Abstract WP260: Post Treatment Follow-up MRI Imaging Biomarkers of Collateral Status are Associated with Short-Term Outcomes in Large Vessel Acute Ischemic Stroke (LVO-AIS)

Background: FLAIR hyperintense vessels (FHV), quantified using the NIH-FHV score (NFS), and the SWI brush sign (SBS) are MRI markers associated with hemodynamic impairment in acute ischemic stroke (AIS). We aimed to evaluate the prognostic significance of post-treatment NFS and SBS in patients with anterior circulation large vessel occlusion (AIS-LVO), including those with successful reperfusion. MATERIALS AND METHODS: We retrospectively analyzed 215 AIS-LVO patients with in-hospital follow-up MRI. NFS and SBS were evaluated and correlated with clinical outcomes including NIHSS shift (≥4-point improvement) and hemorrhagic transformation (HT). Spearman correlation and logistic regression were performed, adjusting for clinical covariates. Analyses were repeated in the successfully reperfused subgroup (mTICI ≥2b). Results: FHV and SBS were observed post-treatment in 38% and 20% of patients, respectively. NFS and SBS were positively correlated (ρ = 0.57, p < .01). NFS inversely correlated with NIHSS shift (ρ = –0.26, p < .01) and reperfusion grade (mTICI; ρ = 0.25, p < .01). NFS was independently associated with worse NIHSS shift (OR 0.60, p < .01) and reduced odds of HT (OR 0.78, p = .04). Among 154 patients with successful reperfusion, 24% of mTICI 3 cases showed FHV. In this subgroup, NFS remained predictive of poor NIHSS shift (OR 0.58, p = .03). SBS alone was not independently associated with outcomes. CONCLUSIONS: NFS on post-treatment MRI is a robust imaging biomarker of persistent perfusion deficits and early neurological outcome, even after successful reperfusion. SBS may reflect complementary collateral dynamics but showed limited independent prognostic utility.