醫(yī)學(xué)影像分析與實(shí)作

醫(yī)學(xué)影像分析與實(shí)作OUTLINEImageacquisitionmethodImageenhancementMethodsofQualitativeImageAnalysisExampleforclinicalmedicalimageanalysisMostnuclearmedicineimagingsystemspresenttheirinformationasdigitalimages.Adigitalimageisstoredinthecomputerasanarrayormatrixofcountvaluesandisdisplayedbyassigningagrayorcolorscalethatdependsonthenumberofcountsineachelement.

DigitalImageTheImagearraysaresquarematricesthathavedimensionsrangefrom32*32upto1024*1024Innuclearmedicine:32*32,64*64,128*128,256*256,512*512,1024*1024Bytemode&wordmode

ImageformationFrameModeListModeDualIsotopeImagingFramemode X-YcoordinateBytemode:256grayscale1byte=8bitsWordmode:65535grayscale2byte=1wordListmode2bytedataseriesEventaddressesTimeflagListmodecanbeformattedanyframesizeListmodeneedmorememorySamplingSamplingsize:pixelsize(mm)=fieldofview(mm)/#ofpixelsWhatshouldthepixelsizebe?1.Thespatialresolutionofimagingsystem2.Thesmallestobjectofinterestintheimage3.Thetimeittakestoperformanyprocessingsteps.4.Theamountofstorageandarchivalspaceavailable.InformationDensityWhatinformationcanweexpecttoperceiveatagivencountdensity?

☆thisdependsonthesizeofthesmallestregionintheimageyouaretryingtoperceiveanditsapparentcontrasttothesurroundingbackground.※Howtodefinetheimageinformationdensity?n>k2/C2d2

n:estimatethecountdensityk:thesignal–to–noiseratio(3~5)C:imageconstrastd:imagediameter◎Imageconstrast=(objectcountdensity-backgroundcountdensity)/backgroundcountdensityImageAcquisitionStaticstudiesWhole-BodyImagingDynamicstudiesGatedAcquisitionSPECTAcquisitionDataAcquisitionMethodFrameModeListModeFramemodeAcquisitionPictureelements64*64128*128256*256Pixel:PictureelementSquaremosaic:Imagematrix,ImagearraypixelarrayResolutionSpatialResolutionTemporalResolutionEnergyResolutionSpatialResolution Eachpixelintheimagematrixhasone-to-onecorrespondencewithagivenlocationintheplaneofNaIcrystalEx:GammacameraFOV=40cmdiameterFor64*64S.R=400/64=6.25mm/pixelFor128*128S.R=400/128=3.13mm/pixelStatisticalNoiseIncreaseSpatialresolutionZoomingHardwareSoftwareZoomcan(1)decreaseBackgroundcount(2)increaseresolutionThespatialresolutionofcomputerimageisultimatelylimitbyresolutionofgammacameraBytemodeV.S.Wordmode1Byte=28bits=256(0-255)1Word=216bits=65536(0-65535)1Word=2BytesBytemodeV.S.WordmodeBytemodeAcquisition:apixeldeepis1byteWordmodeAcquisition:apixeldeepis2byteWhatKindoftheacquisitionmodeweshouldused?Inlowcountstudies=>BytemodeInHighcountstudies=>WordmodeBytemodeV.S.WordmodeBytemode優(yōu)點(diǎn):lessmemory缺點(diǎn):1.deadtime2.truncationerrorWordmode優(yōu)點(diǎn):1.Nodeadtime2.Notruncation缺點(diǎn):morememory

Overflow:Deadtime:Truncation:臨床診斷上使用的應(yīng)用軟體影像增強(qiáng)(Imageenhancement)量化分析(QualitativeImageanalysisECT影像重建(ECTimagereconstruction)ImageEnhancementImagesmoothingfiltersP7ImageEnhancementNine-pointsmooth(mask)w1 w2 w3w4 w5 w6w7 w8 w9111111111ImageEnhancementImageEnhancementImageEnhancementMediumsmoothHalfwaymask=>replaceaverage(weight)>50%countvalue(mask)<50%countvalue(Keep)ImageEnhancementEdge-enhancementfilter(sharpenmask)Mask:(2N+1)*(2N+1)ImageEnhancementPointprocessingoperationsBackgroundsubtractionGrayscalesColortranslationtableFrameprocessingoperationex:ParathyroidscanstudyParathyroidsubtractuinImageEnhancement-1-1-1-18-1-1-1-1影像量化分析ROI(regionofinteresting)createHistogramcreateAnalysisROIandHistogramClinicalmathematicPointprocessingoperationBackgroundsubtraction(pixel-by-pixel)PointprocessingoperationInterpolatedbackgroundsubtraction(weight)Wa=Xb/XaWb=Xa/XbWc=Yd/YcWd=Yc/YdXa:Q距A點(diǎn)距離Xb:Q距B點(diǎn)距離Yc:Q距C點(diǎn)距離Yd:Q距D點(diǎn)距離GrayscalesandcolortableGrayscale(dynamicrange)thenumberofshadesofgraybetweenthesetwoextremesType:LinearexponentiallogarithmicGrayandcolortableGrayscalesandcolordisplayGrayscalesandcolordisplayLungperfusion/ventilationratioTl201myocardialperfusionstudyCreatingROIsAutomaticedgedetectionmethods:CreateROIMethod:CircularROIRectangularROIIrregularROIAutomaticROICurveGenerationandAnalysisThestartingpointforanalyzingtheflowpatternquantitativelyistheconstructionofanactivity-versus-timecurve.MethodEye-ballingThemoveaveragemethodTheweightedmoving-averagemethodTheMovingAveragemethodTheMovingAveragemethodDatasmoothingbycurveFittingClinicalMathematicinNuclearMedicineNuclearCardiologyMultiple-gateequilibriumFirstpassblood-poolStaticmyocardialperfusionstudyRenalfunctionGFRKidneyradioERPFDiureticrenography(Lasix)CaptoprilrenographyOtherExampleforVentricularEjectionFractionMultiplegatemodeEjectionFractionEjectionFractionEjectionFractionEjectionFractionEjectionfractionGastricemptytimestudyExampleforrenalfunctionAnalysistoolsForrenalimageratio:1.Arithmeticmethod2.GeometricmethodForfunctionalimage:1.ROI(regionofinteresting)2.Histogram(Timeactivitycurve,TAC)3.CurvefittingArithmeticv.s.GeometricROIinformation(RINFO)RenalimageratioImageratioArithmeticmethod: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)

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

StartCreateROICreateBackgroundROIFramegroupingCreateTAC(timeactivitycurve)ChoiceintegralareaFinalreportEndProcedureFlowChartGFRrenalfunctionstudyConclusion核子醫(yī)學(xué)造影檢查造影過(guò)程電腦資料分析未來(lái)發(fā)展趨勢(shì)TraceKineticsmodelMathematicToolsNewProcedureMorepowerfulImageprocesstoolTHEENDpractice 請(qǐng)依下列數(shù)據(jù)繪出活性時(shí)間曲線,並做curvesmooth.(三點(diǎn)平均)

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