The Role of MR Imaging for the Surgical Treatment Planning of Breast Cancer: Comparison with US and the Whole-Excised Breast Histopathologic Correlation

Abstract

Purpose: We wanted to evaluate the effectiveness of breast magnetic resonance (MR) imaging as a preoperative evaluation modality, as compared with ultrasonography (US) imaging, and we wanted to determine the correlation of MRI and US with using the whole-excised breast histopathology as the standard reference. (Check this and adjust it as needed.) Materials and Methods: From October 2004 to March 2008, among the 245 patients with breast cancer, 82 patients underwent modified radical mastectomy (MRM). Seven patients were excluded due to receiving neoadjuvant chemotherapy before MRI (n=4) or mammotome excision (n=2) or non-visualization of the mass on US and MR imaging (n=1). The remaining 76 breasts in 75 women (one bilateral) were examined preoperatively with MR imaging and US. On US, 42 cases showed unifocal cancer, 16 showed multifocal cancer and 18 showed multicentric breast cancers. On MRI, 39 cases showed unifocal cancer, 11 showed multifocal cancer and 26 showed multicentric breast cancers. We assessed the US findings to identify the patients who were eligible for breast conservative surgery, and then we evaluated the cancers that were treated with conversion to MRM based on the MR imaging. Results: Histopathologic analysis revealed 45 unifocal, 10 multifocal and 22 multicentric breast cancers. Fiftyfive of the 76 breasts were indicated for MRM based on the US findings due to multicentric cancers (n=18), unifocal or multifocal lesions near the nipple (n=31), or unifocal or multifocal lesions showing extension towards the nipple (n=6). The remaining 21 breasts were classified as suitable for BCS on US, but 5 patients who desired MRM were excluded. Sixteen breasts were altered to MRM based on the additional findings that were suspicious for malignancy on the MR imaging. Among them, 14 (88%) breasts were adequately converted on the surgical plan to MRM based on the histopathologic verification. The remaining 2 breasts had been overestimated. Conclusion: Breast MRI has a significant effect for the preoperative surgical planning of breast cancers and it should be performed for the surgical planning.