The status of axillary lymph node (ALN) is an important reference indicator for breast cancer surgery and systemic treatment, which is also an important prognostic indicator for breast cancer. Therefore, it is extremely important for surgeons to accurately determine whether axillary lymph nodes have metastasis and the number of metastatic lymph nodes. The value of ultrasound diagnosing the status of axillary lymph nodes was controversial in recent publications. Therefore, there is a high need to prove the accuracy and precision of ultrasound for axillary lymph node metastasis in breast cancer patients. The aim of this study is to assess the usefulness of ultrasound in the diagnosis of axillary lymph node status in breast cancer patients by gathering in vivo and vitro ultrasonographic parameters to build a clinical useful categorization system

To facilitate the non-invasive assessment of lymph node status preoperatively, we use ultrasound to detect lymph node metastasis. We designed this study to obtain in vivo and vitro ultrasound features and parameters. Before surgery, the detailed ultrasound features are collected during routine ultrasound examination. After the completion of the axillary surgery, fresh lymph node specimens are collected for in vitro ultrasound evaluation one by one in a specially-designed detection system. Statistical models are built to categorize the probability of metastasis of lymph node according to a proposed categorization system similar as BI-RADS(Breast Imaging Reporting and Data System), which is named NI-RADS (Node Imaging Reporting and Data System).

Inclusion Criteria:

• Histologically confirmed invasive breast cancer.
• Pathological axillary lymph node staging planned.
• Axillary lymph node not removed prior to the study.

Exclusion Criteria:

• Refusal participation in the study.

All patients with invasive breast cancer planned to receive surgical axillary lymph node staging are eligible.