心电前门控冠状动脉CT成像在快心率患者中的应用对策

目的探讨通过增加padding的方法,评估64层螺旋CT前门控冠状动脉CT成像在相对快心率患者的应用价值。方法选择心率>65/min患者30例(病例组),通过增加padding至180ms,重建40%⁸0%相位,评价冠状动脉图像质量,分析有效辐射剂量,并与30例(对照组)用回顾性心电门控螺旋CT冠状动脉重建方法辐射剂量进行对比。结果 98.3%的冠状动脉血管能够满足诊断要求,其中通过增加padding重建收缩期40%80%相位,评价冠状动脉图像质量,分析有效辐射剂量,并与30例(对照组)用回顾性心电门控螺旋CT冠状动脉重建方法辐射剂量进行对比。结果 98.3%的冠状动脉血管能够满足诊断要求,其中通过增加padding重建收缩期40%⁴5%相位窗,28.3%的冠状动脉血管图像质量改善,其中7例患者(23.3%)的12支血管(10.0%)图像质量由不能诊断改善为可以用于诊断;病例组平均辐射剂量明显低于对照组(3.5mSv vs 10.1mSv,P<0.01)。结论前门控轴扫增加padding用于相对快心率患者,可改善图像质量,避免用辐射剂量更高的回顾性心电门控螺旋CT扫描方法。     

Double Flash扫描方式在冠状动脉计算机断层扫描中的应用

目的 探讨双源计算机断层扫描（computerized tomography,CT）大螺距前瞻性心电触发采集模式（Flash模式）在冠状动脉CT中的应用价值.方法 随访中国人民解放军总医院行冠状动脉CT检查的患者120例,其中采用Double Flash扫描方式组60例（A组）,常规螺旋扫描方式组60例（B组）.入选患者在CT检查过程中心率均＜70次/min,窦性心律且节律整齐,且体质量＜100 kg.采用4分法对图像质量进行评价（1分为图像质量极好,2分为图像质量好,3分为图像质量一般,4分为图像质量差）,并记录两组患者整个扫描过程中的总有效剂量值及总剂量长度乘积.结果 两组间图像质量评分比较,差异无统计学意义（P＞0.05）.A组整个扫描过程中的总有效剂量值明显低于B组,差异有统计学意义[（2.6±0.8） mSv vs.（8.6±1.3） mSv,P＜0.05];总剂量长度乘积也明显低于B组,差异有统计学意义[（145.8±13.5） mGy·cm vs.（621.4±129.8）mGy.cm,P＜0.05].结论 双源CT大螺距前瞻性心电触发采集模式应用于心率＜70次/min的患者时与常规螺旋扫描模式比较,在保证图像质量的同时,还可显著降低辐射剂量.     

64层CT冠状动脉成像的前瞻性与回顾性心电门控比较

目的 比较前瞻性心电门控和回顾性心电门控64层CT冠状动脉成像的辐射剂量和成像质量,探讨低剂量前瞻性心电门控CT冠状动脉成像的可行性.方法 两组心率≤65次/min各100例患者分别进行前瞻性和回顾性心电门控扫描,并采用多平面重组(MPR)、最大密度投影(MIP)、曲面重组(CPR)及容积再现(VR)多种重组技术显示冠状动脉,图像质量根据运动伪影影响分为优、良、差,使用剂量长度计算各自的有效辐射剂量,并进行统计学分析.结果 前瞻性组平均辐射剂量为(2.81±0.48)mSv明显低于回顾性组的(10.16±1.09)mSv(P＜0.01);前瞻性组诊断性冠状动脉节段和非诊断性冠状动脉节段为95.2%(1165/1224)和4.8%(59/1224),与回顾性组的94.1%(1186/1261)和5.9%(75/1261)比较,差异无统计学意义.结论 对于心率稳定在65次/min以下的患者,前瞻性心电门控64层CT冠状动脉成像,能以较低的辐射剂量达到回顾性心电门控诊断质量的影像,是切实町行的方法.     

