Comparison Of ⁶⁸Ga-FAPI-04 PET/CT And ¹⁸F-FDG PET/CT In The Diagnosis Of Digestive System Tumors

Objective:Recent advances in fibroblast activating protein inhibitors（FAPI）have shown promising results.FAP is overexpressed by a variety of solid tumor-associated fibroblasts.So ⁶⁸Ga-FAPI-04 can be used to detect multiple types of tumors.The purpose of this study is to compare the diagnostic value of ⁶⁸Ga-FAPI-04 PET/CT and ¹⁸F-FDG PET/CT in digestive system tumors.Methods:This study reviewed and analyzed 89 patients diagnosed with digestive system tumors（17 patients with esophageal cancer,15 with gastric cancer,30 with liver cancer,15with pancreatic cancer,and 12 with colorectal cancer）by pathological examination in our hospital from January 2020 to September 2022.All patients underwent ¹⁸F-FDG PET/CT and ⁶⁸Ga-FAPI-04PET/CT imaging within one week.The intravenous injection activity of⁶⁸Ga-FAPI-04 and ¹⁸F-FDG was 3.7 MBq/kg and 2.0 MBq/kg.Prior to the¹⁸F-FDG PET/CT scan,the participants should fast for at least 6 h,ensuring a blood glucose（BG）less than 11.1 mmol/L.All acquisitions were performed on PET/CT scanner 40-60 min after ⁶⁸Ga-FAPI-04 or ¹⁸F-FDG injection.And none of them received any antitumor therapy.Histopathological examination,multiple imaging examination results（including MRI,enhanced CT,bone scan,PET/CT,and ultrasound）and follow-up imaging examination results were used as the reference criteria for the final diagnosis.Visual analysis and semi quantitative ROI analysis（SUVmax）were used to record the location,size,quantity and imaging agent intake of digestive system tumors.To test whether the sample data conform to a normal distribution,we chose the K-S test.Statistical analysis was performed with Paired-samples T test or Mann-Whitney U test for the maximum standard uptake value（SUVmax）and tumour-to-background ratio（TBR）of lesions in two examination modalities.To analyze the correlation of the SUVmax and the long diameter of the digestive system tumors in two examination methods,we chose the Pearson test correlation method.In addition,by ROC curve analysis,we analyzed the optimal thresholds of SUVmax and TBR for the diagnosis of digestive system tumors.Results:Of the 89 patients who were pathologically diagnosed with digestive system tumors,including 17 esophageal cancer（including 13 males and 4 females,with an age of（58.59±10.68）and a range of 46-81 years）,15gastric cancer（including 7 males and 8 females,with an age of（55.27±9.58）and a range of 34-68 years）,30 liver cancer（including 23 males and 7 females,with an age of（59.83±11.71）and a range of 30-76 years）,15 pancreatic cancer（including 9 males and 6 females,with an age of（62.93±10.72）and a range of 44-78 years）,12 colorectal cancer（including 9 males and 3 females,with an age of（59.50±9.36）and a range of 4-77 years）.From the visual analysis,there were more patients showed clearer primary tumor lesions of⁶⁸Ga-FAPI-04 PET/CT than ¹⁸F-FDG PET/CT among the 89 patients with digestive system tumors（esophageal cancer:16/17,94.1%;gastric cancer:13/15,86.7%;liver cancer:27/30,90.0%;pancreatic cancer:13/15,86.7%;colorectal cancer:11/12,91.7%）.A total of 17 esophageal cancer,including 16cases of SCC and 1 cases of AC.The detection rate of ⁶⁸Ga-FAPI-04 PET/CT and ¹⁸F-FDG PET/CT for primary lesions was 100%（17/17）and 94.1%（16/17）,respectively.The