To understand the impact of radiotracer concentration on our imaging studies, the maximum preclinical imaging time was calculated from the concentrations of [ 18 F]FSPG achieved at end of synthesis (EOS) during each stage in our method optimization (See Table ). Calculations were based on an i.v. injection of 3.0 MBq of [ 18 F]FSPG in a maximum volume of 150 µL. Despite reproducible production of [ 18 F]FSPG in good RCY and high RCP, small animal imaging could not be conducted after optimization of the reaction conditions alone (Table , Entry 1).