@article {1433719,
	title = {Effect of emphysema on CT scan measures of airway dimensions in smokers},
	journal = {Chest},
	volume = {143},
	number = {3},
	year = {2013},
	month = {2013 Mar},
	pages = {687-693},
	abstract = {BACKGROUND: In CT scans of smokers with COPD, the subsegmental airway wall area percent (WA\%) is greater and more strongly correlated with FEV1 \% predicted than WA\% obtained in the segmental airways. Because emphysema is linked to loss of airway tethering and may limit airway expansion, increases in WA\% may be related to emphysema and not solely to remodeling. We aimed to first determine whether the stronger association of subsegmental vs segmental WA\% with FEV1 \% predicted is mitigated by emphysema and, second, to assess the relationships among emphysema, WA\%, and total bronchial area (TBA).

METHODS: We analyzed CT scan segmental and subsegmental WA\% (WA\% = 100 {\texttimes} wall area/TBA) of six bronchial paths and corresponding lobar emphysema, lung function, and clinical data in 983 smokers with COPD.

RESULTS: Compared with segmental WA\%, the subsegmental WA\% had a greater effect on FEV1\% predicted (-0.8\% to -1.7\% vs -1.9\% to -2.6\% per 1-unit increase in WA\%, respectively; P < .05 for most bronchial paths). After adjusting for emphysema, the association between subsegmental WA\% and FEV1 \% predicted was weakened in two bronchial paths. Increases in WA\% between bronchial segments correlated directly with emphysema in all bronchial paths (P < .05). In multivariate regression models, emphysema was directly related to subsegmental WA\% in most bronchial paths and inversely related to subsegmental TBA in all bronchial paths.

CONCLUSION: The greater effect of subsegmental WA\% on airflow obstruction is mitigated by emphysema. Part of the emphysema effect might be due to loss of airway tethering, leading to a reduction in TBA and an increase in WA\%.},
	keywords = {Adult, Airway Remodeling, Bronchography, Female, Forced Expiratory Volume, Humans, Male, Middle Aged, Multivariate Analysis, Pulmonary Emphysema, Regression Analysis, Smoking, Tomography, X-Ray Computed},
	issn = {1931-3543},
	doi = {10.1378/chest.12-0039},
	author = {Diaz, Alejandro A and Han, MeiLan K and Come, Carolyn E and San Jos{\'e} Est{\'e}par, Ra{\'u}l and Ross, James C and Kim, Victor and Dransfield, Mark T and Curran-Everett, Douglas and Schroeder, Joyce D and Lynch, David A and Tschirren, Juerg and Silverman, Edwin K and Washko, George R}
}