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Objective:To explore the uptake characteristics and temporal changes of 68Ga-fibroblast activation protein inhibitors (FAPIs) and 18F-FDG in the anastomotic site of reconstructed digestive tracts after radical surgery for gastrointestinal adenocarcinoma. Methods:A cohort of 43 patients (28 males, 15 females; age range 28-79 years) who underwent radical surgery for gastrointestinal adenocarcinoma and underwent 18F-FDG PET/CT follow-up between November 2020 and June 2022 in the First Affiliated Hospital of the Air Force Medical University was prospectively included. One week after the 18F-FDG PET/CT examination, 68Ga-FAPI-04 PET/CT imaging was performed. ROIs were drawn on the PET images at the highest uptake level of anastomotic sites of reconstructed digestive tract and abdominal wall incisions, and SUV max and target-to-background ratio (TBR) were determined. χ2 test, one-way analysis of variance, Kruskal-Wallis rank sum test (Bonferroni correction) and Wilcoxon signed-rank test were supplied. Results:There were 86 surgical wounds (13 gastric-intestinal anastomotic sites, 14 esophagus-intestinal anastomotic sites, 16 intestinal-intestinal anastomotic sites, and 43 abdominal wall incisions) included. In 68Ga-FAPI-04 PET imaging, SUV max of gastric-intestinal anastomotic sites was higher than that of abdominal wall incisions, with a statistically significant difference (adjusted P=0.014). The TBR did not show statistically significant differences among different types of surgical wounds ( H=3.88, P=0.275). In 18F-FDG PET imaging, SUV max of gastric-intestinal, esophagus-intestinal, and intestinal-intestinal anastomotic sites were all higher than that of abdominal wall incisions, with statistically significant differences (adjusted all P<0.001). There were no statistically significant differences in TBR among different types of surgical wounds ( H=3.02, P=0.388). In 68Ga-FAPI-04 PET imaging, the TBR of all types of anastomotic sites exhibited a decreasing trend with increasing postoperative time. Except for intestinal-intestinal anastomotic sites, the differences in TBR between < 0.5-year and ≥ 1.5-year groups were statistically significant for other types of surgical wounds (adjusted P<0.05). In 18F-FDG PET imaging, the TBR of abdominal wall incisions showed a decreasing trend with increasing postoperative time. However, the TBR of other types of surgical wounds did not show a decreasing trend, and the differences in TBR among different time groups were not statistically significant ( H values: 0.53-2.75, P values: 0.252-0.768). In comparing the two PET imaging agents, for all surgical wounds within the <0.5-year and 0.5-1.5-year groups, the 68Ga-FAPI-04 TBR was consistently higher than the 18F-FDG TBR ( z values: -3.17 and -2.55, P values: 0.002 and 0.011). However, in the ≥1.5-year group, the TBR values tended to be consistent, and the differences were not statistically significant ( z=-0.70, P=0.485). Conclusions:The 18F-FDG uptake in the anastomotic sites of reconstructed digestive tracts reaches a low level under half a year after surgery and does not significantly change over time, while the 68Ga-FAPIs uptake remains relatively high within the first 1.5 years after surgery but decreases over time. These patterns suggest that clinical attention should be paid to the differential diagnosis of anastomotic inflammation or fibrosis, which resulting in agent uptake and local tumor recurrence.
