Comparison of inter- and intra-observer variability of breast density assessments using the fourth and fifth editions of Breast Imaging Reporting and Data System

The ACR BI-RADS guideline is an acceptable method to classify breast density, resulting in substantial inter-observer agreements using criteria outlined in both the fourth and fifth editions. The intra-observer agreement was nearly perfect for radiologists using criteria outlined in both sets of guidelines. Moreover, although the percentage of women who were classified as having dense breasts was higher when radiologists used the fifth edition of ACR BI-RADS guidelines than when they used the fourth edition, this difference was not statistically significant.