What is an Indium Scan?

An indium scan, also known as a leukocyte scan or white blood cell (WBC) scan, is a type of nuclear scan in which a radioactive tracer is used to identify inflammation or infection in specific areas of the body. This procedure employs a radioisotope of indium-111. The scan is a non-invasive imaging procedure that involves minimal discomfort. It is generally not recommended for women who are pregnant or breastfeeding.

The indium scan is a multiple-step procedure conducted by a nuclear medicine technologist. First, the individual's blood is drawn. WBCs are separated from other blood cells and then mixed with a small amount of the indium-111 isotope; this is called tagging. The tagged cells are injected back into the person's body through a vein. A few hours later, when the tagged cells have accumulated in inflamed or infected areas of the body, the gamma rays emitted by the isotope are detected by a full-body scan using special imaging equipment.

The scanning process involves lying completely still on an examination table while imaging cameras move slowly above or below the table. This could take anywhere from 20 minutes to several hours. A second indium scan procedure, or follow-up tests such as an MRI or CT scan, could be required to confirm the presence of infection or inflammation.

An indium scan is a non-invasive and non-surgical procedure. It typically involves minimal discomfort from the blood draw and re-injection of tagged blood cells. The individual could experience a sensation of coldness in the arm immediately after the injection of the radioisotope mix. Rarely, some people could experience an allergic reaction to the indium-111 isotope, which in extreme cases could lead to anaphylactic shock.

Risks inherent in the indium scan procedure are considered to be minimal. Although the process involves some exposure to radioactivity, the isotope generally leaves the body within about two days. An individual might be instructed to drink a large amount of water after the test to help flush the isotope out of the body. A woman who is breastfeeding or pregnant might be advised against having this procedure, or the nuclear medicine technician could use a lower dose of the radioactive isotope.

An indium scan is typically prescribed when a doctor suspects that there could be infection or inflammation in some part of the body, particularly in the abdominal area. An abnormal result on the indium scan indicates the likelihood of an active infection or inflamed area, such as an abscess of the liver or other organs. Inaccurate results are possible because the spleen and liver tend to accumulate WBCs even when there is no active infection or inflammation present.