Abstract T P40: FLAIR Vascular Hyperintensity is a Marker of Collateral Flow Grade and Severity of Leukoaraiosis in Patients with Acute Ischemic Stroke

Abstract

Introduction: FLAIR Vascular Hyperintensity (FVH) is a novel radiographic marker detected on FLAIR MRI sequence in patients with acute ischemic stroke (AIS), which is linked to abnormal blood flow and potentially salvageable brain tissue. Poor leptomeningeal collateral status in AIS patients with proximal artery occlusion (PAO) is associated with larger final infarct size and worse clinical outcomes, which are also known to be affected by severity of white matter hyperintensity (WMH). We sought to evaluate the utility of FVH as a marker of acute collateral vessel status and its association with WMH burden in AIS patients. Methods: Consecutive AIS patients admitted to our center with PAO on baseline CT angiography (CTA) were retrospectively selected from a prospectively derived database. FVH was assessed on admission FLAIR MRI obtained immediately after IV tPA administration. FVH was graded by its location (0-none, 1-proximal, 2-distal, and 3-both); degree (0-none, 1-subtle, 2-prominent, and 3-both); and its score (0-none, 1-less than four hyperintense vessels, and 2-four or more hyperintense vessels). Collateral flow grade was ranked on admission CTA using previously published method. WMH volume (WMHV) was assessed using a validated, semi-automated volumetric MRI-based protocol. The relationship between FVH, collateral flow grade, and WMHV were analyzed. Results: A total of 39 patients were included in this study (mean age 70.5±12.7 years; 56% women, mean NIHSS score 17.2±4.4 points). Median WMHV was 6.0 cm3 (interquartile range [IQR] 3.4-9.6 cm3). Median DWI volume was 17.7 cm3 (IQR 9.9-26.0 cm3). FVH score and collateral flow grade were significantly correlated (Spearman’s rank correlation ρ=0.41, p=0.009). In a univariate regression model, FVH degree was inversely associated with WMHV volume (β=-0.33, p=0.04). Conclusions: FVH score detected on acute FLAIR MRI can be used as a marker of collateral flow grade in patients with AIS. Degree of FVH is inversely associated with WMHV, possibly signifying the diffuse disease of cerebral vasculature in patients with severe leukoraiosis.