To assess the diagnostic accuracy of ^(68)Ga-labeled fibroblast activation protein inhibitor (FAPI) and ^(18)F-labeled FDG PET for the detection of various tumors, we performed a head-to-head comparison of both imaging modalities across a range of tumor entities as part of our ongoing ^(68)Ga-FAPI PET observational trial. Methods: The study included 115 patients with 8 tumor entities who received imaging with ^(68)Ga-FAPI for tumor staging or restaging between October 2018 and March 2022. …