Application value of a whole-heart CT scanner in infants with congenital heart disease

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Objective To investigate the accuracy, image quality and effective dose (ED) of the whole-heart CT scanner in infants with congenital heart disease. Methods Totally 86 consecutive pediatric patients younger than 2 years old with congenital heart disease were enrolled.They were divided into 2 groups: whole-heart CT scanner with low dose group, 43 patients(28 males, 15 females, aged 12 d-19 months) underwent CT acquisition by using the whole-heart CT, and the other 43 patients(23 males, 20 females, aged 19 d-16 months) examined with volume helical shuttle (VHS) of high definition CT were assigned as VHS group.With surgical results as the standard, the sensitivity, specificity, positive predictive value(PPV), negative predictive value(NPV) and the diagnostic accuracy of the 2 groups for cardiovascular abnormalities were evaluated.Attenuation and noise of 2 groups of ascending aorta, main pulmonary artery, and muscle were measured, and the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated.The double blind method was used to evaluate the subjective image quality of the level of intra-cardiac, extra-cardiac and coronary artery.Both the volumetric CT dose index (CTDIvol) and dose-length product(DLP) of each child were recorded, and the ED was also estimated in both groups. Results By using surgical findings as the reference standard, a total of 124 and 113 separate cardiovascular anomalies were confirmed by the whole-heart CT scanner in the low dose group and the VHS group.The diagnostic accuracy in 2 groups was 99.2% and 98.8%, respectively, without significant difference(χ2=0.035, P=0.852). The sensitivity, specificity, PPV and NPV in 2 groups were 97.8%, 99.7%, 98.4%, 99.6% and 95.2%, 99.3%, 98.2%, 98.7%, respectively.No significant difference was found in the attenuation, image noise, SNR, and CNR between 2 groups in the same anatomic regions (all P>0.05). No significant difference was found in subjective image quality between 2 groups on the intra-cardiac and extra-cardiac structure(all P>0.05). But the subjective image quality of coronary artery was significantly higher in whole-heart CT scanner in the low dose group than that of the VHS group(4.02±0.91 vs.2.79±0.74), and the difference was significant(Z=-5.562, P=0.000). ED was (0.59±0.31) mSv in whole-heart CT scanner in the low dose group and (2.28±1.07) mSv in the VHS group, reflecting dose savings of 74% by using the whole-heart CT scanner with high temporal resolution, and the difference was significant(t=-11.285, P=0.000). Conclusions The whole-heart CT scanner with low dose can improve image quality with lower ED, especially for the image quality of coronary artery, which is an effective examination method for the diagnosis of congenital heart disease of children, especially for complex congenital heart disease. Key words: Computed tomography; Congenital heart disease; Radiation dosage; Iterative reconstruction