68Ga-FAPI-04 Versus 18F-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, Ga-68-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 Ga-68-FAPI-04 PET/CT and F-18-FDG PET/CT in hepatocellular carcinoma (HCC), and to assess factors associated with Ga-68-FAPI-04 uptake in HCC. Materials and Methods Twenty-nine patients with suspiciously HCC who received both F-18-FDG and Ga-68-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 (SUVmax and SUVmean) were measured in the lesions and liver background, respectively. The tumour-to-background ratio (TBR) was then calculated as lesion's SUVmax divided by background SUVmean. Results A total of 35 intrahepatic lesions in 25 patients with HCC were finally involved in the statistical analysis. Ga-68-FAPI-04 PET/CT showed a higher sensitivity than F-18-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. SUVmax was comparable between Ga-68-FAPI-04 and F-18-FDG (6.96 +/- 5.01 vs. 5.89 +/- 3.38, P > 0.05), but the TBR was significantly higher in the Ga-68-FAPI-04 group compared with the F-18-FDG group (11.90 +/- 8.35 vs. 3.14 +/- 1.59, P < 0.001). SUVmax and the TBR in Ga-68-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 Ga-68-FAPI-04 PET/CT is more sensitive than F-18-FDG PET/CT in detecting HCC lesions, and Ga-68-FAPI-04 uptake is correlated mainly with tumour size.

Automated summary

Ga-68-FAPI-04 PET/CT is more sensitive than F-18-FDG PET/CT in detecting HCC lesions, and Ga-68-FAPI-04 uptake is mainly correlated with tumor size.