迭代重建技术在前门控结合体质量调节管电压管电流心脏CT成像的研究——降低辐射剂量及控制图像质量简

目的 探讨迭代重建技术（iDose4）在前瞻性心电门控结合体质量调节管电压管电流心脏螺旋计算机断层扫描（computerized tomography,CT）成像中降低辐射剂量及控制图像质量的应用价值.方法 选取实验猪10只,每只猪均进行以体质量调节管电压管电流为基础的常规剂量（A组）及在此基础上降低管电流[分别降低30％（B组）、50％（C组）、70％（D组）]的256层前瞻性心电门控心脏CT扫描,所有数据均分别采用滤波反投影（filtered back projection,FBP）和iDose4重建,计算猪接受的辐射剂量,测量升主动脉根部及左心室腔噪声、信噪比（SNR）、对比噪声比（CNR）,分别对总体图像质量和冠状动脉图像质量进行评分（5分法评分）,3分及以上为图像质量可满足诊断,并对两种重建方法处理后所得结果进行比较.结果 A、B、C、D组的有效辐射剂量（ED）分别为（3.13±0.63） mSv、（2.26±0.51） mSv、（1.61±0.36） mSv、（1.01±0.23）mSv.随着X线剂量降低,图像噪声增加,信噪比、对比噪声比降低,图像质量下降.各组内比较,iDose4重建的图像噪声均较FBP重建者明显降低,而信噪比及对比噪声明显提高,差异均有统计学意义（P均=0.000）.A、B、C、D各组内经FBP/iDose4重建后总体图像质量评分分别为（3.80±0.42）分/（4.60±0.52）分、（3.60±0.52）分/（4.40±0.52）分、（3.00±0.67）分/（3.80±0.42）分、（2.00±0.67）分/（3.40±0.52）分,各组内比较差异均有统计学意义（P＜0.05）.用FBP重建,A、B、C、D组近、远端冠状动脉的可诊断率分别为100％、95％、70％、20％和92％、72％、36％、0;经iDose4重建后,A、B、C组近、远端冠状动脉的可诊断率均大于经FBP重建后A组的可诊断率或与其相当（P＞0.05）,而D组的可诊断率明显低于FBP重建后A组的可诊断率,差异有统计学意义（P＜0.05）.结论 在前门控结合体质量调节管电压管电流心脏CT成像中,应用iDose4较FBP可显著降低图像噪声,提高信噪比及对比噪声比,提高图像质量;用iDose4重建可以在现有辐射剂量基础上降低50％的剂量进行扫描而图像质量保持不变.     

迭代重建使用100kV管电压扫描对肥胖人群冠状动脉CT血管造影图像的影响

目的:探讨在冠状动脉CT血管造影图像(CCTA)检查中使用迭代重建(iterative reconstruction,IR)技术后,针对肥胖人群使用低管电压(100kV)扫描的可行性。方法:共有180例符合纳入标准的连续性受试者(男性112例)入选本前瞻性研究。受试者年龄43~77岁,平均(56.2±9.5)岁,体质量指数(BMI)范围:30~35 kg/m2。采用飞利浦公司256层螺旋CT扫描(Brilliance iCT,Philips Healthcare),回顾心电门控螺旋扫描模式及心电图相关管电流调节模式联合应用。按扫描方案分为高低管电压组(L组:100kV/800mAs;H组:120kV/800mAs),180例受试者随机分配入组。L组采用迭代重建算法重建图像(Idose4,level 4),H组采用滤波反投影算法(filter back projection,FBP)重建图像。图像主观评价法:使用4分单盲评法(1=不能诊断,4=图像极好)评价图像质量,并比较两观察者一致性。图像客观评价法:比较两组冠状动脉4大主干(左主干、前降支、回旋支及右冠状动脉)管腔内的CT值、感兴趣区噪声、信号噪声比及对比噪声比。结果:两组CNR分别为[(31.5±3.2)vs.(30.3±2.5,P0.05)]。两组图像质量评价均为好。两组图像质量评分差异无统计学意义(P0.05)。低电压100kV方案与高电压120kV方案辐射剂量分别为(4.3±0.6)mSv[CTDIvol:(15.7±0.4)mGy]、(7.6±0.4)mSv,[CTDIvol:(26.3±0.3)mGy](P0.001)。结论:在迭代重建技术辅助下,可在CCTA检查中对肥胖受试者(BMI:30~35 kg/m2)使用100kV管电压扫描,所得图像能够满足临床诊断需要。100kV方案较常规120kV方案辐射剂量明显降低。     

