超急性脑梗死再灌注弥散加权--灌注磁共振成像实验研究

目的　应用弥散 -灌注磁共振成像技术对改良线栓法建立的超急性脑梗死再灌注模型进行实验研究。明确该技术对超急性脑梗死再灌注的评价作用。方法　 90只SD大鼠 ,随机分成 5组 ,A组 ( 10只 )假手术做对照 ,其余按栓塞时间 3 0min、1、3、6h均分成B、C、D、E 4组 ;行DWI、PI和常规T2 WI、T1WI扫描 ;DWI和PI原始图像重建获得ADC、CBV、CBF、MTT参数形态图。观察各栓塞时间点再灌注 2、2 4h后各项参数变化。结果　A组DWI、PI成像无异常信号。B组再灌注 2hDWI高信号消失 ,ADC值恢复正常化 ( 88.2 7%± 1.92 % ) ,2 4h继发性ADC值降低和DWI高信号 ;C组再灌注 2h后ADC值轻度升高 ,2 4h明显降低 ;D、E组再灌注 2、2 4hADC值轻度降低或基本不变 ;各组再灌注后 2 4hDWI显示病灶范围无明显扩大。A、B组再灌注后PI各参数指标 (CBV、CBF、MTT)恢复和维持正常 ,而D、E组的信号强度 -时间曲线图有 3种表现 ,分别为高灌注、低灌注和正常灌注。结论　在超急性脑梗死中MCAo 3 0min再灌注后初次DWI异常信号消散是暂时的 ,以后会发生继发性DWI异常信号 ;再灌注可限制病灶进一步扩大 ,保护缺血半影区

An Experimental Study for Hyperacute Cerebral Infarction Reperfusion in Rats by Diffusion Weighted-perfusion Magnetic Resonance Imaging

Objective To assess the role of diffusion-perfusion MRI in evaluating the experimental model of hyperacute cerebral infarction reperfusion in rat.Methods All 90 SD rats were randomly divided into 5 groups, group A(n=10) was sham-operated for control study, group B,C,D,E(n=10 for each)were divided according to time intervals of 30 minutes,1 hour,3 hours,6 hours after occluding the left middle cerebral artery (MCAo)with thread and reflowed at each time end point at the onset of the occlusion. All rats were examined by diffusion weighted imaging(DWI),perfusion imaging(PI),T 1WI,T 2WI during their occlusion and 2,24 hours after reperfusion.Results In group A there was no change in the signal intensity of DWI, PI ; in group B, it could be seen that the initial DWI high-intensity signal shadow disappeared and ADC recovered normally at 2 hours after reperfusion following by secondary DWI hyper-intensity and ADC decreased at 24 hours after reperfusion. In group C, ADC slightly went up at 2 hours after reperfusion and decreased markedly at 24 hours later. In groups D,E, ADC was slightly decreased or unchanged after reflow. In all groups, lesion volume on DWI was not enlarged after reperfusion. Although parameters (CBV,CBF,MTT)values of PI in groups B,C recovered and remained normal, in groups D,E had 3 typical fashions of appearance after reperfusion: hyperperfusion,hypoperfusion and normal perfusion respectively.Conclusion The resolution of initial DWI abnormal signal intensity is transient, and secondary abnormal signal on DWI occurs later on after reperfusion in 30 minutes of MCAo.Ischemic penumbra can be protected by recanalization in hyperacute cerebral infarction.