Diagnostic Performance of MR-guided Vacuum-Assisted Breast Biopsy: 8 Years of Experience.

Breast magnetic resonance imaging (MRI) has demonstrated increased sensitivity over conventional imaging in identifying and characterizing in situ and invasive, multifocal, and multicentric disease. A histologic diagnosis is required for any enhancing lesion displaying suspicious features, especially in the presence of lower and often variable reported specificity values. Breast MRI findings occult on mammography and ultrasound should undergo an MR-guided biopsy. We retrospectively evaluate our 8 years' experience with this procedure. Our study included 259 lesions in 255 consecutive patients referred for MR-guided breast biopsy. MRI screening of women at a high risk for developing breast cancer accounted for 84 lesions, 54 lesions were detected on MRI staging for multifocal and multicentric disease, and 115 were incidental findings or lesions that presented diagnosis related issues on conventional imaging. Six procedures were cancelled due to lack of visualization. MR-guided breast biopsy was performed for 100 mass and 153 nonmass enhancements. Pathology results were classified into benign (113 lesions), high risk (47 lesions), and malignant (40 ductal carcinoma in situ, 38 invasive ductal carcinoma, 15 invasive lobular carcinoma). Subsequent surgery for high risk and malignant findings revealed an underestimation rate of 34% (16/47) for high risk lesions and of 7.5% for ductal carcinoma in situ (3/40). The overall positive predictive value (PPV) was calculated at 43.1% (33.3% for high-risk women, 70.3% for cancer staging, and 37.4% for incidental/undetermined lesions). The PPV was higher for mass (57%) versus nonmass enhancements (34%). MR-guided breast biopsy proved to be a reliable procedure for the diagnosis and management of occult breast MRI findings, or lesions that preclude biopsy under conventional guidance. The PPV displayed significant variation between patient subgroups, correlating higher values with a higher associated breast cancer prevalence.