Onoe R, et al. - In 80 smokers who underwent combined inspiratory and expiratory thoracic computed tomography (CT) scans, researchers evaluated tracheobronchial angles and their changes as well as correlations between tracheobronchial angles and several indices of chronic obstructive pulmonary disease (COPD). They observed that the trachea–left main bronchus [LMB] angle was markedly smaller and the right main bronchus [RMB]–LMB angle was significantly larger at expiration than inspiration. A significant correlation of the trachea–LMB and RMB–LMB angles with lung volume was observed, this was noted particularly at expiration. More severe airflow limitation and larger extent of emphysema were suggested by narrowed RMB–LMB angle. During respiration, changes in tracheobronchial angles were evident, with correlation with severity of COPD and emphysema.