Needle Localization with Sentinel Node Mapping is usually done in association with a needle localization. Typically, a surgeon removes some lymph nodes when he/she does a biopsy. These lymph nodes are analyzed by the laboratory. The results of the node biopsy are used to help stage a cancer of the breast. This staging helps the surgeon and the oncologist determine how to best treat breast cancer. A surgeon will determine if this procedure needs to be done.

To have this procedure done, the patient goes to the Nuclear Medicine Department. The radiologist in this department injects a radioactive isotope (tracer). This tracer collects in the main lymph node (sentinel node). When the patient is in the operating suite, the surgeon uses a probe to locate this node, remove it and send it to the laboratory for analysis.