At 5 h P.I., U87MG tumor was still of a high uptake at 1.81 ± 0.20 %ID/mL, an uptake value only decreased by half when compared with 1.5 h, indicating the stable binding of 99mTc-HYNIC-FAPI-04 to FAP in U87MG tumor. Here, FAP is linked to neoplasm.