First proof-of-principle in vivo PET-imaging animal studies of one of the tested radioligands, [68Ga]Ga-DOTA.SA.FAPi, in HT29 human colorectal xenografts indicated promising results with low background signal and high accumulation in tumor (SUVmean = 0.75), which was higher than [68Ga]Ga-FAPI-04 (SUVmean = 0.45) in human FAP-transfected HT-1080 tumors at the same scanning time [108]. Here, FAP is linked to neoplasm.