Bibliogr. s. e418

Purpose: To determine the diagnostic value of breast magnetic resonance imaging (MRI) in detecting axillary metastatic node in newly diagnosed breast cancer, we assessed the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of breast MRI. Material and methods: Data were collected retrospectively from January 2011 to December 2018. Preoperative breast MRI of women with newly diagnosed breast cancer were reviewed to evaluate the axillary nodal staging by using the morphological characteristic of metastatic axillary lymph node. Statistical analysis was performed to assess the performance of breast MRI in diagnosing metastatic axillary lymph nodes based on the pathological result. Results: A total of 131 women with breast cancer were analysed. Two hundred and twenty-seven axillary lymph nodes from preoperative breast MRIs were considered to be metastasis. 65.65% (86 patients) of the breast MRI results matched with the pathological results: 37 patients with N0 stage, 39 patients with N1 stage, eight patients with N2 stage, and two patients with N3 stage. Sensitivity of breast MRI for axillary nodal staging was 98.5% (95% CI: 92-100%), and the negative predictive value was 96.4% (86.2-99.9%). Specificity of breast MRI for axillary nodal staging was 57.8% (44.8-70.1%) and the positive predictive value was 71% (60.6-79.9%). Conclusions: Our study showed that the breast MRI had a high sensitivity (98.5%) and high NPV (96.4%) in detecting metastatic axillary lymph nodes, but its specificity was only fair (57.8%). Overestimation and underestimation of the MRI in N staging were also found in 20.61% and 12.98% of cases, respectively.