Abstract DP315: Expanding Treatment Options for Acute Ischemic Stroke Using Hyperacute Magnetic Resonance Imaging

Introduction: Hyperacute MRI (hMRI) has been increasingly implemented in the evaluation of acute ischemic stroke (AIS) to expand eligibility for thrombolysis or thrombectomy in patients who would otherwise be excluded. In the setting of suspected stroke mimic, wake-up stroke, or computed tomography (CT) contrast allergy, hMRI can “rule in” a recent-onset stroke or large vessel occlusion (LVO), thereby converting otherwise ineligible patients into candidates for acute treatment. Despite these advantages, hMRI is resource-intensive and its yield remains uncertain. Using a large hMRI database, we examined treatment yield, workflow, and safety across different clinical indications. Methods: We retrospectively reviewed prospectively collected data on all consecutive patients who underwent hMRI for code stroke at a tertiary center between June 2018 and November 2024. Indications were categorized as: (1) stroke mimic (<4.5 hours from last known normal), (2) wake-up or unwitnessed stroke (<4.5 hours from symptom discovery), or (3) LVO rule-out with magnetic resonance angiography (MRA) (<24 hours from last known normal). Clinical characteristics, workflow metrics, thrombolysis rates, and safety outcomes were compared between groups. Number needed to scan (NNS) was calculated as the total hMRIs performed per indication divided by the number of patients treated with thrombolysis. Results: Among 698 patients, hMRI indications included stroke mimic (n=388), wake-up (n=268), and LVO rule-out (n=42). Baseline characteristics were broadly similar, except wake-up patients were older and more often hypertensive than stroke mimic patients (p<0.001 for both). Thrombolysis was administered in 36 (9%) stroke mimic, 42 (16%) wake-up, and 6 (14%) LVO rule-out cases. NNS was 10.9, 6.4, and 7.0, respectively. Door-to-hMRI order and door-to-needle times were shorter in wake-up compared to stroke mimic patients (28 vs 36 min, p<0.001; and 74 vs 89 min, p=0.013). Symptomatic ICH was rare (1–3%) across groups. Conclusion: hMRI identified thrombolysis-eligible patients with an overall NNS of 8.3; yield was highest in wake-up and LVO rule-out indications. Treatment was feasible within therapeutic windows, and the low rate of ICH supports its safety. Further workflow optimization is needed to reduce treatment delays, minimize variability between indications, and improve the efficiency of hMRI integration into acute stroke protocols.