双源CT与64层螺旋CT冠状动脉图像质量及辐射剂量的研究

随着64层螺旋CT的问世,冠状动脉CT血管造影(CTA)作为无创手段更广泛的应用于冠状动脉的检查,但由于其时间分辨率的限制,高心率时冠状动脉CTA的运动伪影不可避免.正因为如此,对于64层螺旋CT,通常需要酒石酸美托洛尔降低心率来提高图像质量.如果酒石酸美托洛尔效果不佳,就需要多扇区重建来提高时间分辨率.     

心率对双源CT冠状动脉CTA成像质量影响分析

多层螺旋CT(MSCT)冠状动脉CTA应用临床以来,心率一直是影响冠状动脉CTA成像质量的重要因素之一[1,2].本文回顾性分析80例不同心率双源CT( dual-source CT ,DSCT)冠状动脉CTA成像资料,评价DSCT在不控制心率状况下冠状动脉成像质量.     

冠状动脉CTA和MRA的研究进展

冠状动脉细小、走行迂曲且随心跳和呼吸运动,因此,冠状动脉的成像技术必须具备较高的时间分辨力和空间分辨力。冠状动脉造影有很高的空间分辨力和时间分辨力(分别为0.13~0.2 mm3和20 m s),从而成为诊断冠状动脉狭窄的金标准,但有创性和检查费用高限制了它的广泛使用。近年来,随着多层螺旋CT和MR快速成像技术的实现,CT和MR作为无创性冠状动脉成像技术已实际地应用于冠心病的筛选和诊断,本文综述冠状动脉CT和MR血管成像(CTA和MRA)的检查技术和临床应用近况。1冠状动脉CTA和MRA的检查技术近年来,CT和MR的时间分辨力和空间分辨力已…     

心率对双源CT冠状动脉血管成像检查辐射剂量的影响

随着双源CT( DSCT)的推出,冠状动脉CT血管成像( CTA)已经成为冠状动脉狭窄患者冠状动脉DSA检查的重要替代手段[1],其安全简便、无创的检查方法在为临床提供更丰富的影像学信息的同时,也不可避免地增加了受检人群的总体受辐射剂量水平,因此,CT扫描时应严格控制辐射剂量.本研究通过比较两家三甲医院1个月的冠状动脉CTA检查,评价双源CT的冠状动脉成像辐射剂量平均水平及相关因素,以期找到实现个性化低剂量冠状动脉扫描相关因素.     

心脏和冠状动脉CT血管成像应用与进展

多层螺旋CT(muhisliee CT,MSCT)以及双源CT(dual source CT,DSCT)的出现,使无创性的心脏和冠状动脉CT血管成像(CT coronary angiography,CTCA)检查成为现实;随着CT技术的发展,MSCT的时间分辨率和空间分辨率明显提高,心脏CT血管成像(CT angiography,CTA)已经成为心脏和冠状动脉疾病无创性的常规检查方法之一.     

二代双源CT不同扫描模式冠状动脉成像及辐射剂量的研究

随着多排螺旋CT技术的快速发展,特别是双源CT(DSCT)的出现,冠状动脉CT血管成像(CTA)已经成为冠状动脉狭窄患者冠脉成像的重要替代手段,其安全、简便、无创的检查方法在为临床提供更丰富的影像学信息的同时,也不可避免地增加了受检人群的总体受辐射剂量水平.因此,CT扫描时应严格控制辐射剂量.第二代双源CT将前瞻性心电门控技术与高螺距扫描相结合,形成了特有的Flash螺旋心脏扫描模式.     

西门子128层螺旋CT诊断冠状动脉狭窄的研究

目的探讨西门子128层螺旋CT冠状动脉成像（CTA）对诊断冠状动脉狭窄的价值。方法收集来我院就诊的疑似冠状动脉狭窄患者36例,均进行128层螺旋CT冠状动脉造影检查和DSA选择性冠状动脉造影检查,观察两种检查方法中冠状动脉狭窄的影像学表现和诊断价值,并与64层以下冠状动脉CTA进行对照。结果 36例冠状动脉狭窄患者的两种检查结果,经统计学分析,西门子128层螺旋CT对冠状动脉狭窄的敏感性为98.08%、特异性为95.69%、准确性为96.43%。与64层以下螺旋CT比较,对患者心率、屏气等方面的要求更加宽松。结论西门子128层螺旋CT对冠状动脉狭窄的诊断价值高,方法简单、快速准确、无创伤,患者易接受,可作为疑似冠状动脉狭窄患者的首选检查手段。     

