['The impact of deep white matter lesions observed at the corona radiata on diffusion-weighted MRI (DWI-W lesions) on the clinical recovery of patients after tissue plasminogen activator (tPA) therapy is unclear. Our goal was to elucidate whether DWI findings before tPA could predict clinical recovery.', 'A total of 83 consecutive patients with hyperacute anterior circulation ischemic stroke were enrolled. All patients underwent MRI within 3 h and received intravenous tPA. The relationships among the Alberta Stroke Program Early CT Score (ASPECTS) on DWI (DWI-ASPECTS), DWI-W lesions, early dramatic improvement (> or =10-point reduction in the total National Institutes of Health Stroke Scale, NIHSS, score or a total NIHSS score of 0-2 after 24 h), early improvement (> or =4-point reduction in the total NIHSS score after 24 h) and worsening (> or =4-point increase in the total NIHSS score after 24 h) were assessed.', 'The median of the baseline DWI-ASPECTS value was 9 (range: 5-10), and DWI-W lesions were found in 36 patients (43%). Patients with early dramatic improvement had a shorter time from onset to tPA (116.1 +/- 34.9 vs. 133.2 +/- 33.1 min; p = 0.0281) and higher DWI-ASPECTS (medians: 9 vs. 9; p = 0.0568). DWI-W lesions were seen less frequently in patients with than without early dramatic improvement (26 vs. 54%; p = 0.0213). Multivariate logistic regression analysis demonstrated that absence of DWI-W lesions (OR: 1.80; 95% CI: 1.08-3.13; p = 0.0279), higher ASPECTS (OR: 1.56; 95% CI: 1.06-2.46; p = 0.0346) and shorter time from onset to tPA (OR: 0.98; 95% CI: 0.97-0.99; p = 0.0429) were independent predictors of early dramatic improvement.'] Is presence of deep white matter lesions on diffusion-weighted imaging a negative predictor of early dramatic improvement after intravenous tissue plasminogen activator thrombolysis?