title: The validity of radiographic estimation of total lung capacity in patients with respiratory disease.
abstract: OBJECTIVE
  To evaluate the validity of a state-of-the-art computerized planimetry technique for estimation of total lung capacity (TLC) from chest radiographs, when applied to patients with clinical lung disease receiving routine chest radiographs.
  
  
  METHODS
  Retrospective clinical survey.
  
  
  METHODS
  An occupational medicine diagnostic clinic.
  
  
  METHODS
  A convenience sample of 40 subjects with asbestos-related lung disease, 5 patients with nonasbestos-related restrictive defects, 15 subjects with occupational asthma, and 10 subjects with irritant tracheobronchitis.
  
  
  RESULTS
  Estimation of TLC using state-of-the-art computerized algorithms demonstrated limited agreement with conventional measures of TLC when applied to patients with occupational lung disease receiving routine chest radiographs. The most pronounced differences occurred in patients with asbestos-related lung disease and restrictive defects, where the radiographic method of measurement significantly overestimated helium dilution TLC by 986 mL (r=0.73, p<0.001) and 1,135 mL (r=0.82, p<0.05), respectively. Good inspiratory effort was associated with significantly increased radiographic TLC relative to helium dilution TLC; however, radiographic features did not fully account for the observed differences between radiographic and helium dilution techniques.
  
  
  CONCLUSIONS
  Our findings suggest that this planimetric technique should not be used as a substitute for conventional measures of TLC in clinic populations receiving routine radiographs. The large diagnostic group specific mean differences observed between radiographic and conventional measures of TLC also suggest that this method is of limited utility in clinical evaluation of occupational lung disease.
authors.affiliation: Department of Medicine, University of Washington, Seattle, USA.
authors.forename: G P
authors.initials: GP
authors.lastname: Pappas
authors.forename: C A
authors.initials: CA
authors.lastname: Brodkin
authors.forename: L
authors.initials: L
authors.lastname: Sheppard
authors.forename: J
authors.initials: J
authors.lastname: Balmes
authors.forename: M
authors.initials: M
authors.lastname: Horike
authors.forename: S
authors.initials: S
authors.lastname: Barnhart
mesh_terms: D000328:Adult; D001194:Asbestos / Q000009:adverse effects; D005260:Female; D006371:Helium; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000000981:diagnostic imaging* / Q000209:etiology; D016273:Occupational Exposure / Q000009:adverse effects; D010991:Plethysmography; D013902:Radiography, Thoracic / Q000379:methods*; D015203:Reproducibility of Results; D012140:Respiratory Tract Diseases / Q000000981:diagnostic imaging* / Q000209:etiology; D012189:Retrospective Studies; D014109:Total Lung Capacity
chemical_list: D001194:Asbestos; D006371:Helium