The impact of magnetic resonance imaging on the management of acute ischemic stroke.

Despite rapid advances in imaging technology, the etiology of stroke remains unestablished in 40% of patients. MRI improves localization in acute stroke. However, it is not known whether "accurate localization" results in better management. We reviewed the hospital records of all patients admitted with a diagnosis of acute ischemic stroke and who had had cranial CTs and MRI within 10 days of admission. Between January 1987 and June 1990, 116 patients (69 men, 47 women; mean age, 66 years) were identified. Compared with CT localization, infarcts were better localized in nine of 39 patients with cerebral cortical lesions, in 20 of 22 patients with brainstem and cerebellar lesions, and in three of three patients with isolated cerebellar lesions. In 22 patients (18.9%), MRI showed multiple infarcts in two or more vascular territories, suggesting embolic disease and leading to anticoagulation. MRI also showed arterial occlusions in 11 patients (9.5%). Based on the information obtained with MRI, the clinical diagnosis was changed in 19 patients (16.3%), resulting in changes in the management of most of those patients. Thus, we confirm earlier reports that MRI improves localization after acute cerebral infarction and show that such information alters patient management.