title: Accuracy of assigned BI-RADS breast density category definitions.
abstract: OBJECTIVE
  Quantitative criteria for the Breast Imaging Reporting and Data System (BI-RADS) mammographic density categories have recently been defined as <25% dense for almost entirely fatty, 25%-50% dense for scattered fibroglandular densities, 51%-75% for heterogeneously dense, and >75% dense for the extremely dense category. The purpose of this study is to compare the range of percent mammographic densities with radiologist-assigned BI-RADS mammographic density categories and compare with the recently issued definitions.
  
  
  METHODS
  In this study, 200 consecutive negative analog screening mammograms were assigned BI-RADS mammographic density categories independently by three radiologists blinded to the other readers' density assignment. Quantitative assessment of percent mammographic density was performed using previously validated software.
  
  
  RESULTS
  All three readers agreed on BI-RADS mammographic density categories in 98 cases (49%), and two of three readers agreed in all 200 cases. Using two reader's consensus, median mammographic density (range) was 6.0% (0.5%-19.2%) for fatty, 14.8% (1.2%-52.7%) for scattered densities, 51.2% (15.9%-82.2%) for heterogeneously dense, and 78.4% (60.1%-87.9%) for extremely dense breasts. The percent mammographic density ranges for fatty and extremely dense breasts correlated well with BI-RADS definitions, whereas the ranges of densities in the scattered and heterogeneously dense categories were considerably broader.
  
  
  CONCLUSIONS
  Fatty and extremely dense BI-RADS categories compare relatively well to defined criteria, and therefore may be helpful in breast cancer risk models. Scattered fibroglandular densities and heterogeneously dense categories have broad percent mammographic density ranges and may not function well in breast cancer risk models.
authors.affiliation: Department of Radiology, University of Virginia, PO Box 800170, Charlottesville, VA 22908, USA. bte6v@virginia.edu
authors.forename: Brandi T
authors.initials: BT
authors.lastname: Nicholson
authors.forename: Alexander P
authors.initials: AP
authors.lastname: LoRusso
authors.forename: Mark
authors.initials: M
authors.lastname: Smolkin
authors.forename: Viktor E
authors.initials: VE
authors.lastname: Bovbjerg
authors.forename: Gina R
authors.initials: GR
authors.lastname: Petroni
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Harvey
mesh_terms: D015502:Absorptiometry, Photon / Q000592:standards*; D001943:Breast Neoplasms / Q000000981:diagnostic imaging*; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000592:standards; D007090:Image Interpretation, Computer-Assisted / Q000592:standards*; D008327:Mammography / Q000592:standards*; D015588:Observer Variation; D017410:Practice Guidelines as Topic; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity