Lymphoscintigraphy is a procedure that provides images of the lymphatic system, a network of small channels similar to blood vessels that circulate fluid (called lymph) and cells (lymphocytes) of the immune system throughout the body. Lymph nodes, which act like a filter for foreign bodies such as germs, viruses and pollen, are located along this network.

Lymphoscintigraphy helps identify the first few or sentinel lymph nodes that filter lymph fluid from the site of a cabcer–those most likely to be affected by cancer.

The procedure involves injecting tiny amounts of radioactive particles (Technetium-99m sulfur-colloid) at the site of the primary cancer. Depending on the site of the cancer, images are then taken with a gamma camera of the patient’s arms and underarms, legs and groins, head, neck and chest, or other areas.

The radiotracer gives off energy in the form of gamma rays that can be detected by the gamma camera. The camera produces images that reflect the amount of radiotracer absorbed throughout the lymphatic system. Using these images and a hand-held probe as a guide, a physician removes only the lymph nodes that have absorbed the radiotracer.

Advantages of Lymphoscintigraphy

Lymphoscintigraphy is a valuable tool for mapping where the cancer might spread to other parts of the body. Because cancers can travel throughout the lymphatic system in unexpected ways, lymphoscintigraphy is helpful in directing the surgeon to potentially cancerous areas that may have otherwise been overlooked. Images generated by the procedure allow physicians to remove only sentinel lymph nodes, sparing patients from undergoing unnecessary removal of normal lymph nodes.