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 < 0.0001). Sensitivity was similar for both readers within each clinical probability category. CONCLUSIONS: Current MRI technology demonstrates high specificity and high sensitivity for proximal PE, but still limited sensitivity for distal PE and 30% of inconclusive results. Although a positive result can aid in clinical decision making, MRI cannot be used as a stand-alone test to exclude PE.

Perfusion defects after pulmonary embolism: risk factors and clinical significance.

BACKGROUND: Little is known about residual abnormalities after pulmonary embolism (PE). OBJECTIVES: To assess risk factors and the clinical significance of perfusion defects in patients with PE. PATIENTS/METHODS: Consecutive patients receiving at least 3 months of anticoagulant for an acute PE were included in a prospective cohort study. Ventilation/perfusion lung scan, echocardiography, 6-min walk test, thrombophilia and hemostatic variables were performed 6-12 months after PE. Perfusion defect was defined as a perfusion defect in at least two segments. RESULTS: Seventy-three out of 254 patients (29%) had perfusion defects during follow-up (median 12 months) and were more likely to have dyspnea, had a higher systolic pulmonary arterial pressure [39 mmHg (SD) (12) vs. 31 mmHg (8); P < 0.001] and walked a shorter distance during the 6-min walk test [374 m (122) vs. 427 m (99); P = 0.004]. Age [odds ratio (OR) 1.35; 95% confidence interval (CI), 1.11-1.63], the time interval between symptom onset and diagnosis (OR, 1.17; 95% CI, 1.04-1.31), pulmonary vascular obstruction at the onset of PE (OR, 1.34; 95% CI, 1.16-1.55) and previous venous thromboembolism (OR 2.06; 95% CI, 1.03-4.11) were independent predictors of perfusion defect after treatment of acute PE. Total tissue factor pathway inhibitor concentration was associated with perfusion defects. CONCLUSIONS: Perfusion defects are associated with an increase in pulmonary artery pressure (PAP) and functional limitation. Age, longer times between symptom onset and diagnosis, initial pulmonary vascular obstruction and previous venous thromboembolism were associated with perfusion defects.

Contribution of indirect computed tomographic venography to the diagnosis of postpartum venous thromboembolism.

BACKGROUND: The diagnostic value of indirect computed tomographic venography (CTV), following thoracic computed tomographic angiography (CTA), has not been specifically evaluated in postpartum patients with suspected pulmonary embolism. OBJECTIVES: To assess the diagnostic value of CTV in postpartum venous thromboembolism. METHODS: We reviewed all CTA and CTV procedures performed during the last 7 years in our institution for suspected pulmonary embolism during the postpartum period. We focused on the quality of CTA, the rates of positive CTA and isolated positive CTV findings, and alternative diagnoses provided by CTV. RESULTS: Fifty-five CTA and 33 CTV procedures were performed for suspected pulmonary embolism in 47 patients referred between 24 h and 2 months after Cesarean (34 patients) or vaginal (13 patients) delivery. Of the 33 patients who had both CTA and CTV, seven had positive CTA findings and four had isolated positive CTV findings. Thus, the absolute increase in the venous thromboembolism detection rate following CTV was 12.1% [95% confidence interval (CI) 4.0-29.1]. Subcapsular hematoma of the liver or spleen was found on CTV in another two patients without venous thromboembolism. Consequently, CTV had a direct impact on clinical management in six of 33 patients (18%). CONCLUSION: Our results suggest that postpartum patients with suspected pulmonary embolism have a significant rate of pelvic vein thrombosis and that the use of CTV leads to a 31% relative increase in the detection rate of venous thromboembolism as compared to CTA alone in these patients.

[Imaging of pulmonary arterial hypertension]. / Imagerie de l'hypertension artérielle pulmonaire.

INTRODUCTION: The investigation of pulmonary arterial hypertension (PAH) requires a rigorous aetiological assessment in which imaging modalities play an important role. BACKGROUND: The chest x-ray may show non-specific signs such as cardiomegaly and dilatation of the pulmonary arteries, and also allows examination of the lung parenchyma. Echocardiography is the essential screening tool and allows evaluation of left ventricular function. Pulmonary ventilation/perfusion scanning is essential to confirm post embolic PAH. Spiral CT has become an essential examination. It allows detailed study of the lung parenchyma, the pulmonary vessels and the cardiac chambers, and also helps determine the aetiology and complete the pre-treatment assessment. Magnetic resonance imaging allows calculation of several haemodynamic parameters and morphological study of the cardiac chambers and pulmonary vessels but requires further evaluation. VIEWPOINT: The improvement in the quality of vascular images and the development of complementary MRI techniques may lead to increase of this modality in the study of PAH. CONCLUSION: Imaging plays a fundamental role in the management of patients suffering from PAH.