MRI before reexcision surgery in patients with breast cancer.

OBJECTIVE: The aims of this study were to assess the diagnostic accuracy of MRI in evaluating patients for residual cancer, identify the prevalence of multicentric or multifocal disease, and evaluate the impact of MRI on surgical treatment planning. SUBJECTS AND METHODS. Of 101 potentially eligible patients, 80 candidates for breast conservation therapy who had primary breast cancer in 82 breasts diagnosed by excisional biopsy with close or positive margins were included in the study group. All patients underwent contrast-enhanced MRI before further surgery and subsequently underwent either reexcision lumpectomy or mastectomy with histopathologic correlation.
RESULTS: Residual carcinoma, either invasive or in situ, was present in 59.8% of the breasts. The sensitivity and specificity of MRI for detecting residual disease were 61.2% and 69.7%, respectively. Twenty-three additional lesions distant from the biopsy site were identified in 19 breasts, and 18 suspicious lesions underwent biopsy. Histology results indicated that six lesions were malignant, so the overall prevalence was 7.3%. The positive predictive value of identifying an additional suspicious lesion was 33.3%. In 24 breasts, MRI changed which procedure would be performed next from reexcision lumpectomy to mastectomy (n = 9), biopsy of an additional lesion in the ipsilateral (n = 12) or contralateral (n = 2) breast, or neoadjuvant chemotherapy (n = 1). Approximately 25% of the breasts underwent mastectomy as definitive surgical treatment.
CONCLUSION: Overlap in the appearances of benign and malignant lesions limits MRI evaluation for residual disease. MRI can show additional suspicious lesions that are likely to be multicentric or multifocal disease. These findings changed the original treatment plan for approximately 30% of breasts.