Optimization of Precursor Synthesis Conditions of (2S,4S)4–[(18)F]FPArg and Its Application in Glioma Imaging

Although the tracer (2S,4S)4–[(18)F]FPArg is expected to provide a powerful imaging method for the diagnosis and treatment of clinical tumors, it has not been realized due to the low yield of chemical synthesis and radiolabeling. A simple synthetic method for the radiolabeled precursor of (2S,4S)4–[(18)F]FPArg in stable yield was obtained by adjusting the sequence of the synthetic steps. Furthermore, the biodistribution experiments confirmed that (2S,4S)4–[(18)F]FPArg could be cleared out quickly in wild type mouse. Cell uptake experiments and U87MG tumor mouse microPET–CT imaging experiments showed that the tumor had high uptake of (2S,4S)4–[(18)F]FPArg and the clearance was slow, but (2S,4S)4–[(18)F]FPArg was rapidly cleared in normal brain tissue. MicroPET–CT imaging of nude mice bearing orthotopic HS683–Luc showed that (2S,4S)4–[(18)F]FPArg can penetrate blood–brain barrier and image gliomas with a high contrast. Therefore, (2S,4S)4–[(18)F]FPArg is expected to be further applied in the diagnosis and efficacy evaluation of clinical glioma.