Positron Emission Tomography

Positron emission tomography, or PET, is a functional imaging technique that uses radioactive tracer molecules to visualize metabolic processes and other physiological activity such as blood flow and regional chemical composition, helping diagnose and manage cancer, cardiac disease and neurological disorders. A radiopharmaceutical is injected into the body, and when the radioactive isotope decays it emits a positron that collides with a nearby electron, producing two gamma rays traveling in nearly opposite directions that detectors capture to reconstruct a three-dimensional image. The concept of emission and transmission tomography was introduced by David E. Kuhl and colleagues in the 1950s and refined through the 1960s and 1970s by Michel Ter-Pogossian and Michael E. Phelps at Washington University, and the tracer fluorodeoxyglucose, first given to human volunteers by Abass Alavi in 1976, became central to modern PET imaging; the combined PET-CT scanner was named medical invention of the year by Time magazine in 2000.