Indium-111 oxine labelled white blood cell (WBC) scan (or In-111 oxine labelled white blood cell scan) is a nuclear medicine test which attempts to localise infection and/or inflammation by injecting the patient's previously extracted and radioactively-labelled white blood cells.
The patient's blood is withdrawn and white blood cells extracted. These are then labelled with indium-111 oxine and injected back into the patient. It is, obviously, imperative that the patient receives his or her own white blood cells back and careful systems must be in place to ensure that this occurs.
The patient is then imaged 24 hours later giving the white blood cells the opportunity to migrate to the site of inflammation/infection.
After detecting a focus of increased uptake within the bone marrow on a WBC scan, a technetium-99m (Tc-99m) sulfur colloid bone scan must be performed to confirm a marrow replacing process in the setting of clinical suspicion for osseous infection (photopenia on Tc-99m sulfur colloid) because reactive marrow (uptake on Tc-99m sulfur colloid) can also demonstrate increased osseous uptake on WBC scans 2.
- photon energy: 174 KeV, 247 KeV 1
- physical half-life: 2.8 days
- normal distribution: spleen, liver, bone (first 4 hours pulmonary activity seen)
- excretion: spleen
- critical organ: spleen
- labelled leucocytes localise at sites of infection through diapedesis, chemotaxis, and enhanced vascular permeability
- cleared by reticuloendothelial system
As is the case with many nuclear medicine tests, it suffers from intrinsically poor spatial resolution. SPECT and SPECT/CT acquisition can help to overcome limitations of poor spatial resolution and improve accuracy in localisation.
- 1. Lewis SS, Cox GM, Stout JE. Clinical utility of indium 111-labeled white blood cell scintigraphy for evaluation of suspected infection. Open forum infectious diseases. 1 (2): ofu089. doi:10.1093/ofid/ofu089 - Pubmed
- 2. Palestro CJ, Love C, Tronco GG, Tomas MB, Rini JN. Combined labeled leukocyte and technetium 99m sulfur colloid bone marrow imaging for diagnosing musculoskeletal infection. Radiographics : a review publication of the Radiological Society of North America, Inc. 26 (3): 859-70. doi:10.1148/rg.263055139 - Pubmed