Experimental Studies On Diffusion Weighted Imaging (DWI) And The Corresponding Pathological Mechanism After The Acute Middle Cerebral Artery Occlusion In Rabbits

Backgrounds and Purposes: Acute stroke has high incidence and high mortality, which heavily threatens human health and life quality, so early diagnosis and therapy are very important. Observing the variety of the conventional magnetic resonance imaging (MRI) and diffusion weighted imaging (DWI) after cerebral ischemia by establishing the rabbit model of the acute middle cerebral artery occlusion (MCAO), we can prove the regularity and the pathological mechanism of focal ischemia lesion, and can make a basis for further studies on the early diagnosis and the therapy of cerebral infarction.Materials and Methods: Forty New Zealand rabbits weighted from 2 to 3 kilograms were divided randomly into two groups: the contrast group (group A, n=4) and the experimental group (group B, n=36). The rabbit models of the acute MCAO were performed according to the transorbital ligation technique modified by Yamamoto. Conventional MRI and DWI were performed at 0.5hr, 1.5hr, 3hr, 6hr, 9hr, 12hr, 15hr, 18hr, 21hr,and 24hr after MCAO. The evolution of the volume of the abnormal area on DWI and ADC value after MCAO were observed, and the related statistical analysis was made. We choiced randomly three rabbits out of the experimental group to be examined with digital subtraction angiographies (DSA) for confirming MCAO again at 6hr, 12hr, and 24hr after operation, and one of the contrast group was examined at 24hr after operation. In the experimental group, we choiced four rabbits for the examination of electron microscopy at 0.5hr, 1.5hr, 3hr, and 6hr after MRI examination, and the others were performed hemeatoxyln eosin (HE) dye at 3hr, 6hr, 12hr, and 24hr after operation. The contrast group was only performed HE dye at 6hr, 12hr, and 24hr after operation.