[MRI of acute cerebral infarction]

Sequential changes of magnetic resonance imaging (MRI) in sixteen patients with acute cerebral infarction are studied in comparison with the findings of computed tomography (CT). The sixteen patients were examined within 36 hours from the onset of symptoms on resistive type MRI (0.15T) using T1 weighted image (IR2000/500) and T2 weighted image (SE2000/80), and on CT. In general, large infarcted lesions of the cortex-subcortex seemed to be visualized earlier than small lesions of the basal ganglia and brainstem. In 8 patients, the infarcted lesions were detected on MRI earlier than on CT. For example, early detecting time within 12 hours were 2, 6, 7, and 10 hours after onset. In two patients of this group, lesions were detected on T2-weighted image earlier than on T1-weighted image. In two cases, small lesions of the brainstem were detected only on MRI. The size of abnormal findings gradually developed and reached a maximum on days 5 to 7 sequentially. The difference between infarction and perifocal edema was not clear even on MRI. The changes gradually subsided and assumed a stable size after about 2 months. Contrast enhancement effect was observed in four patients. In two of these cases, the signal intensity of T2-weighted imaging was decreased just at the region which was enhanced with contrast medium. MRI is useful for early diagnosis of ischemic cerebral infarction, and may elucidate some aspects of the pathophysiology of ischemic stroke.