Objective To explore the diagnostic value and correlation of ¹⁸F-fluorodeoxyglucose (FDG) PET/CT metabolic parameters combined with clinicopathological factors in duodenal stump recurrence after radical subtotal or total gastrectomy for gastric cancer (hereafter referred to as gastric cancer surgery), and to provide a basis for clinical decision-making.

Methods A retrospective case-control study was conducted to analyze the clinical and imaging data of 39 patients who had undergone gastric cancer surgery and received ¹⁸F-FDG PET/CT and tumor marker testing from September 2019 to May 2025. All patients were examined at ≥6 months after surgery and they underwent ¹⁸F-FDG PET/CT and tumor marker testing within 2 weeks at Qingdao Central Hospital, University of Health and Rehabilitation Sciences. Of these patients, 28 were male and 11 were female, with a mean age of (61.2±8.3) years (range: 45–78 years). The 23 patients with duodenal stump recurrence were designated as the positive group, whereas the 16 non-recurrence patients comprised the negative group. Predictive factors for duodenal stump recurrence after gastric cancer surgery were analyzed, and the correlation between ¹⁸F-FDG PET/CT metabolic parameters and clinicopathological factors in duodenal stump was investigated. Comparisons of count data between the two groups were performed using the Fisher exact probability method. Comparisons of measurement data were conducted using the t test or Mann-Whitney U test. Logistic regression analysis was employed to identify influencing factors for duodenal stump recurrence after gastric cancer surgery. Receiver operating characteristic curve was used to evaluate the predictive efficacy of influencing factors. Spearman rank correlation analysis was applied to assess the relationship between variables.

Results Significant differences were observed between the two groups in T stage, clinical stage, and the neural invasion of the primary lesion (3.00 (3.00, 4.00) vs. 3.00 (1.00, 3.00), 3.00 (2.00, 3.00) vs. 2.00 (1.00, 3.00), 18 (78.3%) vs. 8 (50.0%); Z=−2.928, −2.239, Fisher exact probability method; P=0.003, 0.025, 0.030). The positive group exhibited significantly higher maximum standardized uptake value (SUV_max), mean standardized uptake value (SUV_mean), SUV_max normalized to lean body mass (SUL_max), SUV_mean normalized to lean body mass (SUL_mean), total lesion glycolysis (TLG), and SUV_max to liver blood pool ratio than the negative group (6.567 (4.485, 10.995) vs. 1.974 (1.566, 2.546), 4.247 (2.968, 6.869) vs. 1.584 (1.236, 1.963), 5.306 (3.342, 9.665) vs. 1.488 (1.182, 1.976), 3.390 (2.390, 6.038) vs. 1.139 (0.868, 1.554), 36.250 (9.236, 206.096) g vs. 1.319 (0.793, 2.286) g, 2.422 (1.547, 4.659) vs. 0.551 (0.424, 0.670); Z= from −5.159 to −4.968, all P<0.001). Univariate logistic regression analysis revealed that SUV_max (OR=21.790, P=0.034, 95%CI: 1.260−376.789), SUV_mean (OR=40.122, P=0.015, 95%CI: 2.034−791.544), SUL_max (OR=64.395, P=0.047, 95%CI: 1.050−3950.769), SUL_mean (OR=125.790, P=0.022, 95%CI: 1.994−7934.882), TLG (OR=3.356, P=0.038, 95%CI: 1.067−10.558), the SUV_max to liver blood pool ratio (OR=1.083, P=0.015, 95%CI: 1.015−1.155), and neural invasion (OR=6.000, P=0.025, 95%CI: 1.253−28.742) were potential predictors of duodenal stump recurrence after gastric cancer surgery. Multivariate logistic regression analysis identified the SUV_max to liver blood pool ratio (OR=1.073, P=0.022, 95%CI: 1.010−1.140) as an independent predictor of duodenal stump recurrence after gastric cancer surgery. Spearman correlation analysis demonstrated that postoperative pathological T staging had positive correlations with SUV_max, SUV_mean, SUL_max, SUL_mean, TLG, and the SUV_max to liver blood pool ratio in duodenal stump (r=0.398–0.505, all P<0.05). Moreover, SUV_mean, SUL_max, SUL_mean, and the SUV_max to liver blood pool ratio were positively correlated with vascular invasion (r=0.337–0.373, all P<0.05). In addition, SUL_mean and TLG were positively correlated with neural invasion (both r=0.327, both P=0.048). Furthermore, SUV_max, SUV_mean, SUL_max, SUL_mean, TLG, and the SUV_max to liver blood pool ratio were all positively correlated with clinical stage (r=0.426–0.472, all P<0.01).

Conclusions ¹⁸F-FDG PET/CT metabolic parameters combined with clinicopathological factors are superior to conventional imaging in detecting recurrent lesions in the duodenal stump after gastric cancer surgery. For patients with elevated postoperative tumor markers, recurrence should be highly suspected if ¹⁸F-FDG PET/CT imaging reveals a hypermetabolic nodule or mass centered around the stuture nail at the duodenal stump and postoperative histopathological examination indicates neural invasion.