Evaluation of breast microcalcifications according to Breast Imaging Reporting and Data System criteria and Le Gal's classification

Abstract

Introduction/objective: Our aim was to evaluate the positive predictive value (PPV) of the analysis of breast microcalcifications according to Breast Imaging Reporting and Data System (BI-RADS) and Le Gal's classification in identification of malignancy, and to assess the interobserver agreement using these criteria.

Methods and material: Eighty-two patients with breast microcalcifications on their screening mammograms underwent surgical excision after a needle localization at our institution between July 1993 and June 2000. The mammograms were examined by two experienced mammographers retrospectively and independently. Each observer noted the morphology, distribution, associated findings, final assessment categories of microcalcifications according to BI-RADS criteria and the morphologic type of microcalcifications according to Le Gal's classification. The PPVs for each radiologist and the interobserver agreement were determined by using these data and histologic findings.

Results: Histopathologic results yielded malignancy in 25 (30%) cases. The evaluation of microcalcifications according to BI-RADS criteria revealed PPVs of 17% and 25% for category 4 lesions, and 68% and 44% for category 5 lesions. In the assessment of microcalcifications according to Le Gal's classification, the PPV of type 4 lesions was 45% (for both observers), whereas the PPVs of type 5 lesions were 70% and 50%. The interobserver agreement was fair in evaluation of morphology of microcalcifications (kappa:0.31), distribution of microcalcifications (kappa:0.29), final assessment categories (kappa:0.27), and moderate in evaluation of associated findings (kappa:0.48) by using BI-RADS lexicon. It was higher for the assessment of milk of calcium and round microcalcifications than other typically benign microcalcifications, and for fine linear or fine linear branching microcalifications than other probably malignant calcifications. There was a fair interobserver agreement (kappa:0.30) in the description of the morphologic type of microcalcifications according to Le Gal's classification.

Discussions and conclusion: In our study, both BI-RADS lexicon and Le Gal's classification did not succeed expectedly in reducing the ambiguity in assessment of breast microcalcifications. Further studies and perhaps development of new methods are required to improve accuracy and standardization in mammographic interpretation.