Volume 42 Issue 6
Dec.  2018
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Citation:

Study of image quality and diagnostic accuracy of low-dose coronary angiography using third-generation dual-source CT with free breathing and heart rate

  • Corresponding author: Kai Sun, Henrysk@163.com
  • Received Date: 2018-02-24
    Fund Project:

    National Natural Science Foundation of China 81560286

    Inner Mongolia Autonomous Region Health and Family Planning Commission 201302124

  • ObjectiveTo prospectively investigate the diagnostic accuracy, image quality, and radiation doses of electrocardiogram (ECG)-triggered high-pitch acquisition (turbo flash) coronary computed tomography(CT) angiography(CCTA) using third-generation dual-source CT compared with coronary angiography(CAG) for the diagnosis of significant coronary stenoses.MethodsProspectively collected 1003 patients who received the third-generation dual-source CCTA examination from April 2016 to April 2017. Among them, 70 patients underwent coronary angiography(CAG) 30 days after CCTA examination to score the image quality of each segment of coronary artery and calculate the effective radiation dose. The sensitivity, specificity, positive predictive value and negative predictive value of CCTA for coronary artery lesions were calculated using CAG results as the gold standard. The consistency of CCTA and CAG in grading coronary artery stenosis was evaluated by Kappa value and U test.Results(1) Image quality:no non-diagnostic image quality was observed in the right coronary artery nor left anterior descending artery. The rate of coronary segments with non-diagnostic image quality reached 0.04% in the left circumflex artery. (2) Diagnostic accuracy:the sensitivity, specificity, and positive and negative predictive values totaled 97.0%(289/298), 98.3%(706/718), 96.0%(289/301), 98.7%(706/715) for segment assessment and 97.5%(159/163), 85.1% (40/47), 95.8%(159/166), 90.9%(40/44) for vessel assessment, and all the values are 100% for patients assessment. CCTA was highly consistent with the site of coronary artery stenosis shown by CAG(U=2.4, P < 0.05). ⑶ Radiation doses:the effective radiation dose was(1.17±0.29) mSv on average.ConclusionsCCTA using the prospectively ECG-triggered high-pitch mode (turbo flash) of the third-generation dual-source CT system is associated with high diagnostic accuracy for the assessment of coronary artery stenoses at low doses.
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  • [1] 陈伟伟, 高润霖, 刘力生, 等. 《中国心血管病报告》摘要[J].中国循环杂志, 2016, 31(6):521-528. DOI:10.3969/j.issn.1000-3614. 2017.06.001.Chen WW, Gao RL, Liu LS, et al. Summary of China Cardiovascular Disease Report[J]. Chin Circ J, 2016, 31(6):521-528. DOI:10.3969/j.issn.1000-3614.2017.06.001.
    [2] Zhang LJ, Wang Y, Schoepf UJ, et al. Image quality, radiation dose, and diagnostic accuracy of prospectively ECG-triggered high-pitch coronary CT angiography at 70 kVp in a clinical setting:comparison with invasive coronary angiography[J]. Eur Radiol, 2016, 26(3):797-806. DOI:10.1007/s00330-015-3868-z.
    [3] Sun K, Han RJ, Ma LJ, et al. Prospectively electrocardiogram-gated high-pitch spiral acquisition mode dual-source CT coronary angiography in patients with high heart rates:comparison with retrospective electrocardiogram-gated spiral acquisition mode[J]. Korean J Radiol, 2012, 13(6):684-693. DOI:10.3348/kjr.2012.13. 6.684.
    [4] 孙凯, 韩瑞娟, 赵瑞平, 等.不同心率患者采用大螺距双源CT冠状动脉成像的图像质量及影响因素分析[J].中华放射学杂志, 2012, 46(9):773-778. DOI:10.3760/cma.j.issn.1005-1201.2012. 09.001.Sun K, Han RJ, Zhao RP, et al. The image quality and influencing factors of high-pitch dual-source CT coronary angiography in patients with different heart rates[J]. Chin J Radiol, 2012, 46(9):773-778. DOI:10.3760/cma.j.issn.1005-1201.2012.09.001.
    [5] Sun K, Liu GR, Li YC, et al. Intravenous Contrast Material Administration at High-pitch Dual-source CT Coronary Angiography:Bolus-tracking Technique with Shortened Time of Respiratory Instruction Versus Test Bolus Technique[J]. Chin Med Sci J, 2013, 27(4):225-231.
