Clinical Application Of Dual-source CT Coronary Angiography

[Objective]1、To explore the main influence factors on coronary artery image quality with dual-source CT (DSCT).2、To evaluate the accuracy of DSCT coronary angiography in the diagnosis of coronary stenoses,compared with selective coronary angiography (SCAG), the relationship betweem the plaque nature and the stenoses degree on DSCT and SCAG and the difference of coronary artery stenosis≥50%by plaque between DSCT and SCAG.3、To discusse the diagnosis value of DSCT in coronary artery after stenting.4、To discusse the diagnosis value of DSCT in mural coronary artery-myocardial bridge.[Materials and Methods]1. The research of influence factors of coronary artery image quality with DSCT1.1General information200examinees had DSCT scan for coronary angiograph from2009june to2010august.There were118male,29female, and average age was55.17±10.50years old. All DSCT images included a complete examination of ECG data, all patients signed the informed consent of contrast enhancement. The study of exclusion criteria:respiratory adverse, had placed stent or after coronary artery bypass grafting, unable to fit in with check, moderate or above with calcification, pregnancy and unstable hemodynamics, cardiac and renal dysfunction and allergic to iodine contrast medium.1.2Apparatus and methodsRetrospective electrocardiogram(ECG)-gated for coronary angiography was performed with DSCT.Two minutes before CT examination,all patients had5mg nitroglycerin(about every time2spray) under tongue, but didn’t take beta blocker. Before the scanning, placed kind electricity shaft and connected the onoff condition, from head to foot scanning, since the tracheal subcarinal1cm down to the diaphragmatic muscle level. Scanning parameters were as follows:tube voltage120KV, tube current380mA, frame rotating time310ms, collimator width32x0.6mm, level acquisition thickness64x0.75mm, pitch0.2～0.5mm. Using double tube high pressure injector,all subjects first received calcification scanning, subsequently were injected70to85ml nonionic contrast agent (ultravist350mgI/ml or370mgI/ml) by the antecubital vein according to5ml/s flow, followed by45ml saline flushing. Using artificial intelligent trigger scanning system,at ascending aortic root using bolus tracking technology, when the ascending aorta CT value reached the set100Hu threshold, after5seconds delay started scanning image acquisition.1.3Image processingUsing retrospective ECG-gated technique, each subject was manually reconstructed whole phase, after reconstruction all images were transferred to3D workstation (Leonando, Siemens) with the heart post-processing software (Syngo Circulation, Siemens).Using the individual principle, Selected the best image quality for restructed R-R phase, when left and right coronary artery optimal restructed phases were inconsistent, then staging phase displayed. The original image underwent volume rendering technique(VRT)、curved planar reconstruction(CPR) maximum intensity projection (MIP) and so on,and combined with the axis, observated coronary artery image quality, selected the best DSCT image for coronary artery image quality assessment.1.4Coronary artery sectionAccording to the American Heart Association (AHA) suggested scheme, coronary artery is divided into15segments, if the existence of intermediate branch is16. S1=the proximal segment of right coronary artery,S2=the middle segment of right coronary artery, S3=the distal segment of right coronary artery,S4=posterior descending artery;S5=the main branch of left coronary artery;S6=the proximal segment of left anterior descending artery,S7=the middle segment of left anterior descending artery,S8=the distal segment of left anterior descending artery,S9=the first diagonal branch,S10=the second diagonal branch; S11=the proximal segment of left circumflex artery,S12=the first obtuse marginal branch,S13=the distal segment of left circumflex artery, S14=the second obtuse marginal branch,S15=posterior artery of left ventricle, S16=intermediate branch.1.5Image quality evaluationDSCT coronary artery image quality was assessed by two imaging physicians,who were familiar with cardiovascular department and didn’t know patient’s any clinical information, using axial VR, MPR, CPR, and MIP and other reconstructed techniques. When they were not consistent, then negotiated. Left and right coronary artery and its branches out of shape differences and cardiac motion uniqueness decided DSCT coronary artery segment imaging optimal phase inconsistency, first the vessel segment as the unit for image quality was analysised. Image quality judgment standard was as follows:1point excellent, vascular continuity, without motion artifacts, every segment was clear displayed;2points good, vascular continuity, minor artifacts, segmental wall was slightly blurred;3points general, vascular continuity, secondary artifact, segmental wall and surrounding structures were secondary fuzzy;4points poor,severe artifact, vascular discontinuity, wrong layer appeared that can’t evaluate or do not distinguish structure.1-3points can be used for diagnosis,4points can’t. Then patient as the unit for image quality score was analysed:1point, all vascular segment image quality were excellent or good;2points,all vascular sections exist general but count <3, without poor quality;3points,all vascular sections exist general and count≥3, or the presence of quality poor.According to the heart rate (HR),we divided HR into4groups:HR<60/min,60<HR<75/min,75<HR≤90/min,HR>90times/min.1.6Statistical analysisThe SPSS13.0software was applied in this study. Multi variable Logistic gression was used to evaluate the influence factors on image quality. Many groups of rank data non-parametric tests was applied to evalute the influence of different heart rate groups, multiple comparisons using Games-Howell method. P value of less than0.05was considered significant.2. DSCT coronary angiography in the diagnosis of coronary stenoses2.1General information199examinees both DSCT scan and SCAG exam in40days for coronary angiography were retrospective analyzed,who