OBJECTIVE. Thepurpose of thestudy wasto assess thepositive predictive valueofmammographic features and final assessment categories described in the Breast Imaging Re porting and Data System (BI-RADS) for lesions on which biopsies have been performed. SUBJECTS AND METHODS.Weprospectively evaluated 492impalpable mammographically detected lesions on which surgical biopsy (as opposed to percutaneous biopsy) was performed. Each lesion was classified according to BI-RADS descriptors for masses (margins and shape) and calcifications (morphology and distribution) and was categorized by the BI-RADS final assessment categories as category 3 (â€oeprobably benign―), category 4 (â€oesus picious abnormality―), or category 5 (â€oehighly suggestive of malignancy―). Mammographic and pathologic findings were reviewed.

Among MR imaging-detected breast lesions referred for biopsy, carcinoma was found in 25%, of which half were DCIS. Features with the highest PPV were spiculated margin, rim enhancement, and irregular shape for mass lesions and segmental or clumped linear and ductal enhancement for nonmass lesions. Final assessment categories were significant predictors of carcinoma.

Percutaneous biopsy of a nonpalpable breast mass with either US or stereotactic guidance is less expensive than surgery, but cost savings are greater with US-guided biopsy.

Among women at high risk of developing breast cancer, breast MRI led to a recommendation of biopsy in 17%. Cancer was found in 24% of women who underwent biopsy and in 4% of women who had breast MRI screening. More than half the MRI-detected cancers were ductal carcinoma in situ.

MR imaging identified additional sites of ipsilateral cancer in 27% of women with percutaneously proven breast cancer. The yield was highest in women with a family history of breast cancer or infiltrating lobular histology in the index cancer. Change after biopsy was infrequent and did not interfere with the MR imaging interpretation.