PREDICTION OF STROKE OUTCOME WITH ECHOPLANAR PERFUSION-WEIGHTED AND DIFFUSION-WEIGHTED MRI

Objectives: We examined the utility of echoplanar magnetic resonance p erfusion imaging and diffusion-weighted imaging (DWI) in predicting st roke evolution and outcome in 18 patients with acute hemispheric infar ction. Methods: Patients were studied within 24 hours (mean, 12.2 hour s), subacutely (mean, 4.7 days), and at outcome (mean, 84 days). Compa risons were made between infarction volumes as measured on perfusion i maging (PI) and isotropic DWI maps, clinical assessment scales (Canadi an Neurological Scale, Barthel Index, and Rankin Scale), and final inf arct volume (T2-weighted MRI). Results: Acute PI lesion volumes correl ated with acute neurologic state, clinical outcome, and final infarct volume. Acute DWI lesions correlated less robustly with acute neurolog ic state, but correlated well with clinical outcome and final infarct volume. Three of six possible patterns of abnormalities were seen: PI lesion larger than DWI lesion (65%), PI lesion smaller than DWI lesion (12%), and DWI lesion but no PI lesion (23%). A pattern of a PI lesio n larger than the DWI lesion predicted DWI expansion into surrounding hypoperfused tissue (p < 0.05). In the other two patterns, DWI lesions did not enlarge, suggesting that no significant increase in ischemic lesion size occurs in the absence of a larger perfusion deficit. Concl usions: Combined early PI and DWI can define different acute infarct p atterns, which may allow the selection of rational therapeutic strateg ies based on the presence or absence of potentially salvageable ischem ic tissue.