Sentinel Node Localization is Imaging technique used locate the sentinel node. Patients who have been diagnosed as having cancer, most commonly breast cancer and melanoma, may require surgery to remove the primary cancer and also some nearby lymph nodes. The initial spread of these types of cancer is often via the lymphatics. Lymphoscintigraphy shows the direction of lymph flow from the site of the cancer, and also the closest and most important lymph nodes to the cancer. These lymph nodes are called the sentinel lymph nodes. Once they have been located, the surgeon can remove them with a relatively small operation.