(HealthDay News) – Magnetic resonance imaging (MRI) should not be used as a stand-alone test to diagnose pulmonary embolism (PE), according to a study published online Feb. 9 in the Journal of Thrombosis and Haemostasis.

Marie Pierre Revel, MD, PhD, of Hôpital Européen Georges Pompidou in Paris, and colleagues studied 274 patients with suspected PE, referred for computed tomography angiography (CTA) after clinical assessment and D-dimer testing. The MRI protocol included unenhanced, perfusion, and angiographic sequences; the results were interpreted by two independent readers, to evaluate inter-reader agreement. Sensitivity and specificity were evaluated globally and according to PE location and clinical probability category.

The researchers found that, of the 274 patients, 37.5% had PE diagnosed by CTA. Roughly 30% of MRIs were inconclusive. For patients with conclusive MRI results, sensitivity and specificity were 84.5% and 99.1%, respectively, for reader 1, and 78.7% and 100% respectively, for reader 2. Excluding inconclusive MRI results for both readers, inter-reader agreement was excellent. Sensitivity was significantly better for proximal PE (97.7%–100%) than for segmental PE (68%–91.7%) and sub-segmental PE (21.4%–33.3%). Sensitivity was comparable for both readers within each clinical probability category.

“In conclusion, the present study confirms MRI specificity and demonstrates a high sensitivity for proximal PE diagnosis together with high agreement, whereas the sensitivity for segmental and sub-segmental PE remains limited,” the authors write.

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