医学影像分析与实作

醫學影像分析與實作

2020/12/191OUTLINEImageacquisitionmethodImageenhancementMethodsofQualitativeImageAnalysisExampleforclinicalmedicalimageanalysis2020/12/192Mostnuclearmedicineimagingsystemspresenttheirinformationasdigitalimages.Adigitalimageisstoredinthecomputerasanarrayormatrixofcountvaluesandisdisplayedbyassigningagrayorcolorscalethatdependsonthenumberofcountsineachelement.

2020/12/193DigitalImageTheImagearraysaresquarematricesthathavedimensionsrangefrom32*32upto1024*1024Innuclearmedicine:32*32,64*64,128*128,256*256,512*512,1024*1024Bytemode&wordmode

2020/12/194ImageformationFrameModeListModeDualIsotopeImaging2020/12/195Framemode X-YcoordinateBytemode:256grayscale1byte=8bitsWordmode:65535grayscale2byte=1word2020/12/196Listmode2bytedataseriesEventaddressesTimeflagListmodecanbeformattedanyframesizeListmodeneedmorememory2020/12/197SamplingSamplingsize:pixelsize(mm)=fieldofview(mm)/#ofpixelsWhatshouldthepixelsizebe?1.Thespatialresolutionofimagingsystem2.Thesmallestobjectofinterestintheimage3.Thetimeittakestoperformanyprocessingsteps.4.Theamountofstorageandarchivalspaceavailable.2020/12/198InformationDensityWhatinformationcanweexpecttoperceiveatagivencountdensity?☆thisdependsonthesizeofthesmallestregionintheimageyouaretryingtoperceiveanditsapparentcontrasttothesurroundingbackground.※Howtodefinetheimageinformationdensity?n>k2/C2d2

n:estimatethecountdensityk:thesignal–to–noiseratio(3~5)C:imageconstrastd:imagediameter◎Imageconstrast=(objectcountdensity-backgroundcountdensity)/backgroundcountdensity2020/12/199ImageAcquisitionStaticstudiesWhole-BodyImagingDynamicstudiesGatedAcquisitionSPECTAcquisition2020/12/1910DataAcquisitionMethodFrameModeListMode2020/12/1911FramemodeAcquisitionPictureelements64*64128*128256*256Pixel:PictureelementSquaremosaic:Imagematrix,Imagearraypixelarray2020/12/1912ResolutionSpatialResolutionTemporalResolutionEnergyResolution2020/12/1913SpatialResolution Eachpixelintheimagematrixhasone-to-onecorrespondencewithagivenlocationintheplaneofNaIcrystalEx:GammacameraFOV=40cmdiameterFor64*64S.R=400/64=6.25mm/pixelFor128*128S.R=400/128=3.13mm/pixel2020/12/1914StatisticalNoise2020/12/1915IncreaseSpatialresolutionZoomingHardwareSoftwareZoomcan(1)decreaseBackgroundcount(2)increaseresolutionThespatialresolutionofcomputerimageisultimatelylimitbyresolutionofgammacamera2020/12/1916BytemodeV.S.Wordmode1Byte=28bits=256(0-255)1Word=216bits=65536(0-65535)1Word=2Bytes2020/12/1917BytemodeV.S.WordmodeBytemodeAcquisition:apixeldeepis1byteWordmodeAcquisition:apixeldeepis2byteWhatKindoftheacquisitionmodeweshouldused?Inlowcountstudies=>BytemodeInHighcountstudies=>Wordmode2020/12/1918BytemodeV.S.WordmodeBytemode優點:lessmemory缺點:1.deadtime2.truncationerrorWordmode優點:1.Nodeadtime2.Notruncation缺點:morememory

