Clinical Application Of Dual Source CT In Heart And Coronary Angiography

[Objective]1,To study the coronary artery anatomy and assess the diagnostic value of dual source CT(DSCT) angiography in detecting coronary anomalies.2,To discuss the correlation and concordance between DSCT and echocardiogram in left ventricular function analysis.3,To discuss the diagnostic value of DSCT coronary angiography in detecting clinical suspicion or confirmed diagnosis of coronary artery stenosis.[Meterials and Methods]1,Study populationPart one:The coronary artery imaging data of 638 patients (222 women,416 men; mean age 56.2 years; age range 26-87 years) who underwent DSCT angiography were studyed from May 2009 to October 2009.Part two:The image data of 119 patients (48 women,71 men; mean age 60.9 years; age range 28-87 years) who underwent DSCT and echocardiogram examinations within 3 days were studyed from July 2009 to January 2010.Part three:The coronary artery imaging data of 62 patients(19 women,43 men; mean age 62.0 years; age range 36-87 years) who underwent DSCT and coronary angiography(CAG) examinations within a week were studyed from May 2009 to February 2010.2,DSCT scan protocol All the patients were performed by DSCT scanner (SOMATOM Definition, Siemens Medical Solutions, Germany). Before the DSCT scan all patients were sprayed 0.5mg nitroglycerin sublingually for the expansion of coronary artery. After 3 min, the DSCT coronary angiography scan was started by continuously injecting a bolus of 80ml of ultravist (concentration:370mgI/mL) followed by 25ml saline solution into an antecubital vein via a 18-gauge catheter (injection rate 5.0-6.5ml/s) with high-pressure double-barrel syringe(MEDRAD, America). Contrast agent application was controlled by bolus tracking. Region of interest (ROI) was placed into the aortic root, and image acquisition started 5s after the signal attenuation reached the predefined threshold of 80-100 HU.Data acquisition was performed from 1.0-1.5cm below the level of the tracheal bifurcation to the diaphragm in a cranio-caudal direction with a detector collimation of 64 X 0.6mm, gantry rotation time 0.33s, pitch of 0.2-0.5 adapted to the heart rate, scan time 7-11s, tube current 380-430mAs per rotation, and tube voltage 120kV. Electrocardiogram (ECG) pulsing for radiation dose reduction was applied in all patients. ECG was digitally recorded during data acquisition and was stored with the unprocessed CT dataset. After the scan was completed, the machine automatically generated the best diastolic and systolic phase sequence of coronary artery images, reconstruction kernel B26f, slice width 0.75mm and increment 0.5mm.3,Image post-processing and analysisPart one:The reconstruction of image sequences were transferred to Syngo post-processing workstation. Multiplanar reconstruction(MPR), curved planar reconstruction(CPR), volume rendering(VR), maximum intensity projection (MIP) and many other image post-processing techniques were applied to observe the coronary artery origin, course, termination and the relationship of the surrounding tissue. All images were comprehensive assessed by the two radiologists who had experienced in cardiovascular diagnostic imaging at the workstation. Disagreements were solved through the consultation.Part two:The reconstruction image data of 0%-100% phases was load in left ventricular function analysis software. Software automatically outlined left ventricular end-diastolic and end-systolic ventricular cavity surface and the outer surface. Then the software automatically calculates the patients with left ventricular end-diastolic volume(EDV), end-systolic volume(ESV), stroke volume (SV), ejection fraction(EF), wall motion, left ventricular myocardial mass(MM) and other indicators. All image data analysis was down by a radiologist who had experienced in cardiovascular diagnostic imaging.Part three:The reconstruction data was send to the Syngo post-processing workstation, VR, MPR, MIP and other image processing techniques were applied to observed and the variation of coronary artery stenosis. Coronary artery stenosis was divided into five types:no stenosis; mild stenosis (<50%); moderate stenosis (50%-75%); severe stenosis (76%-99%); complete occlusion (100%). All images were comprehensive assessed by the two radiologists who were blinded to invasive coronary angiography results, using a 15-segment classification(based on American Heart Association, AHA), evaluated of all coronary artery diameter≥1.5mm segments. The consensus interpretation was compared with results of conventional invasive coronary angiography.4,Statistics analysisPart one:Based the anomalies of origin, anomalies of course, and anomalies of