Accuracy of MRI in the detection of residual breast cancer after neoadjuvant chemotherapy

OBJECTIVE. This study was undertaken to evaluate the ability of MRI to accurately show residual primary breast malignancy in women treated with neoadjuvant chemotherapy. MATERIALS AND METHODS. Twenty-one patients with locally advanced primary breast carcinoma underwent contrast-enhanced MRI before and after treatment with neoadjuvant anthracycline-based chemotherapy. For each patient, the maximum extent of the MRI abnormality was measured both before and after treatment. These measurements were subsequently compared with physical examination findings and histologic results to determine the ability of MRI to accurately reveal tumor extent after neoadjuvant chemotherapy. RESULTS. MRI after chemotherapy showed a correlation coefficient of 0.75 with histology, which was better than physical examination (r = 0.61). MRI underestimated the extent of residual tumor in two patients by more than 1 cm (including one false-negative examination), was within 1 cm in 12 of 21 patients, and overestimated tumor extent by more than I cm in seven of 21 patients. CONCLUSION. MRI can show residual malignancy after neoadjuvant chemotherapy better than physical examination, particularly in patients who have not had a complete clinical response to therapy.