title: Quantitative CT measures of emphysema and airway wall thickness are related to D(L)CO.
abstract: There is limited knowledge on the relationship between diffusing capacity of the lung for carbon monoxide (D(L)CO) and quantitative computed tomography (CT) measures of emphysema and airway wall thickness.
  
  
  OBJECTIVE
  What is the relationship between D(L)CO and the quantitative CT measures of emphysema and airway wall thickness in subjects with and without COPD?
  
  
  METHODS
  We included 288 COPD subjects (70% men) and 425 non-COPD subjects (54% men). All subjects were current or ex-smokers older than 40 years and all subjects underwent spirometry, diffusing capacity tests and CT examination. Quantitative CT measures included % low attenuation areas < -950 HU (%LAA) and standardized airway wall thickness (AWT-Pi10).
  
  
  RESULTS
  Multiple linear regression analyses showed significant associations between D(L)CO and both %LAA and AWT-Pi10 in the COPD group. The adjusted regression coefficients (SE) for D(L)CO (mmol min(-1) kPa(-1)) were -1.15 (0.11) per 10% increase in %LAA and 0.08 (0.03) per 0.1 mm increase in AWT-Pi10, and the models' adjusted R(2) was 0.65 and 0.49, respectively.
  
  
  CONCLUSIONS
  CT measured emphysema explains a large fraction of the variation of D(L)CO among COPD subjects, and more so in men. Airway wall thickness is also significantly associated with D(L)CO, but explains a much smaller fraction of the variation.
authors.affiliation: Department of Thoracic Medicine, Haukeland University Hospital, Jonas Lies v 65, N-5021 Bergen, Norway. thomas.grydeland@med.uib.no
authors.forename: Thomas B
authors.initials: TB
authors.lastname: Grydeland
authors.forename: Einar
authors.initials: E
authors.lastname: Thorsen
authors.forename: Asger
authors.initials: A
authors.lastname: Dirksen
authors.forename: Robert
authors.initials: R
authors.lastname: Jensen
authors.forename: Harvey O
authors.initials: HO
authors.lastname: Coxson
authors.forename: Sreekumar G
authors.initials: SG
authors.lastname: Pillai
authors.forename: Sanjay
authors.initials: S
authors.lastname: Sharma
authors.forename: Geir Egil
authors.initials: GE
authors.lastname: Eide
authors.forename: Amund
authors.initials: A
authors.lastname: Gulsvik
authors.forename: Per S
authors.initials: PS
authors.lastname: Bakke
mesh_terms: D000704:Analysis of Variance; D002248:Carbon Monoxide / Q000378:metabolism*; D005260:Female; D006801:Humans; D016014:Linear Models; D008168:Lung / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011653:Pulmonary Diffusing Capacity / Q000379:methods*; D029424:Pulmonary Disease, Chronic Obstructive / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D011656:Pulmonary Emphysema / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D013147:Spirometry; D014057:Tomography, X-Ray Computed
chemical_list: D002248:Carbon Monoxide