【作者】 刘婷；

【导师】 成官迅；

【作者基本信息】 南方医科大学 ， 医学影像学与核医学， 2010， 硕士

【摘要】 [目的]1、探讨各种类型心律不齐对双源CT冠状动脉成像图像质量的影响,分析心电编辑软件对心律不齐图像的质量控制。2、比较双源CT前瞻性及回顾性心电门控冠状动脉CTA的图像质量及受检者的辐射剂量,分析前瞻性心电门控扫描模式在CT冠状动脉成像运用中的意义。[材料和方法]1、研究对象的选择第一部分：收集2009年6月-2010年2月间51例在我院行冠状动脉CTA检查心律不齐的患者,所有患者的扫描数据均因心律不齐而采用了心电编辑软件处理,比较处理前后的冠状动脉图像质量,评价心电图编辑技术对修正不同的心律不齐图像的应用价值。51例患者中,年龄36-79岁,中位年龄约为56岁。其中心房颤动21例,房性早搏6例,单发室性早搏16例,频发室性早搏6例,复杂心律不齐2例。第二部分：冠状动脉CTA检查分为两组分别为前瞻性与回顾性心电门控扫描模式行冠状动脉CTA检查,前瞻组随机选取2009.6-2010.2在我院行冠状动脉CTA检查心律规整并心率<75次/分的患者39例,男32例,女7例,年龄25-75岁,心率为43-75次/分,回顾组为随机选取2009.6-2010.2在我院行冠状动脉CTA检查心律规整并心率<75次/分的患者39例,男32例,女7例,年龄24-72岁,心率为37-74次/分,病例筛除标准：对碘对比剂过敏、肾功能不全、心律不齐、心率>80次/分、呼吸控制不佳。2、设备与扫描方法第一部分：西门子双源CT (Siemens Somatom Definition)进行扫描。患者仰卧位,连接心脏电极,先平扫进行钙化积分分析,扫描参数：120kV, 100mAs,准直器宽度为64×0.6mm,旋转时间0.33s/周。冠状动脉成像扫描时参数：120kV,420mAs,心律失常时自动选择0.2螺距,准直器宽度为64×0.6mm。患者肘正中静脉留置套管针,使用双筒高压注射器团注,造影剂为优维显(370mgI/ml),流速为5.0-6.5ml/s,造影剂总剂量约为60-80ml,追加生理盐水25ml,流速为5.0ml/s。扫描范围：气管隆突下1cm至心脏膈面,采用造影剂示踪技术,示踪面定于主动脉根部冠状动脉起始点略高水平,触发阈值为90HU。第二部分：西门子双源CT (Siemens Somatom Definition)进行扫描。患者扫描分为A、B两组,A组为前瞻组,采用前瞻性心电门控扫描模式,扫描参数为：120kV,371mAs,重建层厚为0.75mm,准直器宽度为64×0.6mm；B组为回顾组,采用回顾性心电门控扫描,扫描参数：120kV,420mAs,准直器宽度为64×0.6mm,重建层厚为0.75mm,两组患者扫描范围一致。患者肘正中静脉留置套管针,使用双筒高压注射器团注,造影剂为优维显(370mgI/ml),流速为5.0-6.5ml/s,造影剂总剂量约为60-80ml,追加生理盐水20ml,流速为5.0ml/s。扫描范围：气管隆突下1cm至心脏膈面,采用造影剂示踪技术,示踪面定于主动脉根部冠状动脉起始点略高水平,触发阈值为90HU。3、图象处理及分析第一部分：心电编辑前后的原始图像在syngo后处理工作站的3D、Circulation等功能窗内进行心脏三维重建以及对每支血管进行MIP、CPR、仿真DSA等后处理,并对编辑前后图像质量进行评分。心电编辑时,首先需采用多时相窗重建预览出最佳时相期,再根据实时心电图进行心电图编辑。选择最佳时相期的方法有：1.相对时相法(在RR间期的0-99%以5%的间隔重建20幅图像)；2.绝对时间法(从R波之后0msec开始,以10msec时间间隔重建整个RR间期得到多幅图像)。心电图编辑方法有：1、shift R-peak(R波偏移)；2、disable Sync(废用异常同步)；3、delete Sync(剔除异常同步)；4、insert Sync(插入同步)。对于不同的心律失常采取不同的心电编辑方法,并对不同类型心律不齐患者心电编辑后的图像进行图像质量评分。根据美国心脏协会冠状动脉改良评分方法,图像质量采用0-3级评分法：3分：血管轮廓清晰,连续性好,无阶梯伪影；2分：血管轮廓清晰,连续性差,有少量伪影；1分：血管轮廓清晰,连续性差,有多个阶梯状伪影,但不影响诊断；0分：血管轮廓模糊,连续性差,伪影较多,影响诊断。2分以上图像为优良,0分图像质量差,不足以诊断。第二部分：前瞻性及回顾性心电门控扫描后原始图像传入后处理工作站,在3D、Circulation等后功能窗内对每支血管进行VR、MIP、CPR等心脏及冠状动脉的三维成像,并对重建后图像质量进行评分,评分标准同上,同时纪录前瞻性门控及回顾性门控患者扫描时的剂量参数：CT容积剂量指数(volume CT dose index, CTDIvol),剂量长度乘积(dose-length product, DLP)及有效剂量(effective dose, ED)。ED=DLP×K,即有效剂量等于DLP乘以胸部归一有效剂量系数(k=0.014mSv/mGycm)。4、统计学分析第一部分：统计学分析均采用SPSS统计软件13.0版本,统计学方法采用配对符号秩和检验(Wilcoxon Signed Ranks Test)分析心律不齐患者心电编辑前后图像质量评分,检验水准a=0.05,P<0.05认为差异有统计学意义。第二部分：统计学分析均采用SPSS统计软件13.0版本,两组临床资料的差异用两独立样本t检验(two independent samples t-test)。前瞻性及回顾性心电门控CT容积剂量指数(CTDIvol)、剂量长度乘积(DLP)及有效剂量(effective dose, ED)采用两个独立样本t检验。检验水准a=0.05,P<0.05认为差异有统计学意义。[结果]第一部分：51例病例中,心房颤动有21例,心电编辑前冠状动脉图像评分中0分为15例,1分为5例,2分1例,心电编辑时主要采用R波偏移将采集信号移至最佳时相区,心电编辑后图像评分17例为3分,2例为2分,这2例编辑后效果欠佳原因为心率过快,在100次/分以上；房性早搏有6例,单发室性早搏16例,心电编辑前冠状动脉图像评分中0分为18例,多为右冠状动脉中远段出现错层,形成阶梯伪影,1分占4例,心电编辑采用disable废用此次异常搏动的采集信号,编辑后19例病例均能达到3分,仅3例为2分；频发室性早搏6例,心电编辑前均为0分,心电编辑采用disable联合insert方式废用此次异常搏动的采集信号并插入一次较佳时相的采集信号,单发的二联律或三联律可间隔disable异常搏动的采集信号,心电编辑后2例为3分,3例为2分,1例为1分,造成编辑后仍为1分原因是患者同时呼吸未能配合好；频发室早合并心房颤动2例,室性早搏合并心率快慢不一2例,心电编辑采用shift+disable,心电编辑前为0分,心电编辑后为2分。心电编辑前图像质量与心电编辑后图像质量经配对符号秩和检验(Wilcoxon Signed Ranks Test)后,Z=6.422,P=0.000,差异具有统计学意义,心电编辑后图像质量较编辑前改善,心电编辑技术对提高心律失常患者冠状动脉图像质量有明显作用。第二部分：前瞻组39例患者有2例心率波动伪影导致图像不佳影响观察,其余46例患者共显示578个节段,其中43个节段因为血管细小未纳入统计分析,其余578个节段均能满足临床诊断要求；回顾组有2例呼吸配合欠佳,3例冠脉严重钙化导致图像不佳影响观察,其余43名患者523个节段均能满足临床诊断要求。两组患者在图像质量评价方面无显著差异,t=0.843,P=0.090>0.05。前瞻组有效放射剂量为(4.41±0.476)mSv,回顾组有效放射剂量为(17.66±3.30)mSv,以t=23.655,P=0.000,差异有统计学意义；前瞻组CTDIvol为(23.57±0.072)mGy,回顾组CTDIvol为(79.44±14.75)mGy,以t=24.813,P=0.000,差异有统计学意义；前瞻组DLP为(315.36±33.977)mGy. cm,回顾组DLP为(1261.46±235.68) mGy. cm,以t=24.813,P=0.000,差异有统计学意义。[结论]第一部分：心电编辑功能的运用使得越来越多轻度的心律失常的患者可以采用冠状动脉无创性检查,拓宽了部分心律不齐病人检查的适应症；对于偶发的室性早搏、房性早搏、心房颤动,窦房传导阻滞,心电编辑技术对图象质量的改善能起到显著的作用；对于频发的室性早搏、复杂的心律失常,由于图像信号缺失严重,心电编辑后较难使图像完美,但仍能起到改良作用。第二部分：对于心律整齐的患者,前瞻性心电门控扫描方式与回顾性心电门控扫描方式在图象质量无明显差异,但前者的有效幅射剂量明显降低。因此,与回顾性门控相比前瞻性门控有效降低患者冠状动脉CTA检查中的辐射剂量。更多还原

