Comparison of 68Ga-FAPI-04 and 18F-FDG for the Detection of Primary Gastric Cancers and Metastasis
Abstract Introduction Early and precise diagnosis and staging of gastric cancer are important for its treatment and management. However, the low sensitivity of 18F-fluorodeoxyglucose (18F-FDG) for gastric cancer diagnosis limits its application. Currently, the tracer 68Ga-FAPI, which targets fibroblast activation protein (FAP), is widely used to diagnose various cancers. However, the diagnostic value of 68Ga-FAPI in gastric cancer is still unclear. In this study, we aimed to investigate the potential advantage of 68Ga-FAPI-04 over 18F-FDG in the evaluation of gastric cancer.Methods: Thirty-eight patients with gastric cancer (31 with adenocarcinoma and 7 with signet ring cell carcinoma) were recruited for this study. All of the participants underwent 68Ga-FAPI-04 and 18F-FDG imaging by positron emission tomography (PET)/computed tomography (CT) or PET/magnetic resonance (MR). The results were interpreted by two experienced nuclear medicine physicians, and the maximum standardized uptake value (SUVmax) was calculated.Results: For the detection of primary gastric cancer, the sensitivities of 68Ga-FAPI-04 PET and 18F-FDG PET were 100% (38/38) and 81.6% (31/38), respectively. Four cases of adenocarcinoma and three cases of signet ring cell carcinoma were missed by 18F-FDG PET. The SUVmax of 68Ga-FAPI-04 in tumors greater than 4 cm (11.0 ± 4.5) was higher than tumors less than 4 cm (4.5 ± 3.2) (P = 0.0015). The SUVmax of 68Ga-FAPI-04 was higher in T2-4 tumors (9.7 ± 4.4) than in T1 tumors (3.1 ± 1.5) (P = 0.0002). For the detection of metastatic lesions, the sensitivities of 68Ga-FAPI-04 PET and 18F-FDG PET in 10 patients with regional lymph node metastasis and distant metastasis were 6/10 and 5/10, respectively.Conclusion: Compared to 18F-FDG PET, 68Ga-FAPI-04 PET had superior potential in detecting primary gastric cancers and metastatic lymph nodes, 68Ga-FAPI-04 PET also had a better performance on small gastric cancer detection. 68Ga-FAPI-04 PET could provide better performance for gastric cancer diagnosis and staging.