Magnetic Resonance Diagnosis of Pulmonary Embolism

Overview

* The purpose of this study is to evaluate the diagnostic accuracy of thoracic magnetic resonance imaging with gadolinium-enhanced, unenhanced and perfusion sequences in patients with clinically suspected acute pulmonary embolism * Thoracic CT angiography (CTA) will serve as reference standard * Result of MRI will not interfere with patients' management * Untreated patients with negative CTA will have 3-month follow-up to verify they were free of thrombose-embolic disease

Background In patients with clinically suspected pulmonary embolism (PE)°with a contraindication to thoracic CT angiography, there is a need for an alternative diagnostic procedure. MRI has not been fully evaluated in this field; moreover, recent technological advances make it necessary to re-evaluate its performance for PE diagnosis. Design Prospective monocentric study * Patients with clinically suspected acute pulmonary embolism will undergo thoracic magnetic resonance imaging if inclusion criteria are fulfilled. * A non-inclusion register will be establish for patients fulfilling the inclusion criteria , not included because MRI was not available (off-hours presentation , another patients already included in the protocol on the same day ) Estimated enrolment : 280 (based on a 25% prevalence of PE in our institution and an expected 80% sensitivity of MRI) Study start date: June 2007 Estimated study completion date: 17 months later (40 to 50 presentations for PE suspicion each month, 20 inclusions expected per month) Magnetic Resonance imaging: performed on a 1.5 Tesla unit with 3 different sequences * Unenhanced Steady State Free Precession (SSFP) sequences * Perfusion imaging following Gadolinium injection at a rate of 5 c/s and a dose of 0.1mmol/kg * Magnetic resonance angiography following an injection of 0.1mmol/kg of gadolinium at 3ml/s MRI studies will be interpreted secondarily by 2 independent radiologists, blinded to CTA results and clinical probability. Two different readings will be performed, one global reading and one reading of each sequence separately, displayed in a random order (access base) Objectives * to evaluate MRI performance for PE diagnosis globally * to evaluate the diagnostic value for each sequence (especially the negative predictive value of a normal perfusion sequence) * to evaluate inter-observer agreement MRI and CTA have to be performed within 24 hours

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Outcomes