大鼠超急性期脑缺血的磁共振扩散加权成像研究

目的：利用磁共振扩散加权成像（DWI）评价大鼠超急性期脑缺血的诊断价值。方法：12只Wistar雄性大鼠,采用线栓法制作右侧大脑中动脉闭塞（MCAO）脑缺血模型,分别于栓塞后1h和6h行大鼠冠状位磁共振DWI、T2WI和T1WI检查,并测量缺血区DWI异常高信号的体积、表观扩散系数（ADC）值,将所测值进行比较。磁共振检查结束后处死大鼠,断头取脑行TTC染色,并与DWI结果进行比较。结果：大鼠MCAO后1h进行MRI扫描右侧大脑中动脉供血区DWI可见异常稍高信号,ADC为低信号,T2WI和T1WI均未见异常信号;MCAO后6hDWI可见明显高信号,较1hADC值显著减低（P〈0.01）,DWI上梗死灶体积显著扩大（P〈0.01）,T2WI显示缺血区异常高信号,T1WI可见稍低信号。TTC染色者均显示脑梗死灶,与MCAO后6h的DWI显示脑缺血范围一致。结论：DWI对超急性期脑梗死较常规MRI敏感,是超急性期脑缺血重要的检查方法。

Evaluation of hyperacute cerebral ischemia with MR diffusion-weighted imaging in rats

Objective：To assess the diagnostic value of MR diffusion-weighted imaging （DWI） in hyperacute cerebral ischemia using rat model. Methods：Twelve male Wistar rats were performed right middle cerebral artery occlusion mode1 （MCAO）. DWI,T2WI and T1WI were performed after one hour and six hours,respectively,the values of infarction volume and apparent diffusion coefficient （ADC） were measured. Triphenyltetrazolium chloride （TTC） stainings were executed and compared with DWI. Results：Abnormal hyperintensity was found in the right cerebral ischemic region on DWI after one hour. But there was no abnormal change on T2WI and T1WI. The extent of infarction was larger and the value of ADC was lower after six hours （P0.01）. The abnormal hyperintensity was found on T2WI,and the abnormal hypointensity was found on T1WI in ischemic region. Infarction lesion on TTC staining was consistent with the abnormal on DWI. Conclusion：DWI is superior to conventional MRI for the diagnosis of hyperacute cerebral ischemia.