@article {1433747,
	title = {Intrathoracic tracheal volume and collapsibility on inspiratory and end-expiratory ct scans correlations with lung volume and pulmonary function in 85 smokers},
	journal = {Acad Radiol},
	volume = {18},
	number = {3},
	year = {2011},
	month = {2011 Mar},
	pages = {299-305},
	abstract = {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.},
	keywords = {Aged, Female, Humans, Lung, Male, Middle Aged, Organ Size, Respiratory Mechanics, Smoking, Statistics as Topic, Tidal Volume, Tomography, X-Ray Computed, Trachea},
	issn = {1878-4046},
	doi = {10.1016/j.acra.2010.11.005},
	author = {Yamashiro, Tsuneo and San Jos{\'e} Est{\'e}par, Ra{\'u}l and Matsuoka, Shin and Bartholmai, Brian J and Ross, James C and Diaz, Alejandro and Murayama, Sadayuki and Silverman, Edwin K and Hatabu, Hiroto and Washko, George R}
}