CT灌注成像课件

反映组织的血管化程度及血流灌注情况，获得血液动力学方面的信息。方法：快速造影剂团注后(5ml/s以上)，在首次经过受检组织的过程中对某一选定的层面进行快速动态扫描，获得一系列动态图像，分析造影剂通过每个像素所对应的体素密度的差异，从而得到反映血流灌注情况的参数。CT灌注成像(Perfusion)脑梗塞肝、肾血流灌注及肿瘤的诊断肾移植的血流灌注的评价，了解移植血管的情况电子束CT的灌注可了解心脏灌注，有助于缺血性心肌病的早期诊断CTPerfusion应用由脑局部缺血而阻碍血液扩散是导致中风，占脑中风70%。用血纤维蛋白可溶解闭塞的血管。发生中风后，有效治疗的时间为3小时左右。要尽快了解病情类型、发病时间和局部缺血的程度。在这段时间内常规CT检查较难发现，而灌注CT可应用于急性中风检查。CT灌注脑动脉系统在快速注射造影剂后，计算和脑的扩散有关的参数，从不同侧面提供中风的灌注分布情况：脑血液流量CerebralBloodFlow,CBF

脑血液容量CerebralBloodVolume,CBV

造影剂达到各点最大值的时间TimePeak，TP

平均通过时间Meantransittime，MTT通过CBV与MTT可获得CBFCTPerfusion常规CT通过组织对X线不同衰减来显示图像

CTA通过造影剂在血管内流动来显示血管结构灌注CT利用血液流动有关的参数CBF信号强示流速大；造影剂到达高峰的时间分布图TP，愈大意味着造影到达晚。

CBF直接把它和向脑组织提供氧的总量联系起来，同时也与血液动力学方面有关。CTPerfusion紫色区域为血流量少,大脑急性中风区域红色区域血流量大CBF左半脑症状出现60分钟后，CT平扫无脑异常血液流动，(b)示左侧半脑广泛性和右前部的局部缺血。原因：左颈内动脉闭塞。CBFTime-to-peakimage3天后CT上述病例进行动脉血纤维蛋白溶解处理，治疗后一天，用扩散CT成像显示了治疗效果，3天以后CT平扫，示梗塞形成，"核心"区域与CBF和CBV图像相似。与CBV(b)相比CBF(a)、TP(c)在MCA中局部缺血间不匹配。在脑岛脑皮层背部(箭)有一梗塞灶。再通治疗法后24小时(d)在MCA同样位置示受限梗塞区。71-year-oldfemalepatientwithright-sidedhemiplegia(偏瘫)andglobalaphasia(失语).PlainCT(90minuteslater)revealsnoearlysignsofanischemia(局部缺血).Theparameterimagesdisplaytheentireextentoftheischemiawithahigh-gradereductionofCBFandCBV,alackingdetectionofthecontrastbolusinthetime-to-peakimage.Theinfarction(梗塞)includestheregionoftheanteriorcerebralarteryandlargeportionsoftheregionsuppliedbythemiddlecerebralartery,bothfeaturesindicativeofanocclusionoftheintracranialcarotidbifurcation.Case1Patient(male44)witharight-sidedischemiaintheregionofthemiddlecerebralartery(MCA)whichbegan160minutesago.Typicalfindingsofahigh-gradedisturbanceinperfusionintheinsularcortexandtheposteriorportionofthelentiformnucleuswithareductioninCBFandCBVasaresultofanembolicocclusioninthedistalM1segment.TheotherregionssuppliedbytheMCAdemonstratedgoodleptomeningealcollateralbloodsupplywhichonlyshowedmoderatelyreducedCBFandCBVvalues,aswellasaprolongationofthetime-to-peak.Case2InthecalculationofrelativeperfusionindicesfromCBFvaluesinischemicareasandinmirrorredROIswithintheunaffectedhemisphereprovedtobeavaluablemethodfortheprognosticevaluationofaregionwithreducedperfusion.ThecoreoftheinfarctandtheischemicmarginalzonesdemonstrateclearlydifferentCBFperfusionindices(green-markedROI=0.17versusred-markedROI=0.69).

70minutesaftertheoccurrenceoftheinfarction,theCBFimagerevealedahighgradeischemiainthefrontalregionofthesupplyareaoftheMCAandinthelentiformnucleus(Fig.3a)withaperfusionindexinthegreenmarkedROIof0.07(Fig.3b).Asaresultofthegoodcollateralflow,thedisturbanceinperfusionintheremainingregionoftheMCA,withaperfusionindexof0.82,isnotseentobeveryextensive(red-markedROIinFig.3b).36-year-oldmalepatientwithanembolicocclusionintheM1segmentoftheleftMCAandasimultaneousocclusionoftheleftinternalcarotidarteryasaresultofdissection.Case3Becauseofthepartiallyhigh-gradeischemiaontheonehandandtheexcellentcollateralbloodsupplyofthemarginalregionontheother,fibrinolysiswasnotperformedinspiteoftheshorttimeinterval.Asexpected,thefollow-upCTrevealedthedevelopmentofaninfarctionintheareawhichhadprimarilydemonstratedahigh-gradeischemia.CTPerfusion前景目前认为中风处理的最佳时间在60分钟。通过对造影剂注入位置与方式的研究，灌注CT在不到15分钟中完成中风评价过程。Ischemiaswithamildtomoderatedegreeofseverity(CBFperfusionindex:0.35-0.9)progressedwellunderfibrinolytictherapy.EveninischemicregionswithaCBFindexof<0.35,intra-arterialfibrinolysiscouldpreventthedevelopmentofaninfarctinmorethanhalfofthecases,aslongastheindexdidnotfallbelowacriticalvalueof0.2.Otherwise,ascouldbeverifiedwithfollow-upinvestigationscarriedoutwithcomputedtomographyandmagneticresonancetomography,ischemicnecroseswereseentodevelopwithoutexception.Inthisway,itwaspossibletomakeadifferentiat