title: Computed tomographic measures of airway morphology in smokers and never-smoking normals.
abstract: Bronchial wall area percent (WA% = 100 × wall area/total bronchial cross sectional area) is a standard computed tomographic (CT) measure of central airway morphology utilized in smokers with chronic obstructive pulmonary disease (COPD). Although it provides significant clinical correlations, the range of reported WA% is narrow. This suggests limited macroscopic change in response to smoking or that remodeling proportionally affects the airway wall and lumen dimensions such that their ratio is preserved. The objective of this study is to assess central airway wall area (WA), lumen area (Ai), and total bronchial area (Ao) from CT scans of 5,179 smokers and 92 never smoking normal subjects. In smokers, WA, Ai, and Ao were positively correlated with forced expiratory volume in 1 s (FEV1) expressed as a percent of predicted (FEV1%), and the WA% was negatively correlated with FEV1% (P < 0.0001 for all comparisons). Importantly, smokers with lower FEV1% tended to have airways of smaller cross-sectional area with lower WA. The increases in the WA% across GOLD stages of chronic obstructive pulmonary disease (COPD) can therefore not be due to increases in WA. The data suggest two possible origins for the WA% increases: 1) central airway remodeling resulting in overall reductions in airway caliber in excess of the decreased WA or 2) those with COPD had smaller native airways before they began smoking. In both cases, these observations provide an explanation for the limited range of values of WA% across stages of COPD.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Boston, Massachusetts;
authors.forename: G R
authors.initials: GR
authors.lastname: Washko
authors.forename: A A
authors.initials: AA
authors.lastname: Diaz
authors.forename: V
authors.initials: V
authors.lastname: Kim
authors.forename: R G
authors.initials: RG
authors.lastname: Barr
authors.forename: M T
authors.initials: MT
authors.lastname: Dransfield
authors.forename: J
authors.initials: J
authors.lastname: Schroeder
authors.forename: J J
authors.initials: JJ
authors.lastname: Reilly
authors.forename: J W
authors.initials: JW
authors.lastname: Ramsdell
authors.forename: A
authors.initials: A
authors.lastname: McKenzie
authors.forename: E J R
authors.initials: EJ
authors.lastname: Van Beek
authors.forename: D A
authors.initials: DA
authors.lastname: Lynch
authors.forename: J P
authors.initials: JP
authors.lastname: Butler
authors.forename: M K
authors.initials: MK
authors.lastname: Han
mesh_terms: D000368:Aged; D056151:Airway Remodeling; D016022:Case-Control Studies; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D029424:Pulmonary Disease, Chronic Obstructive / Q000000981:diagnostic imaging* / Q000209:etiology / Q000503:physiopathology; D012720:Severity of Illness Index; D012907:Smoking / Q000009:adverse effects*; D013147:Spirometry; D014057:Tomography, X-Ray Computed; D014797:Vital Capacity
keywords: chronic obstructive pulmonary disease; computed tomographic scan; lumen; wall area