Abstract WMP17: Early DWI Reversal Following Endovascular Reperfusion Is Typically Transient

Abstract

Background and Purpose: There are conflicting reports regarding the incidence and prognostic significance of DWI reversal following reperfusion therapy. The aim of this study was to assess the frequency and extent of early DWI reversal following endovascular therapy and to determine if early reversal is sustained or transient. Methods: This is a substudy of the DEFUSE 2. MRI with DWI and PWI was performed before (DWI 1) and within 12 hours after (DWI 2) endovascular stroke treatment and again at 5 days. Acute DWI lesions were outlined and quantified using mipav software (http://mipav.cit.nih.gov/). Ischemic lesion volumes were outlined on the Day 5 FLAIR then corrected for edema using a validated technique to determine the final infarct volume. Early DWI reversal was defined as (DWI 1 - DWI 2) >3 ml and permanent DWI reversal was defined (DWI 1 - final infarct volume) > 1 ml. Reperfusion was defined as a >50% reduction in PWI volume (Tmax >6 sec) on the MRI performed after endovascular therapy. The prognostic significance of early reversal was assessed in a regression model. Results: 104 patients had a technically adequate DWI and PWI prior to endovascular therapy (performed 4.4 [3.0-6.0] hours after symptom onset). Of these, 77 had an acute DWI lesion >3 ml and a follow-up MRI (156 min [72-342] after completion of endovascular therapy) and a 5 day MRI. Seventeen percent (13/77) of the patients had early DWI reversal representing a median (IQR) of 42.4% (25.0-57.6) of the initial DWI lesion (median volume 10.9 ml [IQR 7.3-18.2]). The incidence of early DWI reversal was 21% (11/52) following reperfusion vs. 8% (2/25) in patients who did not reperfuse (p=0.20). Of the 13 patients with early DWI reversal, permanent DWI reversal occurred in only 2 (volume of permanent DWI reversal 6.9 ml and 4.7 ml). Early DWI reversal was not an independent predictor of clinical outcome. Conclusion: Early DWI reversal occurs in about 15-20% of patients following endovascular therapy and can involve a substantial percentage of the initial DWI volume. However, early DWI reversal is usually transient and does not appear to signify tissue salvage.