This is a multicenter, open-label, prospective Phase 1/2a study to assess safety and tolerability, establish dosimetry and to identify an optimal imaging dose (radioactivity) and imaging time window of 64Cu-LNTH-1363S (64Cu Radiolabeled FAPi PET/CT Imaging Agent) and to compare its imaging biodistribution with FAP expression by immunohistochemistry (IHC) in patients with sarcomas or GIT cancers.