Role of Dual-layer Detector Energy Spectral CT in Resting Myocardial Perfusion Imaging for Patients with Normal Coronary Artery / 中国医学科学院学报

Objective To investigate the role of dual-layer detector energy spectral CT in resting myocardial perfusion imaging for patients with normal coronary artery. Methods One hundred and fifty-six patients with suspected coronary heart disease underwent dual-layer detector energy spectral CT coronary angiography,and resting myocardial perfusion imaging was performed for 28 patients with normal coronary artery.According to American Heart Association's 17-segmentmodel,the iodine density and effective atomic number(Z

Value of CT Angiography Using Low Tube Voltage and Low Contrast Combined with Iterative Model Reconstruction in Patients with Coronary Artery Bypass Grafts / 中国医学科学院学报

Objective To assess the value of CT angiography using low-voltage and low-concentration contrast media (CM) combined with knowledge-based iterative model reconstruction (IMR) in patients with coronary artery bypass grafts (CABG).Methods Totally 71 patients after CABG undergoing CT angiography in our center from June to November 2016 were prospectively enrolled and randomly assigned into groups A and B. The scan protocol for group A was 80 kVp with 300 mgI/ml contrast at an injection rate of 4 ml/s;images were reconstructed by IMR algorithm. The scan protocol for group B was 100 kVp with 370 mgI/ml contrast at an injection rate of 5 ml/s;images were reconstructed by hybrid iterative reconstruction technique. Aorta,left ventricular,and grafts were chosen as regions of interest. The image quality,radiation dose,and contrast load were compared between two groups.Results The signal to noise ratio (SNR) and contrast to noise ratio (CNR) of the ascending aorta,descending aorta,left ventricular,and venous bridge in group A [SNR:19±5,20±5.7,19.1±4.9,and 37±34;CNR:17±4.7,18±5,16±5.4,and 34±32] were significantly higher than those in group B [SNR:16±6 (P=0.012),15.6±5.5 (P=0.002),15±6 (P=0.002),24±8.3 (P=0.035);CNR:14±5.5 (P=0.010),13.8±5(P=0.002),13±5.7 (P=0.014),21±7.8 (P=0.031)],except for left internal mammary artery graft (LIMA),which was not inferior to that in group B. An effective radiation dose reduction of 49% was achieved in group A [(2.3±0.4) mSv,compared with group B (4.5±0.5) mSv (P=0.000)]. The iodine load of group A was (20±1.4) g compared with (29±1.6) g in group B,resulting in a reduction of 31% (P=0.000).Conclusions The low tube voltage (80 kVp) and low contrast protocol combined with IMR in patients with CABG can reduce radiation dose and improve image quality of aorta,left ventricular and venous graft. The image quality of LIMA graft in low dose group is not inferior to that in regular dose group.

Midterm Follow-up of Coronary Artery Bypass Grafting with 64-Slice Multi-detector Computed Tomography: Identification of Risk Factors Affecting Graft Patency / 中国医学科学杂志(英文版)

To identify the risk factors that are associated with the midterm coronary artery bypass grafting (CABG) functionality by assessing patency of left internal mammary artery (LIMA) graft and saphenous vein (SV) graft with 64-slice multi-detector computed tomography (64-MDCT).Methods Patients who underwent CABG operation and postoperative 64-MDCT follow-up examinations from August 2012 to December 2015 were included. The graft patent status was classified into patent and poor patent according to MDCT findings predominantly on 3D reconstructed images by two radiologists. The clinical data and imaging findings of the patients were collected and compared between the patent group and poor patent group. Univariate analysis and the multivariate logistic regression analysis were performed to identify the risk factors that affect graft patency.Results Among 341 patients in the study, there were 330 LIMA grafts [326 anastomosed to the left anterior descending artery (LAD), 4 to right coronary artery (RCA)] and 564 SV grafts (SVG) [100 anastomosed to the diagonal branch (D), 226 to the obtuse marginal branch (OM), and 238 to the RCA territory]. The approximal vessel stenosis exceeding 90% occurred in 268 of 292 patent LIMA grafts, and in 1 of 34 poor patent grafts (χ =167, P<0.001). The patency rate was higher when SVG was anastomosed to OM (85.4%) or RCA territory (81.9%) than to D (69.0%) (χ =15.471, P=0.004). The proximal target vessel stenosis < 90% (OR= 0.015, 95% CI: 0.01-0.14, P=0.000) was independently associated with the closure risk of LIMA grafts, the dyslipidemia (OR= 1.52, 95% CI: 1.0-2.5, P=0.048), history of diabetes (OR = 1.28, 95% CI : 0.90-2.26, P=0.045) and typical angina symptoms (OR=1.81, 95% CI :1.33-4.15, P=0.003) were independently associated with the closure risk of SVG. Conclusions The proximal LAD stenosis less than 90% was adversely associated with graft patency in LIMA recipients; dyslipidemia, diabetes and angina symptoms were associated with the midterm failure in SVG recipients. The choice of the target anastomosis sites may affect the patency of SVG.

Effects of heart rate changes after holding breath and time for recovering stable heart rate on quality of coronary CTA / 医疗卫生装备

Objective To explore the effects of heart rate changes after holding breath and time for recovering stable heart rate on the quality of coronary CTA.Methods Totally 700 patients undergoing coronary CTA examination in some hospital were enrolled into the study,whose data on initial heart rate at rest condition,maximal heart rate during breath holding,stable heart rate after breath holding as well as the time consumed for recovering stable heart rate were collected and analyzed.Results A heart rate trendgram was drawn to find out the rules for heart rate changes and time for recovering stable heart rate,so that proper retrospective or prospective scanning scheme could be determined.Conclusion Mastering the rules in heart rate changes and time for recovering stable heart rate contributes to guiding coronary CTA.