1. Glottis Closure Influences Tracheal Size Changes in Inspiratory and Expiratory CT in Patients with COPD
Nicholas Landini, Stefano Diciotti, Monica Lanzetta, Francesca Bigazzi, Gianna Camiciottoli, Mario Mascalchi Acad Radiol. 2017 Jul;24(7):901-907. doi: 10.1016/j.acra.2017.01.018. Epub 2017 Mar 22.
Rationale and objectives: The opened or closed status of the glottis might influence tracheal size changes in inspiratory and expiratory computed tomography (CT) scans. We investigated if the glottis status makes the tracheal collapse differently correlate with lung volume difference between inspiratory and expiratory CT scans. Materials and methods: Forty patients with chronic obstructive pulmonary disease whose glottis was included in the acquired scanned volume for lung CT were divided into two groups: 16 patients with the glottis closed in both inspiratory and expiratory CT, and 24 patients with the glottis open in at least one CT acquisition. Lung inspiratory (Vinsp) and expiratory (Vexp) volumes were automatically computed and lung ΔV was calculated using the following formula: (Vinsp - Vexp)/Vinsp × 100. Two radiologists manually measured the anteroposterior diameter and cross-sectional area of the trachea 1 cm above the aortic arch and 1 cm above the carina. Tracheal collapse was then calculated and correlated with lung ΔV. Results: In the 40 patients, the correlations between tracheal Δanteroposterior diameter and Δcross-sectional area at each level and lung ΔV ranged between 0.68 and 0.74 (ρ) at Spearman rank correlation test. However, in the closed glottis group, the correlations were higher for all measures at the two levels (ρ range: 0.84-0.90), whereas in the open glottis group, correlations were low and not statistically significant (ρ range: 0.29-0.34) at the upper level, and moderate at the lower level (ρ range: 0.51-0.55). Conclusions: A closed or open glottis influences the tracheal size change in inspiratory and expiratory CT scans. With closed glottis, the tracheal collapse shows a stronger correlation with the lung volume difference between inspiratory and expiratory CT scans.
2. Intrathoracic tracheal volume and collapsibility on inspiratory and end-expiratory ct scans correlations with lung volume and pulmonary function in 85 smokers
Tsuneo Yamashiro, et al. Acad Radiol. 2011 Mar;18(3):299-305. doi: 10.1016/j.acra.2010.11.005. Epub 2011 Jan 6.
Rationale and objectives: To evaluate the correlations of tracheal volume and collapsibility on inspiratory and end-expiratory computed tomography (CT) with lung volume and with lung function in smokers. Materials and methods: The institutional review board approved this study at each institution. 85 smokers (mean age 68, range 45-87 years; 40 females and 45 males) underwent pulmonary function tests and chest CT at full inspiration and end-expiration. On both scans, intrathoracic tracheal volume and lung volume were measured. Collapsibility of the trachea and the lung was expressed as expiratory/inspiratory (E/I) ratios of these volumes. Correlations of the tracheal measurements with the lung measurements and with lung function were evaluated by the linear regression analysis. Results: Tracheal volume showed moderate or strong, positive correlations with lung volume on both inspiratory (r = 0.661, P < .0001) and end-expiratory (r = 0.749, P < .0001) scans. The E/I ratio of tracheal volume showed a strong, positive correlation with the E/I ratio of lung volume (r = 0.711, P < .0001). A weak, negative correlation was found between the E/I ratio of tracheal volume and the ratio of forced expiratory volume in the first second to forced vital capacity (r = -0.436, P < .0001). Also, a weak, positive correlation was observed between the E/I ratio of tracheal volume and the ratio of residual volume to total lung capacity (r = 0.253, P = .02). Conclusions: Tracheal volume and collapsibility, measured by inspiratory and end-expiratory CT scans, is related to lung volume and collapsibility. The highly collapsed trachea on end-expiratory CT does not indicate more severe airflow limitation or air-trapping in smokers.
3. 3D-measurement of tracheobronchial angles on inspiratory and expiratory chest CT in COPD: respiratory changes and correlation with airflow limitation
Rintaro Onoe, Tsuneo Yamashiro, Hiroshi Handa, Shinya Azagami, Shin Matsuoka, Takeo Inoue, Teruomi Miyazawa, Masamichi Mineshita Int J Chron Obstruct Pulmon Dis. 2018 Aug 10;13:2399-2407. doi: 10.2147/COPD.S165824. eCollection 2018.
Purpose: To assess tracheobronchial angles and their changes on combined inspiratory and expiratory thoracic computed tomography (CT) scans and to determine correlations between tracheobronchial angles and several indices of chronic obstructive pulmonary disease (COPD). Materials and methods: A total of 80 smokers underwent combined inspiratory and expiratory CT scans. Of these, 65 subjects also performed spirometry and 55 patients were diagnosed with COPD. On CT scans, 3-dimensinal tracheobronchial angles (trachea-right main bronchus [RMB], trachea-left main bronchus [LMB], and RMB-LMB) were automatically measured by software. Lung volumes at inspiration and expiration were also automatically calculated. Changes in tracheobronchial angles between inspiration and expiration were assessed by the Mann-Whitney test. Correlations of the angles with lung volume, airflow limitation, and CT-based emphysema index were evaluated by Spearman rank correlation. Results: The trachea-LMB angle was significantly smaller and the RMB-LMB angle was significantly larger at expiration than inspiration (P<0.0001). The trachea-LMB and RMB-LMB angles were significantly correlated with lung volume, particularly at expiration. The RMB-LMB angle was significantly correlated with airflow limitation and CT emphysema index (P<0.001-0.05) at inspiration and expiration, suggesting that narrowed RMB-LMB angle indicates more severe airflow limitation and larger extent of emphysema. Conclusion: Tracheobronchial angles change during respiration and are correlated with severity of COPD and emphysema.
