title: Air trapping in sarcoidosis on computed tomography: correlation with lung function.
abstract: OBJECTIVE
  To document the presence and extent of air trapping on high resolution computed tomography (HRCT) in patients with pulmonary sarcoidosis and correlate HRCT features with pulmonary function tests.
  
  
  METHODS
  Twenty-one patients with pulmonary sarcoidosis underwent HRCT and pulmonary function assessment at presentation. Inspiratory and expiratory HRCT were assessed for the presence and extent of air trapping, ground-glass opacification, nodularity, septal thickening, bronchiectasis and parenchymal distortion. HRCT features were correlated with pulmonary function tests.
  
  
  RESULTS
  Air trapping on expiratory HRCT was present in 20/21 (95%) patients. The extent of air trapping correlated with percentage predicted residual volume (RV)/total lung capacity (TLC) (r = 0.499;P < 0.05) and percentage predicted maximal mid-expiratory flow rate between 25 and 75% of the vital capacity (r = -0.54;P < 0.05). Ground-glass opacification was present in four of 21 (19%), nodularity in 18/21 (86%), septal thickening in 18/21 (86%), traction bronchiectasis in 14/21 (67%) and distortion in 12/21 (57%) of patients; there were no significant relationships between these CT features and pulmonary function results.
  
  
  CONCLUSIONS
  Air trapping is a common feature in sarcoidosis and correlates with evidence of small airways disease on pulmonary function testing.
authors.affiliation: Osler Chest Unit, Churchill Hospital, Oxford, UK.
authors.forename: C W
authors.initials: CW
authors.lastname: Davies
authors.forename: A D
authors.initials: AD
authors.lastname: Tasker
authors.forename: S P
authors.initials: SP
authors.lastname: Padley
authors.forename: R J
authors.initials: RJ
authors.lastname: Davies
authors.forename: F V
authors.initials: FV
authors.lastname: Gleeson
mesh_terms: D000328:Adult; D000368:Aged; D000388:Air; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012115:Residual Volume / Q000502:physiology; D012129:Respiratory Function Tests; D017565:Sarcoidosis, Pulmonary / Q000000981:diagnostic imaging* / Q000503:physiopathology; D014057:Tomography, X-Ray Computed