Assessment of MRI-Detected Breast Lesions: A Benign Correlate on Second-Look Ultrasound Can Safely Exclude Malignancy

Introduction: Due to the increasing use of dynamic breast MRI and the limited availability of MR-guided interventions, MRI-detected lesions usually undergo a second-look ultrasound (SLUS). We investigated the safety of a negative SLUS and a benign SLUS correlate in excluding malignant and high-risk lesions (B3) and evaluated criteria for the rate of detection on SLUS. Methods: In the retrospective analysis, all breast MRIs performed between 2011 and 2013 were screened for newly detected lesions. We analyzed the SLUS detection rate dependent on breast density, mass character, lesion size, and histology. We calculated the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of a negative and benign SLUS for malignant lesions (B5) and lesions requiring surgical excision (including high-risk and B5 lesions). Results: We successfully correlated 110 of 397 lesions. The detection rate was significantly higher for mass than for non-mass lesions and correlated with lesion size for mass lesions only. Lesions without/with a benign SLUS correlate were more frequently benign (including B3) or required no further procedure (B2). The sensitivity of SLUS in the detection of B3 and B5 lesions was 58%, and 73% in the detection of B5 lesions. The NPV of a negative or benign SLUS for B3 and B5 lesions was 89%, and 96% for B5 lesions. Discussion: SLUS is a safe diagnostic tool for the management of MRI-detected lesions and can spare patients from undergoing invasive procedures.