A high yield robotic synthesis of 9-(4-[18F]-fluoro-3-hydroxymethylbutyl)guanine ([18F]FHBG) and 9-[(3-[18F]fluoro-1-hydroxy-2-propoxy)methyl]guanine([18F] FHPG) for gene expression imaging

The aim of this study was to develop an automated synthesis of 9-(4-[18F]-fluoro-3-hydroxymethylbutyl)guanine ([18F]FHBG) and 9-[(3-[18F]fluoro-1-hydroxy-2-propoxy)methyl]guanine ([18F]FHPG) using a Scanditronix Anatech RB III robotic system. [18F]HF was produced via 18O(p, n)18F using a Scanditronix MC17F cyclotron. On average, a typical run produced [18F]FHBG and [18F]FHPG with an uncorrected radiochemical yield of 19% and 16%, respectively, at end of synthesis (EOS) from irradiation of 95% enriched [18O]water. The total synthesis time was 80 min. The retention time of [18F]FHBG and [18F]FHPG (the radio-peak) was 3.9 and 4.0 min, respectively, which was consistent with the [19F]FHBG and [19F]FHPG ultraviolet peak. The radiochemical purity was greater than 97%. A robotic, automated method for [18F]FHBG and [18F]FHPG radiosynthesis is therefore feasible. The radiation burden for the operator can be reduced as much as possible. Sufficient radioactivities of [18F]FHBG and [18F]FHPG could be obtained for non-invasive monitoring the expression of transfected gene in vivo with positron emission tomography (PET).