Diffusion-weighted echo planar imaging of acute brain infarction: a preliminary report.

The clinical usefulness of diffusion-weighted echo planar imaging (DW-EPI) was studied in 55 patients with acute brain ischemia. Ischemic lesions were identified on DW-EPI as hyperintense regions in all patients before changes were detected by conventional magnetic resonance imaging techniques in 12 cases studied earlier than 6 hours after onset. The earliest case was verified on DW-EPI at 50 minutes after onset. The ultra-fast imaging technique took less than 2 minutes to perform even for restless patients. Three patients had cardioembolic middle cerebral artery occlusion, and emergent percutaneous transluminal recanalization was carried out. Chronological changes in the signal of brain ischemia on DW-EPI depended on the site and size of the lesion, lacunar infarct of basal ganglia, and/or massive infarct due to major vessel occlusion, and were affected by associated hemorrhagic events. Coronal DW-EPI could more easily demarcate ischemia in the brainstem and/or cerebellum than axial scans when susceptibility artifacts were present. Coronal scans also demonstrated the site and direction of the pyramidal tract and its anatomical correlation with the lesions. DW-EPI has potential for the diagnostic and therapeutic planning of patients with acute brain ischemia.