Background and Purpose-MRI has superior capabilities for the detection of cerebral infarcts compared with CT. CT was used to locate infarcts in most previous studies of atherothrombotic middle cerebral artery (MCA) territory infarcts. Thus, there was a possibility of missing concomitant small infarcts. More accurate identification of topographic lesions in MCA territory with MRI may help to establish the pathogenesis of stroke. The present study determines topographic patterns, distribution of vascular lesions, and probable mechanisms. Methods-Forty-two patients with MCA territory infarcts on routine MRI and no major cause of cardioembolism were studied with conventional angiography or MR angiography. Results-The topographic patterns seen on MRI were subdivided into 4 groups: cortical border-zone infarcts (nϭ6), pial territory infarcts without insular infarct (nϭ3), pial territory infarcts with insular infarct (nϭ14), and large subcortical infarcts (nϭ19). Of 6 patients with cortical border-zone infarcts, 4 had concomitant small cortical or subcortical multiple lesions. Angiography showed intrinsic MCA disease in 4 patients. Of 3 patients with pial territory infarcts without insular infarct, 2 also had small multiple centrum ovale lesions. All had intrinsic MCA disease. Pial territory infarcts with partial or whole insular lesions were present in 10 and 4 patients, respectively. Five patients had additional multiple cortical or subcortical lesions. Ten patients had intrinsic MCA disease. Of the 19 patients with large subcortical infarcts, 12 had centrum ovale infarcts, and 4 had both basal ganglia and centrum ovale lesions. Ten had concomitant small cortical or subcortical lesions. Six patients had intrinsic MCA disease. Conclusions-Similar vascular lesions induce different topographic patterns in MCA territory infarction, which are related to individual vascular variability, degree of primary and secondary collateralization, and pathogenesis of infarcts. Our study indicates that concomitant small cortical or subcortical lesions are also commonly associated findings in diverse patterns of MCA territory infarction, which can mostly be explained by probable embolic mechanism. Key Words: angiography, magnetic resonance Ⅲ cerebral embolism Ⅲ magnetic resonance imaging Ⅲ middle cerebral artery M ost middle cerebral artery (MCA) territory infarcts have been attributed to embolism from the heart or internal carotid artery (ICA), poor perfusion due to ICA occlusion, intrinsic MCA occlusive disease, or intrinsic disease in the lenticulostriate penetrating vessels.Previous studies 1,2 indicated racial differences in atherothrombotic occlusive diseases of the anterior cerebral circulation. Specifically, extracranial atherosclerosis is more common in whites, whereas intracranial atherosclerosis is more frequent in blacks, Chinese, and Japanese. However, how the common intracranial atherosclerotic vascular lesions are associated with topographic patterns of infarcts has not been studied sufficiently.MRI of the brain has supe...
