Comparative study of three different MRI examinations on acute cerebral ischemia in rats

Objective To study the value of three different MRI examination on acute cerebral ischemia in rats.Methods Fifty Wistar rats were randomly divided into 7 groups,including control group and occluded and reperfusion groups. Sixty rats were created cerebral ischemia model with right middle cerebral artery of the rats unilaterally occluded (MCAO) by Zea Longa method, the other ten rats were used as control group. Apply diffusion weighted imaging(DWI), T2FLAIR and general T2WI separately to observe relatively high signal area (rS) and relative density (rD) at different time.Results The control group showed no abnormal signals by the three different MRI examinations. DWI showed high signal (10/10) at 15 minutes after the MCAO(100%). rS and rD increased with time, and changed significantly within 1h, and then increased slowly from 1h to 6h, but the range of the lesions was not clear, and anatomical localization was not accurate. But in most rats (8/10), the T2FLAIR could show high signal 2 h after MCAO, and then rS and rD increased along with the time. In short, T2FLAIR can show the boundary of ischemic area precisely. Only two rats (2/10) could detected high signal intensity on T2WI at 2 h after MCAO, and the most of animals(7/10) showed the high-intensity of ischemic tissue on T2WI at 4 h after MCAO.Conclusion DWI is the preferred imaging method in the diagnosis of acute cerebral ischemia, followed by T2 FLAIR, while the combine application of three different MRI examination is recommended in detecting the ischemic area precisely.