Magnetic Resonance Imaging for Axillary Breast Cancer Metastasis in the Neoadjuvant Setting: A Prospective Study

Abstract

BackgroundBreast magnetic resonance imaging (MRI) for assessment of regional breast cancer metastasis is controversial owing to the variable specificity. We evaluated breast MRI for axillary metastasis in neoadjuvant chemotherapy patients. Materials and MethodsA single-institution, institutional review board–approved prospective trial enrolled female breast cancer patients receiving neoadjuvant chemotherapy from 2008 to 2012 and collected the pre- and post-treatment MRI, pretreatment axillary ultrasound, axillary biopsy, and surgical pathologic findings. The kappa coefficient was used to evaluate the strength of the agreement between the 2 modalities and Fisher's exact test was used to evaluate the association. ResultsA total of 43 patients were included. Of these 45 patients, 35 had stage N1-N2 before treatment. Comparing the abnormal results on the pretreatment MRI scans and axillary biopsy examinations, a consistent diagnosis was found for 92%, with a moderate strength of agreement (kappa coefficient, 0.54). The pretreatment MRI findings were significantly associated with the axillary biopsy results (P = .014). The false-positive rate, false-negative rate, sensitivity, and specificity were 50%, 3%, 97%, 50%, respectively. Comparing the post-treatment MRI and surgical pathologic findings revealed a consistent diagnosis rate of, with a slight strength of agreement (kappa, 0.16). The false-positive rate, false-negative rate, sensitivity, and specificity were 38%, 46%, 55%, and 63%, respectively. The post-treatment MRI findings were not associated with the pathologic lymph node results (P = .342). ConclusionPretreatment breast MRI was more specific for axillary metastasis than was axillary ultrasonography. However, post-treatment breast MRI was not predictive of residual axillary disease and should be used cautiously when altering treatment plans.