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Objective:To establish a method for correction of tail vein extravasation based on PET images and to improve the accuracy of SUV.Methods:The simulation method was established by phantom on Nano PET/CT and images were reconstructed by a three-dimensional ordered-subsets exception maximum algorithm. PET images were analyzed by using the Interview Fusion 1.0 software. The optimal scanning time and the ROI delineated method were found. The accuracy of the simulation method was verified by comparing the activity of simulation method with the mice tail activity measured by the dose calibrator directly on Kunming (KM) mouse ( n=11). Using the simulation method, the impact of extravasation on SUV was proved. Independent-sample t test was used to analyze data. Results:Ten minutes was selected as the optimal scanning time and SUV max 42% threshold was selected as the ROI delineated method. The specific correction formula was as follows: actual activity=image activity/(4.48× V+ 77.05)×100 (0.3 MBq/ml≤leakage concentration<6.5 MBq/ml); actual activity=image activity/(6.65× V+ 71.10)×100 (6.5 MBq/ml<leakage concentration≤14.8 MBq/ml). In the verification experiment, the difference rate between simulated and standard activity was (6.10±2.43)%. In actual operation verification, SUV was underestimated by (6.07±2.67)%. The corrected SUV (0.276±0.078) was not significantly different from the standard SUV (0.277±0.078; t=0.99, P=0.353), while the uncorrected SUV (0.264±0.078) was significantly lower than the standard SUV ( t=7.02, P<0.001). Conclusion:The correction calculation method based on PET images can realize the accurate correction of tail vein leakage activity and the SUV results of animal imaging.
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Objective:To exploring the uptake of fibroblast activation protein (FAP) inhibitor (FAPI) in pancreatic cancer through 68Ga-FAPI-04 PET/CT imaging, and provide a basis for the FAP-targeted imaging of pancreatic cancer. Methods:Pancreatic cancer-patient-derived tumor xenograft (PDX) mouse models ( n=8) were developed, then 68Ga-FAPI-04 and 18F-FDG microPET/CT imaging were performed (4 in each group). The differences of percentage activity of injection dose per gram of tissue (%ID/g) of 68Ga-FAPI-04 and 18F-FDG were analyzed by independent-sample t test. 68Ga-FAPI-04 and 18F-FDG PET/CT imaging were performed in 5 patients (4 males, 1 female, age: 46-74 (63.0±11.9) years) with pancreatic cancer, and the maximum standardized uptake value (SUV max) of 68Ga-FAPI-04 and 18F-FDG in primary pancreatic cancer and the SUV max ratio of liver metastases to liver tissue were compared by paired t test. Results:MicroPET/CT imaging showed that 68Ga-FAPI-04 was obviously uptaken at all time points in the tumor of PDX mice. The uptake of 68Ga-FAPI-04 in PDX mice 60 min after injection was significantly higher than that of 18F-FDG ((6.58±0.44) and (4.29±0.13) %ID/g; t=4.152, P=0.008 9). PET/CT showed that the SUV max of 68Ga-FAPI-04 in pancreatic cancer was significantly higher than that of 18F-FDG (16.82±3.08 and 5.14±2.20; t=6.893, P=0.000 1) and the SUV max ratio of liver metastases to liver tissue of 68Ga-FAPI-04 was also significantly higher than that of 18F-FDG (4.57±1.47 and 1.30±0.16; t=3.803, P=0.019 1). Conclusion:68Ga-FAPI-04 can be highly uptaken in pancreatic cancer, suggesting that FAP can be a potential target for PET/CT imaging of pancreatic cancer.
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Objective To evaluate the value of DWI and ADC value in monitoring the chemotherapy response of advanced gastric carcinoma dynamically.Methods 42 advanced gastric carcinoma patients who were confirmed by histopathology underwent T2 WI and DWI examinations at pre-chemotherapy,post-chemotherapy 3 d,7 d,30 d and 60 d respectively.The longest diameters of tumor pre-chemotherapy and post-chemotherapy 60 d were measured on axial T2 WI,meanwhile the ADC values at different time points were calculated.The mean ADC value among pre-and post-chemotherapy of each group (PR and SD)was compared.Results The ADC value of PR group increased gradually.The mean ADC value before therapy was statistically lower than those at differ-ent time points post-chemotherapy (P < 0.05).The ADC value of SD group increased gradually from pre-chemotherapy to post-chemotherapy 30 d,and then the ADC value decreased at post-chemotherapy 60 d.The differences of the mean ADC values in differ-ent time points were statistically significant (P < 0.05).Conclusion DWI and ADC value can dynamically,quantitatively and early detect and monitor the chemotherapy response of advanced gastric carcinoma.