title: Chronic Obstructive Pulmonary Disease: CT Quantification of Airway Dimensions, Numbers of Airways to Measure, and Effect of Bronchodilation.
abstract: OBJECTIVE
  To determine the effect of bronchodilation on airway indexes reflecting airway disease in patients with chronic obstructive pulmonary disease (COPD) and to determine the minimum number of segmental and subsegmental airways required.
  
  
  METHODS
  This study was approved by the local ethical committee, and written informed consent was obtained from all subjects. Twenty patients with COPD who had undergone pre- and postbronchodilator pulmonary function tests and computed tomographic (CT) examinations were prospectively included. Eight healthy volunteers underwent two CT examinations. Luminal area and wall thickness (WT) of third- and fourth-generation airways were measured twice by three readers. The percentage of total airway area occupied by the wall and the square root of wall area at an internal perimeter of 10 mm (√WAPi10) were calculated. The effects of pathologic status, session, reader, bronchodilation, and CT examination were assessed by using mixed linear model analyses. The number of airways to measure for a definite percentage error of √WAPi10 was computed by using a bootstrap method.
  
  
  RESULTS
  There were no significant session, reader, or bronchodilation effects on WT in third-generation airways and √WAPi10 in patients with COPD (P values ranging from .187 to >.999). WT in third-generation airways and √WAPi10 were significantly different in patients with COPD and control subjects (P = .018 and <.001, respectively). Measuring 12 third- or fourth-generation airways ensured a maximal 10% error of √WAPi10.
  
  
  CONCLUSIONS
  WT in third-generation airways and √WAPi10 are not significantly different before and after bronchodilation and are different in patients with COPD and control subjects. Twelve is the minimum number of third- or fourth-generation airways required to ensure a maximal 10% error of √WAPi10. (©) RSNA, 2015 Clinical trial registration no. NCT01142531 Online supplemental material is available for this article.
authors.affiliation: From the Departments of Radiology (M.H., E.G., T.S.G., P.A.G.) and Pneumology (A.V.M.), Hôpital Erasme, Université Libre de Bruxelles, 808 Route de Lennik, 1070 Brussels, Belgium; and Departments of Radiology (S.A.) and Pneumology (I.D., M.B., V.N.), Centre Hospitalier Universitaire Saint-Pierre, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Maxime
authors.initials: M
authors.lastname: Hackx
authors.affiliation: From the Departments of Radiology (M.H., E.G., T.S.G., P.A.G.) and Pneumology (A.V.M.), Hôpital Erasme, Université Libre de Bruxelles, 808 Route de Lennik, 1070 Brussels, Belgium; and Departments of Radiology (S.A.) and Pneumology (I.D., M.B., V.N.), Centre Hospitalier Universitaire Saint-Pierre, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Elodie
authors.initials: E
authors.lastname: Gyssels
authors.affiliation: From the Departments of Radiology (M.H., E.G., T.S.G., P.A.G.) and Pneumology (A.V.M.), Hôpital Erasme, Université Libre de Bruxelles, 808 Route de Lennik, 1070 Brussels, Belgium; and Departments of Radiology (S.A.) and Pneumology (I.D., M.B., V.N.), Centre Hospitalier Universitaire Saint-Pierre, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Tiago
authors.initials: T
authors.lastname: Severo Garcia
authors.affiliation: From the Departments of Radiology (M.H., E.G., T.S.G., P.A.G.) and Pneumology (A.V.M.), Hôpital Erasme, Université Libre de Bruxelles, 808 Route de Lennik, 1070 Brussels, Belgium; and Departments of Radiology (S.A.) and Pneumology (I.D., M.B., V.N.), Centre Hospitalier Universitaire Saint-Pierre, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Isabelle
authors.initials: I
authors.lastname: De Meulder
authors.affiliation: From the Departments of Radiology (M.H., E.G., T.S.G., P.A.G.) and Pneumology (A.V.M.), Hôpital Erasme, Université Libre de Bruxelles, 808 Route de Lennik, 1070 Brussels, Belgium; and Departments of Radiology (S.A.) and Pneumology (I.D., M.B., V.N.), Centre Hospitalier Universitaire Saint-Pierre, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Alard
authors.affiliation: From the Departments of Radiology (M.H., E.G., T.S.G., P.A.G.) and Pneumology (A.V.M.), Hôpital Erasme, Université Libre de Bruxelles, 808 Route de Lennik, 1070 Brussels, Belgium; and Departments of Radiology (S.A.) and Pneumology (I.D., M.B., V.N.), Centre Hospitalier Universitaire Saint-Pierre, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Marie
authors.initials: M
authors.lastname: Bruyneel
authors.affiliation: From the Departments of Radiology (M.H., E.G., T.S.G., P.A.G.) and Pneumology (A.V.M.), Hôpital Erasme, Université Libre de Bruxelles, 808 Route de Lennik, 1070 Brussels, Belgium; and Departments of Radiology (S.A.) and Pneumology (I.D., M.B., V.N.), Centre Hospitalier Universitaire Saint-Pierre, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Alain
authors.initials: A
authors.lastname: Van Muylem
authors.affiliation: From the Departments of Radiology (M.H., E.G., T.S.G., P.A.G.) and Pneumology (A.V.M.), Hôpital Erasme, Université Libre de Bruxelles, 808 Route de Lennik, 1070 Brussels, Belgium; and Departments of Radiology (S.A.) and Pneumology (I.D., M.B., V.N.), Centre Hospitalier Universitaire Saint-Pierre, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Vincent
authors.initials: V
authors.lastname: Ninane
authors.affiliation: From the Departments of Radiology (M.H., E.G., T.S.G., P.A.G.) and Pneumology (A.V.M.), Hôpital Erasme, Université Libre de Bruxelles, 808 Route de Lennik, 1070 Brussels, Belgium; and Departments of Radiology (S.A.) and Pneumology (I.D., M.B., V.N.), Centre Hospitalier Universitaire Saint-Pierre, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Pierre Alain
authors.initials: PA
authors.lastname: Gevenois
mesh_terms: D000328:Adult; D000368:Aged; D001980:Bronchi / Q000187:drug effects / Q000473:pathology*; D001993:Bronchodilator Agents / Q000494:pharmacology*; D001995:Bronchography; D005260:Female; D006801:Humans; D009241:Ipratropium / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000000981:diagnostic imaging* / Q000503:physiopathology; D012129:Respiratory Function Tests; D014057:Tomography, X-Ray Computed
chemical_list: D001993:Bronchodilator Agents; D009241:Ipratropium