医学影像分析与实作.ppt

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 n k2 C2d2n estimatethecountdensityk thesignal to noiseratio 3 5 C imageconstrastd imagediameter Imageconstrast 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 Gate smethod Start CreateROI CreateBackgroundROI Framegrouping CreateTAC timeactivitycurve Choiceintegralarea Finalreport End ProcedureFlowChart GFRrenalfunctionstudy Conclusion 核子醫學造影檢