A methodological investigation of healthy tissue, hepatocellular carcinoma, and other lesions with dynamic (68)Ga-FAPI-04 PET/CT imaging

BACKGROUND: The study aimed to establish a (68)Ga-FAPI-04 kinetic model in hepatic lesions, to determine the potential role of kinetic parameters in the differentiation of hepatocellular carcinoma (HCC) from non-HCC lesions. MATERIAL AND METHODS: Time activity curves (TACs) were extracted from seven HCC lesions and five non-HCC lesions obtained from (68)Ga-FAPI-04 dynamic positron emission tomography (PET) scans of eight patients. Three kinetic models were applied to the TACs, using image-derived hepatic artery and/or portal vein as input functions. The maximum standardized uptake value (SUV(max)) was taken for the lesions, the hepatic artery, and for the portal veins—the mean SUV for all healthy regions. The optimum model was chosen after applying the Schwartz information criteria to the TACs, differences in model parameters between HCC, non-HCC lesions, and healthy tissue were evaluated with the ANOVA test. RESULTS: A reversible two-tissue compartment model using both the arterial as well as venous input function was most preferred and showed significant differences in the kinetic parameters V(ND), V(T), and BP(ND) between HCC, non-HCC lesions, and healthy regions (p < 0.01). CONCLUSION: Several model parameters derived from a two-tissue compartment kinetic model with two image-derived input function from vein and aorta and using SUV(max) allow a differentiation between HCC and non-HCC lesions, obtained from dynamically performed PET scans using FAPI.