PET with non-standard nuclides

Driven by the ever-increasing availability of preclinical and clinical Positron Emission Tomography (PET) scanners, the use of non-standard PET nuclides has been growing exponentially in the past decade. Largely complementary to the roles of the four standard PET nuclides (¹⁵O, ¹³N, ¹¹C, and ¹⁸F) in PET, non-standard PET nuclides enable the novel design and synthesis of a wider range of PET tracers to probe a variety of biological events. However, characterized by emitting high energy positrons and cascade gamma rays, non-standard PET nuclides with half-lives ranging from seconds to days must be judiciously chosen for specific applications. Generally, chemistries with non-standard PET nuclides are more manageable given a wealth of existing standard operation procedures for the preparation of radiotracers for gamma scintigraphy or Single Photon Emission Computed Tomography (SPECT). This review describes most of the non-standard PET nuclides that have recently been reported for basic PET research or clinical studies with focus on the unique features of their productions, radiochemical procedures, and applications. The main drawbacks of each nuclide are also discussed along with special considerations that must be given towards its practical use in PET.