Diagnostic accuracy of magnetic resonance imaging for an acute pulmonary embolism: results of the ‘IRM‐EP’ study

Background: Magnetic resonance imaging (MRI) has not been validated as an alternative diagnostic test to computed tomography angiography (CTA) in patients with suspicion of a pulmonary embolism (PE). Objectives: To evaluate performance of current MRI technology in diagnosing PE, in reference to a 64‐detector CTA. Patients/methods: Prospective investigation including 300 patients with a suspected PE, referred for CTA after assessment of clinical probability and D‐dimer testing. MRI protocol included unenhanced, perfusion and angiographic sequences. MRI results were interpreted by two independent readers, to evaluate inter‐reader agreement. Sensitivity and specificity were evaluated globally and according to PE location and to clinical probability category. Results: Of 300 enrolled patients, 274 were analyzed and 103 (37.5%) had a PE diagnosed by CTA. For patients with conclusive MRI results (72% for reader 1, 70% for reader 2), sensitivity and specificity were 84.5% (95% confidence interval [CI], 74.9–91.4%) and 99.1% (95% CI, 95.1–100.0%), respectively, for reader 1, and 78.7% (95% CI, 68.2–87.1%) and 100% (95% CI, 96.7–100.0%) for reader 2. After exclusion of inconclusive MRI results for both readers, inter‐reader agreement was excellent (kappa value: 0.93, 95% CI: 0.88–0.99). Sensitivity was better for proximal (97.7–100%) than for segmental (68.0–91.7%) and sub‐segmental (21.4–33.3%) PE (P