医学影像分析与实作.pptVIP

醫學影像分析與實作,.,OUTLINE,ImageacquisitionmethodImageenhancementMethodsofQualitativeImageAnalysisExampleforclinicalmedicalimageanalysis,.,Mostnuclearmedicineimagingsystemspresenttheirinformationasdigitalimages.Adigitalimageisstoredinthecomputerasanarrayormatrixofcountvaluesandisdisplayedbyassigningagrayorcolorscalethatdependsonthenumberofcountsineachelement.,.,DigitalImage,TheImagearraysaresquarematricesthathavedimensionsrangefrom32*32upto1024*1024Innuclearmedicine:32*32,64*64,128*128,256*256,512*512,1024*1024Bytemode&wordmode,.,Imageformation,FrameModeListModeDualIsotopeImaging,.,Framemode,X-YcoordinateBytemode:256grayscale1byte=8bitsWordmode:65535grayscale2byte=1word,.,Listmode,2bytedataseriesEventaddressesTimeflagListmodecanbeformattedanyframesizeListmodeneedmorememory,.,Sampling,Samplingsize:pixelsize(mm)=fieldofview(mm)/#ofpixelsWhatshouldthepixelsizebe?1.Thespatialresolutionofimagingsystem2.Thesmallestobjectofinterestintheimage3.Thetimeittakestoperformanyprocessingsteps.4.Theamountofstorageandarchivalspaceavailable.,.,InformationDensity,Whatinformationcanweexpecttoperceiveatagivencountdensity?thisdependsonthesizeofthesmallestregionintheimageyouaretryingtoperceiveanditsapparentcontrasttothesurroundingbackground.Howtodefinetheimageinformationdensity?nk2/C2d2n:estimatethecountdensityk:thesignaltonoiseratio(35)C:imageconstrastd:imagediameterImageconstrast=(objectcountdensity-backgroundcountdensity)/backgroundcountdensity,.,ImageAcquisition,StaticstudiesWhole-BodyImagingDynamicstudiesGatedAcquisitionSPECTAcquisition,.,DataAcquisitionMethod,FrameModeListMode,.,FramemodeAcquisition,Pictureelements64*64128*128256*256Pixel:PictureelementSquaremosaic:Imagematrix,Imagearraypixelarray,.,Resolution,SpatialResolutionTemporalResolutionEnergyResolution,.,SpatialResolution,Eachpixelintheimagematrixhasone-to-onecorrespondencewithagivenlocationintheplaneofNaIcrystalEx:GammacameraFOV=40cmdiameterFor64*64S.R=400/64=6.25mm/pixelFor128*128S.R=400/128=3.13mm/pixel,.,StatisticalNoise,.,IncreaseSpatialresolution,ZoomingHardwareSoftwareZoomcan(1)decreaseBackgroundcount(2)increaseresolutionThespatialresolutionofcomputerimageisultimatelylimitbyresolutionofgammacamera,.,BytemodeV.S.Wordmode,1Byte=28bits=256(0-255)1Word=216bits=65536(0-65535)1Word=2Bytes,.,BytemodeV.S.Wordmode,BytemodeAcquisition:apixeldeepis1byteWordmodeAcquisition:apixeldeepis2byteWhatKindoftheacquisitionmodeweshouldused?Inlowcountstudies=BytemodeInHighcountstudies=Wordmode,.,BytemodeV.S.Wordmode,Bytemode優點:lessmemory缺點:1.deadtime2.truncationerrorWordmode優點:1.Nodeadtime2.Notruncation缺點:morememory,Overflow:Deadtime:Truncation:,.,臨床診斷上使用的應用軟體,影像增強(Imageenhancement)量化分析(QualitativeImageanalysisECT影像重建(ECTimagereconstruction),.,ImageEnhancement,ImagesmoothingfiltersP7,.,ImageEnhancement,Nine-pointsmooth(mask),.,ImageEnhancement,.,ImageEnhancement,.,ImageEnhancement,MediumsmoothHalfwaymask=replaceaverage(weight)50%countvalue(mask)50%countvalue(Keep),.,.,.,ImageEnhancement,Edge-enhancementfilter(sharpenmask)Mask:(2N+1)*(2N+1),.,.,ImageEnhancement,PointprocessingoperationsBackgroundsubtractionGrayscalesColortranslationtableFrameprocessingoperationex:Parathyroidscanstudy,.,Parathyroidsubtractuin,.,ImageEnhancement,.,影像量化分析,ROI(regionofinteresting)createHistogramcreateAnalysisROIandHistogramClinicalmathematic,.,Pointprocessingoperation,Backgroundsubtraction(pixel-by-pixel),.,Pointprocessingoperation,Interpolatedbackgroundsubtraction(weight),Wa=Xb/XaWb=Xa/XbWc=Yd/YcWd=Yc/Yd,Xa:Q距A點距離Xb:Q距B點距離Yc:Q距C點距離Yd:Q距D點距離,.,Grayscalesandcolortable,Grayscale(dynamicrange)thenumberofshadesofgraybetweenthesetwoextremesType:Linearexponentiallogarithmic,.,Grayandcolortable,.,Grayscalesandcolordisplay,.,Grayscalesandcolordisplay,.,Lungperfusion/ventilationratio,.,Tl201myocardialperfusionstudy,.,CreatingROIs,Automaticedgedetectionmethods:,.,CreateROI,Method:CircularROIRectangularROIIrregularROIAutomaticROI,.,CurveGenerationandAnalysis,Thestartingpointforanalyzingtheflowpatternquantitativelyistheconstructionofanactivity-versus-timecurve.MethodEye-ballingThemoveaveragemethodTheweightedmoving-averagemethod,.,TheMovingAveragemethod,.,TheMovingAveragemethod,.,DatasmoothingbycurveFitting,.,ClinicalMathematicinNuclearMedicine,NuclearCardiologyMultiple-gateequilibriumFirstpassblood-poolStaticmyocardialperfusionstudyRenalfunctionGFRKidneyradioERPFDiureticrenography(Lasix)CaptoprilrenographyOther,.,ExampleforVentricularEjectionFraction,.,Multiplegatemode,.,EjectionFraction,.,EjectionFraction,.,EjectionFraction,.,EjectionFraction,.,Ejectionfraction,.,Gastricemptytimestudy,.,Exampleforrenalfunction,.,Analysistools,Forrenalimageratio:1.Arithmeticmethod2.GeometricmethodForfunctionalimage:1.ROI(regionofinteresting)2.Histogram(Timeactivitycurve,TAC)3.Curvefitting,.,Arithmeticv.s.GeometricROIinformation(RINFO),Renalimageratio,.,Imageratio,Arithmeticmethod:anteriorview:rightkidneycount(Ra)leftkidneycount(La)posteriorview:rightkidneycount(Rp)leftkidneycount(Lp)mean:(Ra+Rp)/2=Rm,(La+Lp)/2=LmRatio:Kr=Rm/(Rm+Lm),Kl=Lm/(Rm+Lm),.,Imageratio,Geometricmethod:anteriorview:rightkidneycount(Ra)leftkidneycount(La)posteriorview:rightkidneycount(Rp)leftkidneycount(Lp)mean:Ratio:Kr=Rm/(Rm+Lm),Kl=Lm/(Rm+Lm),.,Gatesmethod,.,Start,CreateROI,CreateBackgroundROI,Framegrouping,CreateTAC(timeactivitycurve),Choiceintegralarea,Finalreport,End,ProcedureFlowChart,.,GFRrenalfunctionstudy,.,Conclusion,核子醫學造影檢