindifferentmaterials(m/s)AluminiumBoneLiverKidneyBloodFatWaterLungAir64003500157015601570146014936503325PropertiesofSoundPropagationSoundatdifferentfrequencycanbetransmittedinthesamemediumatthesamespeed.Thedifferentmediumhasdifferentspeedforsoundtransmissionwiththesamefrequency.

6WhatisULTRASOUND?Ultrasoundisanysoundwithafrequencyabovetherangeofhumanhearing,approximately20KHz.Themostoftenusedfrquencybandinmedicalimagingisbetween2and10MHz.Soundspeedformula:SupposeCtobe1540m/s,thewavelengthsinsofttissueareintherangeof0.77-0.154mm.Thehighfrequenciesmeanshorterwavelengths.7PrincipleofUltrasoundImaging8PrincipleofUltrasoundImagingApulseispropagatedanditsreflectionisreceived, bothbythetransducer.Keyassumption: -Soundwaveshaveanearlyconstantvelocityof~1500m/sinH2O. -SoundwavevelocityinH2Oissimilartothatinsofttissue.Thus,echotimemapstodepth.

9UltrasoundPrinciple10UltrasoundImage(Embryo)11Ultrasound:ResolutionandTransmissionFrequencyTradeoffbetweenresolutionandattenuation-↑higherfrequency↓shorterwavelength↑higherattenuation Powerloss:TypicalUltrasoundFrequencies: DeepBody 1.5to3.0MHz SuperficialStructures 5.0to10.0MHze.g.15cmdepth,2MHz,60dBroundtripWhynotuseaverystrongpulse?Ultrasoundathighenergycanbeusedtoablate(kill)tissue.Cavitation(bubbleformation)Temperatureincreaseislimitedto1ºCforsafety.12FrequencyUsedinUSImagingTohaveenoughresolutionfortheobservationofhumanorgans,afrequencyhigherthan0.15MHz,awavelengthlessthan1.0cm,hastobeused.Alsothefrequencywilldeterminethedepthofimaging,thelowerthefrequency,thebigthedepthwillbe.Forabdominalimaging,afrequencybetween1.0-3.0MHzhastobeused.Foreyeexamination,afrequencyashighas20MHzisused.ForIVUSimaging,40MHzisused.13Historyofthe

DevelopmentofUltrasound(I)KarlTheodoreDussik,aneurologist/psychiatristfromTheUniversityofVienna,Austriawasregardedasthefirstphysiciantohaveemployedultrasoundinmedicaldiagnosis:locatebraintumorandthecerebralventriclesbymeasuringthetransmissionofultrasoundbeamthroughtheskullin1942.Theearliestuseofultrasoundisintherapyinsteadofdiagnosis:DestroythebasalgangliainpatientswithParkinsonism(WilliamFry,RussellMeyers)Treatmentofpatientswithrheumaticarthritis(JeromeGersten,1953)14Historyofthe

DevelopmentofUltrasound(II)SystematicinvestigationsintousingultrasoundasadiagnostictoolwasmadebyGeorgeLudwig,aphysicianattheNavalResearchInstituteinBethseda,Marylandintheexperimentsonanimaltissuesusingpulse-echoultrasound.“SONICS-techniquesfortheuseofsoundandultrasoundinengineeringandscience”(TheodoreHueter,RichardBolt)bookpublishedin1954.15Historyofthe

DevelopmentofUltrasound(III)AftertheKoreanwar,JohnJulianWildandJohnReidbuiltalinearhand-heldB-modeinstrumentandbecomethefirstpublicationonintensity-modulatedcross-sectionultrasoundimaging.TheyalsoinventedA-modetrans-vaginalandtrans-rectalscanningtransducersin1955.16Historyofthe

DevelopmentofUltrasound(IV)The“Panscanner”developedin1957byDouglassHowryattheUniversityofColorado,USA.Problem:Immersetotallyorpartiallyinwater

17Historyofthe

DevelopmentofUltrasound(V)In1962,thefirstcommerciallyavailable,hand-heldarticulatedarmcompoundcontactscannerwasproducedbyengineersWilliamWrightandEdwardMeyerdinkinUSA.TheworkofHowryandhisteamisthemostimportantpioneeringworkinB-modeultrasoundimagingandcontactscanningthatwehavetoday.

18Pulse-echoRangingApplications:BatsSonarsystemDetectssubmarinesSONAR-SoundNavigationAndRanging.192DUltrasoundImagingA-modeultrasoundHorizontalaxisisusedtorepresenttimewhiletheverticalaxisofthesignalistorepresenttheamplitudeofthesignal.

202DUltrasoundImagingB-modelultrasoundTousethebrightnessofthescreentodisplaytheamplitudeofthesignal.Thegreatertheamplitude,thegreaterthebrightnessofthespot.

