With a cut-off value of 1.321 and 1.123 × 10−3 mm2/sec, the ADC and D values could distinguish HER2 positive gastric cancers from HER2 negative ones with an area under the curve of 0.733 and 0.762, respectively (P = 0.023, 0.011, respectively). This evidence concerns the gene ERBB2 and gastric cancer.