Single-photon emission computed tomography

Single-photon emission computed tomography
A SPECT slice of the distribution of technetium exametazime within a patient's brain
ICD-9-CM	92.0-92.1
MeSH	D01589
OPS-301 code	3-72
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Single-photon emission computed tomography (SPECT, or less commonly, SPET) is a nuclear medicine tomographic imaging technique using gamma rays.^[1] It is very similar to conventional nuclear medicine planar imaging using a gamma camera (that is, scintigraphy),^[2] but is able to provide true 3D information. This information is typically presented as cross-sectional slices through the patient, but can be freely reformatted or manipulated as required.

The technique needs delivery of a gamma-emitting radioisotope (a radionuclide) into the patient, normally through injection into the bloodstream. On occasion, the radioisotope is a simple soluble dissolved ion, such as an isotope of gallium(III). Usually, though, a marker radioisotope is attached to a specific ligand to create a radioligand, whose properties bind it to certain types of tissues. This marriage allows the combination of ligand and radiopharmaceutical to be carried and bound to a place of interest in the body, where the ligand concentration is seen by a gamma camera.