ABSTRACT
PET can be used to provide a variety of biological functions in regional tissues in vivo, using positronemitting tracers that trace different biological pathways. Common positron emitters include F-18, C-11, N-13, and O-15, which are isotopes of elements that form the organic compounds in the body. Thus, these positron emitters can be incorporated radiochemically into a natural molecule or its analog in the body. This characteristic implies that positron-emitting tracers can be made to follow an almost unlimited number of biological processes in the body, thus enabling PET as a very versatile imaging technique. By using different tracers, completely different biological functions can be obtained with the same PET scanner.
