A prospective evaluation of contrast and radiation dose and image quality in cardiac CT in children with complex congenital heart disease using low-concentration iodinated contrast agent and low tube voltage and current

Objective: To the assess image quality, contrast dose and radiation dose in cardiac CT in children with congenital heart disease (CHD) using low-concentration iodinated contrast agent and low tube voltage and current in comparison with standard dose protocol. Methods: 110 patients with CHD were randomized to 1 of the 2 scan protocols: Group A (n - 45) with 120 mA tube current and contrast agent of 270 mgl/ml in concentration (Visipaque (TM), GE Healthcare Ireland, Co., Cork, UK); and Group B (n = 65) with the conventional 160 mA and 370 mgl/ml concentration contrast (Iopamiro (R); Shanghai Bracco Sine Pharmaceutical Corp Ltd, Shanghai, China). Both groups used 80 kVp tube voltage and were reconstructed with 70% adaptive statistical iterative reconstruction algorithm. The CT value and noise in aortic arch were measured and the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. A five-point scale was used to subjectively evaluate image quality. Contrast and radiation dose were recorded. Results: There was no difference in age and weight between the two groups (all p > 0.05). The iodine load and radiation dose in Group A were statistically lower (3976 +/- 747 mgI vs in iodine load and vs 0.776 +/- 0.10 mSv in effective dose; p < 0.001). However, image noise, CT value, CNR, SNR and subjective image quality for the two groups were similar (all p < 0.05), and with good agreement between the two observers. Comparing the surgery results, the diagnostic accuracy for extracardiac and intracardiac defects for Group A was 96% and 92%, respectively, while the corresponding numbers for Group B were 95% and 93%. Conclusion: Compared with the standard dose protocol, the use of low tube voltage (80 kVp), low tube current (120 mA) and low-concentration iodinated contrast agent (270 mgl/ml) enables a reduction of 30% in iodine load and 22% in radiation dose while maintaining compatible image quality and diagnostic accuracy.