Which imaging method uses a radioactive tracer to create functional images of the body, often used to assess metabolic activity?

• A. PKU test
• B. Potassium test
• C. PET scan
• D. Prothrombin Time

Answer: (C)

Imaging that visualizes metabolic activity uses a radioactive tracer to map how tissues are functioning. In a PET scan, a radiotracer such as fluorodeoxyglucose (FDG), a glucose-like molecule labeled with a radioactive isotope, is injected. Tissues that are more metabolically active take up more tracer, and the tracer’s radioactivity is detected to create images showing where metabolism is highest. Because it tracks function rather than structure, PET provides a functional map of the body, useful for evaluating cancer metabolism, brain activity, and heart muscle viability. The other options are laboratory tests or coagulation tests that measure specific substances or time in the blood and do not image metabolic activity.