64排VCT-XT冠脉低剂量扫描技术在老年冠心病患者中的应用价值

目的评价64排螺旋CT低剂量冠状动脉成像在老年冠心病患者中的应用价值。方法 2010年12月至2012年1月80例疑诊冠心病老年患者随机分为2组,常规剂量组(A组)和低剂量组(B组),每组40例,分别进行CT冠脉成像检查,对2组的图像进行质量评分,对有效辐射剂量进行统计学分析。结果低剂量组与常规剂量组图像质量评分差异无统计学意义,同时降低了90%以上的有效辐射剂量,2组辐射剂量有统计学差异(P<0.01)。结论在老年人心率允许的前提下,64排VCT-XT采用前门控扫描技术,能够在大幅降低有效辐射剂量的同时获得满足临床需要的图像质量。     

多层螺旋CT后处理技术在足骨骨折诊断中的应用

目的探讨多层螺旋CT及其后处理技术在足骨骨折诊断中的应用价值。方法对32例足部损伤患者采用16层螺旋CT扫描,获得CT轴位图像,在工作站上进行后处理[多平面重建（MPR）和容积重建（VR）]。结果本组足骨正常5例,跟骨粉碎性骨折8例,跟骨粉碎性骨折后致慢性骨髓炎、骨质疏松4例,距骨骨折5例,骰骨骨折2例,楔骨骨折4例,跖骨骨折4例。MPR＋VR联合处理得到的图像质量优良率明显高于单纯MPR及轴位断层图像（P均〈0．05）。结论16层螺旋CT后处理技术图像质量高,有利于足部骨折的诊断,指导选择治疗方案、制订手术计划。     

64层螺旋CT血管成像与冠状动脉造影对冠心病诊断价值的对比研究

目的评价64层螺旋CT在冠状动脉造影方面的诊断价值。方法58例临床诊断或可疑冠心病患者行64层螺旋CT冠状动脉成像检查,分别对左主干、左前降支、回旋支和右冠状动脉及其分支的重建图像行影像学评价,所有患者均行常规选择性冠状动脉造影检查作为对照。结果58例患者共757(87.0%)节段的冠状动脉(血管直径≥1.5 mm)成像,638节段(84.3%)可用于多层螺旋CT和冠状动脉造影定量分析。冠状动脉造影共发现狭窄101节段,多层螺旋CT发现狭窄104节段,多层螺旋CT对冠状动脉狭窄诊断的敏感性为86.1%,特异性为96.8%。结论64层螺旋CT冠状动脉造影可作为诊断冠状动脉病变的一种无创筛选方法。     

3D自适应迭代算法在64排螺旋CT冠状动脉造影中的应用效果研究

目的探讨3D自适应迭代算法在64排螺旋CT冠状动脉造影中的应用效果。方法选择2014年6月—2015年9月在成都医学院第一附属医院放射科接受冠状动脉造影术的患者92例,根据采用的图像重建算法分为反投影滤波重建算法组和3D自适应迭代算法组各46例。对两组的图像质量进行定量评价和定性评价。结果 3D自适应迭代算法组患者的图像噪声低于反投影滤波重建算法组,信噪比、对比噪声比高于反投影滤波重建算法组(P0.05)。3D自适应迭代算法组患者冠状动脉近、中、远部的图像质量定性评分均高于反投影滤波重建算法组(P0.05)。两组平均有效电离辐射比较,差异无统计学意义(P0.05)。结论 3D自适应迭代算法在64排螺旋CT冠状动脉造影中的应用效果较好,有利于提高图像成像质量。     

