DIFFUSION-WEIGHTED MAGNETIC-RESONANCE-IMAGING IN ACUTE STROKE

Background and Purpose-Diffusion-weighted MRI (DWI) is highly sensitiv e in detecting early cerebral ischemic changes in acute stroke patient s. In this study we compared the sensitivity of DWI with that of conve ntional MRI techniques. Furthermore, we investigated the prognostic va lue of the volume of ischemic lesions on DWI scans and of the apparent diffusion coefficient (ADC). Methods-We performed DWI, fluid-attenuat ed inversion recovery, spin-echo T2-weighted MRT, and spin-echo proton density-weighted MRT in 42 patients with acute stroke and 15 control subjects. The volume of ischemic lesions was measured on early (<60 ho urs after onset) and follow-up MRI scans. Clinical outcome was measure d 4 months after onset of symptoms with the National Institutes of Hea lth Stroke Scale, the Barthel Index, and the Rankin Scale. Results-Wit h DWI, 98% of the ischemic lesions were detected, and with fluid-atten uated inversion recovery, 91% were detected, whereas with early T2-wei ghted or proton density-weighted scans, only 71% (P=0.002, chi(2)) and 80% (P=0.02, chi(2)) of lesions, respectively, were found. Lesion vol ume on early DWI scans correlated significantly with clinical outcome ratings (P<0.01). In patients with a first-ever stroke, a lesion volum e of less than or equal to 22 mt on DWI predicted good outcome with a 75% sensitivity and a 100% specificity. The mean ADC of ischemic lesio ns was 29% lower than the ADC of normal-appearing parts of the brain ( P<0.001). The ADC ratio correlated significantly with clinical outcome (P<0.05). Conclusions-DWI is a better imaging method than conventiona l MRI in detecting early ischemic lesions in stroke patients. Lesion s ize as measured on DWI scans and, to a lesser extent, ADC values are p otential parameters for predicting clinical outcome in acute stroke pa tients.