Evaluating the response of gastric carcinomas to neoadjuvant chemotherapy using iodine concentration on spectral CT: a comparison with pathological regression

•Spectral CT detected the change of IC of gastric carcinomas to NC.•The change of IC had correlation with pathological regression grades.•The response prediction efficacy of IC was better than tumor size.•The response prediction ability of IC on arterial phase was superior to venous phase.