title: High-resolution computed tomography quantitation of emphysema is correlated with selected lung function values in stable COPD.
abstract: BACKGROUND
  The literature shows conflicting results when high-resolution computed tomography (HRCT) scores of emphysema were correlated with different indices of airflow obstruction.
  
  
  OBJECTIVE
  We correlated HRCT scores of emphysema with different indices of airflow obstruction.
  
  
  METHODS
  We performed HRCT of the chest in 59 patients, all smokers or ex-smokers, with stable chronic obstructive pulmonary disease of different severity [GOLD stages I-IV; mean age ± SD 67.8 ± 7.3 years; pack/years 51.0 ± 34.6; percent predicted forced expiratory volume in 1 s (FEV(1)% predicted) 52.3 ± 17.6; post-bronchodilator FEV(1)% predicted 56.5 ± 19.1; FEV(1)/forced vital capacity (FVC) ratio 50.8 ± 10.2; post-bronchodilator FEV(1)/FVC ratio 51.6 ± 11.0; percent diffusion lung capacity for carbon monoxide (DLCO%) 59.2 ± 21.1; DLCO/percent alveolar volume (VA%) 54.5 ± 18.2; percent residual volume 163.0 ± 35.6; percent total lung capacity (TLC%) 113.2 ± 15; residual volume/TLC 1.44 ± 0.2]. All patients were in stable phase.
  
  
  RESULTS
  The mean ± SD visual emphysema score in all patients was 25.6 ± 25.4%. There was a weak but significant correlation between the percentage of pulmonary emphysema and numbers of pack/years (R = +0.31, p = 0.024). The percentage of emphysema was inversely correlated with the FEV(1)/FVC ratio before and after bronchodilator use (R = -0.44, p = 0.002, and R = -0.39, p = 0.005), DLCO% (R = -0.64, p = 0.0003) and DLCO/VA% (R = -0.68, p < 0.0001). A weak positive correlation was also found with TLC% (R = +0.28, p = 0.048). When patients with documented emphysema were considered separately, the best significant correlation observed was between DLCO/VA% and HRCT scan score (p = 0.007).
  
  
  CONCLUSIONS
  These data suggest that in patients with stable chronic obstructive pulmonary disease of varying severity, the presence of pulmonary emphysema is best represented by the impaired gas exchange capability of the respiratory system.
authors.affiliation: Fondazione San Raffaele, IRCCS, Cefalù, Italy.
authors.forename: Silvestro Ennio
authors.initials: SE
authors.lastname: D'Anna
authors.forename: Roberto
authors.initials: R
authors.lastname: Asnaghi
authors.forename: Gaetano
authors.initials: G
authors.lastname: Caramori
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Appendini
authors.forename: Manfredi
authors.initials: M
authors.lastname: Rizzo
authors.forename: Carmelo
authors.initials: C
authors.lastname: Cavallaro
authors.forename: Giorgio
authors.initials: G
authors.lastname: Marino
authors.forename: Francesco
authors.initials: F
authors.lastname: Cappello
authors.forename: Bruno
authors.initials: B
authors.lastname: Balbi
authors.forename: Antonino
authors.initials: A
authors.lastname: Di Stefano
mesh_terms: D000368:Aged; D001993:Bronchodilator Agents; D005260:Female; D006801:Humans; D008297:Male; D015999:Multivariate Analysis; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications*; D011656:Pulmonary Emphysema / Q000000981:diagnostic imaging*; D012129:Respiratory Function Tests; D012720:Severity of Illness Index; D012907:Smoking / Q000453:epidemiology; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D001993:Bronchodilator Agents