Multimodality Evaluation of Regional Breast Lymph Nodes: Impact of Expected Changes in the Upcoming BI-RADS Sixth Edition.

Evaluating regional breast lymph nodes is a critical aspect of breast cancer imaging, directly affecting staging, treatment planning, and overall patient outcomes. Clinical practice is moving toward de-escalation in the axilla, fueled by evidence of unchanged survival rates and low local recurrence rates, as well as the risk of lymphedema. Radiologists need to be skilled at identifying and characterizing suspicious lymph nodes and guiding interventions on them. This approach aligns with the American Society of Breast Surgeons' Choosing Wisely initiative, which advocates for less invasive management when appropriate. Although the sixth edition of the Breast Imaging Reporting and Data System (BI-RADS) atlas has not yet been published, the BI-RADS committee has previewed expected changes at multiple national meetings. A key anticipated update is introduction of a dedicated lymph node category across imaging modalities, accompanied by expanded guidance on lymph node morphology and location. The authors review the expected changes in the context of multimodality imaging, including mammography, US, and MRI, with a focus on axillary, intramammary, internal mammary, and supraclavicular lymph nodes. They present a systematic approach to lymph node evaluation, highlighting modality selection, imaging features suggestive of metastasis, and the role of US-guided core biopsy or fine-needle aspiration for histologic confirmation. Differential considerations and nodal staging are also discussed. ©RSNA, 2026.