Perfusion Magnetic Resonance Imaging Maps in Hyperacute Stroke

Background and Purpose —In ischemic stroke, perfusion-weighted imaging (PWI) and diffusion-weighted imaging (DWI) provide important pathophysiological information. A PWI>DWI mismatch pattern suggests the presence of salvageable tissue. However, improved methods for distinguishing PWI>DWI mismatch tissue that is critically hypoperfused from benign oligemia are required. Methods —We investigated the usefulness of maps of relative cerebral blood flow (rCBF), volume (rCBV), and mean transit time (rMTT) to predict transition to infarction in hyperacute (DWI mismatch patterns. Semiquantitative color-thresholded analysis was used to measure hypoperfusion volumes, including increasing color signal intensity thresholds of rMTT delay, which were compared with infarct expansion, outcome infarct size, and clinical status. Results —Acute rCBF lesion volume had the strongest correlation with final infarct size ( r =0.91, P DWI mismatch volume to overestimate infarct expansion between the acute and outcome study ( P =0.06). Infarct expansion was underestimated by acute rCBV>DWI mismatch ( P 70%), these regions progressed to infarction in all except 1 patient, but infarct expansion was underestimated ( P DWI mismatch region at risk of infarction. Color-thresholded PWI maps show potential for use in an acute clinical setting to prospectively predict tissue outcome.