Lymphogram
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.