64层螺旋CT三维血管成像在主动脉夹层诊断中的价值

目的 探讨64层螺旋CT三维血管成像在主动脉夹层诊断中的价值.方法 对34例主动脉夹层(AD)患者行64层螺旋CT薄层扫描,在工作站采用最大密度投影 (MIP)、多平面重建 (MPR)及容积再现(VRT)技术对轴位图像进行三维重建.结果 34例AD中显示真假腔34例,内膜片27例,壁内血肿7例;27例典型夹层三维成像均显示明确破口,主动脉弓部破口以矢状位显示最佳,降主动脉破口以轴位及冠状显示最佳,VRT显示病变全程较清晰,但对破口及内膜片的显示不如MIP、MPR及轴位.结论 64层螺旋CT三维血管成像能全面清晰显示AD解剖病理改变,尤其是对破口的显示,是AD的重要诊断手段.     

Coronary CT angiography with single-source and dual-source CT: Comparison of image quality and radiation dose between prospective ECG-triggered and retrospective ECG-gated protocols

Background

This study is conducted to investigate and compare image quality and radiation dose between prospective ECG-triggered and retrospective ECG-gated coronary CT angiography (CCTA) with the use of single-source CT (SSCT) and dual-source CT (DSCT).

Methods

A total of 209 patients who underwent CCTA with suspected coronary artery disease scanned with SSCT (n = 95) and DSCT (n = 114) scanners using prospective ECG-triggered and retrospective ECG-gated protocols were recruited from two institutions. The image was assessed by two experienced observers, while quantitative assessment was performed by measuring the image noise, the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR). Effective dose was calculated using the latest published conversion coefficient factor.

Results

A total of 2087 out of 2880 coronary artery segments were assessable, with 98.0% classified as of sufficient and 2.0% as of insufficient image quality for clinical diagnosis. There was no significant difference in overall image quality between prospective ECG-triggered and retrospective gated protocols, whether it was performed with DSCT or SSCT scanners. Prospective ECG-triggered protocol was compared in terms of radiation dose calculation between DSCT (6.5 ± 2.9 mSv) and SSCT (6.2 ± 1.0 mSv) scanners and no significant difference was noted (p = 0.99). However, the effective dose was significantly lower with DSCT (18.2 ± 8.3 mSv) than with SSCT (28.3 ± 7.0 mSv) in the retrospective gated protocol.

Conclusions

Prospective ECG-triggered CCTA reduces radiation dose significantly compared to retrospective ECG-gated CCTA, while maintaining good image quality.     

Comparison of diagnostic accuracy and radiation dose between prospective triggering and retrospective gated coronary angiography by dual-source computed tomography

The purpose of this study was to evaluate and compare the diagnostic accuracy and radiation dose of dual-source computed tomographic (DSCT) coronary angiography for assessment of coronary artery disease using prospective electrocardiographic triggering and retrospective electrocardiographically (ECG) gated spiral scans. One hundred sixteen patients who had undergone dual-source computed tomography and conventional coronary angiography were enrolled in this study. Fifty-four patients were scanned using retrospective ECG-gated protocols (group 1) and 62 patients using prospective ECG-triggered protocols (group 2). Diagnostic accuracy, image quality, and effective dose were compared between groups 1 and 2. Conventional coronary angiography was used as the reference standard. In total 1,709 (98.2%) coronary segments in the 116 patients were assessable with adequate image quality. Sensitivities and specificities of diagnosing coronary heart disease (≥50% stenosis) in a patient-based analysis of DSCT data were 93.3% and 88.9% in group 1 and 96.4% and 85.7% in group 2, respectively (p=0.973 and 0.761). In vessel-based analysis, sensitivities and specificities were 77.4% and 94.1% in group 1 and 79.6% and 92.3% in group 2 (p=0.983 and 0.985). Overall averaged image quality scores (using 1- to 4-point scale) in groups 1 and 2 were 3.3 ± 0.4 and 3.5 ± 0.9, respectively (p=0.268). Prevalence of good (score 3.0) and excellent (score 4.0) image qualities of coronary vessels were 95.4% in group 1 and 92.4% in group 2 (p = 0.861). Effective doses were 8.82 ± 3.50 mSv (range 3.92 to 15.36) in group 1 and 2.95 ± 1.39 mSv (range 0.99 to 6.06) in group 2 (p<0.001). In conclusion, DSCT prospective ECG-triggered coronary angiography has equivalent image quality and diagnostic value compared to that of retrospective ECG-gated scans. Radiation dose was significantly decreased using prospective electrocardiographic triggering.     