64排螺旋CT冠状动脉成像的前瞻性与回顾性心电门控技术的图像质量及辐射剂量的比较研究

目的 研究前瞻性心电门控触发(prospective ECG-triggering)与回顾性心电门控(retrosp-ective ECG gating)两种技术方法行冠状动脉CTA检查时,对冠状动脉图像质量及辐射剂量的比较.方法 33名疑似冠状动脉疾病的患者分两组进行对比研究.前瞻组16例为前瞻性心电门控成像,心率小于65次/min;回顾组17例为回顾性心电门控成像,心率小于75次/min.记录两组的辐射剂量并统计分析,同时进行图像质量评价.结果 两组图像质量比较,差异无统计学意义(P0.05).前瞻性心电门控冠状动脉CTA的平均DLP 234.4 mGy·cm,占回顾性心电门控冠状动脉CTA的平均DLP 974.4 mGy·cm的24.1%.前瞻性心电门控冠状动脉CTA的患者的平均有效剂量为3.2 mSy,回顾心电门控冠状动脉CTA患者的为13.6 mSv,降低76.47%.结论 64排螺旋CT在前瞻性心电门控冠状动脉CTA与回顾性心电门控冠状动脉CTA比较可以获得相似的图像质量,可大幅降低患者的有效剂量对于不能接受高辐射剂量且心率较低的受检人群具有重要的临床价值.     

64排螺旋CT冠状动脉成像的前瞻性与回顾性心电门控技术的图像质量及辐射剂量的比较研究

目的 研究前瞻性心电门控触发(prospective ECG-triggering)与回顾性心电门控(retrosp-ective ECG gating)两种技术方法行冠状动脉CTA检查时,对冠状动脉图像质量及辐射剂量的比较.方法 33名疑似冠状动脉疾病的患者分两组进行对比研究.前瞻组16例为前瞻性心电门控成像,心率小于65次/min;回顾组17例为回顾性心电门控成像,心率小于75次/min.记录两组的辐射剂量并统计分析,同时进行图像质量评价.结果 两组图像质量比较,差异无统计学意义(P0.05).前瞻性心电门控冠状动脉CTA的平均DLP 234.4 mGy·cm,占回顾性心电门控冠状动脉CTA的平均DLP 974.4 mGy·cm的24.1%.前瞻性心电门控冠状动脉CTA的患者的平均有效剂量为3.2 mSy,回顾心电门控冠状动脉CTA患者的为13.6 mSv,降低76.47%.结论 64排螺旋CT在前瞻性心电门控冠状动脉CTA与回顾性心电门控冠状动脉CTA比较可以获得相似的图像质量,可大幅降低患者的有效剂量对于不能接受高辐射剂量且心率较低的受检人群具有重要的临床价值.     

64排螺旋CT冠状动脉成像的前瞻性与回顾性心电门控技术的图像质量及辐射剂量的比较研究

目的 研究前瞻性心电门控触发(prospective ECG-triggering)与回顾性心电门控(retrosp-ective ECG gating)两种技术方法行冠状动脉CTA检查时,对冠状动脉图像质量及辐射剂量的比较.方法 33名疑似冠状动脉疾病的患者分两组进行对比研究.前瞻组16例为前瞻性心电门控成像,心率小于65次/min;回顾组17例为回顾性心电门控成像,心率小于75次/min.记录两组的辐射剂量并统计分析,同时进行图像质量评价.结果 两组图像质量比较,差异无统计学意义(P0.05).前瞻性心电门控冠状动脉CTA的平均DLP 234.4 mGy·cm,占回顾性心电门控冠状动脉CTA的平均DLP 974.4 mGy·cm的24.1%.前瞻性心电门控冠状动脉CTA的患者的平均有效剂量为3.2 mSy,回顾心电门控冠状动脉CTA患者的为13.6 mSv,降低76.47%.结论 64排螺旋CT在前瞻性心电门控冠状动脉CTA与回顾性心电门控冠状动脉CTA比较可以获得相似的图像质量,可大幅降低患者的有效剂量对于不能接受高辐射剂量且心率较低的受检人群具有重要的临床价值.     