SUVmax of ⁶⁸Ga-FAPI-04 PET/CT was（16.89±4.68）.The SUVmax of ¹⁸F-FDG PET/CT was（12.50±5.86）.There was significant difference（P<0.001）.The TBR of ⁶⁸Ga-FAPI-04 PET/CT was（15.97±4.74）.The TBR of ¹⁸F-FDG PET/CT was（8.08±4.23）.There was significant difference（P<0.001）.The long diameter of primary esophageal cancer lesions was（3.08cm±0.87cm）.In ⁶⁸Ga-FAPI-04 PET/CT,the SUVmax-_FAPIwas significantly correlated with the long diameter of the primary esophageal cancer lesions（r=0.975,P<0.001）.In ¹⁸F-FDG PET/CT,the SUVmax-_FDGof the primary esophageal cancer lesions was obviously correlated with it’s long diameter（r=0.760,P<0.001）.The AUC of area under SUVmax-_FAPIcurves was 0.933（P=0.030）,the best diagnostic cutoff values was 3.53.The AUC of area under SUVmax-_FDGcurves was 0.810（P=0.010）,the best diagnostic cutoff values was 5.92.The AUC of area under TBR-_FAPIcurves was 0.967（P=0.037）,the best diagnostic cutoff values was 10.87.The AUC of area under TBR-_FDGcurves was 0.712（P=0.013）,the best diagnostic cutoff values was 7.96.A total of 15 gastric cancer,including 9 cases of intestinal gastric cancer,4 cases of diffuse gastric cancer and 2 cases of mixed gastric cancer.The detection rate of⁶⁸Ga-FAPI-04 PET/CT for primary lesions of gastric cancer was 100%（15/15）.The detection rate of ¹⁸F-FDG PET/CT for primary lesions of gastric cancer was 80.0%（12/15）.The SUVmax of ⁶⁸Ga-FAPI-04 PET/CT was（9.16±2.24）.The SUVmax of ¹⁸F-FDG PET/CT was（3.37±0.93）.The TBR of ⁶⁸Ga-FAPI-04PET/CT was（8.55±1.78）.The TBR of ¹⁸F-FDG PET/CT was（2.21±0.70）.There were significant differences both in SUVmax and TBR of primary gastric cancer lesions（P<0.001）between ⁶⁸Ga-FAPI-04 PET/CT and ¹⁸F-FDG PET/CT.The long diameter of primary gastric cancer lesions was（2.27cm±0.84 cm）.In ⁶⁸Ga-FAPI-04 PET/CT,the SUVmax-_FAPIof the primary gastric cancer lesions was moderately correlated with it’s long diameter（r=0.412,P=0.027）.In ¹⁸F-FDG PET/CT,the SUVmax-_FDGof the primary gastric cancer lesions was not correlated with it’s long diameter（r=0.220,P>0.05）.The AUC of area under SUVmax-_FAPIcurves was 0.806（P=0.012）,the best diagnostic cutoff values was 2.80.The AUC of area under SUVmax-_FDGcurves was 0.750（P=0.026）,the best diagnostic cutoff values was 8.58.The AUC of area under TBR-_FAPIcurves was 0.861（P=0.010）,the best diagnostic cutoff values was 8.31.The AUC of area under TBR-_FDGcurves was0.840（P=0.037）,the best diagnostic cutoff values was 2.32.A total of 30 liver cancer,including 19 cases of HCC,11 cases of ICC.The detection rate of⁶⁸Ga-FAPI-04 PET/CT for primary lesions of liver cancer was 100%（30/30）.The detection rate of ¹⁸F-FDG PET/CT was 90.0%（27/30）.The SUVmax of⁶⁸Ga-FAPI-04 PET/CT was（14.41±5.19）.The SUVmax of ¹⁸F-FDG PET/CT was（7.07±2.55）.The TBR of ⁶⁸Ga-FAPI-04 PET/CT was（11.19±5.37）.The TBR of ¹⁸F-FDG PET/CT was（3.71±1.48）.There were significant differences both in SUVmax and TBR of primary liver cancer lesions（P<0.001）between⁶⁸Ga-FAPI-04 PET/CT and ¹⁸F-FDG PET/CT.The long diameter of primary liver cancer lesions was（6.10cm±2.82cm）.In ⁶⁸Ga-FAPI-04 PET/CT,the SUVmax-_FAPIof the primary liver cancer lesions were moderately correlated with it’s long diameter（r=0.415,P=0.023）.In ¹⁸F-FDG PET/CT,the SUVmax-_FDGof the primary liver cancer lesions were slightly correlated with it’s long diameter（r=0.371,P=0.044）.The AUC of area under SUVmax-_FAPIcurves