It has been hypothesized that positron emission tomography (PET) of radiolabeled FAP inhibitors (FAPI) with short-living positron emitters (e.g., 68Ga/18F) may replace 18F-FDG in several major tumor types (e.g., breast cancer, pancreatic cancer, sarcoma) [3, 11]. This evidence concerns the gene FAP and sarcoma.