Clinical Application Of DSCT In Children With Congenital Heart Disease

PartⅠThe clinical application of different post-processing techniques based on isotropic scan in cardiovascular diseasesObjective:To explore the value of different post-processing techniques based on isotropic scan in cardiovascular diseases.Methods:47 patients suspected of congenital heart disease(CHD) by clinician and TTE were scanned by DSCT using isotropic parameters.All the data were transported to the workstation.Two dimensional(2D) and three dimensional(3D) images were reformed.MPR or MIP was applied to demonstrate the macorpathology of long-axis lesions in 2D images according to the various abnormalities:ASD or VSD (four-chamber plane,MPR);RV outflow tract stenosis(RV outflow tract plane,MPR); single ventricle or double outlet of RV(ventricle outflow plane,MPR or MIP);aorta overriding(short axis plane of LV perpendicular to inter-ventricular septum,MPR or MIP);interrupted aortic arch or aortic coarctation(MIP plane parallel to the long axis of aorta);stenosis of PA and proximum of L/RPA(oblique transverse MIP plane); stenosis of L/RPA and branches(oblique MIP plane parallel to the long axis of L/RPA);collateral vessels(coronal MIP plane);anomalous pulmonary veins return (oblique MIP plane which pulmonary veins enter into atria);anomalous vena cava return(oblique MIP plane which vena cava enter into atria);persistent left superior vena cava(SVC)(oblique MIP plane which left SVC enter into coronary sinus);the proximal segment of RCA(right leaf-lets plane);the whole range of RCA(right coronary sulcus plane);the distal segment of RCA and PDA(diaphragmatic plane); LM and the proximal segment of LAD and LCX(left leaf-lets plane);the middle and distal segment of LAD(cardiac frontal wall plane);the whole range of LAD (interventricular septum plane);the whole range of LCX(left coronary sulcus plane); PDA(oblique MIP or MPR plane parallel to both PA and aorta).3D images were rotated to the optimal angle in which the abnormality was displayed perfectly and images were saved.A four-point scale(1,non-diagnostic;2,barely diagnostic;3, diagnostic;4,optimal diagnostic) was used to evaluate the macorpathology of long-axis lesions.The displaying scores of transverse images were compared with those of 2D and 3D respectively.Results1 2D refomed images were superior to transverse images in the evaluation of both intra-cardiac and extra-cardiac abnormalities(P＜0.05).Compared with the transverse images,VR was good at demonstrating the extra-cardiac abnormalities (P＜0.05),while,it almost can not display the intra-cardiac abnormality(P＜0.05).2 There was the optimal 2D plane for almost every abnormality in CHD.ConclusionMulti-direction adjusted MPR and MIP can display long-axial lesions to the best extent in 2D images,while,VR can give an overview of cardiovascular structures in 3D images.There was the optimal 2D plane for almost every abnormality in CHD. With the optimal 2D plane,we can give an accurate and quick diagnosis of CHD. PartⅡThe value of dose-optimized ECG-gated cardiac and chest DSCTA in children with congenital heart diseaseObjectiveTo assess the value of dose-optimized ECG-gated cardiac and chest DSCTA in children with congenital heart disease(CHD)Methods1,16 children underwent ECG-gated cardiac and chest CTA on DSCT(100 kV;80 mAs) and 9 children on SSCT(100 kV;100 mAs) separately.Subjective image quality was assessed by two cardiovascular radiologists in consensus using a 4-point scale(1=excellent to 4=not diagnostic).Estimation of effective dose was performed on the basis of dose length product(DLP).In a sub-analysis,for each scanner, children were subdivided into two groups according to the mean heart rate during contrast-enhanced scan as follows:(1)90～99 bpm(2) more than 100 bpm.Dose performance and image quality were evaluated between DSCT and SSCT.At the same time,to compare radiation doses between DSCT and SSCT in theory,we assume the virtual scan with the default scanning parameters at the same individual.2,47 patients suspected of CHD by clinician and TTE were underwent dose-optimized ECG-gated cardiac and chest DSCTA.ECG-pulsing with shorter exposure window and weight-based tube voltage and tube current modulation were reliably applied.All the data was transported to the workstation.2D and 3D images were reformed by means of MPR,MIP and VR.All images were evaluated by two experienced cardiovascular radiologists in consensus.TTE were performed in all cases.Surgical or CAG confirmation was both available.DSCT findings were compared with those of operation and TTE.7 cases underwent DSCT after operation. Postoperative evaluation was mainly focused on the stomas and vascular prosthesis.Results1,The image quality of DSCT is superior to that of SSCT(P＜0.05).For the constant pitch of 0.2,no significant difference was found in effective dose between groups in SSCT(P＞0.05).The average effective dose of SSCT was 1.03±0.06 mSv. The average estimated effective doses of DSCT were 0.65±0.05 mSv,0.57±0.08 mSv corresponding to heart rates of 90～100 bpm and more than 100 bpm.DSCT is able to provide robust diagnostic image quality at doses far below that of SSCT(P＜0.05). The virtual scan has also derived that the doses of DSCT has decreased greatly at high heart rates compared with SSCT.2,A total of 168 cardiac abnormalities were confirmed by CAG or operation.The accuracy of DSCT in detecting cardiac abnormalities was 97.62%.There were 59 intra-cardiac abnormalities.The definite diagnostic rate of DSCT and TTE was 94.92 %and 100%,respectively.DSCT was as accurate as TTE in revealing intra-cardiac abnormalities.There were 109 extra-cardiac abnormalities.The definite diagnostic rate of DSCT and TTE was 99.08%and 69.72%,respectively.DSCT was superior to TTE in revealing extra-cardiac abnormalities,especially abnormalities of coronary artery and pheripheral pulmonary vessels.Combination of DSCT and TTE could increase the definite diagnostic rate to 99.40%.All the stomas were unobstructed and vicinal vessels were normal in 5 cases after operation of IAA or aortic coarctation.In 1 case with TOF after Blalock-Taussig shunt and 1 case with abnormal origin of right pulmonary artery after correction operation,DSCT showed the vascular prosthesis were all smooth.ConclusionDSCT realized ECG-gated cardiac and chest angiography with optimized dose in children.As a non invasive imaging technique,DSCT is superior to TTE in detecting cardiovascular abnormalities,especially in revealing vascular abnormalities such as coronary artery and pheripheral pulmonary vessels.The combination of DSCT with TTE can raise the diagnostic accuracy in CHD.DSCT plays an important role in patients screening,presurgical planning and postoperative follow-up in CHD.