Application of optimal contrast medium injection protocol for 128-slice dual-source computed tomography in children with Tetralogy of Fallot

Abstract

To compare the image qualities of different contrast medium injection protocols for 128-slice dual-source computed tomography (DSCT) in children with Tetralogy of Fallot (TOF). A total of 60 patients with TOF were randomly divided into groups A, B and C (n = 20 each). And 128-slice DSCT angiography was performed with sequential mode according to the contrast injection protocols: the volume of contrast medium was 1.2, 1.2 and 1.5 ml/kg and the injection time 10, 12 and 15 s respectively. Contrast medium was followed by a saline bolus for 10 s. Enhancement and noise of ascending aorta, main pulmonary artery, descending aorta and left ventricle were quantified. Signal-to-noise ratio (SNR), dose-length product (DLP) and effective dose (ED) were calculated. The absolute difference of left and right ventricular attenuations was calculated to represent the image uniformity. Subjective image quality was assessed by two radiologists in consensus. No significant difference existed in attenuation or SNR between three groups in the same evaluated anatomic regions. No significant difference existed in image quality of heart chamber and great vessels. The image uniformity (81 ± 65) and subjective image quality of artifacts of superior vena cava were significantly better in group B than those in groups A and C (179 ± 178, 106 ± 66, P < 0.05). The contrast medium injection protocol of 1.2 ml/kg volume contrast medium injected within 12 s may enhance the image quality of 128-slice dual-source CT in children with TOF.