Prediction of stroke outcome with echoplanar perfusion- and diffusion-weighted MRI

TLDR

The study examined whether early echoplanar perfusion imaging and diffusion‑weighted imaging can predict stroke evolution and outcome in patients with acute hemispheric infarction. Patients were imaged within 24 h, subacutely (~4.7 days), and at 84 days, with infarct volumes measured on perfusion imaging, DWI, clinical scales, and final T2 MRI. Acute perfusion lesion volume correlated with neurologic state, clinical outcome, and final infarct volume, whereas DWI lesions correlated less with acute state but well with outcome; patterns where perfusion lesions exceeded DWI predicted lesion expansion, while other patterns showed no enlargement.

Abstract

<b>Objectives: </b> We examined the utility of echoplanar magnetic resonance perfusion imaging and diffusion-weighted imaging (DWI) in predicting stroke evolution and outcome in 18 patients with acute hemispheric infarction. <b>Methods: </b> Patients were studied within 24 hours (mean, 12.2 hours), subacutely(mean, 4.7 days), and at outcome (mean, 84 days). Comparisons were made between infarction volumes as measured on perfusion imaging (PI) and isotropic DWI maps, clinical assessment scales (Canadian Neurological Scale, Barthel Index, and Rankin Scale), and final infarct volume (T2-weighted MRI). <b>Results: </b> Acute PI lesion volumes correlated with acute neurologic state, clinical outcome, and final infarct volume. Acute DWI lesions correlated less robustly with acute neurologic 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 lesion larger than the DWI lesion predicted DWI expansion into surrounding hypoperfused tissue (<i>p</i> &lt; 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. <b>Conclusions: </b> Combined early PI and DWI can define different acute infarct patterns, which may allow the selection of rational therapeutic strategies based on the presence or absence of potentially salvageable ischemic tissue.