termination, we had classified the coronary artery anomalies into three types. These anomalies of origin included either the LCA or the RCA high takeoff, multiple ostia, single coronary artery, either the LCA or the RCA arising from the opposite coronary artery or branch, from the opposite or noncoronary sinus of Valsalva, from the pulmonary artery. These anomalies of course included myocardial bridge, coronary aneurysm and duplication of arteries. These anomalies of termination mainly included congenital coronary artery fistula and coronary arcade, et al.Part two:All DSCT and echocardiogram results were analyzed by an experienced cardiologist and radiologist respectively. Both observers were blinded to each other. Data was processed with SPSS 13.0 statistical package. Measurements were expressed as mean values±standard deviation. The correlation was tested with Pearson test. The difference was tested with paired sample t test. The concordance was tested with Bland-Altman analysis. P< 0.05 was considered statistically significant.Part three:The results of DSCT coronary angiography were compared with CAG which was as a gold standard in diagnosing coronary disease. Wilcoxon signed-rank test was used to compare the difference of DSCT and CAG in detecting coronary artery stenosis, P<0.05 was considered statistically significant. The overall sensitivity, specificity, accuracy, positive predictive value and negative predictive value of DSCT were tested. The concordance was tested with Kappa coefficient to compare the stenosis grading.[Results]Part one:Of 638 cases, left dominance accounted for 2.8%(18 cases), right dominance 89.0%(568 cases), balanced 8.2%(52 cases). The total of coronary anomalies accounted for 9.4%(60 cases), which included RCA high takeoff 3 cases, LCA high takeoff 8 cases, accesssory coronary artery 8 cases, absent LM trunk 2 cases, single coronary artery 2 cases, coronary aneurysm of RCA 1 case, coronary fistula between noncoronary sinus and left atrium 1 case, LCx from RCA 1 case, RCA from left sinus 1 case and myocardial bridge 32 cases.Part two:Correlation analysis of two methods:Pearson correlation coefficient was less than 0.05, indicating the two methods were significantly positive correlation and EDV, ESV, MM showed strong correlation (r>0.75). Paired t test:In addition to EF was no significant difference (t=0.34, P>0.05), the others were significantly different (P<0.05). The EDV, ESV, and SV of DSCT were higher than echocardiogram, MM lower than the echocardiogram. Consistency analysis:Two kinds of examination methods did not have a good consistency and didn't replace the use of each other in clinical practice.Part three:781 coronary segments (diameter≥1.5mm) were well evaluated in 830 coronary segments of 62 cases by DSCT coronary angiography. Wilcoxon signed-rank test result(Z=-4.486, P<0.001) showed two kinds of examination methods had a significant difference in the diagnosis of coronary artery stenosis. DSCT had a lower accuracy in detecting coronary stenosis compared with CAG. The overall sensitivity, specificity, positive predictive value, negative predictive value and accuracy of DSCT coronary angiography for identifying coronary stenosis were 80.2%,95.6%,87.0%,93.0%,91.5%, respectively. Kappa test results(κ=0.655, P< 0.001) showed two kinds of examination methods a moderate consistency. DSCT have a lower accuracy in diagnoseing coronary artery calcification and small branch disease compared with CAG.[Conclusions]Part one:The DSCT angiography could provide optimal visualization of coronary anomalies accurately, because of the improved temporal resolution, spatial resolution and flexible post-processing tool. The DSCT angiography could be considered as a first selective screening method for coronary anomalies.Part two:DSCT and echocardiogram showed a good correlation and concordance in left ventricular function analysis. DSCT examination had great clinical significance in prediction of acute myocardial infarction and assessment of left ventricular function.DSCT left ventricular function analysis and echocardiogram had a good correlation, but these two examination methods didn't have a good consistency. Two methods couldn't completely replace each other in the clinical practice. DSCT left ventricular function analysis could be used as a reference in clinical practice.Part three:DSCT coronary angiography could accurately and noninvasively detect significant coronary stenosis. Compared with CAG, DSCT have a lower diagnostic accuracy because of calcification, bifurcation and small branch disease. However, DSCT can still be considered as a preferred method in screening coronary artery disease before CAG examination and stenting follow up.