Objective  To investigate the influence of reducing contrast agent dose on the image quality and radiation dose in patients with 256-slice CT coronary angiography.

  Methods  Totally 120 patients were randomly divided into experimental group and control group, with 60 cases in each group. A retrospective electrocardiography-gated coronary artery imaging technique was applied. The control group was injected with contrast agent according to the standard of 1 mL/kg, and the observation group reduced the dose of 10 mL contrast agent according to the standard of the control group. The mean CT values of left aortic stem (AO), the left anterior descending branch of proximal and distal parts (LADp, LADd), right coronary artery proximal and distal parts (RCAp, RCAd), LCX proximal and distal parts (LCXp, LCXd) were measured. The image quality of coronary artery segments was evaluated, the display of left ventricle, interventricular septum and right ventricle was analyzed, and the effective radiation dose was calculated.

  Results  All the patients successfully completed their CT examinations. There were no significant differences in the mean CT values of LCXp, LCXd, RCAp, RCAd, LADp and LADd between the two groups (P>0.05). There was no significant difference in the excellent rate of coronary segment between two groups (P>0.05). There was no significant difference in image quality score between the two groups (P>0.05). The observation group showed better ratios of cases with good artifact display in left ventricular wall, interventricular septum, superior vena cava and right ventricular artifacts than the control group (P < 0.05). The dosage of contrast agent in the observation group was significantly lower than that of the control group (P < 0.05).

  Conclusion  In 256-slice CT coronary angiography, reducing the dose of contrast agent can significantly reduce the radiation dose, and the image quality can also meet the diagnostic requirements.