PurposeTo assess the relationship between histopathological features of gastric cancer and the extracellular volume fraction (ECV) measured by preoperative equilibrium contrast-enhanced computed tomography (CECT).Materials and methodsThe study group consisted of 66 patients with surgically resected gastric adenocarcinoma who underwent preoperative multiphasic CECT. Tumor ECVs were calculated using region-of-interest measurements within the gastric cancer and aorta of each case on unenhanced and equilibrium-phase images. The relationship between the mean ECV values and clinicopathological parameters was examined by univariate analysis. Parameters showing a significant difference in the former test were further tested by linear regression and receiver operating characteristic (ROC) curve analyses.ResultsIn the univariate analysis, the values of venous invasion (p= 0.0487) and tumor infiltration (INF) pattern (p< 0.0001) were significantly correlated with the tumor ECV. INF was significantly correlated (β= 0.57,p< 0.0001) in the linear regression analysis. The tumor ECV showed better diagnostic accuracy for predicting INF (INFa/b vs INFc), and the area under the ROC curve value was 0.89.ConclusionTumor ECV determined by equilibrium CECT is significantly correlated with the pathological INF of gastric cancer.