were clinically suspected or definite diagnosised with coronary heart disease.There were141male,59female, and age from32to87old、average age62.25±10.68old.2.2Instrument and methodThe method and post-processing reconstruction of DSCT was same as Part1. SCAG imaging method:using Siemens company DIGITRON Ⅱ DSA instrument, using Seldinger’s method to establish arterial channel, using Judkins method via the femoral artery or radial artery cannulation, respectively injected contrast agent Ou Nai Peck (300mgI/ml)6-8ml、4-6ml to the left and right coronary arteries, including4-6standard posture of LCA (left anterior oblique position, left anterior oblique head, tail, right anterior oblique position, right anterior oblique head, tail),2-3standard position of RCA (left anterior oblique position, right anterior oblique position, left anterior oblique head).2.3Stenoses assessment and plaque rankStenosis degree:Igrade light stenoses, less than50%;Ⅱgrade middle stenoses,50%-75%;Ⅲgrade severe stenosis,76%～95%:Ⅳgrade extremely severe,above95%include occlusion. Plaque was ranked into4groups by current measurement of CT value:soft plaque, less than80Hu; fiber plaque, between80-129Hu: calcified plaque, above130Hu; mixed plaque, including calcifed and noncalcified component.2.4Statistical analysisUsing SPSS13.0software,we calculated the difference between DSCT and SCAG in the diagnosis of coronary stenoses,evaluted the difference in the diagnosis of coronary stenoses(≥50%) between DSCT and SCAG,and calculated the accuracy、sensitivity、specificity of DSCT.We calculated the relationship between plaques nature and stenosis degree on DSCT Or SCAG,and the difference between DSCT and SCAG in the diagnosis of coronary stenoses(≥50%) caused by plaque.Two independent samples non-parametric test was applied to evaluate the difference between DSCT and SCAG in the diagnosis of coronary stenoses.Matching four form chi-square test was applied to evaluate the difference in the diagnosis of coronary stenoses(≥50%) between DSCT and SCAG.Many groups of rank data non-parametric test was applied to evalute the relationship between plaque nature and stenosis degree on DSCT Or SCAG, multiple comparisons using Games-Howell method. Four form chi-square test was applied to evaluate the difference between the result of DSCT and SCAG in the diagnosis of coronary artery stenosis (≥50%) caused by plaque.P value of less than0.05was considered significant.3. The diagnosis value of DSCT in coronary artery after stenting.3.1General information25examinees both DSCT scan and SCAG exam in one month for coronary angiography were retrospectively analyzed,who had stents with coronary heart disease.There were16male,9female, and age from32to71years old,average age61.67±10.94old.4. The diagnosis value of DSCT in mural coronary artery-myocardial bridge. Materials and Methods was same as Part2[Results]1. The influence factors on coronary artery image quality with DSCT.1.1Of2688segments,2644segments can be used to evaluate,44segments can not. The rate of segment used to estimate was98.36%.1.2Heart rate was the main influence factor on coronary artery image quality,and the relationship of them showed negative correlation.The image quality in the group with heare rate less than60times/min is the best.2. DSCT coronary angiography in the diagnosis of coronary stenoses.2.1That exists significant difference in the diagnosis of coronary artery stenosis between DSCT and SCAG,when we put vascular segment as the unit(P<0.05),but no significant difference, when we put vascular branche、left and right coronary artery and patient as the unit(P>0.05). 2.2That exists no significant difference in the diagnosis of coronary artery stenosis (≥50%) between DSCT and SCAG, when we put vascular segment、vascular branche、left and right coronary artery and patient as the unit (P>0.05), with stronger coincidence degree. Its corresponding Se、Sp and accurancy is respectively90.38%、97.05%、95.75%;92.65%、97.04%、95.45%;93.21%、93.22%、93.22%;94.12%、78.26%、90.45%.2.3That exists significant difference between plaque nature and stenosis degree on DSCT or SCAG(P>0.05),and between the two there was significant difference on SCAG (P<0.05).Calcified plaque always caused mild lumen diameter stenoses.However,the mixed plaque aways leaded to serious lumen diameter stenoses.2.4That exists no significant difference difference between DSCT and SCAG in the diagnosis of coronary artery stenosis (≥50%) caused by plaque(P>0.05).3. The diagnosis value of DSCT in coronary artery after stenting.3.1The total of57stents were found in25cases of patients. with coronary stent That exists no significant difference in the diagnosis of coronary artery stent restenosis between DSCT and SCAG, with stronger coincidence degree. Its corresponding Se、Sp and degree of accurancy is respective96.30%、93.33%、94.74%.4. The diagnosis value of DSCT in mural coronary artery-myocardial bridge.4.113MCA-MB were found on SCAG,but48MCA-MB on DSCT in the199examinees both DSCT scan and SCAG exam.The detection rate of DSCT is obviously higher than SCAG.4.2The middle segment of left anterior descending artery is the most frequental site of myocardial bridge.[Conclusions] 1、Heart rate is the main influence factor on coronary artery image quality with DSCT. To obtain the ideal DSCT coronary artery image, heart rate should be controlled in more than75/min.2、DSCT coronary angiography.as a non-invasive technique,can be used for the screening and diagnosis of coronary heart disease.but there still exists some limitations.3、In a certain extent,DSCT can distinguish the nature of plaque and relative stability,plays an important role in preventing acute coronary events.4、Coronary angiography with DSCT can not only accurately,clearly show that the number and position of stents.but also can evaluate whether stents restenosis, becomes an important mean of follow-up in patients with coronary heart disease after stent implantation.5、Coronary angiography with DSCT can betterly show the distribution of mural coronary artery-myocardial bridge, its detection rate was significantly higher than that of SCAG.