目的　探讨超急性期确认局灶脑缺血半暗带的范围和演变规律。方法　用易卒中型肾血管性高血压大鼠(RHRSP)行左侧腔内线栓MCAO术 ,分别在闭塞 12h内的不同时间点及再灌注 48h后行T2 加权成像 (T2 WI)、磁共振弥散加权成像 (DWI)和磁共振灌注加权成像 (PWI)。将大鼠处死后行TTC染色 ,比较在闭塞不同的时间点上在两次T2 WI和DWI上病灶的演变和TTC染色上梗死灶的改变。结果　DWI在闭塞 30min时显示出确切的病灶 ,而T2 WI要在 3h以后才能显示出病灶 ;自 30min至 6h ,DWI所显示的病灶持续扩大 ,可逆性部分占首次DWI上病灶的百分比 (%RP)逐渐缩小 ,最终为负数 ;PWI在MCAO闭塞的即刻即在时间 信号强度曲线上表现为最大下降幅度的减小 ,复通后上升 5 0 %以上 ;半暗带部分水的表面弥散系数值 (ADC)为 (0 5 6± 0 0 2 )× 10 -5cm2 /s。结论　DWI能在超急性期 (3h以内 )显示出缺血病灶 ,根据梗死中心和梗死周边的ADC值的不同可以分辨出可逆性和不可逆性损伤的缺血组织 ;本模型的缺血半暗带存在的时间为6h。 Objective To investigate the extent and evolution of focal cerebral ischemic penumbra in hyperacute stage. Methods MCAO was performed in the right thoracic cavity of rats with stenosed renovascular hypertension (RHRSP). T2 weighted imaging (T2WI) was performed at different time points within 12h after occlusion and 48h after reperfusion. Weighted Imaging (DWI) and Magnetic Resonance Perfusion Weighted Imaging (PWI). After the rats were sacrificed, TTC staining was performed to compare the evolution of lesions on T2 WI and DWI and the changes of infarction on TTC staining at different time points of occlusion. Results DWI showed the exact lesion at occlusion 30 min, and T2 WI did not show lesion after 3 h. The lesion showed by DWI continued to expand from 30 min to 6 h, and the reversible portion accounted for the percentage of lesions on the first DWI (% RP ), And finally it was negative. The PWI showed the largest reduction in the immediate signal intensity curve of occlusion of MCAO, which increased by more than 50% after recanalization; the surface diffusion coefficient of some water in the penumbra ADC) was (0 56 ± 0 0 2) × 10 -5 cm 2 / s. Conclusion DWI can show ischemic lesions in the hyperacute phase (within 3 hours), and the ischemic tissues with reversible and irreversible lesions can be distinguished according to the ADC value of the infarct center and infarct circumference. The ischemic penumbra in this model The time of existence is 6h.