Comparison of Diagnostic Performance, Semiquantitative Analysis, and Staging Performance of [18F]FAPI-42 and 2-[18F]FDG PET/CT in Lymph Node Metastases

Abstract

Abstract Background This study was to compare the diagnostic performance, semiquantitative analysis, and staging performance of [18F]-labelled fibroblast activation protein inhibitor ([18F]FAPI-42) and 2-[18F]fluoro-2-deoxy-D-glucose(2-[18F]FDG) PET/CT in lymph node (LN) metastases. Methods From the detection of metastatic LNs, the semiquantitative value of the LN metastases, and the evaluation of N staging, a retrospective analysis of 56 patients diagnosed with LNs metastases who underwent [18F]FAPI-42 and 2-[18F]FDG PET/CT scans within a week for staging or restaging was performed. We analyzed, and compared the diagnostic performance and SUVmax of primary tumors and recurrent lesions, as well as the SUVmax, TBR, and diagnostic performance of metastatic LNs between [18F]FAPI-42 and 2-[18F]FDG PET/CT. Results A total of 216 metastatic LNs from 56 patients were detected and semi-quantitatively analyzed. Compared to 2-[18F]FDG PET/CT, [18F]FAPI-42 PET/CT presented a better diagnostic performance based on patients (98.2% vs. 92.9%, P = 0.364), based on lesions (87.5% vs. 78.7%, P = 0.015). Regarding semiquantitative analysis, the SUVmax of LNs metastases on [18F]FAPI-42 PET/CT presented higher uptake than that on 2-[18F]FDG PET/CT (SUVmax 5.0 vs. 3.9, P = 0.002). For differentiating metastatic LNs to normal LNs, the SUVmax of [18F]FAPI-42 in metastatic LNs was significantly higher in the non-metastatic LNs (SUVmax, 5.0 vs. 1.2, P < 0.001). Comparing the management of N staging between two tracers, [18F]FAPI-42 estimated precisely more patients than 2-[18F]FDG PET/CT (83.9% vs. 78.4%, P = 0.468). Conclusion [18F]FAPI-42 PET/CT showed superior diagnostic performance, the quantitative capability of metastatic LNs, and the management of N staging in patients with cancers compared to 2-[18F]FDG PET/CT.