rhACE2 administrations in KM mice
For subcutaneous-rhACE2 and tumor rhACE2 models, different doses of rhACE2 were directly injected into the corresponding positions 30 min before PET imaging; For the in situ rhACE2-intraperitoneal liver or -spleen model, after anesthetizing mice with 1.25% tribromoethanol at 0.2 ml/10g 30 min in advance, the target organ was exposed after opening the abdomen, and different contents of rhACE2 were injected using insulin needles, and the injection volume was not more than 50μL; The anterior fontanelle is the origin, 1.7 mm on the right, 0.7 mm anteriorly, and 3 mm deep for fixed-point injection of the right caudate nucleus.