Acute Cerebral Infarction in a Rabbit Model: Perfusion and Diffusion MR Imaging

Heo, Suk Hee; Seo, Jeong Jin; Yim, Nam Yeol; Jeong, Gwang Woo; Yoon, Woong; Kim, Yun Hyeon; Jeong, Young Yeon; Chung, Tae Woong; Kim, Jeong; Park, Jin Gyoon; Kang, Heoung Keun

Abstract

PURPOSE
The present study was undertaken to evaluate the usefulness of cerebral diffusion (DWI) and perfusion MR imaging (PWI) in rabbit models with hyperacute cerebral ischemic infarction. MATERIALS AND METHODS: Experimental cerebral infarction were induced by direct injection of mixture of Histoacryl glue, lipiodol, and tungsten powder into the internal cerebral artery of 6 New-Zealand white rabbits, and they underwent conventional T1 and T2 weighted MR imaging, DWI, and PWI within 1 hour after the occlusion of internal cerebral artery. The PWI scan for each rabbit was obtained at the level of lateral ventricle and 1cm cranial to the basal ganglia. By postprocessing using special imaging software, perfusion images including cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT) maps were obtained. The detection of infarcted lesion were evaluated on both perfusion maps and DWI. MTT difference time were measured in the perfusion defect lesion and symmetric contralateral normal cerebral hemisphere. RESULTS: In all rabbits, there was no abnormal signal intensity on T2WI. But on DWI, abnormal high signal intensity, suggesting cerebral infarction, were detected in all rabbits. PWI (rCBV, CBF, and MTT map) also showed perfusion defect in all rabbits. In four rabbits, the calculated square of perfusion defect in MTT map is larger than that of CBF map and in two rabbits, the calculated size of perfusion defect in MTT map and CBF map is same. Any rabbits do not show larger perfusion defect on CBF map than MTT map. In comparison between CBF map and DWI, 3 rabbits show larger square of lesion on CBF map than on DWI. The others shows same square of lesion on both technique. The size of lesion shown in 6 MTT map were larger than DWI. In three cases, the size of lesion shown in CBF map is equal to DWI. But these were smaller than MTT map. The calculated square of lesion in CBF map, equal to that of DWI and smaller than MTT map was three. And in one case, the calculated square of perfusion defect in MTT map was largest, and that of DWI was smallest. CONCLUSION: DWI and PWI may be useful in diagnosing hyperacute cerebral ischemic infarction and in evaluating the cerebral hemodynamics in the rabbits.