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

<jats:sec><jats:title>Background</jats:title><jats:p>Fibroblast activation protein (FAP) is commonly expressed in activated stromal fibroblasts in various epithelial tumours. Recently, <jats:sup>68</jats:sup>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 <jats:sup>68</jats:sup>Ga-FAPI-04 PET/CT and <jats:sup>18</jats:sup>F-FDG PET/CT in hepatocellular carcinoma (HCC), and to assess factors associated with <jats:sup>68</jats:sup>Ga-FAPI-04 uptake in HCC.</jats:p></jats:sec><jats:sec><jats:title>Materials and Methods</jats:title><jats:p>Twenty-nine patients with suspiciously HCC who received both <jats:sup>18</jats:sup>F-FDG and <jats:sup>68</jats:sup>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<jats:sub>max</jats:sub> and SUV<jats:sub>mean</jats:sub>) were measured in the lesions and liver background, respectively. The tumour-to-background ratio (TBR) was then calculated as lesion’s SUV<jats:sub>max</jats:sub> divided by background SUV<jats:sub>mean</jats:sub>.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>A total of 35 intrahepatic lesions in 25 patients with HCC were finally involved in the statistical analysis. <jats:sup>68</jats:sup>Ga-FAPI-04 PET/CT showed a higher sensitivity than <jats:sup>18</jats:sup>F-FDG PET/CT in detecting intrahepatic HCC lesions (85.7% <jats:italic>vs</jats:italic>. 57.1%, <jats:italic>P</jats:italic> = 0.002), including in small (≤ 2 cm in diameter; 68.8% <jats:italic>vs</jats:italic>. 18.8%, <jats:italic>P</jats:italic> = 0.008) and well- or moderately-differentiated (83.3% <jats:italic>vs</jats:italic>. 33.3%, <jats:italic>P</jats:italic> = 0.031) tumors. SUV<jats:sub>max</jats:sub> was comparable between <jats:sup>68</jats:sup>Ga-FAPI-04 and <jats:sup>18</jats:sup>F-FDG (6.96 ± 5.01 <jats:italic>vs</jats:italic>. 5.89 ± 3.38, <jats:italic>P</jats:italic> &gt; 0.05), but the TBR was significantly higher in the <jats:sup>68</jats:sup>Ga-FAPI-04 group compared with the <jats:sup>18</jats:sup>F-FDG group (11.90 ± 8.35 <jats:italic>vs</jats:italic>. 3.14 ± 1.59, <jats:italic>P</jats:italic> &lt; 0.001). SUV<jats:sub>max</jats:sub> and the TBR in <jats:sup>68</jats:sup>Ga-FAPI-04 positive lesions were associated with tumour size (both <jats:italic>P</jats:italic> &lt; 0.05), but not the remaining clinical and pathological features (all <jats:italic>P</jats:italic> &gt; 0.05).</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p><jats:sup>68</jats:sup>Ga-FAPI-04 PET/CT is more sensitive than <jats:sup>18</jats:sup>F-FDG PET/CT in detecting HCC lesions, and <jats:sup>68</jats:sup>Ga-FAPI-04 uptake is correlated mainly with tumour size.</jats:p></jats:sec>