| Objective:The purpose of this study was to explore the clinical value of 68Ga-FAPI PET/CT in the diagnosis,staging,and recurrence detection of digestive tract tumors to construct a more accurate molecular imaging diagnosis technique,which is helpful to guide clinical decision-making of patients with digestive tract tumors.Methods:Part Ⅰ:Images from patients diagnosed or suspected of liver malignancy who underwent 18F-FDG and 68Ga-FAPI PET/CT between October 2019 through June 2020 were retrospectively analyzed.The numbers of positive lesions identified by 18F-FDG or 68Ga-FAPI PET/CT were compared using the Wilcoxon signed-rank test.McNemar’s test was used to compare the detection rates of primary and metastatic lesions among different imaging methods.18F-FDG and 68Ga-FAPI PET/CT performance for detecting new HCC lesions and informing changes in the BCLC classification and treatment strategies were compared using McNemar’s test.Between-lesion differences in the uptake values were compared using a one-way analysis of variance(ANOVA).The background hepatic activity of liver parenchyma,as revealed by 18F-FDG and 68Ga-FAPI PET/CT,was compared between patients with and without cirrhosis using the Mann-Whitney U test.Part Ⅱ:Images from patients with gastric,duodenal,and colorectal cancers who underwent contemporaneous 18F-FDG and 68Ga-FAPI PET/CT between October 2019 through June 2020 were retrospectively analyzed.A total of 35 patients met the admission criteria.18F-FDG and 68Ga-FAPI uptakes were compared by using the Wilcoxon signed-rank test.McNemar’s test was used to compare the diagnostic performance between the two techniques.Results:Part Ⅰ:The sensitivities of CE-CT,MRI,68Ga-FAPI,and 18F-FDG/CT for detecting primary liver tumors were 96%,100%,96%,and 65%,respectively.Regarding the detection rate of all intrahepatic lesions,the per-lesion detection rate of 68Ga-FAPI PET/CT was slightly lower than that of MRI(85%vs.100%,P=0.34)and significantly higher than that of 18F-FDG PET/CT(85%vs.52%,P<0.001).In the diagnosis of all malignant lesions,the detection rate of 68Ga-FAPI and 18F-FDG PET/CT for diagnosing suspicious lesions was 87%and 65%,respectively(P<0.001).Part Ⅱ:In treatment-naive patients(n=19),68Ga-FAPI PET/CT led to upstaging of the clinical TNM stage in four(21%)patients compared with 18F-FDG PET/CT.Tracer uptake was higher with 68Ga-FAPI PET/CT than with 18F-FDG PET/CT in primary lesions(gastric cancer:12.7 vs 3.7,respectively,P=0.003;colorectal cancer:15.9 vs 7.9,P=0.03),involved lymph nodes(6.7 vs 2.4,P<0.001),and distant metastases(liver metastases:9.7 vs 5.2,P<0.001;peritoneal metastases:8.4 vs 3.6,P<0.001;bone metastases:4.3 vs 2.2,P<0.001;lung metastases:4.4 vs 1.9,P=0.01).In addition,the sensitivity of 68Ga-FAPI PET/CT was higher than that of 18F-FDG PET/CT in the detection of primary tumors(100%vs 53%,respectively;P=0.004),lymph nodes(79%vs 54%,P<0.001),and distant metastases(89%vs 57%,P<0.001).Conclusion:68Ga-FAPI PET/CT was superior to 18F-FDG PET/CT in the detection of primary and metastatic lesions in digestive tract tumors,with higher tracer uptake in most primary and metastatic lesions.Consequently,68Ga-FAPI PET/CT has potential clinical value in the diagnosis,staging,and recurrence detection of digestive tract tumors. |
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