    [6] Wu FZ, Wu MT. 2014 SCCT guidelines for the interpretation and reporting of coronary CT angiography:a report of the Society of Cardiovascular Computed Tomography Guidelines Committee[J]. J Cardiovasc Comput Tomogr, 2015, 9(2):e3. DOI:10.1016/j.jcct.2015.01.003.
    [7] Leipsic J, Abbara S, Achenbach S, et al. SCCT guidelines for the interpretation and reporting of coronary CT angiography:a report of the Society of Cardiovascular Computed Tomography Guidelines Committee[J]. J Cardiovasc Comput Tomogr, 2014, 8(5):342-358. DOI:10.1016/j.jcct.2014.07.003.
    [8] Trattner S, Halliburton S, Thompson CM, et al. Cardiac-Specific Conversion Factors to Estimate Radiation Effective Dose From Dose-Length Product in Computed Tomography[J]. JACC Cardiovasc Imaging, 2018, 11(1):64-74. DOI:10.1016/j.jcmg.2017.06.006.
    [9] 孙凯, 韩瑞娟, 马利军, 等.大螺距双源CT前瞻性心电门控扫描评价冠状动脉狭窄的临床研究[J].中华放射学杂志, 2012, 46(1):49-53. DOI:10.3760/cma.j.issn.1005-1201.2012.01.012.Su K, Han RJ, Ma LJ, et al. The study of diagnostic accuracy of prospectively electrocardiogram-triggered high-pitch spiral acquisition using Flash dual-source CT for the assessment of coronary stenoses[J]. Chin J Radiol, 2012, 46(1):49-53. DOI:10.3760/cma.j.issn.1005-1201.2012.01.012.
    [10] Zheng M, Wei M, Wen D, et al. Transluminal attenuation gradient in coronary computed tomography angiography for determining stenosis severity of calcified coronary artery:a primary study with dual-source CT[J]. Eur Radiol, 2015, 25(5):1219-1228. DOI:10.1007/s00330-014-3519-9.
    [11] Sato S, Horii Y, Yoshimura N, et al. Coronary computed tomography angiography using 128-slice dual-source computed tomography in patients with severe calcification[J]. Jpn J Radiol, 2017, 35(8):432-439. DOI:10.1007/s11604-017-0650-y.
    [12] Mangold S, Wichmann JL, Schoepf UJ, et al. Diagnostic accuracy of coronary CT angiography using 3rd-generation dual-source CT and automated tube voltage selection:Clinical application in a non-obese and obese patient population[J]. Eur Radiol, 2017, 27(6):2298-2308. DOI:10.1007/s00330-016-4601-2.
    [13] Apfaltrer G, Szolar DH, Wurzinger E, et al. Impact on Image Quality and Radiation Dose of Third-Generation Dual-Source Computed Tomography of the Coronary Arteries[J]. Am J Cardiol, 2017, 119(8):1156-1161. DOI:10.1016/j.amjcard.2016.12.028.
    [14] Linsen PV, Coenen A, Lubbers MM, et al. Computed Tomography Angiography with a 192-slice Dual-source Computed Tomography System:Improvements in Image Quality and Radiation Dose[J]. J Clin Imaging Sci, 2016, 6:44. DOI:10.4103/2156-7514.192840.
    [15] Gordic S, Husarik DB, Desbiolles L, et al. High-pitch coronary CT angiography with third generation dual-source CT:limits of heart rate[J]. Int J Cardiovasc Imaging, 2014, 30(6):1173-1179. DOI:10.1007/s10554-014-0445-5.
    [16] Meyer M, Haubenreisser H, Schoepf UJ, et al. Closing in on the K edge:coronary CT angiography at 100, 80, and 70 kV-initial comparison of a second-versus a third-generation dual-source CT system[J]. Radiology, 2014, 273(2):373-382. DOI:10.1148/radiol.14140244.
    [17] Hell MM, Bittner D, Schuhbaeck A, et al. Prospectively ECG-triggered high-pitch coronary angiography with third-generation dual-source CT at 70 kVp tube voltage:feasibility, image quality, radiation dose, and effect of iterative reconstruction[J]. J Cardiovasc Comput Tomogr, 2014, 8(6):418-425. DOI:10.1016/j.jcct.2014. 09. 003.
    [18] Hausleiter J, Meyer TS, Martuscelli E, et al. Image quality and radiation exposure with prospectively ECG-triggered axial scanning for coronary CT angiography:the multicenter, multivendor, randomized PROTECTION-Ⅲ study[J]. JACC Cardiovasc Imaging, 2012, 5(5):484-493. DOI:10.1016/j.jcmg.2011.12.017.
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Study of image quality and diagnostic accuracy of low-dose coronary angiography using third-generation dual-source CT with free breathing and heart rate

