大鼠脑缺血再灌注后血管源性水肿与血脑屏障开放相关性的MRI评价

Correlative evaluation by MRI between vasogenic edema and blood-brain barrier disruption during postischemic reperfusion in rats

目的:探讨脑缺血再灌注后血管源性水肿和血脑屏障(BBB)开放之间的相关性。方法:雄性Wistar大 鼠6只,采用线栓法制作局灶性脑缺血2h再灌注6h模型,应用T2WI和增强T1WI分别对血管源性水肿和BBB开 放进行动态监测。分别测量再灌注前(0h)和再灌注后1h、2h、3h、4h、5h及6h感兴趣区(ROI)的信号强度,计 算其在T2WI上的信号强度变化率(Rc)和在T1WI上的强化率(Re),并分析Rc、Re之间的相关性。结果:Rc比Re 先升高,在Re开始出现升高前Rc、Re之间没有明显的相关性,Re升高后Rc、Re之间具有高度的相关性,且T2WI 和增强T1WI上高信号出现的部位及范围相互吻合。结论:在脑缺血再灌注损伤中,血管源性水肿和BBB开放之 间具有相关性,利用增强MRI评价早期BBB轻度开放的敏感性有限。综合运用T2WI和增强T1WI检测脑缺血再 灌注损伤能够获得更丰富的信息。

Aim: To explore the correlation between vasogenic edema and blood-brain barrier (BBB) disruption during postischemic reperfusion quantatively. Methods: Transient focal ischemia was induced for 2 hours and then reperfusion by using the filament occlusion model for another 6 hours in 6 male Wistar rats. Vasogenic edema and blood-brain barrier disruption was dynamically monitored respectively with T_2WI and contrast-enhanced T_1WI. Signal intensities of the region of interest (ROI) before reperfusion (0 h) and 1 h, 2 h, 3 h, 4 h, 5 h, 6 h after reperfusion were measured, and the rates of signal intensity changing (Rc) of the ROI on T_2WI as well as the rates of contrast enhancement (Re) of the ROI on T_1WI were calculated. Correlation between Rc and Re was analyzed. Results: Rc was ahead of Re to present significant arising. No prominent correlation between Rc and Re was found before Re initially arose. A high degree correlation between Rc and Re had been demonstrated since Re initially arose. Furthermore, the regions and the extents of the hyperintensity coincided with each other on both T_1WI and T_2WI. Conclusion: There is a correlation between BBB disruption and vasogenic edema during cerebral postischemic reperfusion. The sensitivity for contrast-enhanced MRI to evaluate the early slight disruption of BBB is limited. Much information can be acquired by using T_2WI combined with contrast-enhanced T_1WI to examine the cerebral postischemic reperfusion injury.