To evaluate the feasibility of CT angiography of pediatric complex congenital heart disease by using low radiation dose and low isotonic contrast agent dose combined with iDose⁴ iterative reconstruction technique.

Prospectively, a total of 57 continuous patients with suspected congenital heart disease under or equal to 2 years old in our hospital between Mar 2016 and Jan 2017 were divided into 2 groups according to the reservation number. " double low" group included 32 patients using 80 kVp, 80 mAs, Iodixanol (270 mg I/ml) and iDose ⁴ - 4iterative reconstruction algorithm; routine group included 25 patients using 100 kVp, 100 mAs, Iopromide (370 mg I/ml) and filtered back projection algorithm. Individualized injections were taken on the weight of children and the iodine intake was calculated. CT values of left atrium, left ventricle, right atrium, right ventricle, ascending and descending aorta at the level of tracheal bifurcation, midpoint of aortic arch, pulmonary trunk, left and right pulmonary artery, pectoralis major and erector spinae on both sides as well as background noise at the level of aortic arch were measured, and signal to noise ratios (SNR) and contrast to noise ratios (CNR) were calculated. The quality of all images was evaluated subjectively. Scan length (L), volume CT dose index (CTDI_vol) and dose-length-product (DLP) were recorded, and the effective dose (E) and size-specific dose estimate (SSDE) were calculated. The diagnostic coincidence rates for CTA examinations of these two groups were calculated and compared with the surgery or cardiac catheterization examination called the " gold standard" .

The iodine intake of " double low" group and routine group was (2.53±1.09) and (3.46±1.29)g, respectively, with statistically significant difference ( t=2.976, P<0.05). No statistically significant difference existed in CT value of heart cavities, large blood vessels or CT value of muscles, background noise, SNR, CNR at the level of aortic arch or subjective evaluation for image quality between the two groups (P>0.05). The consistency of subjective evaluation for image quality of the two groups was good(Kappa=0.55, 0.76). Compared with routine group, CTDI_vol, SSDE, DLP, E of double low group descended by 57.19%, 56.71%, 56.74%, 53.33% respectively (t=54.107, 28.269, 15.338, 11.441, P<0.05). The diagnostic coincidence rates of the two groups were 96.6% and 97.1% respectively (P>0.05).

Using 80 kVp, 80 mAs and Iodixanol (270 mg I/ml) combined with iDose⁴ iterative reconstruction technique for CT angiography of pediatric complex congenital heart disease, the image quality could meet the requirements for clinical diagnosis, and the radiation dose and the iodine dose of contrast agent could be lowered.

Chinese clinical trial registry, ChiCTR1800016576.

Low dose; Congenital heart disease; Tomography, X-ray computed; Iterative reconstruction; Contrast agent