Which imaging modality is described as "single photon emission CT"?

The term "single photon emission CT" refers specifically to SPECT, which stands for Single Photon Emission Computed Tomography. This imaging modality combines the technology of conventional CT with nuclear medicine and allows for the visualization of metabolic processes in the body.

In SPECT, a radioactive substance is administered to the patient, which emits gamma rays. A gamma camera detects these rays and a computer processes the data to create cross-sectional images of the body. This provides critical information about blood flow and metabolic activity in tissues, particularly useful in assessing conditions such as cancer, cardiovascular diseases, and neurological disorders.

Other imaging modalities listed, such as CT scans, magnetic resonance imaging, and X-rays, do not involve the use of radioactive tracers and do not provide the same functional information that SPECT does. CT scans typically focus on structural imaging using X-rays, while MRI utilizes magnetic fields and radio waves to create detailed images of soft tissues; X-rays are primarily used for evaluating bony structures.