was 0.872（P=0.010）,the best diagnostic cutoff values was 7.08.The AUC of area under SUVmax-_FDGcurves was 0.818（P=0.003）,the best diagnostic cutoff values was 14.11.The AUC of area under TBR-_FAPIcurves was 0.814（P=0.004）,the best diagnostic cutoff values was 10.17.The AUC of area under TBR-_FDGcurves was 0.688（P=0.031）,the best diagnostic cutoff values was 3.63.A total of 15 pancreatic cancer.The detection rates of the two methods for primary lesions of pancreatic cancer were 100%（15/15）.The SUVmax of ⁶⁸Ga-FAPI-04 PET/CT was（15.53±2.86）.The SUVmax of¹⁸F-FDG PET/CT was（7.68±2.35）.The TBR of ⁶⁸Ga-FAPI-04 PET/CT was（10.85±2.84）.The TBR of ¹⁸F-FDG PET/CT was（4.51±1.44）.There were significant differences both in SUVmax and TBR of primary pancreatic cancer lesions（P<0.001）between ⁶⁸Ga-FAPI-04 PET/CT and ¹⁸F-FDG PET/CT.The long diameter of primary pancreatic cancer lesions was（3.02cm±0.78cm）.In⁶⁸Ga-FAPI-04 PET/CT,the SUVmax-_FAPIof the primary pancreatic cancer lesions was obviously correlated with it’s long diameter（r=0.656,P=0.008）.In¹⁸F-FDG PET/CT,the SUVmax-_FDGof the primary pancreatic cancer lesions was not correlated with it’s long diameter（r=0.361,P>0.05）.The AUC of area under SUVmax-_FAPIcurves was 0.980（P=0.003）,the best diagnostic cutoff values was 14.62.The AUC of area under SUVmax-_FDGcurves was0.886（P=0.026）,the best diagnostic cutoff values was 6.41.The AUC of area under TBR-_FAPIcurves was 0.980（P=0.003）,the best diagnostic cutoff values was 10.08.The AUC of area under TBR-_FDGcurves was 0.955（P=0.009）,the best diagnostic cutoff values was 4.12.A total of 12 colorectal cancer.The detection rates of the two methods for primary lesions of colorectal cancer were100%（12/12）.The SUVmax of ⁶⁸Ga-FAPI-04 PET/CT was（14.83±3.26）.The SUVmax of ¹⁸F-FDG PET/CT was（7.25±1.65）.The TBR of ⁶⁸Ga-FAPI-04PET/CT was（14.93±4.62）.The TBR of ¹⁸F-FDG PET/CT was（5.09±1.26）.There were significant difference both in SUVmax and TBR（P<0.001）between ⁶⁸Ga-FAPI-04 PET/CT and ¹⁸F-FDG PET/CT.The long diameter of primary colorectal cancer lesions was（2.64 cm±0.53 cm）.In ⁶⁸Ga-FAPI-04PET/CT,the SUVmax-_FAPIof the primary colorectal cancer lesions was obviously correlated with it’s long diameter（r=0.566,P=0.045）.In ¹⁸F-FDG PET/CT,the SUVmax-_FDGof the primary colorectal cancer lesions was not clearly correlated with it’s long diameter（r=0.067,P>0.05）.The AUC of area under SUVmax-_FAPIcurves was 0.889（P=0.002）,the best diagnostic cutoff values was 7.56.The AUC of area under SUVmax-_FDGcurves was0.771（P=0.023）,the best diagnostic cutoff values was 11.50.The AUC of area under TBR-_FAPIcurves was 0.963（P=0.021）,the best diagnostic cutoff values was 12.84.The AUC of area under TBR-FDG curves was 0.771（P=0.023）,the best diagnostic cutoff values was 4.42.Conclusion:1.Overall,the detection rate of ⁶⁸Ga-FAPI-04 PET/CT for digestive system tumors was higher than ¹⁸F-FDG PET/CT.2.For digestive system tumors,the uptake of ⁶⁸Ga-FAPI-04 was higher than that of ¹⁸F-FDG PET/CT,and it is easier to find the hidden lesions.3.In the gastrointestinal tract,the uptake of ⁶⁸Ga-FAPI-04 was significantly lower than ¹⁸F-FDG,so it has an ideal TBR,which is conducive to improving the detection rate of primary tumors in the digestive system.And ⁶⁸Ga-FAPI-04 PET/CT can also more clearly display the contour of the lesions and the invasion around the lesions.