Positron Emission Tomography (PET)
A scanner that finds where an injected radioactive tracer, such as a radioactive sugar, collects in the body shows cancer, heart disease and working brain areas, not just organ shapes.
Open in the interactive tree →By 1973 Michael Phelps had built a first PET scanner, a Boston positron camera recorded the first image of regional brain metabolism that year, and Michel Ter-Pogossian's group in St. Louis completed a multi-slice scanner in 1974. In August 1976 Abass Alavi gave fluorodeoxyglucose (FDG), a radioactive sugar, to the first human volunteers at the University of Pennsylvania; FDG is now widely used to diagnose, stage and monitor cancer. PET showed that blood flow and sugar use rise in active brain areas, which prepared the ground for fMRI, and tracers for amyloid now reveal plaques in living Alzheimer's patients.
Prerequisites
- Radioactivity1896The tracer is a radioactive atom; the scanner detects its decay.
- Antimatter1932The scan detects positrons, the antimatter twins of electrons.
- Particle Accelerators1932Cyclotrons make the short-lived radioactive tracers.
- CT and MRI Scanning1971PET rebuilds slice images by computer, as CT does.
Unlocks
- Functional MRI1992PET showed first that active brain areas draw more blood; fMRI tracks a related signal without radiation.
- Alzheimer's and Brain DeclineopenFDG and amyloid PET help tell Alzheimer's from other dementias in living patients.