可控性大鼠急性脑局部缺血模型的建立及CT灌注成像与病理学评价

目的 建立稳定、可控的脑局部缺血动物模型，并通过CT灌注成像和病理学方法对其进行评价。方法 雄性Wistar大鼠28只，随机分为4组(假手术组、脑梗死15min组、脑梗死30min、再灌注1h组及低灌注6h组)，每组7只鼠。在激光多普勒血流仪监测下采用改良的线栓法制作可控性脑局部缺血动物模型。利用CT灌注成像对各组动物模型的缺血状态进行观察，并与光学显微镜、电子显微镜结果以及红四氮唑(TTC)染色标本对照。结果 脑梗死15min组在激光多普勒血流仪监测下将局部脑血流量(rCBF)控制为5％～22％，CT灌注成像显示7只大鼠局部脑血流量均下降，TIC染色呈浅红色，未见明确梗死病灶，病理学检查显示部分神经元变性和星形细胞肿胀。脑梗死30min再灌注1h组在激光多普勒血流仪监测下将rCBF控制为4％～23％，病理学检查显示7只大鼠脑缺血灶内星形细胞肿胀明显，可见大量神经元变性，标本TTC染色所示的白色梗死区与CT灌注成像异常区域一致。在低灌注6h组，由于rCBF下降程度较小(为38％～55％)，病理学显示7只大鼠星形细胞肿胀明显而神经元变性轻微，TTC染色未见明确梗死病灶。假手术组7只大鼠均未见上述各种异常表现。结论 可控性大鼠急性脑局部缺血模型稳定可靠，能模拟出不同灌注程度的缺血状态，除了可用于脑梗死的研究外，更适用于脑梗死前期的急性脑局部缺血的研究。功能CT灌注成像是评价急性脑局部缺血模型的1种准确、敏感的方法。

Modeling of a controllable acute regional cerebral ischemia in rats and evaluation with CT perfusion imaging and histopathology

Objective To establish a stable and controllable model of acute regional cerebral ischemia in rats, and to evaluate it by CT perfusion imaging and histological study. Methods Twenty eight male Wistar rats were randomly divided into 4 groups, and there were 7 rats in each group. The sham operation rats were defined as the first group, rats suffered from cerebral ischemia for 15 minutes were classified as the second group, rats suffered from cerebral ischemia for 30 minutes and then reperfusion for 1 hour as the third group, and rats suffered from hypo perfusion for 6 hours as the fourth group. Cerebral ischemia or hypo perfusion were induced by inserting a nylon thread of different diameter into right middle cerebral artery (MCA) of rats under the monitoring of regional cerebral blood flow (rCBF) by the Laser Doppler Blood Perfusion Monitor (BPM). rCBF was also examined by dynamic CT perfusion imaging. At the end of the observation time, rats were decapitated, and three rats of each group were performed 2,3,5 triphenyltetrazolium chloride (TTC) staining and four rats were performed histological study. Results In the second group, rCBF was controlled within 5% to 22% under the monitoring by BMP and CT perfusion imaging showed the decreased rCBF in 7 rats, but TTC staining showed red appearance indicating no infarction focus formed. Electronic microscopic study revealed astrocytic swelling and a few of neuronal degeneration. In the third group, rCBF was controlled within 4% to 23% under the monitoring by BMP. There were more severe astrocytic swelling and a lot of neuronal degeneration. The abnormal areas in CT perfusion images were the same as TTC staining. In the fourth group, in accordance with less decrease ment of rCBF (from 38% to 55%) in 7 rats, there were obvious astrocytic swelling and subtle neuronal degeneration. TTC stain did not show ischemia area. All these abnormal changes were not observed in the sham operation rats. Conclusion The controllable acute regional cerebral ischemic model in rats is very stable and repeatable. It can be simulated into the ischemic state of different perfusion level. This model is suitable for the research of acute cerebral infarction and regional cerebral ischemia. The facts that parallel changes existed among BMP measurement, CT perfusion imaging, and brain histology indicated that CT perfusion imaging is accurate and sensitive in evaluating acute regional ischemia.