ENLARGEMENT OF HUMAN CEREBRAL ISCHEMIC LESION VOLUMES MEASURED BY DIFFUSION-WEIGHTED MAGNETIC-RESONANCE-IMAGING

We aimed to determine the frequency and time course of the enlargement of ischemic cerebral lesions following human stroke and to study the effect of the state of perfusion on lesion enlargement. Acute lesion v olumes were measured on diffusion-weighted magnetic resonance images a nd compared with lesion volumes measured on T2-weighted images at 7 da ys or later. Forty-four measurements were performed between 2 and 53 h ours after stroke onset in 28 patients. Thirteen patients also had mag netic resonance perfusion imaging performed. In 12 (43%) of 28 patient s the initial lesion volume increased by 20% or more. The number of st udies showing enlargement of the ischemic lesion volume ranged from 12 (43%) of 28 at or after 2 hours to 10 (38%) of 26 at or after 6 hours , 5 (33%) of 15 at or after 24 hours, and 2 (33%) of 6 at or after 48 hours. In 7 of the 10 patients in whom the hypoperfusion volume acutel y exceeded the volume of the abnormality on diffusion-weighted images, lesion volume increased by 20% or more. This study provided evidence that substantial enlargement of human cerebral ischemic lesion volumes can occur beyond the first 6, 12, or 24 hours after onset. A mismatch acutely between the region of hypoperfusion (larger) and the region o f diffusion abnormality (smaller) may be predictive of ischemic lesion enlargement.