Acute perfusion and diffusion abnormalities predict early new MRI lesions 1 week after minor stroke and transient ischemic attack.

BACKGROUND AND
PURPOSE: Transient ischemic attack and minor stroke are associated with high ischemic recurrence in the first week. We prospectively studied the correlation between baseline diffusion/perfusion deficits and development of new ischemic lesions.
METHODS: Patients with transient ischemic attack and those with minor stroke (n=50) underwent MRI at admission. Acute perfusion-weighted imaging deficit (Tmax+2-second delay) and diffusion-weighted imaging (DWI) lesion volumes were measured planimetrically. Follow-up scans were examined for new DWI/fluid-attenuated inversion recovery lesions at Days 7 and 30.
RESULTS: Twenty-eight patients (56%) had acute DWI lesions. New DWI lesions developed in 9 of 50 patients (18%) at 1 week and 11 of 50 (cumulative 22%) at 4 weeks. Patients with new infarcts were more likely to have baseline DWI lesions (χ²=8.264, P=0.003). Baseline DWI lesion volume was significantly larger in those who developed new lesions at Day 7 (median, 13.2 mL; interquartile range, 12 versus median 0.1 mL; interquartile range, 2 mL; P<0.001) and Day 30 (11.1 mL; interquartile range, 13 mL versus 0.1 mL; interquartile range, 13 mL; P<0.001). Thirty-eight patients had baseline perfusion-weighted imaging. Patients with recurrent lesions were more likely to have baseline perfusion deficits (χ²=19.5, P<0.0001). All new lesions developed within the baseline hypoperfused regions. Baseline DWI lesion volume predicted new lesion development at day 7 (OR, 1.17 per mL; CI, 1.05 to 1.30; P=0.005) and Day 30 (OR, 1.39 per mL; CI, 1.03 to 1.26; P=0.009) by regression analysis.
CONCLUSIONS: Early recurrence of stroke is much more likely in patients with larger baseline DWI and perfusion-weighted imaging lesions. MRI lesion "recurrence" appears to be related to completion of the natural history of the original cerebrovascular syndrome rather than de novo events in most patients.