Basilar segmental bronchi: thin-section CT evaluation.

Thin (1.5- and 5.0-mm) section contiguous computed tomographic (CT) scans obtained through the basilar segmental bronchi in 31 patients were reviewed in order to delineate normal anatomy and common variations of lower lobe airways. In each case, the frequency with which individual segmental and subsegmental bronchi were seen was established, as were variations in branching patterns. All basilar segmental bronchi were identified except in one case in which images of the left lung were obscured due to respiratory and cardiac motion. In the right lung, a division into subsegmental bronchi was identified in 84 of 150 (56%) visualized segmental bronchi. Six separate patterns of basilar segmental subdivision were found. In the left lung, subsegmental bronchi were identified arising from 51 of 145 (35%) visualized segmental bronchi. Five separate patterns of bronchial subdivision were found in the left lung. It is concluded that thin-section CT allows precise identification of all basilar segmental bronchi and, consequently, can play a significant role in the cross-sectional evaluation of lower lobe bronchial and parenchymal abnormalities.