磁敏感加权成像评价大鼠超急性期脑缺血

Susceptibility weighted imaging in evaluation on rat hyperacute cerebral ischemia

目的探讨SWI评价大鼠超急性脑缺血的价值。方法对健康雄性Wistar大鼠40只,采用线栓法构建超急性大脑中动脉闭塞(MCAO)模型;于栓塞20min及2.5h分别行SWI及DWI,参照缺血2.5h时的DWI及ADC图,分别测量20min及2.5h时梗死区、周围区及对侧镜像区(ROI1、ROI2、ROI3、ROI4和ROI'1、ROI'2、ROI'3、ROI'4)的相位弧度值及SWI信号值,并比较不同ROI及相同ROI两个时间点间的相位弧度值及SWI信号值。结果栓塞20min和2.5h时,各ROI的相位弧度值及SWI信号值差异均有统计学意义(P均<0.01),且ROI1与ROI2、ROI'3与ROI'4、ROI1与ROI'1差异均有统计学意义(P<0.05)。结论 SWI在大鼠MCAO 20min后即可显示脑缺血,表现为SWI信号及相位弧度值降低。随着缺血时间延长,缺血核心区SWI信号升高,接近正常脑组织,预示不可逆梗死。

Objective To investigate the value of SWI in evaluation on hyperacute cerebral ischemia of rat models. Methods Models of middle cerebral artery occlusion （MCAO） were established in 40 male healthy Wistar rats, and SWI and DWI were performed 20 rain and 2.5 h later. On the basis of DWI and ADC map at 2.5 h, the phase radians and SWI signal intensity values of the infarction core, peri-infarction area, and counterparts in the contralateral hemisphere （ROI1, ROI2, ROI3, ROI4 and ROI1, ROI2, ROI3, ROI4） were measured respectively, the phase radians and SWI signal intensity values in different ROIs and the same ROI in different time points were compared. Results Twenty miniutes and 2.5 h af-ter occlusion of MCA, statistical differences of phase radians and SWI signal intensity values were found among different ROIs （all P〈0.01）, as well as between ROll and ROI2, ROra and ROI4, ROI1 and ROI1 （all P〈0.05）. Conclusion Cerebral ischemia in rat can be detected as early as 20 min after MCAO with SWI, manifesting as signal intensity decrease on SWI and phase radian. With development of ischemia, signal of ischemia core may restore to nearly normal on SWI, indicating irreversible infarction in the core area.