(68)Ga-FAPI-04 Versus (18)F-FDG PET/CT in the Detection of Hepatocellular Carcinoma

BACKGROUND: Fibroblast activation protein (FAP) is commonly expressed in activated stromal fibroblasts in various epithelial tumours. Recently, (68)Ga-FAPI-04 has been used for tumour imaging in positron emission tomography/computed tomography (PET/CT). This study aimed to compare the diagnostic performances of (68)Ga-FAPI-04 PET/CT and (18)F-FDG PET/CT in hepatocellular carcinoma (HCC), and to assess factors associated with (68)Ga-FAPI-04 uptake in HCC. MATERIALS AND METHODS: Twenty-nine patients with suspiciously HCC who received both (18)F-FDG and (68)Ga-FAPI-04 PET/CT were included in this retrospective study. The results were interpreted by two experienced nuclear medicine physicians independently. The maximum and mean standardized uptake values (SUV(max) and SUV(mean)) were measured in the lesions and liver background, respectively. The tumour-to-background ratio (TBR) was then calculated as lesion’s SUV(max) divided by background SUV(mean). RESULTS: A total of 35 intrahepatic lesions in 25 patients with HCC were finally involved in the statistical analysis. (68)Ga-FAPI-04 PET/CT showed a higher sensitivity than (18)F-FDG PET/CT in detecting intrahepatic HCC lesions (85.7% vs. 57.1%, P = 0.002), including in small (≤ 2 cm in diameter; 68.8% vs. 18.8%, P = 0.008) and well- or moderately-differentiated (83.3% vs. 33.3%, P = 0.031) tumors. SUV(max) was comparable between (68)Ga-FAPI-04 and (18)F-FDG (6.96 ± 5.01 vs. 5.89 ± 3.38, P > 0.05), but the TBR was significantly higher in the (68)Ga-FAPI-04 group compared with the (18)F-FDG group (11.90 ± 8.35 vs. 3.14 ± 1.59, P < 0.001). SUV(max) and the TBR in (68)Ga-FAPI-04 positive lesions were associated with tumour size (both P < 0.05), but not the remaining clinical and pathological features (all P > 0.05). CONCLUSIONS: (68)Ga-FAPI-04 PET/CT is more sensitive than (18)F-FDG PET/CT in detecting HCC lesions, and (68)Ga-FAPI-04 uptake is correlated mainly with tumour size.