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1、Chapter13161BrainNeoplasmsIncollaborationwithA.HiwatashiOtherstudieshavesuggestedthatADCcorrelatesnot13.1Introductiononlywithtumorcellularity,butalsowithtotalnu-clearareaandtumorgrade[8,12,13,17,19],withRoutineMRimagingisthemostsensitivemethodofhigh-gradetumorshaving
2、highcellulardensityanddetectingtumorsofthebrain.Itis,however,notspe-decreasedADC.OtherstudieshavecorrelatedareascificenoughtodeterminethehistologicnatureofofdecreasedADCandfoundittobeassociatedwithmosttumors.Diffusion-weighted(DW)imagingcanincreasedcholineonMRspectros
3、copy.Cholineisadifferentiatebetweentumorandinfection[1–51]andmarkerforcellmembraneturnover[7,9].canprovideinformationabouttumorcellularity,Althoughthereisageneralprincipleofhigh-therebyhelpinginthecharacterizationandgradinggradegliomashavinghighDWsignalwithdecreasedo
4、fbraintumors.ThischapterwilldemonstrateDWADC,therearestillcontroversiesregardinghowwellimagingcharacteristicsofintracranialtumors.DWimagingcandifferentiatebetweenhigh-gradeprimarybraintumors,lymphomaandmetastasis.Krabbeetal.reportedthatboththecontrast-enhanc-13.2Glio
5、masingportionsandtheperitumoraledemaofmetasta-sishavehigherADCthanhigh-gradegliomas[6].InThesignalintensityofgliomasonDWimagesisvari-theindividualcasethedistinctionbetweenmetasta-ableanddependsmainlyontheirT2andapparentsisandhigh-gradegliomaisoftendifficulttomake,diff
6、usioncoefficient(ADC)values[1–22].Thus,someassomehigh-gradegliomasalsohavehighADC[18,gliomasarehyperintenseonDWimageswithde-46].Forlymphomas,Guoetal.reportedthatADCwascreasedADC,whichreflectsareducedvolumeofthegenerallylowerthaninhigh-gradegliomas.Thisextracellularspac
7、e.Othergliomashaveanormalorcouldbeusefultodifferentiatethetwo[16],butintheincreasedADC,thatistheDWsignalisaT2shine-clinicalsituationthereisoftenoverlapbetweenlym-througheffect(Figs.13.1,13.2,13.3,13.4,13.5,13.6phomaandhigh-gradelymphoma.Inourexperi-and13.7).ence,theA
8、DCoflymphomarangesbetween0.51and0.71×10-3mm2/s,whereasthatofhigh-gradegliomasrangesbetween0.58and0.89×10-3mm2/s.Lym-13.2.1High-Grad
