Malignancy rates of non-masslike enhancement on breast magnetic resonance imaging using American College of Radiology Breast Imaging Reporting and Data System descriptors.

The purpose of this study was to evaluate the malignancy rates for non-masslike enhancement on breast magnetic resonance imaging by American College of Radiology Breast Imaging Reporting and Data System descriptors. We retrospectively reviewed breast magnetic resonance imaging reports with non-masslike enhancement performed at Mayo Clinic Florida from April 1, 2003, through March 14, 2007. Each descriptor of non-masslike enhancement as per the American College of Radiology Breast Imaging Reporting and Data System magnetic resonance lexicon was correlated with percutaneous biopsy pathologic results and/or surgical pathologic results and follow-up imaging. Positive predictive values were obtained for each Breast Imaging Reporting and Data System descriptor. We identified 578 incidents of non-masslike enhancement in 378 patients. Of 343 non-masslike enhancements that could be correlated with pathology results, 141 (41.1%) were malignant. Of the malignant lesions, 53% were found to be ductal carcinoma in situ at percutaneous biopsy. Clumped pattern of enhancement and segmental distribution of non-masslike enhancement had the highest sensitivities of 40.5% and 23.5%, respectively. Asymmetric pattern and segmental distribution had the highest positive predictive values of 75.0% and 57.4%, respectively. We concluded that the moderate positive predictive values make it difficult to establish guidelines for management of non-masslike enhancement and reveal the current limitations of breast magnetic resonance imaging.