[en] To demonstrate the two-phase spiral CT features of pseudo-wall thickening and tumor in the gastric antrum, and to evaluate the possibility of differential diagnosis by analyzing two-phase spiral CT scans. We retrospectively reviewed 120 cases in which two-phase spiral CT scans showed focal wall thickening in the prepyloric antrum of the stomach. Our series included 60 cases of gastric cancer (including seven of early gastric cancer) and 60 cases of normal prepyloric antrum. All patients underwent two-phase spiral CT and upper gastrointestinal series (n=83) and / or gastric endoscopy (n=80). All cancer cases were confirmed by biopsy (n=60). We evaluated the differential points between gastric cancer and pseudo-wall thickening of the gastric antrum. The mean thickness of the antral wall was 19.0mm in the cancer group and 12.5mm in the normal group. Thirty-one cases (51.7%) in the cancer group and 51 (85.0%) in the normal group showed concentric wall thickening, while in each group, the remainder showed eccentric wall thickening. The common enhancement patterns of thickened wall in the cancer group were 1) a thick enhanced mucosal layer during the arterial phase, with diffusely enhanced whole wall thickness during the venous phase (n=21) ; 2) a thick enhanced mucosal layer during the arterial phase, with thicker and more intense enhancement of the same area during the venous phase (n=18). In the normal group, the common enhancement pattern was a thin enhanced mucosal layer during both the arterial and venous phase (n=34). In the cancer group, the common associated findings were regional lymphadenopathy (n=43) and food remnants in the stomach (n=15), and in the normal group, intraluminal normal mucosal folds in the thickened segment (n=50). The findings of food remnants despite overnight fasting and intraluminal normal folds occurred only in the cancer and normal group, respectively. Pseudo-wall thickening frequently showed thin enhancement of the mucosal layer on both the arterial and venous phases of two-phase spiral CT scan ; a tumor frequently showed a thick enhanced mucosal layer during the arterial phase, with diffusely enhanced whole-wall thickness during the venous phase or a thick enhanced mucosal layer during the arterial phase, with thicker and more intense enhancement of the same area during the venous phase. The finding of thin and homogeneously enhanced intraluminal normal mucosal folds in the thickened segment strongly suggested that the lesion was a pseudo-lesion