Objective To explore the feasibility of integrated imaging of portal vein and hepatic vein with"three low-contrast agents"combined with energy spectrum CT technology.Methods A total of 100 patients with enhanced abdominal CT scans were selected.The patients were randomly divided into two groups.The patients of experimental group(n=50)were injected with the isotonic con-trast agent iodixanol(320 mg I/mL)at a flow rate of 3 mL/s and a total volume of 1.2 mL/kg,and underwent energy spectrum CT scan in the portal venous phase.The patients of control group(n=50)were injected with the sub-hypertonic contrast agent iohexol(350 mg I/mL)at a flow rate of 5 mL/s and a total volume of 1.5 mL/kg,and underwent conventional multi-phase spiral CT enhancement scan.The image quality and radiation dose of portal vein and hepatic vein were compared between the two groups.Results The CT value of main portal vein in the experimental group was higher than that in the control group,and the difference was statistically sig-nificant(P＜0.05).There was no statistical significance in main portal vein contrast-to-noise ratio(CNR),main portal vein signal-to-noise ratio(SNR),hepatic vein CT value,and hepatic vein CNR between the two groups(P＞0.05).The SNR and image standard deviation(SD)of the hepatic vein in the control group were better than those in the experimental group(P＜0.05).There was no statistical significance in the subjective scores of portal vein and hepatic vein between the two groups(P＞0.05).The volume CT dose index(CTDIvol),dose length product(DLP),and effective dose(ED)of the portal venous phase spectrum CT scan in the experimental group were lower than those of the conventional single-phase spiral CT scan in the control group(P＜0.05).Conclusion"Three low-contrast agents"combined with energy spectrum CT technology can realize integrated imaging of portal vein and hepatic vein in late portal vein,and can reduce radiation dose.