title: Reproducibility of lung and lobar volume measurements using computed tomography.
abstract: OBJECTIVE
  Lung and lobar volume measurements from computed tomographic (CT) imaging are being used in clinical trials to assess new minimally invasive emphysema treatments aiming to reduce lung volumes. Establishing the reproducibility of lung volume measurements is important if they are to be accepted as treatment planning and outcome variables. The aims of this study were to (1) investigate the correlation between lung volumes assessed on CT imaging and on pulmonary function testing (PFT), (2) compare the two methods' reproducibility, and (3) assess the reproducibility of CT lobar volumes.
  
  
  METHODS
  CT imaging and body plethysmography were performed at baseline and after a 9-month interval in multicenter emphysema treatment trials. Lung volumes were measured at total lung capacity (TLC) and at residual volume (RV). Lobar volumes were measured on CT imaging using a semiautomated technique. The correlations between CT and PFT volumes were computed for 486 subjects at baseline. Reproducibility was assessed in terms of the intraclass correlation coefficient (ICC) for 126 subjects from the control group at TLC and 120 subjects at RV.
  
  
  RESULTS
  Correlations between CT and PFT lung volumes were 0.86 at TLC and 0.67 at RV. At TLC, the ICCs were 0.943 for CT imaging and 0.814 for PFT. At RV, the ICCs were 0.886 for CT imaging and 0.683 for PFT. CT lobar volumes showed good reproducibility (all P values < .05).
  
  
  CONCLUSIONS
  CT lung and lobar volume measurements could be captured in a multicenter trial setting with high reproducibility and were highly correlated with those obtained on PFT. CT imaging showed significantly better reproducibility than PFT between interval lung volume measurements, offering the potential for designing emphysema treatment trials involving fewer subjects.
authors.affiliation: Thoracic Imaging Research Group, Los Angeles, Los Angeles, CA 90024, USA. mbrown@mednet.ucla.edu
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Brown
authors.forename: Hyun J
authors.initials: HJ
authors.lastname: Kim
authors.forename: Fereidoun
authors.initials: F
authors.lastname: Abtin
authors.forename: Irene
authors.initials: I
authors.lastname: Da Costa
authors.forename: Richard
authors.initials: R
authors.lastname: Pais
authors.forename: Shama
authors.initials: S
authors.lastname: Ahmad
authors.forename: Erin
authors.initials: E
authors.lastname: Angel
authors.forename: Chiayi
authors.initials: C
authors.lastname: Ni
authors.forename: Eric C
authors.initials: EC
authors.lastname: Kleerup
authors.forename: David W
authors.initials: DW
authors.lastname: Gjertson
authors.forename: Michael F
authors.initials: MF
authors.lastname: McNitt-Gray
authors.forename: Jonathan G
authors.initials: JG
authors.lastname: Goldin
mesh_terms: D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008168:Lung / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011656:Pulmonary Emphysema / Q000000981:diagnostic imaging*; D011856:Radiographic Image Enhancement / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D013902:Radiography, Thoracic / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*