Abstract: Objective To study the relation between collateral circulation and ischemic brain lesions in patients with unilateral middle cerebral artery stenosis or occlusion.Methods Twenty-seven patients with unilateral middle cerebral artery stenosis or occlusion were divided into two groups according the status of collateral circulation.Comparisons were made between the results of the two groups in cerebral blood flow perfusion imaging.Results In 4 patients with unilateral middle cerebral artery stenosis and 7 patients with unilateral middle cerebral artery occlusion,collateral circulation appeared,and in 13 patients with unilateral middle cerebral artery stenosis and 3 patients with unilateral middle cerebral artery occlusion,collateral flow could not be seen.Collateral flow appeared more frequently in the patients with unilateral middle cerebral artery occlusion than in those with unilateral middle cerebral artery stenosis(χ²=5.632,P=0.018).In the frontal,temporal,parietal,occipital cortices and basal ganglia,the cerebral blood flow volumes were not significantly different between the two groups.In the thalamus however,they showed significant difference(t=-2.393,P=0.025).Conclusion Ischemic brain lesions in patients with unilateral middle cerebral artery stenosis or occlusion does not in accord with the degree of vascular stenosis.It would improve the understanding of the severity of middle cerebral artery stenosis or occlusion considerably by combining angiographic information and perfusion data.

Key words: middle cerebral artery stenosis or occlusion, tomography, emission-computed, collateral circulation