窄窗扫描技术在高心率患者320排CT冠状动脉成像中的应用研究

目的：探讨高心律患者320排CT冠状动脉成像使用前瞻性心电门控窄窗扫描技术对图像质量和辐射剂量的影响。方法80例心率在80~100次/min的患者随机分成观察组和对照组。观察组按R- R间期30％～50％进行前瞻性窄窗扫描3个心动周期,对照组按R- R间期30％～80％进行常规扫描3个心动周期,冠状动脉节段图像质量采用4级评分法评分,辐射剂量值由设备自动计算。结果可评价血管段和优良率两组间差异无统计学意义（P＞0.05）。冠状动脉总节段、右冠状动脉（RCA）、左冠状动脉主干（LM）、左前降支（LAD）和旋支（LCX）的质量评分两组间差异无统计学意义（P＞0.05）。观察组的RCA和LCX与心律波动呈中等程度负相关（r =0.41、0.47）。观察组和对照组平均辐射剂量分别为（7.63±3.29）和（12.85±2.71）mSv,差异有统计学意义（t=1.384,P＜0.05）。结论窄窗扫描技术可应用在心律波动不大的高心率患者,能明显降低辐射剂量而不影响图像质量。     

心电门控320排容积CT在急性胸痛中应用价值的前瞻性研究

目的:探讨前瞻性心电门控320排容积CT对急性胸痛成像的可行性及诊断价值。方法:对连续61例急性胸痛患者不控制心率条件下行前瞻性心电门控wide-volume模式并强制在一个心动周期扫描,曝光时间窗根据心率不同预设在40%~50%R-R间期(心率≥70次/min)或70%~80%R-R间期(心率70次/min)。2个volume涵盖自胸廓入口至心膈面,对比剂采用三相注射法以便同时显示主动脉、冠状动脉、肺动脉三大血管床。评价三大血管床的图像质量及对胸痛病因的诊断能力。记录患者的有效辐射剂量、对比剂用量。结果:61例患者的三大血管床(主动脉、冠状动脉及肺动脉)均得到明显均匀强化。主动脉和肺动脉均获得良好的可诊断图像(可诊断率达100%,61/61)。2例患者因屏气不良冠状动脉图像无法评价,在其余59例患者的625个冠状动脉节段中,图像质量为1级的占94.2%(589/625),2级图像质量占3.2%(20/625),总的可评价率达97.4%。观察者之间总的一致性较好(k=0.83,95%CI:0.60~1.00)。平均有效辐射剂量为(5.44±1.15)mSv,对比剂总量平均为(75.7±4.35)mL。本扫描计划对胸痛病因阳性诊断率为82%(50/61),CTA诊断为阴性的18%(11/61)的患者中随诊一月内无不良并发症出现。结论:320排容积CT的前瞻心电门控wide-volume扫描模式在不控制心率情况下可低辐射剂量及低对比剂用量地对急性胸痛患者进行评价。     

Performance Evaluation of a Multi-Slice CT System with 16-Slice Detector and Increased Gantry Rotation Speed for Isotropic Submillimeter Imaging of the Heart

