Intracranial atherosclerosis may be related to the risk of ischemic stroke. High-resolution magnetic resonance imaging (H-R MRI) makes it possible to measure the intracranial atheroma in vivo. The aim of this study was to evaluate the plaque burden of the middle cerebral artery (MCA) using H-R MRI, and to determine its relationship with both cerebral infarction size and plaque burden in the carotid artery (CA). 54 patients with MCA territory infarction were enrolled and HR-MRI was performed within 7 days following stroke onset. The lumen area (LA), wall area (WA), total vessel area (TVA), and the normalized wall index (NWI) of MCA and CA were measured. We analyzed the status of MCA and CA atheroma, and the size of cerebral infarction, in the corresponding vascular territory. We observed a significant positive correlation between the NWI of the index artery and the volume of the ipsilateral ischemic lesions. In addition, the mean NWI of MCA was significantly correlated with that of the ipsilateral CA (left, r = 0.88, P.0.001; right, r = 0.79, P.0.001), and the plaque burden of the M1 segment of MCA was significantly higher than that of the ipsilateral CA (P < 0.05). There was no significant correlation between the TVA and WA of MCA and that of CA. Our findings suggest that MCA atherosclerosis is significantly correlated with cerebral infarction. In ischemic stroke patients, the plaque burden of M1 segment of MCA is more significant than that of CA.