One-stop [18F]FDG and [68Ga]Ga-DOTA-FAPI-04 total-body PET/CT examination with dual-low activity: a feasibility study

Purpose Positron emission tomography/computed tomography (PET/CT) based on fibroblast activation protein inhibitors (FAPI) has shown complementary values to 2-[ 18 F]-fluoro-2-deoxy-D-glucose ([ 18 F]FDG) in cancer imaging. This study aimed to investigate the feasibility of a one-stop FDG-FAPI dual-tracer imaging protocol with dual-low activity for oncological imaging. Methods Nineteen patients with malignancies underwent one-stop [ 18 F]FDG (0.37 MBq/kg) PET (PET FDG ) and dual-tracer PET 30–40 and 50–60 min (hereafter, PET D30–40 and PET D50–60 , respectively) after additional injection of [ 68 Ga]Ga-DOTA-FAPI-04 (0.925 MBq/kg), with a single diagnostic CT to generate the PET/CT. The lesion detection rate and tumor-to-normal ratios (TNRs) of tracer uptake were compared between PET FDG /CT and PET D50–60 /CT and between PET D50–60 /CT and PET D30–40 /CT. In addition, a visual scoring system was established to compare the lesion detectability. Results The dual-tracer PET D50–60 and PET D30–40 /CT showed similar performance in detecting primary tumors but presented significantly higher lesion TNRs than PET FDG . Significantly, more metastases with higher TNRs were identified on PET D50–60 than PET FDG (491 vs. 261, P