title: Breast imaging reporting and data system (BI-RADS) lexicon for breast MRI: interobserver variability in the description and assignment of BI-RADS category.
abstract: OBJECTIVE
  To retrospectively evaluate interobserver variability between breast radiologists when describing abnormal enhancement on breast MR examinations and assigning a BI-RADS category using the Breast Imaging Reporting and Data System (BI-RADS) terminology.
  
  
  METHODS
  Five breast radiologists blinded to patients' medical history and pathologic results retrospectively and independently reviewed 257 abnormal areas of enhancement on breast MRI performed in 173 women. Each radiologist described the focal enhancement using BI-RADS terminology and assigned a final BI-RADS category. Krippendorff's α coefficient of agreement was used to asses interobserver variability.
  
  
  RESULTS
  All radiologists agreed on the morphology of enhancement in 183/257 (71%) lesions, yielding a substantial agreement (Krippendorff's α=0.71). Moderate agreement was obtained for mass descriptors - shape, margins and internal enhancement - (α=0.55, 0.51 and 0.45 respectively) and NME (non-mass enhancement) descriptors - distribution and internal enhancement - (α=0.54 and 0.43). Overall substantial agreement was obtained for BI-RADS category assignment (α=0.71). It was however only moderate (α=0.38) for NME compared to mass (α=0.80).
  
  
  CONCLUSIONS
  Our study shows good agreement in describing mass and NME on a breast MR examination but a better agreement in predicting malignancy for mass than NME.
authors.affiliation: Centre Hospitalier Universitaire de Montréal, Breast Centre, Radiology Department, 3840 Rue Saint Urbain, Montréal, QC H2W1T8, Canada. Electronic address: monelkhoury@gmail.com.
authors.forename: Mona
authors.initials: M
authors.lastname: El Khoury
authors.affiliation: Centre Hospitalier Universitaire de Montréal, Breast Centre, Radiology Department, 3840 Rue Saint Urbain, Montréal, QC H2W1T8, Canada.
authors.forename: Lucie
authors.initials: L
authors.lastname: Lalonde
authors.affiliation: Centre Hospitalier Universitaire de Montréal, Breast Centre, Radiology Department, 3840 Rue Saint Urbain, Montréal, QC H2W1T8, Canada.
authors.forename: Julie
authors.initials: J
authors.lastname: David
authors.affiliation: Centre Hospitalier Universitaire de Montréal, Breast Centre, Radiology Department, 3840 Rue Saint Urbain, Montréal, QC H2W1T8, Canada.
authors.forename: Maude
authors.initials: M
authors.lastname: Labelle
authors.affiliation: Centre Hospitalier Universitaire de McGill, Cedar Breast Centre, Radiology Department, 687 Pine Avenue West, Montreal, QC H3A1A1, Canada.
authors.forename: Benoit
authors.initials: B
authors.lastname: Mesurolle
authors.affiliation: Centre Hospitalier Universitaire de Montréal, Breast Centre, Radiology Department, 3840 Rue Saint Urbain, Montréal, QC H2W1T8, Canada.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Trop
mesh_terms: D000328:Adult; D000368:Aged; D001940:Breast / Q000473:pathology*; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000473:pathology; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008875:Middle Aged; D015588:Observer Variation; D011873:Radiology Information Systems / Q000706:statistics & numerical data*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D055815:Young Adult
keywords: BI-RADS lexicon; Breast cancer; MRI