Abstract 2674: DWI Reversal is associated with Small Infarct Volume and Early Reperfusion in Patients with TIA and Minor Stroke. Data from VISION and CATCH study groups

Abstract

Introduction: One-third of patients with TIA and minor ischemic stroke (MIS) have evidence of ischemic penumbra, defined as hypoperfused regions that have not been irreversibly damaged. Diffusion weighted Imaging (DWI) lesions are thought to represent irreversibly damaged tissue. DWI reversal therefore has implications in accurate estimation of penumbra. We aimed to determine the rate of DWI reversal in this population. Methods: Patients with TIA/MIS (NIH Stroke Scale ≤ 3) were prospectively enrolled and imaged within 24 hours of symptom onset as part of two prospective imaging cohorts. Patients were included if their baseline modified Rankin scale (mRS) score was ≤1. All patients were followed clinically for 3 months and had a repeat MRI either at day 30 or 90. Baseline diffusion and perfusion lesions and follow-up FLAIR final infarct volumes were measured. Results: 418 patients were included; 55.5% had DWI lesions and 37% had PWI (Tmax+2s delay) deficits at baseline. A total of 337 (81%) patients had follow-up imaging. DWI reversal occurred in 22/192 (11.5%) of patients who had a diffusion lesion at baseline. The median time from symptom onset to follow-up imaging was not significantly different between those with or without DWI reversal (78.6 days, IQR=33.3 vs. 79.7 days, IQR= 59.4, p=0.65). The median DWI lesion volume was significantly smaller in those with reversal (0.27ml, IQR=0.75 ml) compared to those who did not reverse (1.45 ml, IQR=3.8 ml, p<0.001). Patients with concurrent perfusion deficits (Tmax+2s) were significantly less likely to have DWI reversal (6%) compared to those without evidence of tissue hypoperfusion (20%; p=0.003). DWI reversal occurred in 4% of patients with penumbral patterns ((Tmax+2s)-DWI) and 18% of those without penumbra (p=0.003).Severity of hypoperfusion defined as greater prolongation of Tmax (+2,+4, +6, +8s) did not affect the likelihood of DWI reversal (linear trend p=0.147). No patient with DWI reversal had a mRS of ≥2 at 90 day, compared to 19% of those with evidence of infarction on follow-up imaging (p= 0.02). Conclusion: DWI reversal is common in patients with TIA/MIS and is more likely to occur in those with smaller baseline lesions without concurrent tissue hypoperfusion. DWI reversal therefore should not have a significant effect on the accuracy of penumbra definition. These data suggest early reperfusion is correlated with DWI reversal and better clinical outcome as measured by mRS.