Perfusion Magnetic Resonance Imaging Maps in Hyperacute Stroke

Abstract
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<0.001) and clinical outcome (r=0.67, P<0.01). There was a trend for...