title: Interreader scoring variability in an observer study using dual-modality imaging for breast cancer detection in women with dense breasts.
abstract: OBJECTIVE
  To evaluate variability in the clinical assessment of breast images, we evaluated scoring behavior of radiologists in a retrospective reader study combining x-ray mammography (XRM) and three-dimensional automated breast ultrasound (ABUS) for breast cancer detection in women with dense breasts.
  
  
  METHODS
  The study involved 17 breast radiologists in a sequential study design with readers first interpreting XRM-alone followed by an interpretation of combined XRM + ABUS. Each interpretation included a forced Breast Imaging Reporting and Data System scale and a likelihood that the woman had breast cancer. The analysis included 164 asymptomatic patients, including 31 breast cancer patients, with dense breasts and a negative screening XRM. Of interest were interreader scoring variability for XRM-alone, XRM + ABUS, and the sequential effect. In addition, a simulated double reading by pairs of readers of XRM + ABUS was investigated. Performance analysis included receiver operating characteristic analysis, percentile analysis, and κ statistics. Bootstrapping was used to determine statistical significance.
  
  
  RESULTS
  The median change in area under the receiver operating characteristic curve after ABUS interpretation was 0.12 (range 0.04-0.19). Reader agreement was fair with the median interreader κ being 0.26 (0.05-0.48) for XRM-alone and 0.34 (0.11-0.55) for XRM + ABUS (95% confidence interval for the difference in κ, 0.06-0.11). Simulated double reading of XRM + ABUS demonstrated tradeoffs in sensitivity and specificity, but conservative simulated double reading resulted in a significant improvement in both sensitivity (16.7%) and specificity (7.6%) with respect to XRM-alone.
  
  
  CONCLUSIONS
  A modest, but statistically significant, increase in interreader agreement was observed after interpretation of ABUS.
authors.affiliation: Department of Radiology, MC2026, University of Chicago, 5841 S Maryland Ave, Chicago, IL 60637, USA. kdrukker@uchicago.edu
authors.forename: Karen
authors.initials: K
authors.lastname: Drukker
authors.forename: Karla J
authors.initials: KJ
authors.lastname: Horsch
authors.forename: Lorenzo L
authors.initials: LL
authors.lastname: Pesce
authors.forename: Maryellen L
authors.initials: ML
authors.lastname: Giger
mesh_terms: D000071060:Breast Density; D001943:Breast Neoplasms / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D016013:Likelihood Functions; D042361:Mammary Glands, Human / Q000002:abnormalities; D008327:Mammography / Q000379:methods*; D015588:Observer Variation; D012372:ROC Curve; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D016217:Ultrasonography, Mammary / Q000379:methods*