In positron emission tomography (PET), which of the following is typically used to detect metabolic activity?

In positron emission tomography (PET), the use of Carbon-11 is significant because it is a radioactive isotope that emits positrons, which are essential for the functioning of PET imaging. PET scans are designed to visualize metabolic activity in the body, and Carbon-11 can be incorporated into various biomolecules, allowing researchers and clinicians to track biological processes in real-time.

When Carbon-11 is injected into a patient, it can bind to glucose, amino acids, or other compounds, depending on the specific tracer being used. As the tracer undergoes decay, it emits positrons that interact with electrons in the body, producing gamma rays that are detected by the PET scanner. This allows for precise imaging of areas with increased metabolic activity, such as tumors or areas of inflammation.

In contrast, the other isotopes mentioned have different uses in nuclear medicine and do not facilitate the same metabolic imaging capabilities. Technetium-99m is commonly used for single-photon emission computed tomography (SPECT) and has a different mechanism of action. Iodine-131 is primarily used in thyroid therapy and imaging but is not suitable for metabolic imaging at the level required for PET scans. Gallium-67 is typically used for infection and tumor imaging, but again