Preoperative staging of gastric cancer: a prospective comparison of gastric filling ultrasonography and enhanced CT with implications for surgical decision-making.

Background: Accurate preoperative staging is essential for optimizing treatment strategies in gastric cancer. While gastric-enhanced CT is widely used, its accuracy remains suboptimal, particularly for early-stage tumors. Gastric filling ultrasonography, a non-invasive technique using oral contrast to displace intraluminal gas, offers potential advantages in mural visualization. This prospective study compared the diagnostic performance of gastric filling ultrasonography and gastric-enhanced CT against postoperative pathological staging. Methods: We enrolled 406 patients with histologically confirmed gastric cancer who underwent both imaging modalities prior to surgery. Preoperative T and N stages assigned by each modality were compared with pathological results. Diagnostic accuracy, sensitivity, specificity, and area under the ROC curve (AUC) were calculated. McNemar's test was used for paired comparisons, DeLong test for AUC comparisons, and Kappa statistics for agreement assessment. Univariate logistic regression identified factors affecting ultrasound accuracy. Results: For T-staging, overall accuracy was 72.7% (295/406) for ultrasound vs. 63.5% (258/406) for CT ( Conclusions: Gastric filling ultrasonography demonstrates superior accuracy over gastric-enhanced CT for preoperative T1/T2 and N-staging, with substantial agreement with pathological findings. This non-invasive and radiation-free examination method can serve as an effective complement to CT, and is particularly suitable for gastric cancer at the T1 and T2 stages. We have proposed a complementary imaging protocol to assist in surgical decision-making, which is expected to enable clinicians to make more accurate preoperative staging assessments for patients with gastric cancer. Registration: It was registered in the ClinicalTrials.gov (NCT05596864).