320排动态容积CT冠状动脉成像诊断冠心病的初步应用

目的探讨320排动态容积CT冠状动脉成像(CTA)诊断冠心病的准确性。方法 2010年3月至2010年9月对临床拟诊为冠心病的82例患者先后行冠状动脉CTA及冠状动脉造影(ICA)检查,并以ICA为金标准,评估320排CTA诊断冠状动脉狭窄≥50%及≥70%的敏感度、特异度、阳性预测值及阴性预测值。结果 CTA成像质量4分71例(86.6%),平均心率为67次/min;3分10例(12.2%),平均心率为74次/min;2分1例(1.2%),心率为83次/min;1分0例,全部病例均无阶梯伪影。CTA发现174个狭窄≥50%的节段,ICA发现144个以ICA为金标准,320排CTA诊断狭窄≥50%的敏感度、特异度、阳性预测值及阴性预测值分别为93.1%、96.0%、77.0%和99.0%。CTA发现40个狭窄≥70%的节段,ICA发现40个。以ICA为金标准,320排CTA诊断狭窄≥70%的敏感度、特异度、阳性预测值及阴性预测值分别为100%、95.6%、45.5%和100%。结论 320排CTA图像质量好,诊断冠心病准确可靠。     

Evaluation of CT coronary artery angiography with 320-row detector CT in a high-risk population

Objectives

The aim of this article was to prospectively evaluate the accuracy and radiation dose of 320-detector row dynamic volume CT (DVCT) for the detection of coronary artery disease (CAD) in a high-risk population.

Methods

60 patients with a high risk of CAD underwent DVCT without preceding heart rate control and also underwent invasive coronary angiography (ICA), which served as the standard reference.

Results

On a per segment analysis, overall sensitivity was 95.3%, specificity was 97.6%, positive predictive value was 90.6%, negative predictive value was 98.8% and Youden index was 0.93. In both heart rate subgroups, diagnostic accuracy for the assessment of coronary artery stenosis was similar. The accuracy of the subgroup with an Agatston score ≥100 was lower than that for patients with an Agatston score <100. However, the difference between DVCT and ICA results was not significant (p=0.08). The mean estimated effective dose of CT was 12.5±9.4 mSv. In those patients with heart rates less than 70 beats per minute (bpm), the mean radiation exposure of DVCT was 5.2±0.9 mSv. The effective radiation dose was significantly lower than that of ICA (14.1±5.9 mSv) (p<0.001). When the heart rate was >70 bpm, a significantly higher dose was delivered to patients with DVCT (22.6±5.2 mSv, p<0.001) than with ICA (15.0±5.3 mSv, p<0.001).

Conclusion

DVCT reliably provides high diagnostic accuracy without heart rate/rhythm control. However, from a dosimetric point of view, it is recommended that heart rate should be controlled to <70 bpm to decrease radiation dose.The small diameter of the coronary segments, their complex three-dimensional geometry and their rapid movement throughout the cardiac cycle represent the major challenges for artefact-free coronary CT angiography (CTA). With each scanner generation, motion artefacts re-appear as a major cause of image quality degradation during coronary CTA [1-10]. Coronary CTA studies of each coronary artery with four-multidetector CT (MDCT) at a gantry rotation time of 500 ms had significantly decreased image quality with increasing mean heart rates [3]. Using 16-MDCT at a gantry rotation time of 420 ms, Hoffmann et al [2] found a significant negative correlation between overall image quality and mean heart rate. Even using 64-section CT, with its gantry rotation speed of 330 ms, elevated and irregular heart beats were found to cause relevant degradation of image quality [1,4,9,11]. Using dual-source CT (DSCT) with an increased temporal resolution of 83 ms, there was no significant correlation between mean heart rate and the overall image quality for any coronary segment or for any individual coronary artery. Nonetheless, irregular heart rates still slightly affect the image quality of non-invasive coronary angiography, even with DSCT [10,12].The 320-detector row dynamic volume CT (DVCT) is characterised by 320 slice detectors with a thickness of 0.5 mm and gantry rotation time of 350 ms. With a wide coverage of 16 cm in the z-axis, the whole heart can be covered within one cardiac cycle. Theoretically, DVCT makes it possible to scan patients with an irregular heart rate without “stair-step” artefacts. At the same time, DVCT avoids the overlapping rotations of helical CT, and the application of prospective echocardiogram (ECG) gating has become more feasible. Recent studies of DVCT have mainly been based on a low heart rate [13-17]. Few studies have investigated the diagnostic accuracy in higher heart rates and arrhythmia. Our purpose was to systematically evaluate the diagnostic accuracy and exposure dose of DVCT in a high-risk population with high and irregular heart rates.     

