What is a Positron Emission Tomography (PET) scan?

A technique in nuclear medicine for cross- sectional imaging. It enables a non-invasive assessment and localization of metabolic activity to be made. Positron emission tomography is a functional imaging technique that uses radioactive substances known as radiotracers to visualize and measure changes in metabolic processes, and in other physiological activities including blood flow, regional chemical composition, and absorption. PET scans originally were used to study activity in the brain. Now they are also used for investigating the chest and abdomen.