    Corresponding author: Kai Sun, Henrysk@163.com
  • 1. Department of Image, Baotou Central Hospital, Central Clinical Medical College, Baotou Medical College, Baotou 014040, China
  • 2. Department of Cardiology, Baotou Central Hospital, Central Clinical Medical College, Baotou Medical College, Baotou 014040, China
  • 3. Department of Image, Baotou Cancer Hospital, Baotou 014030, China
Fund Project:  National Natural Science Foundation of China 81560286Inner Mongolia Autonomous Region Health and Family Planning Commission 201302124

Abstract: ObjectiveTo prospectively investigate the diagnostic accuracy, image quality, and radiation doses of electrocardiogram (ECG)-triggered high-pitch acquisition (turbo flash) coronary computed tomography(CT) angiography(CCTA) using third-generation dual-source CT compared with coronary angiography(CAG) for the diagnosis of significant coronary stenoses.MethodsProspectively collected 1003 patients who received the third-generation dual-source CCTA examination from April 2016 to April 2017. Among them, 70 patients underwent coronary angiography(CAG) 30 days after CCTA examination to score the image quality of each segment of coronary artery and calculate the effective radiation dose. The sensitivity, specificity, positive predictive value and negative predictive value of CCTA for coronary artery lesions were calculated using CAG results as the gold standard. The consistency of CCTA and CAG in grading coronary artery stenosis was evaluated by Kappa value and U test.Results(1) Image quality:no non-diagnostic image quality was observed in the right coronary artery nor left anterior descending artery. The rate of coronary segments with non-diagnostic image quality reached 0.04% in the left circumflex artery. (2) Diagnostic accuracy:the sensitivity, specificity, and positive and negative predictive values totaled 97.0%(289/298), 98.3%(706/718), 96.0%(289/301), 98.7%(706/715) for segment assessment and 97.5%(159/163), 85.1% (40/47), 95.8%(159/166), 90.9%(40/44) for vessel assessment, and all the values are 100% for patients assessment. CCTA was highly consistent with the site of coronary artery stenosis shown by CAG(U=2.4, P < 0.05). ⑶ Radiation doses:the effective radiation dose was(1.17±0.29) mSv on average.ConclusionsCCTA using the prospectively ECG-triggered high-pitch mode (turbo flash) of the third-generation dual-source CT system is associated with high diagnostic accuracy for the assessment of coronary artery stenoses at low doses.

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  • 冠心病是我国第一位致死性疾病,其发病率呈逐年上升趋势,目前,心血管病死占城乡居民总病死原因的首位,心血管病的疾病负担日渐加重,已成为重大的公共卫生问题[1]。冠状动脉CT成像(coronary computed tomography angiography,CCTA)以其检查的无创性、较高的准确率和快捷性等优点而成为检测冠状动脉狭窄的重要手段[2-3],但伴随而来的较高的辐射剂量问题也引起了人们的关注。传统的多排螺旋CCTA对人体的电离辐射较高,且由于时间分辨率所限,CCTA易受心率和呼吸运动的影响产生伪影[4],进而会降低诊断冠心病的准确率。第3代双源CT可使患者在自然呼吸并且无心率干预下完成高质量扫描,并且有效辐射剂量极低。本研究应用第3代双源CT Turbo Flash模式进行冠状动脉成像,并与传统冠状动脉造影(coronary angiography,CAG)进行比较,评价该方法诊断冠状动脉狭窄的准确性、图像质量及有效辐射剂量。