无常规心率控制下64排螺旋CT诊断冠状动脉狭窄的应用价值

目的 以有创性冠状动脉造影(ICA)为"金标准",评估无常规心率控制下64排螺旋CT冠状动脉成像(CTA)诊断冠状动脉狭窄的可靠性.资料与方法 35例患者先后行64排螺旋CT冠状动脉CTA和ICA,CTA扫描前所有患者均未常规控制心率.在未获知ICA结果的情况下,两位观察者独立对CTA结果作出评价.以冠状动脉管腔狭窄程度≥50%作为确定冠状动脉狭窄存在的标准.结果 ICA共显示75处冠状动脉管腔狭窄.64排螺旋CT冠状动脉CTA诊断冠状动脉狭窄的敏感度、特异度、阳性预测值及阴性预测值分别为:97.3%(73/75), 98.9%(468/473),93.6%(73/78)和99.6%(468/470).结论 在无常规心率控制条件下,64排螺旋CT冠状动脉CTA诊断冠状动脉狭窄仍具有很高的准确性.     

320排CT冠状动脉成像平均心率对图像质量和辐射剂量的影响

目的:探讨不同心率条件下320排容积CT冠状动脉血管成像的图像质量和辐射剂量.方法:将259例临床怀疑或确诊的冠状动脉疾病的患者(含35例心律失常患者)分为3组;A组79例,心率≤65次/分;B组120例,65＜心率＜80次/分;C组60例,心率≥80次/分.扫描完成后选用最佳的重建时相,对冠状动脉进行容积再现(VR)...     

Rationale and design of the ViCTORY (Validation of an Intracycle CT Motion CORrection Algorithm for Diagnostic AccuracY) trial

BackgroundCoronary CT angiography (CTA) has emerged as an effective noninvasive method for direct visualization of the coronary arteries, with high diagnostic performance compared with invasive coronary angiography (ICA). However, coronary CTA is prone to artifacts, including coronary motion, which may reduce its diagnostic performance. Intracycle motion compensation algorithms (MCAs) from a combination of software and hardware techniques now allow for correction of coronary motion, but the diagnostic performance of MCAs compared with traditional coronary CTA reconstruction methods remains unexplored.MethodsViCTORY (Validation of an Intracycle CT Motion CORrection Algorithm for Diagnostic AccuracY) is a prospective international multicenter trial of 218 patients which is designed to evaluate the performance of MCAs for the diagnosis of anatomically obstructive coronary artery disease (CAD) compared with an ICA reference standard, on a per-patient, per-vessel, and per-segment basis. Patients enrolled into ViCTORY will undergo investigational coronary CTA and clinically indicated ICA and will not receive heart rate-lowering medications before coronary CTA. Coronary CTA images will be reconstructed by conventional standard methods as well as by MCAs. Blinded core laboratory interpretation will be performed for coronary CTA and ICA in an intent-to-diagnose fashion.ResultsThe primary end point of ViCTORY is the per-patient diagnostic accuracy of MCAs for the diagnosis of anatomically obstructive CAD compared with ICA. Secondary end points will include other per-patient, per-vessel, and per-segment diagnostic performance characteristics, including accuracy, sensitivity, specificity, positive predictive value, and negative predictive value. Other key secondary end points will include diagnostic interpretability, image quality, the upper heart rate threshold of utility of MCAs, and the additive value of MCAs to traditionally reconstructed coronary CTA.ConclusionViCTORY will determine whether MCAs improve the diagnosis of obstructive CAD in patients undergoing coronary CTA who are not receiving heart rate-lowering medications.     

双源CT在心律失常患者冠状动脉成像中的应用

目的:探讨双源CT在心律失常患者的冠状动脉成像扫描技术及图像后处理中的应用。方法:452例怀疑冠心病的患者行双源CT冠状动脉成像,心律失常患者70例,其中增强扫描过程中平均心率>100次/min的患者共56例,房性早搏(atrial premature beat)6例,室性早搏(ventricular oremature beat)5例,房颤(atrial fibrillation)3例。双源CT自动重建最佳收缩期(best diast)、最佳舒张期(best syst)图像,若图像欠佳者编辑心电图,然后重建图像,把增强扫描图像行多平面重组(MPR)、最大密度投影(MIP)、容积再现技术(VRT)重建、曲面(CPR)重建。将图像质量分为3级,以美国心脏协会(Americanheart association,AHA)推荐的解剖分段方法为标准评价冠状动脉各个节段的图像质量。结果:70例心律失常患者经过心电图编辑后冠状动脉重建的最佳时相均为收缩期。共评价561个节段冠状动脉,其中图像质量1级者占87.9%(493/561),图像质量2级者占7.5%(42/561),图像质量3级者占4.6%(26/561)。结论:双源CT用于心律失常患者的冠状动脉成像可获得满意的冠状动脉各节段图像。     

