脑缺血再灌注大鼠模型FAIR-PWI研究

目的:探讨流动敏感交替反转恢复序列灌注成像(FAIR- PWI)对大鼠脑缺血后再灌注的评价.方法:使用GE 3.0T MRI成像仪,在完成T1WI、T2WI、弥散加权成像(DWI)和FAIR - PWI序列后,对SD大鼠行暂时性右侧大脑中动脉闭塞(TMCAO)手术,分别在脑缺血3h和再灌注3h及21h行重复上述MRI检查；最后进行病理学TTC染色观察梗死区域及范围.结果:TMCAO后3h时,患侧大脑半球DWI信号升高、FAIR - PWI灌注增加、且皮质相对脑血流量(rCBF)大于基底节区；再灌注3h及21h后,患侧大脑半球DWI信号面积(0.63±0.1.2cm2、0.48±0.23cm2)仍高于FAIR - PWI高灌注面积(0.51±0.26cm2、0.34±0.44cm2,P=0.01),皮质及基底节区rCBF较缺血时增加.TTC染色示梗死面积(0.42±0.78cm2)小于DWI异常信号面积,而大于FAIR - PWI高灌注面积,且梗死区以基底节为主.结论: FAIR- PWI结合DWI能对早期缺血再灌注进行动态观察及半定量测量,可能为临床溶栓治疗方案的预后判断和随访提供重要参考.

Flow Sensitive Alternating Inversion Recovery PerfusionWeighted Imaging in Acute Brain Ischemia and Early Reperfusion of Rats

Purpose:To evaluate the value of flow sensitive alternating inversion recovery perfusion weighted imaging（FAIR - PWI） in cerebral ischemia and reperfusion of rats.Methods:Firstly,SD rats underwent MRI scan including T₁ WI,T₂ WI,diffusion weighted imaging（DWI） and FARI - PWI on a 3.OT machine.Then right side cerebral ischemic model of transient middle cerebral artery occlusion（TMCAO） was operated on rats,and 3 hours later previous MR imaging was repeated.After that,the nylon embolus were extracted for reperfusion,3 hours and 21 hours after reperfusion the same MRI exam was performed repeatedly.Lastly,rats were sacrificed for TTC staining,and the infarction size was measured. Results:At 3h after TMCAO,signal intensity of affected side on DWI and FAIR - PWI was increased, and cortical perfusion was higher than basal ganglia perfusion.At 3h and 21h after reperfusion,the size of lesion area on DWI were still larger（0.63±0.12cm²,0.48±0.23cm²） than that on FAIR - PWI（0.51±0.26cm²、0.34±0.44cm²,P = 0.0103,P = 0.0129）;both cortical perfusion and basal ganglia perfusion were higher than those during ischemic phase.Lastly,the size of infarct area on TTC stain（0.42±0.78 cm²） was less than that of DWI,but larger than that of FAIR - PWI,and the infarct areas were mostly located at basal ganglia.Conclusion:As a noninvasive method,combined with DWI,FAIR - PWI can dynamically detect early ischemia and reperfusion without administration of contrast media,which may provide important information for thrombolysis therapy and follow up.