Abstract 35: Early Diffusion Weighted Imaging and Perfusion Weighted Imaging Lesion Volumes Forecast Final Infarct Size in DEFUSE 2

Abstract

Background: It is hypothesized that early DWI lesions accurately estimate the size of the irreversibly injured ischemic core and that appropriately thresholded PWI lesions (Tmax > 6 seconds) approximate the volume of critically hypoperfused tissue. With incomplete reperfusion, the union of baseline DWI and post-treatment PWI is hypothesized to predict infarct volume. Methods: This is a substudy of DEFUSE 2; all patients who had technically adequate MRI scans at 3 time points were included: just prior to endovascular therapy, within 12 hours post-therapy, and at 5 days. Baseline DWI and early follow-up PWI lesion volumes were determined by the RAPID software program and manually adjusted by the DEFUSE 2 core lab if needed. Final infarct volumes were assessed on the Day 5 FLAIR and corrected for edema. Reperfusion was defined based on the reduction in PWI lesion volume between baseline and early follow-up MRI. DWI and PWI volumes were correlated with final infarct volumes. Results: Seventy-eight patients were eligible; the 28 patients with >90% reperfusion show a high correlation between early DWI volume and final infarct volume (r = 0.81, p < 0.001) with a slope of 0.95. Twelve patients with <10% reperfusion have a high correlation between baseline PWI (Tmax >6 sec) volume and final infarct volume with a slope of 1.17 (r = 0.93, p < 0.001). Using all 78 patients, the union of baseline DWI with early follow-up PWI is highly correlated with final volume (r = 0.86, p < 0.001) with a slope of 1.01. The median absolute difference between observed and predicted final volume is 15 ml (IQR, 4.8-32.8). Conclusions: Early DWI and PWI (Tmax > 6 sec) volumes provide a reasonable approximation of final infarct volume following endovascular therapy.