Uptake characteristics of 68Ga-FAPI-04 and 18F-FDG in surgical wounds after radical surgery for gastrointestinal adenocarcinoma / 中华核医学与分子影像杂志

ABSTRACT

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.