THE BREAST IMAGING REPORTING AND DATA SYSTEM - POSITIVE PREDICTIVE VALUE OF MAMMOGRAPHIC FEATURES AND FINAL ASSESSMENT CATEGORIES

OBJECTIVE. The purpose of the study was to assess the positive predict ive value of mammographic features and final assessment categories des cribed in the Breast Imaging Reporting and Data System (BI-RADS) for l esions on which biopsies have been performed. SUBJECTS AND METHODS. We prospectively evaluated 492 impalpable mammographically detected lesi ons on which surgical biopsy las opposed to percutaneous biopsy) was p erformed. Each lesion was classified according to BI-RADS descriptors for masses (margins and shape) and calcifications (morphology and dist ribution) and was categorized by the BI-RADS final assessment categori es as category 3 (''probably benign''), category 4 (''suspicious abnor mality''), or category 5 (''highly suggestive of malignancy''). Mammog raphic and pathologic findings were reviewed. RESULTS. Carcinoma was p resent in 225 (46%) of 492 lesions. For the 492 lesions subject to bio psy, BI-RADS final assessment categories were category 3 in eight lesi ons (2%), category 4 in 355 (72%), and category 5 in 129 (26%). The fe atures with highest positive predictive Value for carcinoma were spicu lated margins (81%), irregular shape (73%), linear calcification morph ology (81%), and segmental or linear calcification distribution (74% a nd 68%, respectively). Carcinoma was present in 105 (81%) of 129 categ ory 5 lesions compared with 120 (34%) of 355 category 4 lesions (p < . 001). The frequency of carcinoma was higher in category 5 than in cate gory 4 lesions for all mammographic lesion types and all interpreting radiologists. CONCLUSION. The standardized terminology of the BI-RADS lexicon allows quantification of the likelihood of carcinoma in an imp alpable breast lesion. The features with highest positive predictive v alue-spiculated margins, irregular shape, linear morphology, and segme ntal or linear distribution-warrant designation of a lesion as categor y 5.