ABSTRACT
Objective:To investigate the kinetic metrics of 68Ga-fibroblast activation protein inhibitor (FAPI)-04 in pancreatic cancers and normal organs by using total-body PET dynamic imaging. Methods:From December 2020 to December 2021, 68Ga-FAPI-04 total-body PET/CT dynamic imaging were performed on 6 pancreatic cancer patients (3 males, 3 females, median age 55.5 years) in Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University. Images were respectively analyzed. Manual delineations of volume of interests (VOIs) on multiple normal organs and pathological lesions were performed and time-to-activity curves (TACs) were generated. A reversible two-tissue compartment model (2TCM) was fitted for each tissue TAC. Rate constants including K1, k2, k3 and k4, and the total volume of distribution ( Vt) were obtained and compared by tissue types. Wilcoxon rank sum test and Spearman correlation analysis were used for data analysis. Results:Kinetic metrics varied significantly among normal organs and pancreatic cancer lesions ( z values: 2.00-1 240.00, all P<0.05). The highest K1 among lesions was observed in primary tumor (0.30 min -1), which was observed in the spleen (1.42 min -1) among normal organs. The highest k2 among lesions was observed in peritoneal metastases (0.24 min -1), which was observed in the spleen (2.59 min -1) among normal organs. Primary tumor showed the highest k3 of 0.17 min -1 among lesions, and the pancreas had the highest k3 of 0.16 min -1 among normal organs. Primary tumor had the highest k4 of 0.03 min -1 among lesions, and the heart, lungs, parotid glands had high k4(0.06 min -1) among normal organs. Vt were higher in pathological lesions compared to normal organs, with the highest in primary tumor (13.78 ml/cm 3). There were correlations between Vt in lesions and SUV mean( rs=0.86, P<0.001) or SUV max ( rs=0.77, P<0.001). Conclusion:The rate constants including K1, k2, k3 and k4, and Vt of 68Ga-FAPI-04 vary among normal organs and lesions.