The indium white blood cell scan is a nuclear medicine procedure in which white blood cells (mostly neutrophils) are removed from the patient, tagged with the radioisotope Indium-111, and then injected intravenously into the patient.
The tagged leukocytes subsequently localize to areas of relatively new infection.
The study is particularly helpful in differentiating conditions such as osteomyelitis from decubitus ulcers for assessment of route and duration of antibiotic therapy.
Both the gallium scan and indium-111 white blood cell imaging may be used to image fever of unknown origin (elevated temperature without an explanation).
However, the indium leukocyte scan will localize only to the approximately 25% of such cases which are caused by acute infections, while gallium is more broadly sensitive, localizing to other sources of fever, such as chronic infections and tumors.