Ultrasound Evaluation of the Axilla in the Breast Imaging Setting.

Ultrasound evaluation of the axilla plays a critical role in the setting of newly diagnosed breast cancer as surgical management evolves toward more targeted axillary nodal resection. Regional nodal involvement by metastatic carcinoma is one of most important prognostic factors in breast cancer and guides local, regional, and systemic treatment. Ultrasound also evaluates response to neoadjuvant chemotherapy. This article will review ultrasound techniques and the anatomy and the morphology of axillary lymph nodes. Lymph node staging in breast cancer will also be discussed. Ultrasound-guided interventions and localizations and emerging technologies of elastography and contrast-enhanced ultrasound will be discussed. In addition, this article will discuss the role of ultrasound as it applies to management of the axilla since the American College of Surgeons Oncology Group Z011 and Z1071 trials. Finally, other causes of benign and malignant axillary lymphadenopathy, not related to breast cancer, are discussed.