Objective: To evaluate the clinical value of minidose technique on dual-source CT combined with contrast medium optimization in childrent with complex congenital heart disease（CCHD）.
Methods: From July2016 to June 2017, twenty-eight consecutive children(mean age12.4±13.5M,male17 ,female 11,mean weight7.5±2.78Kg) suspected with CCHD were included.All patients underwent transthoracic echocardiography and DSCT angiography with minidose technique mode, with low rate and weight-based low-dose contrast medium injection program. The average CT attenuation and noise were measured in superior vena cava，the pulmonary trunk and ascending aorta.Image quality were assessed by two radiologists using a five point scale independently.Interobserver agreement on grades was assessed by Kappa statistics .The DLP value were recorded in order to calculate dose(ED)..Operation were performed in all patients .With surgical results as the standard, the diagnostic sensitivity and specificity by DSCT and TTE for the intra-and extra-cadiac anomalies, the cardiac and great vessels connecting part were evaluated.
Results: There was a high consistence for image quality scoring between the two observers (Kappa=0.87, P<0.05). The score of average image quality was 4.59±0.51,artifacts of superior vena cava was 4.36±0.66,the mean ED were1.76±0.43mSv and the volume of contrast medium was 6.53±2.78ml.The diagnostic sensitivity and specificity of intracardiac anomalies,the cardiac and great vessels connecting part, extracadiac anomalies by DSCT and TTE were 90% and 95.1%,93% and 100%，93.3% and 98.6%,94.1% and 95.8%,100% and 100%,86.3% and 86.5%.,respectively.
Conclusion: THe HR and HRvariation in children with CCHD was high ,an irregular HR often results in misregistration artefacts with prospective mode on DSCT.While with comparatively low radiation dose,minidose retrospective mode shows excellent image quality by selected the best reconstruction phase of cardiac cycle, and provides a comprehensive evaluation of the cardiac anatomy,including the coronary arteries. Combined with the optimized contrast medium injection protocol, this scan mode can significantly improve the diagnostic accuracy of CCHD in children．