线栓法兔大脑中动脉闭塞模型在急性脑缺血磁共振研究中的价值

目的观察线栓法兔MCAo模型缺血区水分子扩散变化的规律,探讨该模型在急性脑缺血磁共振研究中的价值.方法新西兰雄性大白兔48只,其中6只用来做空白对照,42只用来行线栓法MCAo,对于插线成功的动物,在插线后30 min、1 h、2 h、3 h、6 h、10 h、24 h及7天分别行T2WI和DWI检查,观察MCAo后缺血区扩散异常在各时段扩散异常容积及ADC值的变化规律,比较枕动脉起源于颈内动脉及颈外动脉的情况下,扩散异常容积及ADC值的变化规律的异同.结果在MCAo 30 min后,DWI上即出现异常高信号,高信号范围逐渐增大,约在24 h后范围增大不再明显.在T2WI上出现异常的平均时间是(2.34±0.97)h,约在MCAo 10 h后T2WI上病变范围与DWI上的扩散异常区一致.MCAo后缺血区ADC值的变化表现为早期的逐渐下降以及随后的回升,基底节区ADC值的下降早于额顶叶皮质区.在枕动脉起自颈内动脉组与枕动脉起自颈外动脉组之间,扩散异常的容积及ADC演变的差别在统计学上无显著性意义.结论线栓法兔MCAo模型缺血区水分子的扩散变化规律符合以往描述的大脑中动脉闭塞后缺血区的演变规律,适合于进行急性脑缺血的磁共振研究.

The value of MCAo model using intraluminal thread technique in MRI study of acute cerebral ischemia in rabbit

Objective To observe the evolution of focal ischemic lesion on DWI and T2WI after MCAo using intraluminal thread technique, and investigate the value of this model in the MRI study of acute cerebral ischemia in rabbit. Methods Forty-eight New Zealand white rabbits were included in the study (6 for contrast and 42 for MCAo). For the rabbits that the thread had been inserted into ICA successfully, T2WI and DWI were performed 30 min, 1 h, 2 h, 3 h, 6 h, 10 h, 24 h and 7 d after MCAo. The evolution of the volume of DWI abnormality and ADC after MCAo were observed, and evolution of focal ischemic lesion on DWI and T2WI after MCAo between rabbits of which occipital artery originating from ICA and those from ECA was compared. Results Abnormal high-intensity signal on DWI was observed 30 min after MCAo in basal ganglia region and extended to the frontal-parietal lobe gradually till 24 h after MCAo. Abnormal signal appeared on T2WI at an average time of (2.34±0.97)h and extended to the same size as that on DWI at 10 h after MCAo. The ADC value of the focal ischemic lesion decreased gradually at the acute stage and increased subsequently. The ADC decrease of the basal ganglia region was prior to that in the frontal-parietal lobe. Between the rabbits of which occipital artery originating from ICA and those from ECA, no obvious difference of the evolution of the volume of DWI abnormality and ADC was found. Conclusion The evolution of focal ischemic lesion by intraluminal thread technique complies with the evolution of ischemia after MCAo described previously. This model is appropriate for the MRI study of acute cerebral ischemia.