Objective: Our study aims to head to head compare the application of gallium-68-fibroblast activation protein inhibitor (68Ga-FAPI) positron emission tomography/computed tomography (PET/CT) and fluorine-18-fluorodeoxyglucose (18F-FDG) PET/CT in primary and metastatic lesions of gastric tumor to determine the superior diagnostic tool.
Materials and methods: A systematic search, up to March 31, 2023, across PubMed, Embase, and Cochrane Library databases utilized a data-specific Boolean logic strategy. Sensitivity (SEN) and specificity (SPE) evaluations of 68Ga-FAPI and 18F-FDG PET/CT in gastric cancer lesions were conducted. The quality of the studies was assessed using QUADAS-2, and publication bias was examined through Begg and Egger tests.
Results: Analysis involved 141 gastric tumor patients and 2753 metastatic lesions in five studies, with overall satisfactory study quality and no apparent publication bias. Patient-level data showed a combined SEN of 0.95 (95% CI: 0.90-0.98) for 68Ga-FAPI and 0.84 (95% CI: 0.77-0.89) for 18F-FDG. At the lesion level, combined SEN were 0.91 (95% CI: 0.84-0.96) for 68Ga-FAPI and 0.72 (95% CI: 0.63-0.80) for 18F-FDG. The pooled SEN for detecting lymph node metastases was 0.78 (95% CI: 0.74-0.82) for 68Ga-FAPI and 0.35 (95% CI: 0.30-0.39) for 18F-FDG, with pooled SPE values of 0.99 (95% CI: 0.98-0.99) and 0.97 (95% CI: 0.96-0.98), respectively. For detecting distant metastases, pooled SEN values were 0.97 (95% CI: 0.96-0.98) and 0.69 (95% CI: 0.66-0.72) for 68Ga-FAPI and 18F-FDG, with pooled SPE values of 0.86 (95% CI: 0.82-0.89) and 0.64 (95% CI: 0.59-0.68), respectively.
Conclusion: This meta-analysis concluded that 68Ga-FAPI PET/CT was significantly more sensitive than 18F-FDG PET/CT in assessing primary gastric tumors, lymph nodes, and distant metastases, but the difference in the specificity of lymph node metastasis was not significant.