APA Dictionary of Psychology

an imaging technique using radiolabeled tracers, such as 2-deoxyglucose labeled with fluorine-18, that emit positively charged particles (positrons) as they are metabolized. Used to evaluate cerebral metabolism and blood flow as well as the binding and transport of neurotransmitter systems in the brain, PET enables documentation of functional changes that occur during the performance of mental activities. It is also used to detect damage or disease (e.g., cancer) in other organs of the body.