Saline flush effect for enhancement of aorta and coronary arteries at multidetector CT coronary angiography

Purpose: To prospectively investigate the effect of the injection rate of a saline solution as a bolus chaser for the enhancement of the aorta and coronary arteries at multidetector computed tomographic (CT) coronary angiography. Materials and Methods: Institutional review board approved this study, and all patients gave informed consent. One hundred consecutive patients (59 men, 41 women; mean age, 58 years +/- 11 [standard deviation]) underwent 64-section CT coronary angiography for coronary artery disease. They were divided into five groups (each group, n = 20) according to the injection rate of saline solution (3, 4, 5, 6, and 7 mL/sec). Iodinated contrast medium (60 mL) was injected intravenously at a rate of 4 mL/sec, followed by 60 mL saline solution administered intravenously at a rate of 3-7 mL/sec, depending on the groups. Attenuation values of the aortic root, right coronary artery, left anterior descending artery, and left circumflex artery were measured. Analysis of variance with the Scheffe method was used to evaluate statistical significance of the differences in attenuation according to the injection rate of saline solution. Results: The degree of contrast enhancement was affected by the injection rate of saline solution, and the attenuation values were higher as the injection rate increased up to 4-5 mL/sec (P <.05). The values plateaued at rates over 5 mL/sec in the aorta and over 4 mL/sec in the coronary arteries. Conclusion: An injection rate of 4-5 mL/sec as a saline solution chaser is optimal for achieving maximum attenuation values of the aorta or coronary arteries by using 64-section CT with 60 mL contrast material.