ORIGINAL RESEARCH ADULT BRAIN Hyperintense Vessels on FLAIR: Hemodynamic Correlates and Response to Thrombolysis

BACKGROUNDAND PURPOSE: Hyperintense vessels on baseline FLAIR MR imaging of patients with ischemic stroke have been linked to leptomeningeal collateralization, yet the ability of these to maintain viable ischemic tissue remains unclear. We investigated whether hyperintense vessels on FLAIR are associated with the severity of hypoperfusion and response to thrombolysis in patients treated with intravenous tissue-plasminogen activator. MATERIALS AND METHODS: Consecutive patients with ischemic stroke with an MR imaging before and within 24 hours of treatment, with proved vessel occlusion and available time-to-maximum maps were included (n 62). The severity of hypoperfusion was charac-terized on the basis of the hypoperfusion intensity ratio (volume with severe/mild hypoperfusion [time-to-maximum 8 seconds / time-to-maximum 2 seconds]). The hypoperfusion intensity ratio was dichotomized at the median to differentiate moderate (hypo-perfusion intensity ratio 0.447) and severe (hypoperfusion intensity ratio 0.447) hypoperfusion. Good outcome was defined as a modified Rankin Scale score of2. RESULTS: HyperintensevesselsonFLAIRwere identified in54patients (87%). PatientswithextensivehyperintensevesselsonFLAIR (4 sections) had higher NIHSS scores, larger baseline lesion volumes, higher rates of perfusion-diffusion mismatch, and more severe hypoperfusion (hypo-perfusion intensity ratio). In stepwise backward multivariate regression analysis for the dichotomized hypoperfusion intensity ratio (including stroke etiology, age, perfusion deficit, baseline lesion volume, smoking, and extent of hyperintense vessels on FLAIR), extensive hyperintens