增强MRI评价脑缺血再灌注后大鼠血脑屏障的通透性

Evaluation of blood-brain barrier permeability during reperfusion following focal cerebral ischemia in rats using contrast-enhanced MRI

目的 通过增强 MRI来研究脑缺血再灌注后大鼠血脑屏障 (BBB)通透性的改变。方法 采用线栓法制备大鼠局灶性脑缺血再灌注模型。脑缺血 4h后再灌注。用 1.5 T超导型 MR机进行大鼠脑冠状位扫描 ,随后经股静脉注入 Gd- DTPA,迅速行同层间歇扫描 (每隔 10 m in扫描 1次 ) ,持续 10 0 min。以双侧对称的脑实质为兴趣区 ,测得兴趣区信号强度 (SI) ,求其增强率。结果 脑缺血 4h,再灌注 5 0 min时 ,缺血侧纹状体增强率与对侧相比差别具有非常显著性意义 (P<0 .0 1)。再灌注 70 min时 ,缺血侧大脑皮层增强率较对侧增高 (P<0 .0 5 )。缺血侧侧脑室在再灌注 10 m in时可见明显强化。结论 纹状体区 BBB比大脑皮层更易受到再灌注损伤 ,血脑屏障较早受到破坏。增强 MRI是一种敏感的在活体条件下检测 BBB损伤的理想方法。

Objective Contrast-enhanced MRI was used to observe blood brain barrier (BBB) permeability during reperfusion following middle cerebral artery occlusion (MCAO) in rats. Methods The left middle cerebral arteries were transiently occluded by inserting a nylon thread into the carotid artery. Reperfusion was performed following 4h of MCAO. T 2 W and T 1 W images were obtained in a 1.5T magnet before and after Gd DTPA was injected intravenously. The percent enhancement of signal intensity (SI) was calculated. Results Enhancement of the striatum was seen following 50min reperfusion and enhancement of the cerebral cortex was evident following 70min reperfusion in the attacked hemisphere. The lateral ventricle of the ischemic hemisphere showed enhancement following 10min reperfusion. Conclusion BBB damage has a stronger tendency to occur in the striatum than in the cerebral cortex. Disruption of the blood cerebrospinal fluid barrier happens easily. MR enhancement is proposed as a sensitive method for quantification of BBB injury in vivo.