Résumé
Objective:To investigate the clinical utility of 68Ga-labeled fibroblast activation protein inhibitor (FAPI) PET/CT in the detection of primary and metastatic gastric signet-ring cell carcinoma (GSRCC) and compared the results with those of 18F-FDG PET/CT. Methods:A total of 21 patients (10 males, 11 females, average age 52 years) with primary and metastatic GSRCC who underwent 68Ga-FAPI and 18F-FDG PET/CT at the First Affiliated Hospital of Xiamen University from June 2020 to May 2022 were retrospectively analyzed. Pathological results of surgery and (or) biopsy were used as the " gold standard" for final diagnosis. In cases whose surgery or tissue biopsies were not available, clinical and radiographic follow-up results were used as the reference standards. Wilcoxon signed-rank test was used to compare the SUV max of 18F-FDG and 68Ga-FAPI. McNemar χ2 test was used to compare the detection rate between 18F-FDG and 68Ga-FAPI PET/CT. Results:68Ga-FAPI PET/CT showed higher SUV max than 18F-FDG in primary tumors (5.3(2.4, 15.7) vs 2.4(1.8, 2.5); z=2.31, P=0.021), local recurrences (7.8(6.0, 8.9) vs 2.4(1.9, 3.4); z=2.20, P=0.028), lymph nodes metastases (7.7(4.5, 12.2) vs 2.4(1.9, 3.6); z=6.01, P<0.001) and bone/visceral metastases (6.7(5.3, 11.1) vs 2.4(2.0, 3.4); z=11.36, P<0.001). Regarding diagnostic accuracy, 68Ga-FAPI PET/CT showed higher sensitivities than 18F-FDG for primary tumors (7/9 vs 2/9; χ2=3.20, P=0.063) and local recurrences (7/7 vs 2/7; χ2=3.20, P=0.063). It also demonstrated higher lesion detection rates than 18F-FDG for suspicious lymph node metastases (86%(65/76) vs 32%(24/76); χ2=31.37, P<0.001) and bone/visceral metastases (99%(184/185) vs 39%(73/185); χ2=107.08, P<0.001). Conclusions:68Ga-FAPI PET/CT showed higher tumor uptake and lesion detection rate than 18F-FDG in the primary and metastatic GSRCC. 68Ga-FAPI PET/CT demonstrates good diagnostic performance for tumor detection, staging, and restaging of GSRCC, which is helpful to further guide clinical treatment strategy.
Résumé
Objective To synthesize 18F-AlF-NOTA-G-TMTP1 and evaluate its potential for PET imaging on nude mice bearing high-metastatic potential hepatoma cells.Methods NOTA-G-TMTP1 was synthesized by the standard Fmoc-solid phase synthetic protocols and radiolabeled with 18F using NOTA-AlF chelation method.The nude mice models bearing low-metastatic potential HCC97L and high-metastatic potential HCCLM3 xenografts were established separately.The tumor-targeting characteristics of 18F-AlF-NOTA-G-TMTP1 were assessed by microPET/CT and biodistribution assay.Results NOTA-G-TMTP1 was labeled with 18F in one step with (25±6)％ labeling yield (n=5).The radiochemical purity of 18F-AlF-NOTA-G-TMTP1 was more than 95％ with a specific activity more than 11.1 GBq/μmol.The octanol/water partition coefficient (logP) for 18F-AlF-NOTA-G-TMTP1 was-3.166±0.022.The tumor to muscle ratios were 1.8± 0.4 and 4.7±0.2 at 35 min post injection for HCC97L and HCCLM3,respectively.The uptake of 18F-AlF-NOTA-G-TMTP1 in HCCLM3 tumor was inhibited (61.4％) by unlabeled G-TMTP1.Conclusion 18F-AlF-NOTA-G-TMTP1 has been successfully synthesized.It shows specific uptake by tumor induced by the high-metastatic potential hepatoma cells.