title: Chronic obstructive pulmonary disease: thin-section CT measurement of airway wall thickness and lung attenuation.
abstract: OBJECTIVE
  To prospectively evaluate airway wall thickness and lung attenuation at spirometrically gated thin-section computed tomography (CT) in patients with chronic obstructive pulmonary disease (COPD) and to correlate gated CT findings with pulmonary function test (PFT) results.
  
  
  METHODS
  The ethical committee approved the study, and all patients gave informed consent. Forty-two consecutive patients with COPD (20 with and 22 without chronic bronchitis [CB]) underwent gated thin-section CT and PFTs on the same day. The percentage wall area (PWA) and the thickness-to-diameter ratio (TDR) for all depicted bronchi that were round and larger than 2 mm in diameter, the mean lung attenuation (MLA), and the pixel index (PI) at -950 HU were determined. The reproducibility of the airway measurements was preliminarily tested by performing a five-trial examination in a patient with COPD and in a control patient. Differences in airway and lung attenuation measurements between the patients with and those without CB were evaluated at Mann-Whitney U testing. Simple and multiple regression analyses were used to assess the correlation between thin-section CT and PFT measurements.
  
  
  RESULTS
  The mean intraoperator coefficient of variation for airway measurements was 7.8% (range, 3.8%-13.4%). An average of nine bronchi per patient were assessed. Patients with CB had significantly higher PWAs, TDRs, and MLAs and significantly lower PIs than patients without CB (P < .05 for all values). The combination of PWA, TDR, and PWA normalized to body weight correlated significantly (P < .05) with the forced expiratory volume in 1 second-to-slow vital capacity ratio and the diffusing capacity of the lung for carbon monoxide in patients with but not in patients without CB. PFT results correlated better with MLA and PI in patients without CB.
  
  
  CONCLUSIONS
  Bronchial wall measurements differ between patients who have COPD with CB and those who have COPD without CB. The correlation between airway dimensions and indexes of airway obstruction in patients with COPD and CB indicates that the bronchial tree is the site of anatomic-functional alterations in this patient group.
authors.affiliation: Radiodiagnostic Section, Department of Clinical Physiopathology, University of Florence, Viale Morgagni 85, Florence 50134, Italy.
authors.forename: Ilaria
authors.initials: I
authors.lastname: Orlandi
authors.forename: Chiara
authors.initials: C
authors.lastname: Moroni
authors.forename: Gianna
authors.initials: G
authors.lastname: Camiciottoli
authors.forename: Maurizio
authors.initials: M
authors.lastname: Bartolucci
authors.forename: Massimo
authors.initials: M
authors.lastname: Pistolesi
authors.forename: Natale
authors.initials: N
authors.lastname: Villari
authors.forename: Mario
authors.initials: M
authors.lastname: Mascalchi
mesh_terms: D000328:Adult; D000368:Aged; D001991:Bronchitis / Q000150:complications; D001995:Bronchography / Q000379:methods*; D002908:Chronic Disease; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000000981:diagnostic imaging*; D012044:Regression Analysis; D015203:Reproducibility of Results; D012129:Respiratory Function Tests; D013147:Spirometry; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014797:Vital Capacity