The logistic prediction model yielded the following equation: Logit P (the probability of HER2 positive in GC) = −3.547 + 1.512 × enhancement ratio in the arterial phase + 0.913 × intratumoral necrosis (0, absent; 1, present) + 1.328 × tumor margin (0, well-defined; 1, poorly-defined) + 1.714 × CA125 level (0, <35.00 U/mL; 1, ≥35.00 U/mL). The gene discussed is ERBB2; the disease is neoplasm.