The test is performed in a hospital radiology department or in the health care provider's office by an X-ray technician.
If leg or arm swelling is being evaluated, you may be offered a sedative to help relax. You will be put in a specially constructed chair or on the X-ray table. The skin of each foot is cleansed, and a small amount of blue dye is injected between the toes into the webbing.
Within 15 minutes, thin, bluish lines appear on the top of the foot. This identifies the lymphatics. Then, a local anesthetic is given and a small incision is made into one of the larger blue lines. A needle or catheter (a thin flexible tube) is inserted into a lymphatic channel in each foot, and a contrast medium is injected into each foot at a very slow rate (60 to 90 minutes for all the contrast medium to be injected).
A fluoroscope (a special X-ray machine that projects the images on a TV monitor) is used to follow the travels of the dye as it spreads through the lymphatic system up 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 axilla or arm pit for breast cancer) to determine possible routes of cancer spread.
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