@article {473096,
	title = {The Effect of Emphysema on Computed Tomographic Measures of Airway Dimensions in Smokers.},
	journal = {Chest },
	volume = {143},
	year = {2013},
	month = {Mar 08},
	pages = {1-7},
	abstract = {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. Since emphysema is linked to loss of airway tethering and may limit airway expansion, increases in WA\% may be related to emphysema and not solely due to remodeling. We aimed to first determine if the stronger association of subsegmental vs. segmental WA\% with FEV1\% predicted is mitigated by emphysema; and second, to assess the relationships between emphysema, WA\%, and total bronchial area (TBA). METHODS: We analyzed CT segmental and subsegmental WA\% (WA\%=100*wall area/TBA) of six bronchial paths and corresponding lobar emphysema, lung function, and clinical data in 983 smokers with COPD. RESULTS: Compared to segmental, 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\<0.05 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\<0.05). 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 reduction in TBA and increase in WA\%.},
	author = {Diaz, A A and Han, M K and Come, C E and San Jose Est{\'e}par, Ra{\'u}l and Ross, J C and Kim, V and Dransfield, M T and Curran-Everett, D and Schroeder, J D and Lynch, D A and Tschirren, J and Silverman, E K and Washko, G R}
}