68 Ga‐PET: a powerful generator‐based alternative to cyclotron‐based PET radiopharmaceuticals

PET (positron emission tomography) is a powerful diagnostic and imaging technique which requires short‐lived positron emitting isotopes. The most commonly used are accelerator‐produced 11 C and 18 F. An alternative is the use of metallic positron emitters. Among them 68 Ga deserves special attention because of its availability from long‐lived 68 Ge/ 68 Ga generator systems which render 68 Ga radiopharmacy independent of an onsite cyclotron. The coordination chemistry of Ga 3+ is dominated by its hard acid character. A variety of mono‐ and bifunctional chelators have been developed which allow the formation of stable 68 Ga 3+ complexes and convenient coupling to biomolecules. 68 Ga coupling to small biomolecules is potentially an alternative to 18 F‐ and 11 C‐based radiopharmacy. In particular, peptides targeting G‐protein coupled receptors overexpressed on human tumour cells have shown preclinically and clinically high and specific tumour uptake. Kit‐formulated precursors along with the generator may be provided, similar to the 99 Mo/ 99m Tc‐based radiopharmacy, still the mainstay of nuclear medicine. Copyright © 2008 John Wiley & Sons, Ltd.