Longitudinal magnetic resonance imaging study of perfusion and diffusion in stroke: Evolution of lesion volume and correlation with clinical outcome

A prospective longitudinal diffusion-weighted and perfusion-weighted magnet ic resonance imaging (DWI/PWI) study of stroke patients (n = 21) at five di stinct time points was performed to evaluate lesion evolution and to assess whether DWI and PWI can accurately and objectively demonstrate the degree of ischemia-induced deficits within hours after stroke onset. Patients were scanned first within 7 hours of symptom onset and then subsequently at 3 t o 6 hours, 24 to 36 hours, 5 to 7 days, and 30 days after the initial scan. Lesion evolution was dynamic during the first month after stroke. Most pat ients (18 of 13, 95%) showed increased lesion volume over the first week an d then decreased at 1 month relative to 1 week (12 of 14, 86%), Overall, le sion growth appeared to depend on the degree of mismatch between diffusion and perfusion at the initial scan. Abnormal volumes on the acute DWI and PW I (<7 hours) correlated well with initial National Institutes of Health (NI H) stroke scale scores, outcome NIH stroke scale scores, and final lesion v olume, DWI and PWI can provide an early measure of metabolic and hemodynami c insufficiency, and thus can improve our understanding of the evolution an d outcome after acute ischemic stroke.