title: Pulmonary nodule detection with low-dose CT of the lung: agreement among radiologists.
abstract: OBJECTIVE
  The purpose of our study was to assess relative intra- and interobserver agreement in detecting pulmonary nodules when interpreting low-dose chest CT screening examinations.
  
  
  METHODS
  Two hundred ninety-three selected low-dose CT examinations of the lung were independently interpreted by three radiologists to detect and classify pulmonary nodules. The data set selected was enriched with examinations depicting pulmonary nodules. A subset of 30 examinations was interpreted twice. All pulmonary nodules greater than 1.0 mm were marked. All nodules greater than 3.0 mm were marked, measured, and scored as to their probability of being benign or malignant. Nodule-based and examination-based relative reviewer agreements were evaluated using percentage of agreement and kappa statistics. Similar assessments were performed on the subset of examinations interpreted twice.
  
  
  RESULTS
  The three radiologists identified a total of 470, 729, and 876 pulmonary nodules of which 395, 641, and 778 were rated as noncalcified with some level of suspicion for being malignant. Nodule-based interobserver agreement among the radiologists was poor (highest kappa value in a paired comparison, 0.120). Examination-based agreement was higher (highest kappa value in a paired comparison, 0.458). Intraobserver agreement was higher than interobserver agreement for examination-based agreement (highest kappa = 0.889) but lower for nodule-based agreement (highest kappa = -0.035). Agreement improved as the suspicion of malignancy increased.
  
  
  CONCLUSIONS
  Unaided intra- and interobserver agreement in detecting pulmonary nodules in low-dose CT of the lung is relatively low. Computer-assisted detection may provide the consistency that is needed for this purpose.
authors.affiliation: Department of Radiology, Imaging Research Division, University of Pittsburgh, 300 Halket St., Ste. 4200, Pittsburgh, PA 15213, USA. leaderjk@upmc.edu
authors.forename: Joseph K
authors.initials: JK
authors.lastname: Leader
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Warfel
authors.forename: Carl R
authors.initials: CR
authors.lastname: Fuhrman
authors.forename: Sara K
authors.initials: SK
authors.lastname: Golla
authors.forename: Joel L
authors.initials: JL
authors.lastname: Weissfeld
authors.forename: Ricardo S
authors.initials: RS
authors.lastname: Avila
authors.forename: Wesly D
authors.initials: WD
authors.lastname: Turner
authors.forename: Bin
authors.initials: B
authors.lastname: Zheng
mesh_terms: D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging*; D008297:Male; D015588:Observer Variation; D003074:Solitary Pulmonary Nodule / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*