The excellent tumor-targeting efficacy of FAP has been confirmed by multiple clinical studies. The results unequivocally establish FAPI as a tumor-targeting ligand with significant potential, demonstrating important application prospects in translational oncology. However, its therapeutic effects remain under investigation. An ideal radiopharmaceutical for cancer treatment should possess outstanding targeting specificity and relatively prolonged tumor retention time. Previous studies have shown that radiolabeled FAPI variants (FAPI-04 and FAPI-46) rapidly and satisfactorily accumulate in tumors, while exhibiting low physiological uptake in normal tissues. However, prior FAP-related tracers demonstrated relatively short retention times in small pulmonary lesions. Our aim is to design a FAPI trimer, Trap-(FAPI)3, to optimize pharmacokinetics and evaluate whether this novel drug offers superior advantages over its monomer analogs in the imaging diagnosis and staging of pulmonary tumors.