Ex vivo MRI of axillary lymph nodes in breast cancer

PurposeTo provide a strategy for precise co-localization of lymph nodes on axillary lymph-node dissection (ALND) specimens both on pathology and MR.To identify nodal features suggestive of metastatic involvement on a node-to-node basis.Materials and methodsNational Institutional review-board approved this prospective study of 18 patients with breast cancer referred for ALND. Ex vivo T1 and inversion recovery (IR) T2 WI of ALND specimens tightly positioned within scaled plastic cranes was performed immediately after surgery. The correspondence of MR-based or pathologically based nodes location was assessed. The MR size and morphological presentation of metastatic and normal nodes were compared (Student's t-test or Mann–Whitney test). Quantitative variables were compared using Pearson coefficient.Results207 nodes were retrieved on pathology and 165 on MR. MR–pathological correlation of nodes location was high regarding MR-identified nodes (r = 0.755). An MR short axis threshold of 4 mm yielded the best predictive value for metastatic nodal involvement (Se = 78.6%; Sp = 62.3%). Irregular contours (Se = 35.7%; Sp = 96.7%), central nodal hyper-intensity on IR T2 WI (Se = 57.1%; Sp = 91.4%), and a cortical thickness above 3 mm (Se = 63.6%; Sp = 83.2%) were significantly associated with metastatic involvement.ConclusionEx vivo MR allows node-to-node correlation with pathology. Morphological MR criteria can suggest metastatic involvement.