212DUltrasoundImagingB-modelultrasoundscan:SectorscanLinearscanPPI(planpositionindicator)

SectorLinearPPI222DUltrasoundImagingM-modeultrasoundAlsocalledMotionultrasound

232DUltrasoundImagingDopplerultrasound

24UltrasoundDopplerTransducer25UltrasoundDopplerPrinciple26UltrasoundDopplerImage272DUltrasoundMachine28UltrasoundImagingWhyuseultrasound?LowcostandportablesystemSafestimagingmodalityFast,real-timeimagingSuitabilityforviewingthesofttissuesandorganssuchasprostate,liver,heart,lung……29Limitationsof2D

UltrasoundImaging2Dtechniquemustbuildthe3Dimagementallyleadstoinaccuracy&variabilityleadstolongproceduresSpatiallyflexibletechniquedifficultiesinreproducingsameviewdifficultiesinpatientfollow-updifficultiesininterventionalprocedures303DUltrasound:Side-firescan3DReconstruction3DMotorizedScan(uniform)31RotationalMover(Side-Fire)32ParallelScanning333DCarotidUS:Freehandscan34Scanningmodein3Dultrasound

Mechanicalscanning

Parallelscanning

Rotationalscanning

Fanscanning

Randomscanning,freehandscanning

Realtime3Dvolumeprobe:

2Darraytransducer

volumeprobe35Parallelscanning36Side-fireScanning37Randomscanningwithalocalizationsystem38IntravascularUltrasoundImaging39IVUSCatheterConfiguration40TheAnalysisofIVUSImage41AngiographyVSIVUS42DiseasecanonlybeidentifiedbyIVUS43TheIVUSCatheterUsagein

USAandWorld44IVUSApplications45MeasurementofPlaque464DIVUS473DUSapplication:fetusdefectdetectionBorninfant3Dfetusimage48493DProstateUltrasoundImagebyusingtransrectaltransducer50ProstateBrachytherpy:

Segmentedprostate51ContinuityBased3DProstateSegmentationinUSImage

52NeedleDetectionin3D53Plaquesegmentation:

Carotid3DUSimage54Volumeofplaque:964mm3Plaquesegmentedfromthe3DUSCarotidimage55xnzpxpznyn

3DUSGuidedBreastBiopsyApparatus56InterfaceusedinourRFAblationsystem

573DRotationalScanningProbe

583DUSImagingSystembasedonRotationalScanning59Reconstructioncomparisonofporkliver：Sideview

TraditionalmethodOurmethod60Reconstructioncomparisonofporkliver：Topview

TraditionalmethodOurmethod61Waterimageacquiredatthree

differenttimes62Pininsertedintowateratthreedifferenttimes63PinsegmentedresultBeforeinsertionDetectedpinAfterinsertion643DUltrasoundApplication:ProstateBrachytherapyProstatecanceristhesecondleadingcausedeathofnorthernAmericanmenTheAmericanCancerInstituteestimates230,110newcase,29,900deadin2004.CanadianCancerSocietyestimates20,100newcases,4,200deadin2004.Prostatecanceriscurableatearlystage.65StandardTreatmentsof

ProstateCancerWatchfulwaiting:Mostpatientsrequestorneedtreatment.Radicalprostatecotomy:Goldstandardbutwithsignificantmorbidity,suchasincontinenceandimpotence.Externalbeamradiation,suchasIMRT:Longtreatmenttime,killthenormaltissue.Prostatebrachytherapy:Shortstay,safefornormaltissue66BrachytherapyOperation67Side-fireScannedTransrectalProbe

68NeedleTrackingandGuidanceUnder3DUltrasoundImagingNeedtoknowwheretheneedleisandwhereitwillgo.Determinethetippositionoftheneedle.Theprocessinghastobeperformedinreal-time.69ObliqueNeedleInsertion70Whyis

NeedleSegmentationinUSImagesDifficult?

Ultrasoundimagespeckle&shadowsLarge3Dimage357

326

352

1byte=40MBHighaccuracyrequiredReal-timeprocessing(30fps,or33msperimage)71MotivationforOur3DNeedleSegmentationNeedleisconspicuousinaprojectedimage.LineobjectcanbereconstructedfromtwoorthogonalprojectionsApproximateneedleinsertionpointanddirectionisknown72Flowchartforour3DNeedleSegmentation

Steps1&2Step3Step473Step1:VolumeRendering

(RayCasting)Castraysthrough3DimagetoimageplaneVoxelsIn-1,…,I074Step1:VolumeRenderingFront-to-backraytracingequations:Grayleveldistributionofneedlevoxels:Gaussiantransferfunctions:Luminancec

(

I

)Opacity

(

I

)

75ExampleofVolumeRenderingWithrenderingWithoutrenderingAgarphantom76Step2:VolumeCroppingComplexbackground,largevolumeEstimateneedleposition/orientationfromaprioriknowledge:ManualinsertionMotorizedmechanicaldeviceLocalizingsystem(e.g