Development of an 18F radiolabeling method using solid phase chemistry

Abstract

New radiotracers are constantly being developed to expand the clinical applications of positron emission tomography (PET). One of the challenges in the development of PET tracers is the incorporation of a positron emitting isotope. Short half-lives combined with added safety measures when working with radioactive materials require a fast and simple synthesis. This project describes a solid phase fluorine-18 (t1/2 = 110 min) radiolabeling procedure that allows removal of impurities through filtration. The synthesis takes an indirect approach by first labeling a small molecule with F-18 and then coupling this molecule to an amine containing compound using solid phase dichlorotriazine (DCT). This procedure has been used to label various compounds containing primary and secondary amine groups without the need for an additional purification step. The total synthesis time required is approximately 80 min from the from delivery of the [ 18F]fluoride, with a decay corrected radiochemical yield of 3% for the example tested (yield will likely vary depending on the substrate). This demonstrates the potential of solid phase reagents like DCT to be used in radiolabeling, but further development is required to improve yields for this reaction.