Fully automated radiosynthesis and quality control of estrogen receptor targeting radiopharmaceutical 16α-[ 18 F]fluoroestradiol ([ 18 F]FES) for human breast cancer imaging.

16α-[18F]Fluoroestradiol ([18F]FES) is the most successful estrogen receptor (ER) targeting radiopharmaceutical to date. [18F]FES has been extensively used for positron emission tomography (PET) to assess the ER expression in breast cancer and to monitor the response of breast cancer to antiestrogen therapy. To address local investigator needs for [18F]FES-PET, we sought to adapt established literature methods to our in-house multi-purpose 18F-radiosynthesis module for [18F]FES production. Here we describe facile fully automated radiosynthesis and quality control (QC) of [18F]FES using our home-built automated multi-purpose 18F-radiosynthesis module. [18F]FES was produced via two-step-one-pot synthesis using cyclic sulfate precursor, and purified by semi-preparative reversed-phase (RP) high performance liquid chromatography (HPLC) with a C18 column followed by solid-phase extraction (SPE) with a C18 Plus Sep-Pak cartridge trap/release formulation. The overall synthesis time was 75–80 min, and the radiochemical yield was 30–35% decay corrected to end of bombardment (EOB), based on H[18F]F. The radiochemical purity was >99%, and the molar activity (Am) was 182–470 GBq/μmol at EOB. The [18F]FES dose meets all QC criteria for clinical use, and is suitable for clinical PET study of breast cancer.