Clinical validity of a normal pulmonary angiogram in patients with suspected pulmonary embolism - A critical review

AIM: To determine the validity of a normal pulmonary angiogram in the exclusion of pulmonary embolism (PE), based on the safety of withholding anticoagulant therapy in patients with a normal pulmonary angiogram. MATERIALS AND METHODS: A review of English reports published between 1965 and April 1999 was carried out. Eligible articles described prospective studies in patients with suspected PE and a normal pulmonary angiogram, who remained untreated and were followed-up for a minimum of 3 months. Articles were evaluated by two authors, using pre-defined criteria for strength of design. End points consisted of fatal and non-fatal recurrent thromboembolic events. A sensitivity analysis was performed, by removing one study at a time from the overall results and by comparing pre- and post-1990 publications. RESULTS: Among 1050 patients in eight articles included in the analysis, recurrent thromboembolic events were described in 18 patients (1.7% 95% CI: 1.0-2.7%). These were fatal in three patients (0.3% 95% CI: 0.02-0.7%). The recurrence rate of PE decreased from 2.9% (95% CI: 1.4-6.8%) before 1990 to 1.1% (95% CI: 0.5-2.2%) after 1990. CONCLUSION: It would appear that the ability to exclude PE by angiography has improved over the years, as indicated by recurrence rate of PE. The low recurrence rate of PE supports the validity of a normal pulmonary angiogram for the exclusion of PE. (C) 2001 The Royal College of Radiologists

Comparison of contrast-enhanced magnetic resonance angiography and conventional pulmonary angiography for the diagnosis of pulmonary embolism: a prospective study

Background Diagnostic strategies for pulmonary embolism are complex and consist of non-invasive diagnostic tests done to avoid conventional pulmonary angiography as much as possible. We aimed to assess the diagnostic accuracy of magnetic resonance angiography (MRA) for the diagnosis of pulmonary embolism, using conventional pulmonary angiography as a reference method. Methods In a prospective study, we enrolled 141 patients with suspected pulmonary embolism and an abnormal perfusion scan. Patients underwent MRA before conventional pulmonary angiography. Two reviewers, masked with respect to the results of conventional pulmonary angiography, assessed MRA images independently. Statistical analyses used chi(2) and 95% CI. Findings MRA was contraindicated in 13 patients (9%), and images were not interpretable in eight (6%). MRA was done in two patients in whom conventional pulmonary angiography was contraindicated. Thus, MRA and conventional pulmonary angiography results were available in 118 patients (84%). Prevalence of pulmonary embolism was 30%. Images were read independently in 115 patients, and agreement obtained in 105 (91%), kappa=0.75. MRA identified 27 of 35 patients with proven pulmonary embolism (sensitivity 77%, 95% CI 61-90). Sensitivity of MRA for isolated subsegmental, segmental, and central or lobar pulmonary embolism was 40%, 84%, and 100%, respectively (p Interpretation MRA is sensitive and specific for segmental or larger pulmonary embolism. Results are similar to those obtained with helical computed tomography, but MRA has safer contrast agents and does not involve ionising radiation. MRA could become part of the diagnostic strategy for pulmonary embolism