【Abstract】 [Objective]1. Explore various types of arrhythmias in the dual-source CT coronary image quality of the role of imaging. Analysis arrhythmias image quality control by ECG editing software.2. Comparison prospective and retrospective ECG-gated of dual-source CT coronary CTA image quality and radiation dose. Analysis the meaning of prospective ECG-gated scanning mode in the CT coronary angiography.[Meterials and Methods]1、The choice of subjectsPart I:51 cases arrhythmia patients among the patients of our hospital undergoing coronary CTA between June 2009 and February 2010, all the patients in the scan data were used for cardiac arrhythmia and ECG editing software to process and compare the treatment before and after image quality, editing features of the revised assessment of ECG arrhythmias different image value.51 patients, age 36 to 79 years old, with a median age of about 56 years old, of which 19 cases of atrial fibrillation, atrial premature beats in 6 cases, a single premature ventricular beats in 16 cases,5 cases of frequent premature ventricular contractions,2 rooms ventricular conduction block in 1 case, frequent ventricular premature 2 cases of atrial fibrillation, ventricular premature arrhythmia in 2 cases. Part II:78 patients underwent coronary CTA of our hospital in June 2009～February 2010, aged 25 and 65 years, median age 42 years, heart rate were 48～78 times/min between the coronary CTA, divided into two groups were prospectively and retrospectively ECG-gated coronary CTA, forward-looking group of 39 cases,39 cases review group. Case screening criteria:allergy to the iodine contrast agent, renal insufficiency, cardiac arrhythmia, heart rate large than 80 times/min, respiratory control was bad (coughing)2、Equipment and scanning methodsPart I:Siemens dual-source CT (Siemens Somatom Definition). Patient supine, connect the heart electrodes, first of all, scan for calcium score analysis, the parameters of scanning:120kV, 100mAs, collimator width 64×0.6mm, tube rotation time of 0.33s/week. Coronary artery imaging scan parameters:120kV,380mAs, pitch select 0.2, collimation width 64×0.6mm. Median cubital vein in patients with indwelling catheter, using binoculars high pressure syringe bolus injection of contrast agent was Iopromide (370 mgl/ml), the flow rate of 5.0～6.5ml/s, the total dose of contrast agent is about 60-80ml, inject NS 25ml, the flow rate of 5.0ml/s. Scan range:Carina 1cm to the heart diaphragm, using contrast agent tracer, tracer surface set at a little higher starting point of the aortic root coronary artery, trigger threshold was 90HU.Part II:Siemens dual-source CT (Siemens Somatom Definition). Patients divided into A, B groups, A:The forward group, scan parameters:120kV,371mAs, slice thickness 0.75mm, collimator width 64×0.6mm; B:The review group, scan parameters:120kV, 420mAs, collimator width 64×0.6mm, reconstruction thickness is 0.75mm, two groups were the same scan range, Median cubital vein in patients with indwelling catheter, using binoculars high pressure syringe bolus injection of contrast agent was Iopromide (370 mgl/ml), the flow rate of 5.0～6.5ml/s, the total dose of contrast agent is about 60-80ml, inject physiologic saline 20ml, the flow rate of 5.0ml/s. Scan range:coryna lcm to the heart diaphragm, using contrast agents