A NEW METHOD TO IMPROVE IN-BORE MIDDLE CEREBRAL-ARTERY OCCLUSION IN RATS - DEMONSTRATION WITH DIFFUSION-WEIGHTED AND PERFUSION-WEIGHTED IMAGING

Background and Purpose-In-bore middle cerebral artery occlusion (MCAO) enables investigators to acquire preischemic MRI data and to image is chemic changes immediately after occlusion, We have developed a highly successful in-bore MCAO method. This study describes the methods and pertinent techniques. Methods-Sixty-seven Sprague-Dawley rats were sub jected to temporary (n=36) or permanent (n=31) MCAO. The occluding dev ice consisted of a supporting tubing, a driving line, and a silicone-c oated 4-0 nylon suture occluder, Outside the magnet, the occluder was positioned in the carotid canal. MCAO was achieved in the magnet bore by remotely advancing the driving line until resistance was felt. Diff usion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) were acquired before and immediately after occlusion and were used to docu ment the presence of MCAO. Results-Fifty-nine (88.1%) rats were succes sfully occluded, demonstrating hyperintensity on DWI, perfusion defici ts on PWI, and no subarachnoid hemorrhage at postmortem examination. T he average values of the apparent diffusion coefficient in both the fr ontoparietal cortex and the lateral caudoputamen significantly decreas ed as early as 3 minutes after the onset of ischemia. The failures inc luded preocclusion damage (1/67), sliding out of the occluder during o cclusion (1/67), no occlusion (2/67), and arterial perforation (4/67). Conclusions-Our in-bore MCAO method is easily performed and is as suc cessful as MCAO induced outside the magnet.