The indium white blood cell scan, or simply indium scan, is a nuclear medicine procedure in which white blood cells, which are 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 infection.
Helpful in differentiating conditions such as osteomyelitis and decubitus ulcers, and for assessment of route and duration of antibiotic therapy.
The gallium scan has a sensitivity advantage over the indium scan in imaging osteomyelitis of the spine, lung infections and inflammation, and in detecting chronic infections, because it binds to neutrophil membranes, even after neutrophil death, whereas localization of neutrophils labeled with indium requires them to be functional.
Indium imaging is better at localizing acute infections, where live neutrophils are actively localizing to the infection, for imaging for osteomyelitis that does not involve the spine, and for locating abdominal and pelvic infections.