tracer, tracer surface set at a little higher starting point of the aortic root coronary artery, trigger threshold was 90HU. 3、Image Processing and AnalysisPartⅠ:Dual source CT automatically after the reconstruction of the best images systole and diastole. Will not edit the original images in 3D post-processing workstation and Circulation functions within each window of blood vessels VR、MIP、CPR and other three-dimensional heart and coronary artery imaging, and image quality score before editing. ECG editing, first of all, need to rebuild the preview window using temporal phase of the best, and then conducted under real-time ECG-editing. Selection of optimum methods are:1. Relative phase method (0%～99% 20 image reconstruction intervals 5% interval in the RR); 2. Absolute time method (after 0 msec from R wave began to 10 msec time interval reconstruction of the RR interval have multiple images). ECG editing methods are:1.shift R-peak (Rwave offset); 2.disable Sync (with the exception synchronization waste); 3.delete Sync (excluding abnormal synchronization); 4.insert Sync (insert synchronization). Adopt different for different ECG arrhythmias editing method, and after ECG editing image image quality score.According to the American Heart Association, coronary artery improved segmentation method, image quality with 0～3 score:3:Vascular outline a clear, good continuity, no step artifacts; 2 score:a clear outline of blood vessels, poor continuity, a small amount of artifacts; 1 score:Vascular outline clear, poor continuity, a number of ladder-like artifacts, but does not affect the diagnosis; 0 score:vascular blurring, poor continuity, more artifacts, affect the diagnosis.2 points or more images is well,0:not diagnosis.PartⅡ:Prospective gating and retrospective gating incoming scanned original image post-processing workstations, and Circulation in the 3D function of the window after the vessels were on each VR, MIP, CPR and other heart and coronary arteries of three-dimensional imaging, and after reconstruction image quality score, Grading Ibid Also record prospective gating and retrospectively gated scan dose in patients with parameters:CT dose index volume (volume CT dose index, CTDIvol), dose length product (dose-length product, DLP) and effective dose (ED). ED=DLP×K, the effective dose (ED) is equal to the normalized DLP times the effective dose coefficient of the chest (k=0.014mSv/mGycm).4、Statistical analysisPartⅠ:Statistical analysis use SPSS version 13.0 statistical software, Statistically paired sign rank test Wilcoxon Signed Ranks Test to analysis cardiac arrhythmias in patients before and after editing the image quality score, Test levelα=0.05, P<0.05 considered significant difference.PartⅡ:Statistical analysis use SPSS version 13.0 statistical software, two different clinical samples with two independent samples t-test. Prospective gating and retrospective gating group Groups CT volume dose index (CTDIvol), dose length product (DLP) and effective dose (ED) with a mean of two independent samples t test. Test levelα=0.05, P<0.05 that the difference was statistically significant.