Overflow:Deadtime:Truncation:2020/12/1919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)2020/12/1920ImageEnhancementImagesmoothingfiltersP72020/12/1921ImageEnhancementNine-pointsmooth(mask)w1 w2 w3w4 w5 w6w7 w8 w91111111112020/12/1922ImageEnhancement2020/12/1923ImageEnhancement2020/12/1924ImageEnhancementMediumsmoothHalfwaymask=>replaceaverage(weight)>50%countvalue(mask)<50%countvalue(Keep)2020/12/19252020/12/19262020/12/1927ImageEnhancementEdge-enhancementfilter(sharpenmask)Mask:(2N+1)*(2N+1)2020/12/19282020/12/1929ImageEnhancementPointprocessingoperationsBackgroundsubtractionGrayscalesColortranslationtableFrameprocessingoperationex:Parathyroidscanstudy2020/12/1930Parathyroidsubtractuin2020/12/1931ImageEnhancement-1-1-1-18-1-1-1-12020/12/1932影像量化分析ROI(regionofinteresting)createHistogramcreateAnalysisROIandHistogramClinicalmathematic2020/12/1933PointprocessingoperationBackgroundsubtraction(pixel-by-pixel)2020/12/1934PointprocessingoperationInterpolatedbackgroundsubtraction(weight)Wa=Xb/XaWb=Xa/XbWc=Yd/YcWd=Yc/YdXa: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2020/12/1935GrayscalesandcolortableGrayscale(dynamicrange)thenumberofshadesofgraybetweenthesetwoextremesType:Linearexponentiallogarithmic2020/12/1936Grayandcolortable2020/12/1937Grayscalesandcolordisplay2020/12/1938Grayscalesandcolordisplay2020/12/1939Lungperfusion/ventilationratio2020/12/1940Tl201myocardialperfusionstudy2020/12/1941CreatingROIsAutomaticedgedetectionmethods:2020/12/1942CreateROIMethod:CircularROIRectangularROIIrregularROIAutomaticROI2020/12/1943CurveGenerationandAnalysisThestartingpointforanalyzingtheflowpatternquantitativelyistheconstructionofanactivity-versus-timecurve.MethodEye-ballingThemoveaveragemethodTheweightedmoving-averagemethod2020/12/1944TheMovingAveragemethod2020/12/1945TheMovingAveragemethod2020/12/1946DatasmoothingbycurveFitting2020/12/1947ClinicalMathematicinNuclearMedicineNuclearCardiologyMultiple-gateequilibriumFirstpassblood-poolStaticmyocardialperfusionstudyRenalfunctionGFRKidneyradioERPFDiureticrenography(Lasix)CaptoprilrenographyOther2020/12/1948ExampleforVentricularEjectionFraction2020/12/1949Multiplegatemode2020/12/1950EjectionFraction2020/12/1951EjectionFraction2020/12/1952EjectionFraction2020/12/1953EjectionFraction2020/12/1954Ejectionfraction2020/12/1955Gastricemptytimestudy2020/12/1956Exampleforrenalfunction2020/12/1957AnalysistoolsForrenalimageratio:1.Arithmeticmethod2.GeometricmethodForfunctionalimage:1.ROI(regionofinteresting)2.Histogram(Timeactivitycurve,TAC)3.Curvefitting2020/12/1958Arithmeticv.s.GeometricROIinformation(RINFO)Renalimageratio2020/12/1959ImageratioArithmeticmethod: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)

2020/12/1960ImageratioGeometricmethod:anteriorview:rightkidneycount(Ra)leftkidneycount(La)posteriorview:rightkidneycount(Rp)leftkidneycount(Lp)mean:Ratio:Kr=Rm/(Rm+Lm),Kl=Lm/(Rm+Lm)2020/12/1961Gate’smethod

2020/12/1962StartCreateROICreateBackgroundROIFramegroupingCreateTAC(timeactivitycurve)ChoiceintegralareaFinalreportEndProcedureFlowChart2020/12/1963GFRrenalfunctionstudy2020/12/1964Conclusion核子醫學造影檢查造影過程電腦資料分析未來發展趨勢TraceKineticsmodelMathematicToolsNewProcedureMorepowerfulImageprocesstool2020/12/1965THEEND2020/1