Development of an economical method to synthesize O-(2-[¹⁸ F]fluoroethyl)-L-tyrosine (¹⁸ FFET)

Positron emission tomography (PET) using O-(2-[¹⁸ F]fluoroethyl)-L-tyrosine ([¹⁸ F]FET) has shown great success in differentiating tumor recurrence from necrosis. In this study, we are reporting the experience of synthesis [¹⁸ F]FET by varying the concentration of TET precursor in different chemistry modules. TET precursor (2-10 mg) was used for the synthesis of [¹⁸ F]FET in an automated (MX Tracerlab) module (n = 6) and semiautomated (FX2N Tracerlab) module (n = 19). The quality control was performed for all the preparations. For human imaging, 220 ± 50 MBq of [¹⁸ F]FET was briefly injected into the patient to acquire PET-MR images. The radiochemical purity was greater than 95% for the final product in both modules. The decay corrected average yield was 10.7 ± 4.7% (10 mg, n = 3) and 8.2 ± 2.6% (2 mg, n = 3) with automated chemistry module and 36.7 ± 7.3% (8-10 mg, n = 12), 26.4 ± 3.1% (5-7 mg, n = 4), and 35.1 ± 3.8% (2-4 mg, n = 3) with semiautomated chemistry modules. The PET imaging showed uptake at the lesion site (SUV_max  = 7.5 ± 2.6) and concordance with the MR image. The [¹⁸ F]FET was produced with a higher radiochemical yield with 2.0 mg of the precursor with substantial yield and is suitable for brain tumor imaging.