Scoring System Based on BI-RADS Lexicon to Predict Probability of Malignancy in Suspicious Microcalcifications
To develop a scoring system allowing quantification of the probability of malignancy of suspicious microcalcifications based on Breast Imaging Reporting and Data System (BI-RADS). A total of 163 microcalcification lesions surgically excised in 147 women (aged 28–65 years) were included. Two radiologists independently reviewed each lesion with BI-RADS (4th edition). The interobserver agreement and positive predictive value (PPV) for each descriptor were determined and multivariate analysis was used to develop a scoring system. The scores were compared between benign and malignant lesions and among BI-RADS categories by using the two-sample t-test or the analysis of variance. To assess the discriminative power of the scoring system, the area under the receiver–operating characteristic curve (AUC) and cutoff values for categorization were determined. For the test of the scoring system, the validation data set from a different facility was applied. Interobserver agreement was fair to moderate for distribution, morphology, and category (κ = 0.45, 0.40, and 0.37). PPVs were significantly different among BI-RADS descriptors and categories (P < 0.0001). Of the scoring system developed, the AUC was 0.75. The scores between benign and malignant lesions were significantly different. By means of cutoff values, PPV in category 4a, 4b, 4c, and 5 was 7.0%, 15.0%, 44.8%, and 83.3%, respectively. For the validation data set, the AUC was 0.79 and the PPV in category 4a, 4b, 4c, and 5 was 9.4%, 24.1%, 62.5%, and 80.0%, respectively. In suspicious microcalcifications, our scoring system based on BI-RADS (4th edition) could help to derive a specific final category with good stratification of the probability of malignancy.