BACKGROUND: 4-slice CT scanners have shown limitations in clinical application for noninvasive coronary CT angiography (CTA). We evaluate advances in ECG-gated scanning of the heart and the coronary arteries with recently introduced 16-slice CT equipment (SOMATOM Sensation 16, Siemens, Forchheim, Germany). MATERIALS AND METHODS: The technical principles of ECG-gated cardiac scanning, scan parameters, and detector design of the new scanner are presented. ECG-gated scan and image reconstruction techniques and ECG-controlled dose modulation ("ECG pulsing") for a reduction of the patient dose are described, key parameters for image quality and simulation results presented, and phantom studies and initial patient experience discussed. The impact of reduced gantry rotation time (0.42 s) on temporal resolution and initial estimations of the patient dose are presented. RESULTS: Extensions of ECG-gated reconstruction algorithms used for 4-slice CT provide adequate image quality for up to 16 slices. For each detector collimation different slice widths are available for retrospective reconstruction with well-defined slice sensitivity profiles (SSPs). For coronary CTA the heart can be covered with 0.75 mm collimation within a 20-s breathhold. The best possible spatial resolution is 0.5 x 0.5 x 0.6 mm. For 0.42 s gantry rotation time, temporal resolution reaches its optimum (105 ms) at a heart rate of 81 bpm. Effective patient dose for coronary CTA is 4-5 mSv using ECG-pulsed acquisition. CONCLUSION: The clinical performance of coronary CTA by means of spatial resolution, temporal resolution and scan time is substantially improved with the evaluated 16-slice CT scanner. Also, display of smaller coronary segments and instent visualization are substantially improved.     

Flash双源CT大螺距冠状动脉成像与冠状动脉造影对比的临床研究

目的评价Flash双源CT大螺距前瞻性心电门控扫描模式（flashspril）诊断冠状动脉狭窄的准确性。方法30例患者行Flash双源CT冠状动脉成像（CTCA）后进行冠状动脉造影术（CCA）检查。以冠状动脉造影术结果作为金标准,统计Flash双源CTCA显示冠脉病变的敏感性、特异性、阳性预测值和阴性预测值,统计冠状动脉各段图像质量评分及有效射线剂量。结果①准确性评价：基于节段水平分析,敏感性93．2％,特异性96．8％,阳性预测值86．0％,阴性预测值98．5％。基于血管水平分析,敏感性97．9％,特异性83．8％,阳性预测值88．7％,阴性预测值96．8％。基于患者水平分析,敏感性、特异性、阳性预测值、阴性预测值均为100％。CTCA显示冠状动脉狭窄结果与CCA高度一致。②图像质量：右冠状动脉不可诊断血管节段占右冠状动脉的3．4％,左冠状动脉主干、前降支不可诊断血管节段为0,回旋支不可诊断血管节段低于1．0％。③射线剂量：平均有效射线剂量（1．72±0．10）mSv。结论Flash双源CTflashspril模式CTCA评价冠状动脉狭窄的准确性高,图像质量好,运动伪影小,有效射线剂量低。     

Safety and efficacy of intravenous esmolol before prospective electrocardiogram-triggered high-pitch spiral acquisition for computed tomography coronary angiography

Background In order to acquire a high quality image with a low radiation dose, prospective electrocardiogram （ECG）-triggered computed tomography coronary angiography （CTCA） requires a stable heart rate （HR） 〈 65 beats/min. Esmolol has the advantage of reduc-ing HR. The objective of this article is to assess the value of intravenous esmolol treatment before prospective ECG-tr/ggered high-pitch spiral acquisition for CTCA. Methods From March 2013 to June 2013, 313 patients underwent prospective ECG-triggered CTCA. Two hundred and thirty two of them received esmolol before angiography. We retrospectively analyzed clinical characteristics, esmolol dose, radiation exposure dose, and the change in HR and blood pressure in these 232 patients. Results A total of 232 patients with a HR 〉 65 beats/rain before CTCA examination received intravenous esmolol treatment （mean dose of 57.26±15.39 rag）, The mean initial HR （HR1）, slowest HR （HR2）, and the HR 30 min after HR2 （HR3） were 75.06± 5.59, 60.75 ±4.00, and 75.54 ± 5.96 beats/min, respectively （HR1 vs. HR2, P 〈 0.0001; HRI vs. HR3, P = 0.377）. The mean time from esmolol administration to HR2 was 24.25 ± 4.97 s and the mean effective radiation dose was 2.28 ± 0.02 mSv. Conclusions HR could be rapidly controlled at an optimum level with intravenous esmolol before prospective ECG-triggered high-pitch spiral acquisition for CTCA. Consequently, the patients received a very low radiation dose.