Databases, Protein ; Protein Structure, Secondary ; Proteins ; chemistry

Objective:To automatically synthesize Al 18F-fibroblast activation protein inhibitor (FAPI)-74, and explore its value of clinical application. Methods:Al 18F-FAPI-74 was synthesized automatically by the commercial synthesis module CFN-MPS-100, and its yield, radiochemical purity and stability were determined. Sixteen normal Kunming (KM) mice were randomly divided into 4 groups and euthanized at 10, 30, 60 and 90 min after Al 18F-FAPI-74 injection, and the biodistribution was measured. MicroPET/CT dynamic scanning (60 min) was performed in 5 rat pancreatic tumor-bearing BALB/c nude mice to observe the tumor uptake. Al 18F-FAPI-74 PET/CT imaging was performed on 3 volunteers (1 male, 2 females; age: 37, 41, 43 years) to evaluate the clinical application value of Al 18F-FAPI-74. Results:The automated synthesis time of Al 18F-FAPI-74 was about 35 min, with the synthesis yield of (21.34±3.86)% (without attenuation correction, n=5) and the radiochemical purity more than 99%. The radiochemical purity was still more than 96% after placement at 37 ℃ for 6 h. Biodistribution in normal mice and microPET/CT dynamic scanning in tumor-bearing nude mice showed that consistently high uptake in the kidneys and bladder, and the tumor uptake was the highest at 20 min, and the maximum tumor-to-muscle ratio was 3.16±0.01 at 60 min. PET/CT imaging on volunteers showed that there was a small amount of uptake in myocardium, most organs such as the liver and lung had background uptake, and the maximum SUV max of persistent high uptake of tumor was 17.08. Conclusions:Al 18F-FAPI-74 has the advantages of simple synthesis, high yield, stable quality and good imaging performance in mice and volunteers. It is a kind of imaging agent that meets the requirements of clinical diagnosis.