Application Of128-slice Dual-source CT In The Diagnosis Of Congenital Heart Disease In Infants And Children

Part I Accuracy, image quality and radiation dose comparison of prospective ECG-gated sequential and high-pitch acquisition on128-slice dual-source CT angiography in infants and children with congenital heart diseaseObjective:To compare accuracy, image quality and radiation dose between prospective ECG-gated sequential and high-pitch acquisition on128-slice dual-source CT (DSCT) angiography in infantsandchildren with congenital heart disease (CHD).Materials and Methods:Ninety-six children suspected with CHD were prospectively enrolled, and a total of92patients were finally included in this study. Forty-six patients (male28, female19) underwent DSCT angiography with sequential mode, and the other46patients (male27, female19)were examined withhigh-pitch mode. CT parameters were as follows:0.28s gantry rotation time,2x64x0.6mm detector collimation, a slice collimation2x128x0.6mm by z-flying focal spot technique,80kV tube voltage and weight adapted setting for tube current (60mAs/rotation for patients＜5kg body weight,60-79mAs/rotation for patients5-10kg body weight,80-120mAs/rotation for patients>10kg body weight). In the sequential group, the acquisition window was set at40%-40%of the R-R interval. In the high-pitch group, data acquisition was prospectively ECG-triggered starting at10%of the R-R interval using a pitch of3.4. Surgery was performed in70patients, and conventional cardiac angiography (CCA) was performed in22patients. With surgical and/or CCA results as the standard, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and the diagnostic accuracy of the two groups for the cardiovascular abnormalities was evaluated. Blinded to the results of surgical and/or CCA findings, two cardiac radiologists with more than5years’ experience interpreted the image quality of intracardiac structures, great vessels and the proximal and middle segments of coronary arteries using a5-grade scoring system.The CT attenuation, the noise and signal-to-noise ratio (SNR) in the ascending aorta and the pulmonary trunk were measured. The effective radiation dose was calculated. The diagnostic accuracy, the subjective and objective image quality and radiation doseof the two groups were compared.Results:All92patients underwent successful DSCT angiography with either sequential or high-pitch acquisition. Patients of the two groups were adequately matched regarding to the age (t=0.484, P＞0.05), body weight (t=0.139, P＞0.05) and heart rate (t=0.516, P＞0.05). The mean scan time in high-pitch group was significantly lower (t=18.891, P＜0.05) than that in the sequential group. Using surgical and/or CCA findings as the reference standard, a total of134and144separate cardiovascular anomalies were confirmed in high-pitch group and sequential group, respectively. The diagnostic accuracy of high-pitch group and sequential group was98.79%and99.53%, respectively. There was no significant difference in the diagnostic accuracy between high-pitch group and sequential group (x2=3.182, P＞0.05). The sensitivity, specificity, PPV and NPV were94.03%,99.71%,98.44%and98.86%, respectively by high-pitch group, and97.92%,99.78%,98.60%and99.67%, respectively by sequential group. Two small atrial septal defects,1small ventricular septal defect and1small patent ductus arteriosus were not identified, and1pulmonary artery atresia was misdiagnosed as severe pulmonary artery stenosis in the high-pitch group. One small atrial septal defect and1patent ductus arteriosus were not identified, and1severe pulmonary artery stenosis was misdiagnosed as pulmonary artery atresia in the sequentialgroup. Both high-pitch and sequential CT data acquisitions misdiagnosed the normal atrial septum as1small atrial septal defect. Eleven cases of coronary artery anomalies were all identified in the sequential group. There were6cases of coronary artery anomalies in thehigh-pitch group, only3cases were identified. There was excellent agreement for the image quality scoring of the intracardiac structures (k=0.81), great vessels (k=0.85) and the proximal and middle coronary arteries (k=0.85) between the two observers. There was no significant difference in the image quality of extracardiac great vessels (u=981.000, P＞0.05) between the two groups. The image quality of intracardiac structures and coronary arteries was significantly better in theacquisition group than that in the high-pitch group (u=594.500and397.500, P＜0.05). There was no significant difference between the high-pitch group and the sequential group regarding to the CT attenuation (t=1.272and0.745, P＞0.05), the noise (t=1.736and1.811, P＞0.05) and the SNR (t=0.942and0.795, P＞0.05) in the ascending aorta and pulmonary trunk. The mean effective dose of the high-pitch group and the sequential group was0.27±0.11mSv and0.39±0.17mSv, respectively.There was significant difference in the mean effective dose (t=4.316, P<0.05) between the two groups. A decrease of31%dose reduction was shown in the high-pitch group.Conclusion:Bothsequential and high-pitch mode for128-slice DSCT angiography provide high accuracy for the assessment of CHD in infantsandchildren, while the high-pitch mode, even with some image quality declined, further significantly lowers the radiation dose. Part II Application of prospective ECG-gated high-pitch128-slicedual-source CT angiography in the diagnosis of congenital extracardiac vascular anomalies in infants and childrenObjective:To investigate the value of prospective ECG-gated high-pitch128-slicedual-source CT (DSCT) angiography in the diagnosis of congenital extracardiac vascular anomalies ininfants and children in comparison with transthoracic echocardiography (TTE).Materials and Methods:Eighty consecutive infants or children clinically diagnosed of congenital heart disease and suspected with extracardiac vascular anomaly were enrolled, and75patients were finally included in this prospective study. There were43males and32females. The mean age was16.84±19.45months, the mean body weight was9.02±4.61kg, and the mean heart rate was119.73±15.10bpm. All patients underwent prospective ECG-gated high-pitch DSCT angiography after TTE with an interval of1-7days. The mean scan time was0.37±0.06seconds. DSCT parameters were as follows:0.28s gantry rotation time,2x64x0.6mm detector collimation, a slice collimation2x128x0.6mm by z-flying focal spot technique,80kV tube voltage and weight adapted setting for tube current (60mAs/rotation for patients<5kg body weight,60-79mAs/rotation for patients5-10kg body weight,80-120mAs/rotation for patients＞10kg body weight). The high-pitch mode was used with a pitch of3.4and the prospectively ECG-triggered data acquisition starting at10%of the R-R interval. All patients underwent two-dimensional TTE and Doppler Flow from the parasternal, apical, subxiphoid and suprasternal approaches using a SONOS7500ultrasound system. The examinations were performed by an experienced echocardiographic technician, and the data were evaluated by a trained pediatrician and the echocardiographic technician. Conventional cardiac angiography (CCA) was performed in29patients, and surgery was performed in46patients. The diagnostic accuracy and sensitivity of high-pitchDSCT angiography and TTE were compared according to the surgical/CCA findings. The image quality of DSCT was independently assessed by two cardiac radiologists with more than5years’experience using a five-point scale. The effective radiation dose (ED) was calculated.Results:A total of17congenital heart diseases and162separate extracardiac vascular anomalies were confirmed by surgical/CCA findings in75patients. The diagnostic accuracy of high-pitchDSCT angiography and TTE was99.67%and97.89%, respectively. The sensitivity of high-pitchDSCT angiography and TTE was97.53%and79.62%, respectively. There was significant difference regarding to the diagnostic accuracy and the sensitivity between high-pitchDSCT angiography and TTE (x2=23.561and28.013, P＜0.05). TTE failed to identify2partial anomalous pulmonary venous returns,1aortic dysplasia,2coarctations of the aorta,5pulmonary artery stenoses,1pulmonary artery dilation,4pulmonary slings,1patent ductus arteriosus,8 major aortopulmonary collateral arteries,1persistent left superior vena cava and3coronary artery anomalies. TTE misdiagnosed1case of pulmonary artery atresia as truncus arteriosus,2cases of absence of one pulmonary artery as pulmonary sling,1coarctation of the aort as interruption of the aortic arch and1major aortopulmonary collateral artery as patent ductus arteriosus. Although3total anomalous pulmonary venous returns were identified by TTE,1mixed type was misdiagnosed as cardiac type. Two bicuspid aortic valves and1single coronary artery were not identified by high-pitchDSCT angiography. High-pitchDSCT angiography misdiagnosed a normal arterial ligament as patent ductus arteriosus and a severe pulmonary artery stenosis as pulmonary artery atresia. The agreement on the image quality scoring of DSCTbetween the two observers was excellent (k=0.81), and the mean score of image quality was4.1±0.7. The mean ED of DSCT was0.29±0.08mSv.Conclusion:Prospective ECG-gated high-pitch128-sliceDSCT angiography with low radiation dose and high diagnostic accuracy and sensitivity has an obvious advantage over TTE in the diagnosis of congenital extracardiac vascular anomalies in infants and children.