The [ 18 F]FSPG produced using our optimized synthesis protocol was used to image tumors in a subcutaneous A549 non-small cell lung cancer model. Representative static [ 18 F]FSPG PET/CT maximum intensity projection of 40-60 min summed activity (Fig. ) revealed typical [ 18 F]FSPG biodistribution, characterized by high uptake in the tumor and pancreas, with radiotracer excreted via the urinary system . No uptake was observed in the bone, indicating the absence of free [ 18 F]fluoride.