Utility of [⁶⁸Ga]FAPI-04 and [¹⁸F]FDG dual-tracer PET/CT in the initial evaluation of gastric cancer.

Abstract

We aimed to investigate the role of [⁶⁸Ga]FAPI-04 and [¹⁸F]FDG dual-tracer PET/CT for the initial assessment of gastric cancer and to explore the factors associated with their uptake. This study enrolled 62 patients with histopathologically confirmed gastric cancer. We compared the diagnostic performance of [⁶⁸Ga]FAPI-04, [¹⁸F]FDG, and combined dual-tracer PET/CT. The standardized uptake value (SUV) and tumor-to-background ratio (TBR) were also measured, and the factors that influence tracer uptake were analyzed. [⁶⁸Ga]FAPI-04 PET/CT detected more primary lesions (90.3% vs 77.4%, p = 0.008) and peritoneal metastases (91.7% vs 41.7%, p = 0.031) and demonstrated higher SUV_max and TBR values (p < 0.001) of primary lesions compared to [¹⁸F]FDG PET/CT. Dual-tracer PET/CT significantly improved the diagnostic sensitivity for the detection of distant metastases, compared with stand-alone [¹⁸F]FDG (97.1% vs 73.5%, p = 0.008) or [⁶⁸Ga]FAPI-04 (97.1% vs 76.5%, p = 0.016) PET/CT. Subsequently, treatment strategies were changed in nine patients following [⁶⁸Ga]FAPI-04 and [¹⁸F]FDG dual-tracer PET/CT. Nevertheless, [⁶⁸Ga]FAPI-04 uptake was primarily influenced by the size and invasion depth of the tumor. Both [⁶⁸Ga]FAPI-04 and [¹⁸F]FDG PET/CT showed limited sensitivity for detecting early gastric cancer (EGC) (37.5% vs 25.0%, p > 0.05). In this initial study, [⁶⁸Ga]FAPI-04 and [¹⁸F]FDG dual-tracer PET/CT were complementary and improved sensitivity for the detection of distant metastases pre-treatment in gastric cancer and could improve treatment stratification in the future. [⁶⁸Ga]FAPI-04 had limited efficacy in detecting EGC. • [⁶⁸Ga]FAPI-04 and [¹⁸F]FDG dual-tracer PET/CT are complementary to each other for improving diagnostic sensitivity in the initial evaluation of distant metastases from gastric cancer. • [⁶⁸Ga]FAPI-04 PET/CT showed limited sensitivity in detecting EGC. • Need for further validation in a larger multi-centre prospective study.