Prediction of hemorrhagic transformation following acute stroke - Role of diffusion- and perfusion-weighted magnetic resonance imaging

Background: Acute diffusion-weighted (DWI) and perfusion-weighted (PWI) mag netic resonance imaging (MRI) findings may correlate with secondary hemorrh agic transformation (HT) risk in patients with stroke. This information cou ld be of value, particularly in individuals being considered for thrombolyt ic therapy. Objective: To determine the relationship between DWI and PWI findings and t he risk of secondary HT in patients with acute stroke. Design: Retrospective case series. Setting: Academic medical center. Patients: Twenty-seven patients with acute stroke capable of being evaluate d with DWI/PWI 8 hours or less after symptom onset. Main Outcome Measures: Apparent diffusion coefficient values, perfusion del ay measurements, and subsequent MRI or computed tomographic scans detected HT. Results: The mean +/- SD apparent diffusion coefficient of ischemic regions that experienced HT was significantly lower than the overall mean +/- SD a pparent diffusion coefficient of all ischemic areas analyzed (0.510 +/-0.14 0X10(-3) mm(2)/s vs 623 +/-0.113X10(-3) mm(2)/s; P=.004). This difference r emained significant when comparing the HT-destined ischemic areas with the non-MT-destined areas within the same ischemic lesion (P=.02). Patients rec eiving recombinant tissue-type plasminogen activator (rt-PA) experienced HT significantly earlier than patients not receiving rt-PA (P=.002). Moreover , a persistent perfusion deficit in the area of subsequent hemorrhage at 3 to 6 hours after the initial MRI scan was identified in significantly more patients who experienced HT than in those who did not (83% vs 30%; P=.03). Conclusion: Both DWI and PWI scans detect abnormalities that are associated with HT. These findings support a role for MRI in identifying patients who are at increased risk for secondary HT following acute ischemic stroke.