Synthesis and preliminary studies of O-(2-[18F] fluoroethyl)-L-tyrosine as a positron emission tomography imaging agent

OBJECTIVE: To develop a 18F-labeled amino acid, O-(2-[18F]fluoroethyl) - L-tyrosine(18F-FET), as a positron emission tomography (PET) tracer for imaging cerebral tumors. METHODS: 18F-FET was synthesized. Preclinical studies including sterility, endotoxin, and toxicity tests were performed. Two brain tumor cases were studied using 18F-FET and compared with 18F-FDG. RESULTS: Radiochemical purity of 18F-FET was over 95% which remained stable for 6 hours. The 18F-FET injection was sterile and its endotoxin content accorded with the standards of Chinese Pharmacopoeia. The uptake of 18F-FET in the normal brain tissues was significantly lower than that of the tumor, and the images of the brain tumor were clearer than those of 18F-FDG. CONCLUSION: 18F-FET can accumulate in the tumor tissues to give high quality images. It suggests that 18F-FET may be a safe and effective tracer for brain tumor imaging.