MRI-based predictive factors of axillary lymph node status in breast cancer.

To evaluate the diagnostic value of diffusion-weighted imaging (DWI) in combination with conventional MRI in predicting metastatic axillary lymph nodes (ALN) in breast cancer (BC). We reviewed pathological findings and clinical breast MRI examinations of 169 patients with invasive BC who were evaluated at the Hôtel-Dieu de France Hospital in 2009-2015. Morphological parameters and apparent diffusion coefficient (ADC) value were compared with pathological nodal status. Independent t-test/chi-square test and a Pearson correlation analysis were used. With pathological diagnosis as reference, MRI-based interpretations were 87.5% specific and 70.3% sensitive. On conventional MRI, the round shape of lymph nodes (LNs), loss of fatty hilum, irregular margins and hypo-intensity/heterogeneous intensity on T2-weighted sequence were statistically significantly different between metastatic and nonmetastatic groups (P < .001, each). Mean size of metastatic ALN was larger compared with negative ALN (13.9 mm vs. 10.9 mm, P < .001). LNs ≥ 12 mm were associated with higher risk of metastasis (P < .001). ADC value was not significantly different between both groups (P = .862). Conventional MRI using the ALN shape, signal intensity in T2-weighted sequences, loss of fatty hilum, regularity of the margins and size of the LNs can evaluate the axilla with high specificity. ADC value could not be used as a reliable parameter.