Observer Variability of the Breast Imaging Reporting and Data System (BI-RADS) Lexicon for Mammography

Abstract

Aim: We aimed to determine the inter- and intra-observer variabilities between breast radiologists and a general radiologist in categorizing mammographic lesions using the Breast Imaging Reporting and Data System (BI-RADS), and to evaluate the effects of the histopathologic results on the variability. Methods: Mammograms from 142 women who underwent biopsy were evaluated. 3 breast radiologists (2 with >10 years experience and 1 with 1 year experience) and 1 general radiologist retrospectively reviewed mammograms twice within an 8-week interval. Inter- and intra-observer variabilities were assessed with Cohen’s kappa statistic, and the positive predictive value for final assessments was calculated. Results: The intra-observer variability for mass and calcification assessments was moderate to almost perfect (kappa values: 0.41–1) for breast imagers and was fair to substantial for the general radiologist (kappa values: 0.21–0.8). Inter-observer agreement between the breast imagers was higher than between the breast and general radiologists. There was no apparent difference in agreement between observers for malignant and benign subgroups. Conclusions: The differences in intra- and inter-observer agreement between the breast imagers and the general radiologist affirm the utility of the BI-RADS lexicon. The histopathologic re-sults of the lesions do not affect the agreement. BI-RADS is a simple and adequate tool for assessing mammograms, even after only 1 year of training.