Anatomic distribution of pulmonary emboli at pulmonary angiography: Implications for cross-sectional imaging

PURPOSE: To determine how often emboli detected angiographically in peripheral pulmonary arterial branches would be missed with cross-sectional imaging. MATERIALS AND METHODS: Seventy-nine of 88 consecutive pulmonary angiograms interpreted as positive for pulmonary emboli were reviewed retrospectively to detect pulmonary emboli. Three angiograms interpreted as negative when reviewed retrospectively were excluded. Findings of 76 angiograms in 76 patients (32 men, 44 women; aged 19-85 years) were correlated with the results of scintigraphy (n = 72) and Doppler ultrasound (n = 60), clinical presentation (n = 76), and follow-up with chart review (n = 72). RESULTS: Two hundred five emboli were identified. Nineteen patients had solitary emboli. Sixty emboli were in the upper lobes. The largest arterial branch with pulmonary embolism was lobar in 14 patients, segmental in 38, subsegmental in 20, and smaller in three. CONCLUSION: If cross-sectional imaging can depict emboli in only segmental and larger arterial branches, then emboli in 23 of 76 patients (30%) would have been missed with cross-sectional imaging.