PET imaging agents for Alzheimer’s disease

Abstract

In the past four decades, PET (positron emission tomography) imaging has been developed into a common diagnostic tool. After an i.v. injection of a small amount of radioactive probe, PET images are taken based on the decay of shortlived positron-emitting isotopes. The emitted positron collides with a neighboring electron to produce two 511 KeV gamma rays roughly 180 apart. It is based on this physical principal and the positron coincident signals that the point source of the gamma rays can be deduced by using a coincident circuit for detectors 180 apart. Currently, there are three FDA-approved imaging agents (Amyvid, NeuraCeq, and Vizamyl) available for mapping Aβ in the brain of patients suspected of having Alzheimer’s disease. There is a strong interest in measuring tau deposition by PET imaging in a quantitative manner. Several useful Tau imaging agents have been tested in humans; however, they have not been fully validated as those of Aβ imaging agents.