[Results]PartⅠ:The study of 51 cases in 19 patients with atrial fibrillation, ECG editing images before coronary score is divided into 13 cases of 0 and 1 is divided into five cases,2 points,1 case of ECG R wave editing mainly partial shift will move the best collection signal phase zone, ECG editing the image score of 3 points in 17 cases,2 cases of 2 minutes, after which 2 cases, poor editing because too fast for the heart rate at 100 times/min; atrial premature beats in 6 cases,16 cases of single premature ventricular contractions, cardiac image editing score of 0 before the coronary artery is divided into 18 cases of right coronary section are staggered to form a ladder of artifacts, a share of 4 cases, edited by ECG abnormal pulse disable waste collection with the signal, edited 19 cases were able to achieve three points, only 3 cases of 2 points; frequent premature ventricular beats in 6 cases ECG Pre-editing were 0 edited by ECG joint insert mode disable the abnormal beating of disuse and insert a better signal acquisition phase of the acquisition signal, the second single joint legal or triple law can disable abnormal beating of the collection interval signal, ECG edited 2 cases were excellent, good in 3 cases,1 case,1 min at the same time due to respiratory failure in patients with good; 2 atrioventricular block in 1 case, using shift +disable+insert combined with ECG 0 points before editing, editing of ECG after 2 minutes; frequent ventricular premature 2 cases of atrial fibrillation, ventricular premature+arrhythmia in 2 cases, ECG editing using shift+disable, ECG Pre-editing to 0 points, the heart 2 minutes after editing power. Edit the image quality of ECG and ECG before editing the image quality by paired signed rank test (Wilcoxon Signed Ranks Test) after, Z=6.422, P=0.000, the difference was significant, ECG editing to improve image quality than the pre-editing, cardiac arrhythmia editing technology to improve image quality in patients with coronary artery plays a significant role.PartⅡ:Prospective gate group 2 patients heart rate fluctuations affect the artifacts lead to poor image observation, and the remaining 46 patients showed a total of 578 segments,43 segments as small vessels are not included in statistical analysis, the remaining 578 segments can meet the clinical diagnosis requirements; review group 2 patients with poor breathing, three cases of severe coronary artery calcification in effect result in poor image observation, and the remaining 43 patients with 523 segments can meet the clinical diagnostic requirements. Image quality evaluation of the two groups with no significant difference,t=0.843, P=0.090> 0.05. Prospect Group effective radiation dose (4.41±0.476) mSv, the effective radiation dose was recalled group (17.66±3.30) mSv, with t=23.655, P=0.000, significant difference; forward-looking group CTDIvol was (23.57±0.072) mGy, review group CTDIvol was (79.44±14.75) mGy, to t=24.813, P=0.000, significant difference; forward-looking group of DLP was (315.36±33.977) mGy.cm, DLP review group was (1261.46±235.68) mGy.cm,t=24.813, P=0.000, the difference was statistically significant.[Conclusions]PartⅠ:ECG editing function allows the use of more and more patients with mild arrhythmia can be used noninvasive coronary artery; Occasional PVCs, atrial premature, atrial fibrillation, sinoatrial block, ECG editing techniques to improve the quality of the image can play a significant role; Frequent PVCs, complex arrhythmia, due to the image signal Lack of serious cardiac image editing is more difficult to perfect, but improvements can still play a role..PartⅡ:For the patients with cardiac rhythm neat, forward-looking ECG-gated scanning and retrospective ECG-gated scanning was no significant difference in image quality, but the former significantly reduced the effective radiation dose. Therefore, compared with retrospective gating reduces the forward-looking gated coronary CTA, the radiation dose.更多还原