Head-to-Head Comparison of <sup>68</sup>Ga-FAPI-46 and <sup>18</sup>F-FDG PET/CT for Evaluation of Head and Neck Squamous Cell Carcinoma: A Single-Center Exploratory Study
Chetsadaporn Promteangtrong, Dheeratama Siripongsatian, Attapon Jantarato, Anchisa Kunawudhi, Peerapon Kiatkittikul, Sukanya Yaset, Natphimol Boonkawin, Chanisa Chotipanich
Abstract
<sup>68</sup>Ga-conjugated fibroblast activation protein inhibitor (<sup>68</sup>Ga-FAPI) has become an attractive agent for positron emission tomography (PET). This study aimed to compare <sup>68</sup>Ga-FAPI-46 PET/computed tomography (CT) with <sup>18</sup>F-fluorodeoxy-D-glucose (<sup>18</sup>F-FDG) PET/CT for detecting primary cancer and metastatic lesions in patients with head and neck squamous cell carcinoma (HNSCC). <b>Methods:</b> Twelve patients and twenty-eight patients with HNSCC underwent <sup>68</sup>Ga-FAPI-46 and <sup>18</sup>F-FDG PET/CT for initial staging and recurrence detection, respectively. Concordance and diagnostic accuracy of both tracers were analyzed. Semiquantitative parameters, including the maximum and mean of standardized uptake value (SUV<sub>max</sub> and SUVmean) and tumor-to-background ratio (T/B) were compared. FAP expression tumor volume (FTV) and total lesion FAP expression (TLF) of <sup>68</sup>Ga-FAPI-46 were compared with metabolic tumor volume (MTV) and total lesion glycolysis (TLG) of <sup>18</sup>F-FDG, respectively. Differences between semiquantitative parameters were analyzed using paired t-tests. <b>Results:</b><sup>68</sup>Ga-FAPI -46 PET/CT was 83.3% and 96.4% concordant with <sup>18</sup>F-FDG PET/CT for initial staging and recurrence detection, respectively. Eighteen lesions had histopathological validation and both tracers displayed 100% sensitivity, 50% specificity, and 94.4% accuracy for lesion-based analysis. FTV was greater than MTV (<i>P</i> < 0.05), but no significant differences were observed for the other parameters. <b>Conclusion:</b><sup>68</sup>Ga-FAPI-46 PET/CT showed good concordance and comparable diagnostic performance compared with <sup>18</sup>F-FDG PET/CT for initial staging and recurrence detection in patients with HNSCC.