Incidental enhancing lesions found on preoperative breast MRI: management and role of second-look ultrasound.

Purpose: This study prospectively assessed second-look ultrasound (US) for the evaluation of incidental enhancing lesions identified on preoperative breast magnetic resonance imaging (MRI).

Materials And Methods: Between 2004 and 2007, 182 patients with malignant breast lesions detected on US and/or X-ray mammography and confirmed by cytology/histology underwent preoperative breast contrast-enhanced (CE)-MRI. Patients with incidental lesions on breast MRI underwent second-look high-resolution US directed at the site of the incidental finding. Diagnosis of incidental lesions was based on biopsy or 24-month follow-up.

Results: Breast MRI detected 55 additional lesions in 46/182 (25.2%) patients. Forty-two of 55 (76.3%) lesions were detected on second-look US in 38/46 (82.6%) patients. Malignancy was confirmed for 24/42 (57.1%) correlate lesions compared with 7/13 (53.8%) noncorrelate lesions. Second-look US depicted 8/9 (88.8%) Breast Imaging Reporting and Data System (BI-RADS) 5, 16/22 (72.7%) BI-RADS 4 and 18/24 (75%) BI-RADS 3 lesions. Sensitivity, specificity, accuracy and positive and negative predictive values for lesion detection/diagnosis was 100%, 88.9%, 94.6%, 90.3% and 100% for MRI and 64.3%, 70.4%, 67.3%, 69.2% and 65.5% for second-look US. Improved performance for US was obtained when masslike lesions only were considered.

Conclusions: Second-look US is a confirmatory method for incidental findings on breast MRI, particularly for mass-like lesions.