前瞻性心电触发扫描模式应用于心律不齐患者冠状动脉CTA检查的可行性研究

目的：探讨心律不齐患者采用前瞻性心电触发扫描模式行冠状动脉CTA检查的可行性。方法：回顾性搜集本院行冠状动脉CTA检查的13例心律不齐患者的病例资料。所有患者均行双源CT扫描结合前瞻性心电触发扫描模式,每个R波后250～350ms采集,管电压120kVp,自动毫安。对比剂采用碘克沙醇（270mgI／mL）,注射30mL。记录所有患者的辐射剂量。将冠状动脉分为15个节段,由2名影像科医师进行图像质量评价,并测量cT值。对结果进行统计学分析。结果：13例患者均一次完成检查,平均有效辐射剂量为（2．61±1．29）mGy。主观评估了冠状动脉CTA的172个节段,有163个节段达到诊断要求,94．77％满足临床诊断要求。80．12％的节段管腔内CT值〉250HU。结论：心律不齐患者应用前瞻性心电触发扫描模式时,行冠状动脉cTA检查可以得到较好的图像质量,基本满足临床诊断要求。     

Heart rate adaptive optimization of spatial and temporal resolution for electrocardiogram-gated multislice spiral CT of the heart.

PURPOSE: We introduce a reconstruction method for electrocardiogram (ECG)-gated multislice spiral computed tomography (CT) examinations of the heart [adaptive cardio volume (ACV) reconstruction]. It is evaluated for a four-slice CT system (Siemens Somatom VolumeZoom). METHOD: State-of-the-art reconstruction techniques for ECG-gated multislice spiral CT use scan data from N consecutive heart cycles for image reconstruction. With increased N, the temporal resolution improves up to t rot /(2 N ) ( t rot is the 360 degrees rotation time of the scanner) but at the expense of insufficient volume coverage or loss of longitudinal resolution, especially at low heart rates. With the ACV technique, the number N of consecutive heart cycles used for image reconstruction is automatically adapted to the momentary heart rate of the patient, ranging from N = 1 at very low heart rates up to N = 3 at high heart rates, to maintain both high z resolution (reconstructed slice width close to the collimated slice width) and adequate temporal resolution. We evaluated slice sensitivity profiles and investigated 10 patients with different heart rates ranging from 55 to 110 beats/min for CT angiography (CTA) studies of the coronary arteries and compared the results with those from a reconstruction with fixed N ( N = 1 and N = 2). Axial images as well as multiplanar reformations were used for an evaluation of image quality. RESULTS: With the ACV approach, the complete heart may be scanned at 1 mm slice width within 25-35 s. A narrow slice sensitivity profile (full width at half-maximum of approximately 1.3 mm) is maintained for all heart rates. Diagnostic results can be obtained for heart rates up to about 95 beats/min by individual patient optimization of the ECG gating parameters. Improved temporal resolution at the expense of reduced longitudinal resolution may degrade the image quality of CTA studies at low heart rates by blurring plaques and stenoses. CONCLUSION: The results indicate the potential of the ACV reconstruction technique for high-resolution coronary CTA in a wide range of heart rates.     

不同对比剂对双源CT冠状动脉成像中患者心率的影响

目的 探究双源CT冠状动脉成像中,静脉注射碘克沙醇320与碘普罗胺370对比剂对患者心率的影响.方法 回顾性搜集行冠状动脉CTA检查的389例患者的病例资料,根据注射对比剂不同分为2组,A组采用碘克沙醇320,B组采用碘普罗胺370,记录CT增强扫描前屏气状态下心率(基础心率)、扫描过程中注射对比剂时屏气状态下心率(注射时心率).基础心率<75次/min时,舌下含服硝酸甘油0.25 mg.比较所有患者注射对比剂前后的心率变化并对2组患者的心率变化进行比较.结果 注射对比剂后心率变化>10次/min的患者A组有8例(4.4%),B组有10例(4.8%),2组无统计学差异(P>0.05).经静脉内注射对比剂时,2种对比剂均使患者心率减低(碘克沙醇下降4.2次/min、碘普罗胺下降2.7次/min,P>0.05),服用硝酸甘油均减轻对比剂对心率的影响.结论 经静脉注射碘克沙醇320与碘普罗胺370后,均约有4%的患者心率变化>10次/min,2种对比剂对心率的影响是一致的.