Serial MRI studies from patients in the Echoplanar Imaging Thrombolytic Evaluation Trial with initial diffusion-weighted imaging (DWI) lesion volume >82 cm3 were analyzed. Two independent readers outlined the hemisphere and lateral ventricle on the involved side and calculated respective volumes at baseline and days 3 to 5. We assessed interrater agreement, volume change between scans, and the association of volume change with early neurologic deterioration (National Institutes of Health Stroke Scale score worsening of ¡Ý4 points), a 90-day modified Rankin scale (mRS) score of 0 to 4, and mortality.
Of 12 patients who met study criteria, average baseline and follow-up DWI lesion size was 138 cm3 and 234 cm3, respectively. The mean time to follow-up MRI was 62 hours. Concordance correlation coefficients between readers were >0.90 for both hemisphere and ventricle volume assessment. Mean percent hemisphere volume increase was 16.2 ¡À 8.3 % (P < .0001), and the mean percent ventricle volume decrease was 45.6 ¡À 16.9 % (P < .001). Percent hemisphere growth predicted early neurologic deterioration (area under the curve [AUC] 0.92; P = .0005) and 90-day mRS 0 to 4 (AUC 0.80; P = .02).
In this exploratory analysis of severe ischemic stroke patients, statistically significant changes in hemisphere and ventricular volumes within the first week are consistent with expected changes of cerebral edema. MRI-based analysis of hemisphere growth appears to be a suitable biomarker for edema formation.