magnetic resonance diagnosis of pulmonary embolism

Conditions: Lung Diseases; Pulmonary Embolism

Summary: * 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

Eligibility criteria:
inclusion criteria: * clinically suspected acute pulmonary embolism * 18 years old or more * d-dimers more than 500 or high clinical probability of pulmonary embolism according to the revised geneva score * thoracic ct angiography performed within 24 hours * informed consent exclusion criteria: * - contraindication to mri (pace maker, claustrophobia, any implanted ferromagnetic foreign body) * obese patients too large to fit in mri unit * allergy to gadolinium-containing contrast agent or to iodinated contrast media * renal insufficiency (clearance less than 30 ml/mn) * anticoagulation at a curative dose started more than 48 hours prior to mri * life expectancy less than 3 months * pregnancy

Keywords: magnetic resonance imaging/methods magnetic resonance angiography perfusion imaging pulmonary embolism/diagnosis