P131 Targeted ultrasonography for MRI-detected lesions of preoperative breast cancer patients

Abstract

Goals: Magnetic resonance imaging (MRI) is commonly performed to preoperatively evaluate the extent of breast cancer. However, proper management of secondary lesions detected by using MRI is sometimes challenging. Although MRI-guided biopsy is recommended to examine such lesions, the procedure is rarely performed. Therefore, these lesions are often investigated by using ultrasonography (US). Furthermore, the treating physicians might not always be familiar with the MRI lexicon by the American College of Radiology Breast Imaging Reporting and Data System (BI-RADS) for the management of MRI-detected lesions, possibly because MRI and US findings do not always correspond. The aim of this study was to examine the identification and malignancy rates of MRI-detected lesions by using US in preoperative breast cancer patients based on the BI-RADS lexicon. Methods:Of the 725 primary breast cancer patients who underwent preoperative breast MRI at Chiba University Hospital between November 2011 and June 2014, 102 were detected with secondary lesions and included in this study. We retrospectively analysed the identification rate of these lesions by using US and their malignancy frequency based on the BI-RADS classification. Results: MRI detected a total of 111 lesions, including 24 belonging to category 2, 40 of category 3, 45 of category 4, and 2 of category 5. The identification rates on US for each category were 50%, 60%, 89%, and 100%, respectively. Biopsy was performed to examine all lesions detected on US, and the malignancy rates for each category were 0%, 29%, 55%, and 100%, respectively. One patient who was diagnosed with category 4 lesions on MRI but undetectable on US eventually showed a relapse. Conclusion: The application of US for MRI-detected lesions is useful and convenient. However, approximately 10% of the cases with an MRI category of ≥4 were undetectable on US, especially non-mass enhancement lesions. Therefore, it is critical to improve detection capability, for example, by using real-time virtual sonography or repeating MRI within a short time period. Disclosure of Interest: No significant relationships.