Different MRI examination on early cerebral ischemia in rats

Objective To study the value of different MRI examination on early cerebral ischemia in rats. Methods Fifty-two Wistar rats were randomly divided into 6 groups, 46 rats were created focal cerebral ischemia model in middle cerebral artery territory by Zea Longa method, the other 6 rats were used as normal control group and sham-operated group. Apply diffusion weighted imaging (DWI), superparamagnetic iron oxide (SPIO) perfusion T2WI and general MRI separately to observe the models at different time. Results DWI showed high signal 30-90 minutes after the occlusion of middle cerebral artery (100%), but the range of the lesions was not clear. SPIO perfusion T2WI could detect low perfusion area within 1 h after cerebral artery occlusion, but couldn't reflect the pathological changes. T2WI showed abnormal signal intensity in 6-12 h after cerebral ischemia (70%) and could show the boundary of ischemic area precisely. No abnormal signal intensity could be found on T1WI within time of observation. Conclusion DWI and SPIO perfusion T2WI can provide useful imaging information for diagnoses of hyperacute cerebral ischemia. T2WI is helpful in localizing and judging the range of cerebral ischemia. No abnormality could be identified on T1WI at early cerebral ischemia. The application of different MRI methods is recommended in diagnosing early cerebral ischemia.