| Objective: To establish an subhuman middle cerebral artery occlusion (MCAO) model of monkey which can be recanalized and suitable for conventional clinical imaging modalities; to discovery the hemodynamic changes with time within 24 hours after MCAO in monkey by serial perfusion CT examinations; to evaluate the clinical values of perfusion CT for cerebral ischemia; to elucidate the value of perfusion CT for identifying cerebral ischemic penumbra.Part one: dynamic perfusion CT studies of MCAO model in monkeysMaterials and methods: Six adult monkeys ranging from 6~8 kg in weight were used in our study. Model was made in DSA after monkeys were anesthetized. Exposing and puncturing unilateral femoral artery, a 5-F catheter sheathe was positioned in femoral artery. A 4-F catheter was passed coaxially through the sheathe to the arch of aorta, right common carotid artery, left common carotid artery , angiography was performed for each of the three arteries respectively. The more straight side of common carotid artery was selected for embolizing. Keeping the 4-F catheter in common carotid artery, a silk of 3-F SP catheter (3 inches in diameter) was passed coaxially to superselect to one of larger branches of middle cerebral artery. Pulling and rotating the silk to stimulate the endothelial membrane to produce thrombus.Plain CT scan, perfusion CT, plain MR1 scan were performed for each of monkey before MCAO. Four parameters were calculated by perfusion CT, such as cerebral blood flow (CBF), cerebral blood volume (CBV) , mean transit time (MTT) , time to peak (TTP). Plain CT and perfusion CT were performed 2, 4, 8 hours after MCAO. The occluded artery was reperfusion by withdrawing the silk at 8 hours after MCAO. After reperfusion for 16 hours (24 hours after MCAO), plain CT scan, perfusion CT, plain MRI scan were performed again. Plain MRI scan was performed 1 week after MCAO if the monkey was still alive. The animal was killed by overanesthetized after MRI examination. Brain specimen was studied with TTC and HE staining for pathological observation.Results: Perfusion CT demonstrated there was difference in perfusion among cerebral cortex, medulla and basal ganglia under physiological situation before MCAO. Cerebral cortex and basal ganglia had same perfusion, which was higher than that of medulla.Four monkeys had cerebral infarction successfully, two for bilateral cerebral hemispheres focal infarction, two for unilateral cerebral hemisphere focal infarction. Two animals died during operation.There was no significant difference about the values of CBV, CBF between contralateral hemisphere and non-ischemia area of ipsilateral hemisphere, including cortex, medulla, basal ganglia, before MCAO and at each time point after MCAO. No difference were found about respective CBV values of cortex, medulla, basal ganglia before MCAO and at each time point after MCAO. The CBF values of cortex and basal ganglia were decreased after MCAO, which was 80% of that before MCAO at 2 hours and continued to decrease 2-4 hours, stayed in 60% during 4~24 hours. The CBF of medulla was consistent before MCAO and at each time point after MCAO.Perfusion CT can demonstrate hypoperfused area as early as 2 hours after MCAO, which showed decreased local CBF, slightly decreased local CBV, prolonged MTT, delayed or lack ofTTP.At 2 hours after MCAO, the hypoperfusion area on CBV map was smaller than that of 4, 8, 24 hours after MCAO, no significant difference was found among the latter three time points. The hvpoperfusion areas on CBF map, MTT map, TTP map were similar at each time point after MCAO. At 2 hours after MCAO, the hvpoperfusion area on CBV map was smaller than that on CBF map, MTT map, TTP map. There was no significant difference about the hypoperfusion areas among each of the parameter at 4, 8, 24 hours after MCAO. At 2 hours after MCAO, the area of "CBF>CBV" was 76% of hypoperfusion area on CBF map. There was a temporal declined trend of percentage of "CBF>CBV" area to hypoperfusion area on CBF map after MCAO.The...
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