早期脑梗死缺血半暗带磁共振扩散和灌注加权成像的实验研究

An experimental study of ischemic penumbra of early cerebral infarction in rabbits by using diffusion and perfusion weighted imaging

目的探讨磁共振扩散加权成像(DWI)和灌注加权成像(PWI)对早期脑梗死缺血半暗带(IP)的诊断价值。方法新西兰大白兔35只,实验组28只,对照组7只。实验组经眶内入路电凝大脑中动脉,在术后0.5、1、2、4、6、8h和12h依次进行相应时间点的SE序列T2WI、DWI和PWI检查后,立即取不同时间点的兔脑标本进行光镜和电镜检查。结果6h前,T2WI上异常高信号区小于DWI和PWI上异常信号区体积,DWI上异常高信号区体积明显小于PWI上相对高信号区体积,DWI和PWI不匹配区随时间延长逐渐缩小;8h后,T2WI、DWI和PWI上异常范围区无显著性差异。结论DWI和PWI结合能灵敏地确定IP的存在,其范围随MCAO的持续时间而逐渐缩小,表明IP是一个动态变化的过程。

Objective To explore the value of diffusion weighed imaging (DWI) and perfusion weighted imaging (PWI) in the diagnosis of the ischemic penumbra (IP) of superacute infarction.Methods 35 New Zealand rabbits regardless of male or female were randomized into two groups,28 rabbits were included in the experimental group and 7 rabbits were classified as control group.For the experimental group, a transobital electrocoagulation was carried out to occlude the middle cerebral artery.After the rabbits of experimental group were underwent T_2WI,DWI and PWI in 0.5h,1h,2h,4h,6h,8h and 12h,specimens of the brain tissue which were obtained correspondently to DWI scan were observed by microscopy and electrical microscopy respectively. Results The volume of the abnormal high signal intensity of T_2WI was smaller than that on DWI and PWI,and the volume of the abnormal high signal intensity of DWI was smaller than that on DWI and PWI before 6h. The mismatch area between PWI and DWI became smller with the time coursing.There was no significant difference between T_2WI,DWI and PWI after 8h.The abnormal high signal intensity on DWI firstly appeared in the basal ganglia at 0.5h. Conclusion DWI and PWI could sensitively detect IP. Its volume gradually becomes smaller with the time coursing after MCAO, and indicates that evolution of IP is a dynamic process.