Evolution of cerebral infarct volume assessed by diffusion-weighted magnetic resonance imaging

Background: Knowledge of the natural evolution of ischemic brain lesions ma y be a crucial aspect in the assessment of future stroke therapies. Objective: To establish daily changes of ischemic cerebral lesion volume us ing diffusion-weighted magnetic resonance imaging. Design: Prospective cohort study. Setting: Referral center. Patients and Methods: Serial magnetic resonance imaging scans were performe d in consecutive untreated stroke patients. The baseline scan was obtained within 48 hours after symptom onset; subsequent scans, 12 to 48 hours, 3 to 4 days, S to 7 days, and 30 days after baseline. Lesion volumes were measu red on each scan by 2 independent observers. Main Outcome Measure: Daily change in lesion volume. Results: A total of 112 magnetic resonance imaging scans were obtained in 2 4 patients. An early increase in lesion volume was seen in all patients. Ma ximum lesion volume was reached at a mean of 74 hours. Lesion volumes incre ased by a mean (+/- SEM) of 21%+/- 112% during day 2 and 10%+/- 12% during day 3. No significant change occurred during day 4. During days S, 6, and 7 , statistically significant mean (+/- SEM) decreases of 6%+/-8%, 3%+/-4%, a nd 4%+/-5%, respectively, were observed. Conclusions: Ischemic lesions follow a relatively consistent pattern of gro wth during the first 3 days and subsequent decrease in size. These data in conjunction with data regarding the evolution of lesion volume during the f irst 24 hours after symptom onset may be useful in the design of pilot stud ies of therapies for acute stroke.