A Comparison of Residual Tumor Accuracy Prior to Re-Excision between Breast Magnetic Resonance Imaging and Ultrasonography

Abstract

Purpose: We aimed to evaluate the accuracy of breast magnetic resonance imaging (MRI) versus ultrasonography (US) in detecting residual tumor prior to a second re-excision. Methods: Fifty-seven breast cancer patients diagnosed by vacuum-assisted breast biopsy (VABB) or excisional biopsy and scheduled for breast-conserving surgery (BCS) were included. They underwent breast MRI or US after an excisional biopsy or VABB to determine the extent of residual tumor around the excision site or multifocal cancers, followed by immediate curative surgery. We evaluated the correlation between the radiologic and pathologic findings after breast surgery. Results: Pathologic residual tumors were found in 42 patients (73.6%), and 13 patients (22.8%) demonstrated pathologic multifocal breast cancer. When detecting residual tumor using MRI, the sensitivity, specificity, positive predictive value, and negative predictive value were 59.5%, 46.7%, 75.8%, and 29.2%, respectively. For US, the sensitivity, specificity, positive predictive, and negative predictive values were 41.4%, 90%, 92.3%, and 34.6%, respectively. Invasive ductal breast cancers seemed to be more enhancing than ductal carcinoma in situ or extensive intraductal components containing breast cancer. MRI findings of residual tumors were not associated with residual tumor size (positive, 1.16 cm; negative, 1.0 cm; p= 0.65). Thirty-nine patients (68.4%) underwent BCS, while 18 patients (31.6%) underwent mastectomy. Conclusion: The MRI accuracy of detecting residual lesions around previous scars was lower than that of US, except for sensitivity; however, other lesions distinct from the primary cancer and multifocal lesions were more frequently identified on MRI than US.