Abstract WP132: The Significance of Fluid-Attenuated Inversion Recovery Vascular Hyperintensity in Combination With Occlusion Site and Reperfusion Status by Mechanical Thrombectomy for Proximal and Distal Middle Cerebral Artery Occlusion

Abstract

Introduction: In patients with acute ischemic stroke, FLAIR vascular hyperintensity (FVH) is a reliable indicator of large vessel occlusion and salvageable tissue requiring mechanical thrombectomy (MT). However, its significance in distal arterial occlusion has not been established. This study aimed to investigate the significance of FVH in DWI-negative areas, in combination with occlusion site and reperfusion status, by MT for regional tissue outcomes in proximal and distal middle cerebral artery (MCA) occlusion. Methods: The clinical records of patients admitted to a single institute between April 2017 and June 2022, who presented with MCA occlusion with initial NIHSS ≥ 5 and underwent MT within 24 h of onset were retrospectively analyzed. Proximal occlusion was defined as M1 segment occlusion, and distal occlusion as M2 or M3 segment based on initial MRA. Each cortical MCA area in Alberta Stroke Program Early CT Score (ASPECTS) ipsilateral to the occluded vessel was categorized into group A (DWI-, FVH-) or B (DWI-, FVH+) based on initial MRI. Regional collateral status on initial angiogram, expanded Thrombolysis in Cerebral Infarction (eTICI) grade on final angiogram, and regional unfavorable tissue outcome with the appearance of low or high density on CT 24 h after MT were recorded. Univariate and multivariate analyses using mixed-effects models for regional unfavorable tissue outcome were performed. Results: A total of 103 patients (56 with proximal and 47 with distal occlusion) were included. Categorizing cortical areas resulted in 256 areas in group A and 171 in group B. The rate of unfavorable tissue outcome in order of eTICI 0-2a, 2b50-67, and 2c-3 reperfusion status in group A were 14.3%, 11.3%, and 6.0%, respectively (p=0.06) while those in group B were 47.1%, 34.0%, and 12.9%, respectively (p<0.01). In multivariate analysis, eTICI 0-2b67 vs. eTICI 2c-3 in group B of distal occlusion was an independent predictor for unfavorable regional tissue outcome (OR 7.8, 95% CI 1.1-55.6, p=0.04), along with ASPECTS M2 or M5 and poor angiographical collaterals. Conclusions: FVH in DWI-negative areas can reveal penumbra tissue secondary to both proximal and distal MCA occlusions. However, salvage requires fairly reliable reperfusion in distal occlusion.