Lymphography is a medical imaging technique in which a radiocontrast agent is injected, and then an X-ray picture is taken to visualize structures of the lymphatic system, including lymph nodes, lymph ducts, lymphatic tissues, lymph capillaries and lymph vessels. Lymphangiography is the same procedure, used only to visualize the lymph vessels. The X-ray film or image of the vessels and nodes is called a lymphogram or a lymphangiogram.
Radiographs can be taken after injection of a radiopaque contrast medium into small lymphatic vessels (these are made visible by prior subcutaneous injection of patent blue dye). The resulting lymphogram is used to find the locations of large vessels and nodes, and to identify sites of blockage in lymphatic drainage.
Lymph nodes can also be detected via radionuclide imaging after injection of radioactive colloids. Macrophages phagocytose these foreign bodies and sequester in the nodes.
- A needle or catheter is inserted into a lymphatic channel in either the foot or arm, and a contrast medium is injected into the body at a very slow rate (approximately 60 to 90 minutes for all the contrast medium to be injected).
- A fluoroscope is used to follow the dye as it spreads through the lymphatic system through the legs, into the groin, and along the back of the abdominal cavity.
- Once the contrast medium is injected, the catheter is removed, and the incisions are stitched and bandaged. X-rays are taken of the legs, pelvis, abdomen, and chest areas. The next day, another set of X-rays may be taken.
- If a site of cancer (breast or melanoma) is being studied to evaluate spreading, a mixture of blue dye and a radioactive tracer is injected next to the mass. Special cameras detect the spread of tracer along lymph channels to outlying nodes.
- A surgeon will then use the visible blue dye or radioactivity within nodes to guide biopsy within adjacent tissues (such as the arm pit for breast cancer) to determine possible routes of cancer spread.
This test is not used as often as it once was, because of the adoption of CT scan and the PET scan technologies.
The name comes from the Greek words lymph (νυμφε), "water nymph", and graphien, "to write or record".