title: Mild intermittent asthma: CT assessment of bronchial cross-sectional area and lung attenuation at controlled lung volume.
abstract: OBJECTIVE
  To evaluate, with thin-section computed tomography (CT), changes in bronchial cross-sectional area and lung attenuation induced by bronchial stimulation in patients with mild intermittent asthma, at a given lung volume monitored with pneumotachography.
  
  
  METHODS
  Twelve patients with mild intermittent asthma who were nonsmokers (National Institutes of Health staging) and six nonsmoking healthy volunteers, age and sex ratio-matched, were examined by using helical thin-collimation CT at the level of basal bronchi at 65% of total lung capacity. Three sets of acquisitions were obtained: at baseline and after inhalation of methacholine and then salbutamol. Cross-sectional areas of bronchi greater than 4 mm(2) were segmented and calculated from CT images. Lung attenuation was measured in the anterior, lateral, and posterior areas of the right lung parenchyma. Gas trapping was evaluated by using thin-section CT at residual volume in six of the patients with asthma. Statistical analysis included two factors repeated-measurement analysis of variance and Mann-Whitney and Kruskal-Wallis nonparametric tests.
  
  
  RESULTS
  Bronchial cross-sectional areas and lung attenuation did not vary significantly compared with baseline values following bronchial challenge in healthy volunteers or patients with asthma. However, in patients with asthma, bronchial cross-sectional areas were significantly smaller than in healthy volunteers, except after inhalation of salbutamol. Lung attenuation and anteroposterior attenuation gradient were significantly higher in patients with asthma than in healthy patients (P <.001). Air-trapping scores were significantly higher after methacholine challenge.
  
  
  CONCLUSIONS
  Helical thin-collimation CT at controlled lung volume and at full expiration associated with bronchial challenge may help evaluate bronchoreactivity and inflammation in mild intermittent asthma.
authors.affiliation: Department of Radiology, Hôpital Pitié-Salpêtrière, 47-83 Boulevard de l'Hôpital, 75651 Paris 13, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Beigelman-Aubry
authors.forename: André
authors.initials: A
authors.lastname: Capderou
authors.forename: Philippe A
authors.initials: PA
authors.lastname: Grenier
authors.forename: Christian
authors.initials: C
authors.lastname: Straus
authors.forename: Marie-Hélène
authors.initials: MH
authors.lastname: Becquemin
authors.forename: Thomas
authors.initials: T
authors.lastname: Similowski
authors.forename: Marc
authors.initials: M
authors.lastname: Zelter
mesh_terms: D000328:Adult; D001249:Asthma / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008176:Lung Volume Measurements; D008297:Male; D012720:Severity of Illness Index; D014057:Tomography, X-Ray Computed