| Objective:To explore the clinical value of low-dose prospective ECG-triggering dual-source CT (DSCT) angiography in infants and children with complex congenital heart disease (CHD) compared with transthoracic echocardiography (TTE).Materials and Methods:Complex CHD is defined as congenital heart disease with more than one separate cardiovascular anomaly by their transthoracic echocardiography findings in this study. We prospectively enrolled 45 patients with complex CHD between. A total of thirty-five patients with complex CHD could be included in this study. All patients underwent low-dose prospective ECG-triggering DSCT angiography and TTE. The following acquisition parameters were used:2x32x0.6 mm detector collimation, a slice collimation of 2×64×0.6 mm enabled by Z-Sharp technology, and a gantry rotation time of 0.33 second. Body weight-based adjustments of tube voltage and tube current are performed:<5 Kg, tube voltage 80 kV, tube current 40-59 mAs; 5-10 Kg, tube voltage 80 kV, tube current 60-79 mAs;>10 Kg, tube voltage 80 kV, tube current 80-120 mAs. Prospective ECG-triggering technology necessitated a cycle time of 1.25 seconds for one acquisition and the subsequent table feed. The data acquisition window was 380msec with padding technique. The centre of the data acquisition window was set at 40% of the R-R interval. A dual-head power injectorwas used. The delay time is set to 25s.All images were transferred to an external workstation (Multi Modality Workplace, Forchheim, Siemens) for further analysis. In addition to the CT axial slices, multiple planar reformation (MPR), volume rendering (VR) and maximum intensity projection (MIP) were used to visualise cardiac abnormalities. Two radiologists with more than 5 years’experience in cardiac radiology semi-quantitatively assessed the overall image quality independently on a five-point scoring system. The accuracy of DSCT angiography and TTE was compared by using the non-parametric Chi-squared test. A p value<0.05 was considered to indicate a significant difference.Result:The final diagnoses of the thirty-five patients were pulmonary artery atresia with ventricle septal defect (n=5, Fig.1), tetralogy of Fallot (n=10, Figs.2-3), double outlet right ventricle (n=5), interrupted aortic arch (n=2), coarctation of the aorta (n=3 Fig.4), anomalous origin of one pulmonary artery (n=1), total anomalous pulmonary venous return (n=2), anomalous systemic venous return (n=1), and transposition of great arteries (n=6) by surgical and/or CCA findings as the reference standard.A total of 146 separate cardiovascular deformities were confirmed by surgical and/or CCA findings. The accuracy of low-dose prospective ECG-triggering DSCT angiography and TTE in diagnosing separate cardiovascular deformities was 97.3% (142/146) and 92.5% (135/146) respectively. DSCT was as accurate as TTE in revealing cardiovascular deformities (X2=3.48,P<0.05).The overall deformity-based sensitivity, specificity, positive predictive value and negative predictive value were 97.3%,99.8%,99.3% and 99.3% respectively by DSCT angiography, and 92.5%, 99.8%,99.3% and 98.2% respectively by TTE.In four patients, TTE missed all of the coronary artery anomalies. In one patient with tetralogy of Fallot, the right coronary artery arose from the left coronary sinus of Valsalva, which distributed two larger branches crossing in front of the right ventricular outlet. In another patient with transposition of great arteries, both the right coronary artery and the left coronary artery arose from the non-coronary sinus of Valsalva with a common ostium. The left main coronary crossed between the main pulmonary artery and the left atrium. In the remaining two patients, one coronary-pulmonary fistula and one high-take off of the left coronary artery were missed by TTE. TTE missed two major aortopulmonary collateral arteries, three distal pulmonary artery stenoses, and one anomalous systemic venous return. TTE misdiagnosed one patient as having coarctation of the aorta; operative and DSCT findings confirmed the actual diagnosis of interrupted aortic arch. On the other hand, DSCT misdiagnosed one normal atrium as one atrial septal defect and missed three atrial septal defects and a very small patent ductus arteriosus.Interobserver agreement was reached in all patients. The average subjective overall image quality score of prospective ECG-triggering DSCT was 4.3±0.7. Diagnostic images were obtained in all examinations. There was good agreement (κ=0.78) between the two reviewers.The mean volume CT dose index was 1.39±0.40 mGy (0.83-1.92). The mean dose-length product was 19.86±6.27 mGy·cm (10-32) resulting in an estimated mean effective radiation dose of 0.38±0.09 mSv (0.25-0.58).Conclusion:Prospective ECG-triggering DSCT angiography with very low effective radiation dose allows the accurate diagnosis of anomalies in infants and children with complex CHD compared with TTE. It has great promise to become a commonly used second-line technique for complex CHD. Objective:to compare the image quality and radiation dose of prospective ECG-triggering versus retrospective ECG-gated dual-source CT imaging in infants and children with congenital heart diseases.Materials and Methods:We retrospectively evaluated 100 dual-source CT images that were obtained using two different protocols (prospective non-helical ECG-triggering [n =50] versus retrospective helical ECG-gated [n=50]) in patients younger than 6 years. Two radiologists evaluated the image quality, using a 3-or 5-point scale, in terms of the overall subjective image quality, the degree of homogeneity of vascular enhancement, the stair-step artifacts, and the visualization of the coronary artery. The objective image noise (standard deviation of attenuation) was calculated. We compared the mean score of image quality and the estimated radiation dose. A p value<0.05 was considered to indicate a significant difference.Result:The mean overall image quality in the prospective group was seam as those scores in the retrospective group (P>0.05). The mean score of the stair-step artifacts and the visualization of the coronary artery in the prospective group were also seam as those scores in the retrospective group. The mean score of the homogeneity of vascular enhancement in the retrospective group than those scores in the prospective group (P< 0.05). As a parameter of objective image noise, the mean standard deviation of attenuation in the prospective group was also seam as those scores in the retrospective group (29.0±5.1 vs.27.7±6.0). The mean estimated effective dose was higher for the retrospective ECG-gated helical scan than that for the prospective non-helical scan (0.73 vs.0.35 mSv, respectively, P=.000).Conclusion:The prospective ECG-triggering technique can be obtained with a low radiation dose and seam image quality, as compared to Retrospective ECG-gated helical dual-source CT, for the evaluation of congenital heart diseases in pediatric patients who are younger than 6 years old. |
PDF Full Text Request