Breast Nonmass Enhancement Detected with MRI: Uility and Lesion Characterization with Second-Look Ultrasonography

The purpose of this study was to verify the utility of second-look ultrasonography (US) in evaluating nonmass enhancement (NME) lesions detected on breast magnetic resonance imaging (MRI) by analysing its correlation and imaging features. From July 2008 to June 2012, 102 consecutive MRI-detected NME lesions were subsequently evaluated with US. Lesions were evaluated according to the established Breast Imaging Reporting and Data System (BI-RADS) lexicon. The correlation between MRI-detected NME lesion characteristics, lesion size, histopathological findings and features at second-look US were analysed. Second-look US identified 44/102 (43%) of the NME lesions revealed by MRI. A US correlate was seen in 34/45 (76%) malignant lesions compared with 10/57 (18%) benign lesions (p < 0.0001). The likelihood of malignancy was significantly higher for NME lesions with a US correlate than lesions without: 34/44 (77%) versus 11/58 (19%) (p < 0.0001). The malignancy of the 44 (43%) MRI-detected NME lesions with a US correlate was significantly associated with US lesion margins and BI-RADS categories (p = 0.001 and 0.002 respectively). Second-look US of MRI-detected NME lesions is useful for decision-making as part of the diagnostic workup. Familiarity with the US features associated with malignancy improves the utility of US in the workup of these NME abnormalities.