Image quality and radiation exposure in pediatric cardiovascular CT angiography from different injection sites

The purpose of this article is to evaluate the effect of different injection sites (i.e., head, arm, or leg vein) on image quality and radiation exposure in pediatric cardiovascular CT angiography (CTA) with 64-MDCT.

CTA was performed in 61 children with suspected extracardiac abnormalities. Patients were assigned to three groups according to the different injection sites: head, arm, or leg vein. Enhancement of heart chamber and great vessels and background noise were quantified. Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), dose-length product (DLP), and effective dose (ED) were calculated. Subjective image quality was assessed by two radiologists in consensus.

There was no significant difference among all groups in the mean attenuation of the heart chamber, pulmonary artery (PA), and aorta. There was also no significant difference in their mean attenuation, background noise, SNR, and CNR. However, there were significant differences among the three groups for aorta image quality (p = 0.006), despite the nonsignificant differences in heart chamber and PA image quality. There also were significant differences among the three groups for total DLP and ED (p = 0.01 for both), with prescanning DLPs of 17.6%, 20.2%, and 24.5%, respectively, of the total DLP for each group.

Although all injection sites can yield diagnostic-quality images with a low radiation dose in pediatric cardiovascular CTA, the injection site has a slight impact on the image quality of different targeted areas with a significantly different radiation dose. The optimization of a prescanning protocol may open an avenue to reduce the radiation dose associated with cardiovascular CTA.