Reassessment of pulmonary angiography for the diagnosis of pulmonary embolism: relation of interpreter agreement to the order of the involved pulmonary arterial branch.

PURPOSE: To reassess the validity of conventional pulmonary angiography in the diagnosis of pulmonary embolism (PE) in main, lobar, segmental, and subsegmental pulmonary arteries.
MATERIALS AND METHODS: Data are from examinations of 375 patients with angiographically diagnosed PE who participated in the Prospective Investigation of Pulmonary Embolism Diagnosis. The average co-positivity of readings of the pulmonary angiograms was evaluated in relation to the order of the largest pulmonary artery that showed PE.
RESULTS: Among 217 patients whose angiograms showed PE in main or lobar pulmonary arteries, as well as in smaller orders of arteries, there was an average co-positivity of 98% (95% Cl = 96%, 98%). Among 136 patients whose pulmonary angiograms showed PE in segmental or subsegmental pulmonary arteries but not in larger orders of arteries, the average co-positivity was 90% (95% Cl = 85%, 95%). Among 22 patients with PE limited to the subsegmental arteries, the average co-positivity was 66% (95% Cl = 46%, 86%).
CONCLUSION: Conventional pulmonary angiography is not precise for the diagnosis of PE limited to subsegmental arteries. To evaluate subsegmental arteries, techniques that improve the visualization of PE in small arteries should be used.