Clinical application of oral contrast-enhanced ultrasound in evaluating the preoperative T staging of gastric cancer.

Background: Oral contrast-enhanced ultrasound (OCEUS) is widely used in the noninvasive diagnosis and screening of gastric cancer (GC) in China.

Aim: To investigate the clinical application of OCEUS in evaluating the preoperative T staging of gastric cancer.

Methods: OCEUS was performed before the operation, and standard ultrasound images were retained. The depth of infiltration of GC (T-stage) was evaluated according to the American Joint Committee on Cancer 8^th edition of the tumor-node-metastasis staging criteria. Finally, with postoperative pathological staging as the gold standard reference, the sensitivity, specificity, negative predictive value, positive predictive value, and diagnostic value of OCEUS T staging were evaluated.

Results: OCEUS achieved diagnostic accuracy rates of 76.6% (T1a), 69.6% (T1b), 62.7% (T2), 60.8% (T3), 88.0% (T4a), and 88.7% (T4b), with an average of 75.5%. Ultrasonic T staging sensitivity exceeded 62%, aside from T1b at 40.3%, while specificity was over 91%, except for T3 with 83.5%. The Youden index was above 60%, with T1b and T2 being exceptions. OCEUS T staging corresponded closely with pathology in T4b (kappa > 0.75) and moderately in T1a, T1b, T2, T3, and T4a (kappa 0.40-0.75), registering a concordance rate exceeding 84%.

Conclusion: OCEUS was effective, reliable, and accurate in diagnosing the preoperative T staging of GC. As a noninvasive diagnostic technique, OCEUS merits clinical popularization.