In comparison, although U87MG tumor was of obvious 68Ga-FAPI-04 uptake and clearly visible at 1 h P.I., the tumorous radioactive signals were fuzzy at 1.5 h P.I. 99mTc-HYNIC-FAPI-04 specifically bound to FAP-positive tumors and qualified with the ability of evaluating tumor fibrosis over longer time windows. Here, FAP is linked to neoplasm.