Abstract TP287: Efficient Multimodal-MRI versus CT Selection for Anterior Circulation Large Vessel

Abstract

Background: Prompt diagnosis and revascularization of large vessel occlusion ischemic stroke is associated with better functional outcome. While both MRI and CT modalities are current standard of care options for initial imaging, and MR imaging provides greater lesion conspicuity and spatial resolution to inform management, few series have yet demonstrated that multimodal MR may be performed speedily and efficiently in AIS-LVO patients. Methods: In a prospectively maintained Comprehensive Stroke Center Registry, we analyzed all anterior circulation LVO thrombectomy patients: 1) arriving directly by EMS transport from the field, 2) with initial NIHSS ≥6, between 2012-2017. Throughout this period, imaging policy was multimodal MRI (including DWI/GRE/MRA w/wo PWI) as the initial evaluation in all patients without contraindications, and multimodal CT (including CT with CTA, w/wo CTP) in the remainder. Achieved process times were compared with national recommendations for door-to-needle (45m, AHA/ASA Target Stroke) and door-to-puncture (90m, SVIN). Results: Among 106 LVO thrombectomy patients, MRI was used in 62.3% and CT in 37.7%. MRI and CT patients were similar in age, 72.5 v 71.3y; severity (NIHSS) 16.4 v 18.2); and IV tPA door-to-needle times, median 45 vs 46 mins. However, MRI patients had longer onset-to-door times, median 100 vs 50 mins. From Jan 2012-Dec2014, in MRI vs CT groups, median door-to-imaging times were 20 min vs 18 min, p=0.88 and door-to-puncture times 102 vs 93 min, p=0.39. From Jan 2015-Dec2017, after the publication of the positive thrombectomy trials and endorsement of endovascular stroke treatment in US guidelines, in MRI vs CT groups, median door-to-imaging times were 17 min vs 17 min (p=0.93) and door-to-groin puncture 86 vs 71 min (p=0.02). There was no difference in functional outcome (mRS 0-2) between groups. Conclusions: Optimized imaging processes enable acute AIS-LVO patients to be evaluated by multimodal MR with care speeds faster than national recommendations for door-to-needle and door-to-puncture times. While some patients have absolute contraindications to high magnetic fields, MRI, with its greater pathophysiologic insight, remains a highly viable primary imaging strategy in acute ischemic stroke patients.