Dual-energy CT for evaluating the tumor regression grade of gastric cancer after neoadjuvant chemotherapy.

Abstract

Objectives: To evaluate the clinical value of dual-energy CT (DECT) parameters in estimating tumor regression grade (TRG) of gastric cancer after neoadjuvant chemotherapy (NAC).

Materials and methods: In this retrospective study, the patients with pathologically confirmed gastric cancer were classified into two groups based on TRG results: the effective group and the ineffective group. DECT parameters, including iodine concentration (IC), normalized iodine concentration (NIC), and slope of the energy spectrum curve (λ), were obtained. Quantitative parameters and their change rates were compared before and after chemotherapy. The receiver operating characteristic (ROC) curves were plotted.

Results: A total of 54 patients were included and divided into the effective group (n = 21) and the ineffective group (n = 33). After NAC, the change rates of parameters in the venous phase (%ΔIC-v, %ΔNIC-v, and %Δλ-v) were notably higher in the effective group were higher than in the ineffective group (all p < 0.05). The consistency between the response evaluation criteria in solid tumors version 1.1 (RECIST 1.1) and TRG was fair, with a Kappa value of 0.299 (p < 0.05). The %ΔIC-v, %ΔIC-d, %ΔNIC-v, %ΔNIC-d, and %Δλ-v exhibited moderate or strong correlations with TRG, with correlation coefficients (r) of -0.624, -0.475, -0.766, -0.516, and -0.431, respectively (all p < 0.05). %ΔNIC-v achieved a significantly greater area under the curve (AUC) compared to RECIST 1.1 (AUC, 0.877; 95% CI: 0.772-0.957; vs AUC, 0.649; 95% CI: 0.496-0.803; p < 0.05) for estimating TRG in gastric cancer.

Conclusion: DECT parameters, particularly %ΔNIC-v, show promise in assessing the efficacy of NAC for gastric cancer.

Key points: Question Two-dimensional morphological change is insufficient for accurately assessing the pathological TRG following NAC in gastric cancer. Findings DECT parameters show higher preoperative predictive efficacy than RECIST 1.1 for TRG in gastric cancer. Clinical relevance DECT-derived quantitative parameters offer a reliable and noninvasive tool for the preoperative prediction of pathological response in gastric cancer patients undergoing NAC.