MRI评价兔局灶性脑缺血再灌注模型的时间特征性研究

MRI Study of Time Characteristics in A Rabbit Model of Focal Cerebral Ischemia-reperfusion

目的:利用MRI研究兔局灶性脑缺血再灌注模型,观察脑缺血再灌注不同时间点的动态变化规律。材料和方法:建立兔局灶性脑缺血再灌注模型,72只雄性新西兰白兔,被随机分为3组,其中A组8只,为空白对照组;B组24只,为假手术对照组;C组40只,为缺血再灌注组。采用改良颈内动脉线栓造模方法,用导丝置入颈内动脉,阻闭左侧大脑中动脉,于阻闭2h后抽出导丝,恢复再灌注,于再灌注后0h、1h、3h、6h、12h、24h、3d、7d(均n=5)对实验动物进行行为评分、MRI及形态学评价。结果:空白对照组、假手术组MRI上未见异常信号,缺血再灌注组表现在MCA供血区T2WI、DWI出现高信号,并随缺血再灌注时间有逐渐增大趋势,3d后T2WI、DWI高信号范围有所减小。TTC染色异常的部位与DWI所显示的区域一致。增强T1WI显示缺血6h内缺血半球有对比增强。结论:应用MR影像学方法可对兔局灶性脑缺血再灌注后血脑屏障的开放及脑水肿进行动态时间评价,为脑缺血的诊断和治疗奠定了基础。

Purpose： To explore time characteristics and dynamic changes in a rabbit model of focal cerebral ischemia-reperfusion at different time points with MRI techniques. Materials and Methods： A rabbit model of cerebral ischemia-reperfusion was established. Seventy-two male New Zealand white rabbits were randomly divided into three groups： group A rabbits （n=8） underwent no operation, group B rabbits （n=24） underwent sham operation, group C rabbits （n=40） underwent an operation of ischemic brain injury, in which the occlusion of left middle cerebral artery was induced by guide wire for 2 hours. The time points of reperfusion for group C rabbits were 0h, 1h, 3h, 6h, 12h, 24h, 3d, 7d（n=5）. At different points, the following examinations were carried out： MR scanning, neurological deficit score and gross anatomy. Results： No abnormal signal was seen on MRI in group A and group B rabbits. High signal was seen on DWI and T2WI and high-intensity signal area enlarged with the time and the signal area decreased 3 days, which was correlation with 2, 3, 5-triphenyltetrazolium chloride （TTC）- stained for infarct volume calculation after MCAO. The ischemic hemisphere showed contrast enhancement in 6h reperfnsion on enhanced T1WI .Conclusion： The apply of MRI in focal cerebral ischemia-reperfnsion at different time points can elucidate time characteristics in reperfusion injury and laid a foundation of diagnosis and treatment of cerebral ischemia injury.