Acute ischemic stroke (AIS) is a leading cause of death and long-term disability worldwide. In patients with suspected large vessel occlusion, rapid diagnosis and reperfusion therapy are critical, as treatment delays are associated with worse functional outcomes and increased mortality. Current French guidelines recommend brain magnetic resonance imaging (MRI) as the reference imaging modality because of its high diagnostic accuracy. However, MRI availability remains limited in many stroke centers, often resulting in delays in diagnosis and treatment. Conversely, computed tomography (CT) is more widely available and can substantially shorten time to reperfusion, although it may be less sensitive for early ischemic changes.

The MAGRITTE study aims to determine whether an initial CT-based imaging strategy is more cost-effective than an MRI-based strategy for patients with suspected severe acute ischemic stroke within 6 hours of symptom onset.

This is a prospective, multicenter, randomized controlled trial with two parallel groups enrolling 600 adult patients presenting with a high suspicion of acute ischemic stroke due to proximal large vessel occlusion (National Institutes of Health Stroke Scale [NIHSS] score ≥10). Participants will be randomized to undergo either CT with CT angiography or MRI with MR angiography as the first-line diagnostic imaging examination. Additional perfusion imaging may be performed at the investigator's discretion.

The primary objective is to compare the cost-utility of the two diagnostic strategies at 12 months, expressed as the incremental cost per quality-adjusted life year (QALY) gained, using EQ-5D-5L-derived utilities. Secondary objectives include lifetime cost-effectiveness modeling, 5-year budget impact analysis, comparison of functional outcomes, mortality, imaging-to-treatment and reperfusion times, symptomatic intracranial hemorrhage, diagnostic accuracy, management pathways, adverse events, radiation exposure, and healthcare costs.

The study will provide evidence on whether a CT-first imaging strategy can improve the efficiency of acute stroke care while maintaining favorable clinical outcomes and reducing healthcare costs.