1.   资料与方法

    1.1.   临床资料

  • 前瞻性收集本院2016年4月至2017年4月临床疑诊为冠心病且需行CCTA的患者1003例,其中男性486例、女性517例,年龄27~88 (59±10)岁,体重40~109 (68.6±10.9)kg,身高130~190 (165.6±7.7)cm,身体质量指数(14.7~36.3) (24.9±3.1)kg/m2。心率45~113 (76±14)次/min,心率>70次/min者618例。其中有70例患者行CCTA后30 d内行CAG检查。

    排除标准:有对比剂过敏史、严重肝和(或)肾功能不全病史(肾小球滤过率 < 60 mL/min)、心功能不全、安装起搏器、患瓣膜病或其他心脏疾病(如心肌病或先天性心脏病、各种心律失常)、怀孕或哺乳期妇女。所有患者均于检查前签署了知情同意书。

  • 1.2.   CCTA检查

  • 采用第3代双源CT (德国西门子公司SOMATOM Force),检查前均不作呼吸训练,高心率患者不给予药物控制心率。扫描前常规舌下喷硝酸甘油2次。扫描模式为Turbo Flash模式,在一个心动周期采集数据。当患者心率>70次/min时,采集窗选择在最佳收缩期范围(50%~60%);当患者心率≤70次/min时,采集窗选择在最佳舒张期范围(20%~30%)。先行冠状动脉钙化积分扫描,扫描范围从气管分叉下2 cm到膈部,扫描方向从头向足,采用bolus-tracking技术[5],非离子对比剂碘海醇(欧乃派克,美国通用公司)的参考总量为50 mL,对比剂总量和流速可根据不同的身体质量指数进行调节,用双筒高压注射器(德国Ulrich,Missouri-XD2001)以5 mL/s的参考流速肘静脉注射,升主动脉根部为ROI (阈值100 HU),峰值时间后延迟4 s开始扫描,之后以5 mL/s注入生理盐水40 mL。扫描参数:准直2×96×0.6 mm,z-飞焦点方法采集2×192×0.6 mm,螺距3.2,采用自动管电流、管电压。图像重建层厚0.75 mm,重建间隔0.4 mm,采用软组织卷积核(B36f)。血管壁钙化的患者采用锐利组织卷积核(B49)重建图像来补偿伪像。图像经容积再现技术、最大密度投影、曲面重建、多平面重组和心血管优化分析软件等处理,筛选最佳CT图像用于血管评价。

  • 1.3.   图像评价方法

  • 采用双盲法由两位从业5年以上的放射科主治医师对患者图像进行评价,意见不一致时请主任医师会诊,得出最终结果。对直径≥1.5 mm的冠状动脉,根据美国心血管CT协会最新推荐的标准改良分段法[7-8],将冠状动脉树分为一级18个节段,闭塞血管以远段不记入分析。冠状动脉图像分为4级,相应评为1~4分:1分为血管显示良好,边界清晰,无伪影或血管中断;2分为血管边界模糊,有轻度伪影;3分为血管有中度伪影,尚能满足诊断要求;4分为血管显示不清,有严重伪影,不能作出诊断。统计冠状动脉图像质量并进行评分。

  • 1.4.   有效辐射剂量

  • 通过CT自动计算得到剂量长度乘积(dose length product,DLP),单位有效剂量(effective dose,ED)=k×DLP (k值参照2017年Trattner等[9]的研究,心脏k=0.026 mSv·mGy-1·cm-1)。

  • 1.5.   CAG

  • 选用PHILIPS FD10数字血管造影机,常规左CAG取4~6个体位、右CAG取2~3个体位投照,以CAG导管直径为基准。对左右冠状动脉及其主要血管内径进行定量分析。图像分析由两名从事CAG工作5年以上的介入科主治医师在未知CCTA结果的情况下独立完成,意见不一致时请主任医师会诊,得出最终结果。

  • 1.6.   统计学分析

  • 采用SPSS 21.0软件对数据进行统计学分析。计量资料以x±s表示,以CAG结果为金标准,计算CCTA显示冠状动脉病变的灵敏度、特异度、阳性预测值和阴性预测值。CCTA与CAG评价冠状动脉狭窄分级采用一致性检验,得出Kappa值后进行U检验。P<0.05表示差异有统计学意义。

2.   结果
  • 所有患者均顺利完成CCTA和CAG检查,无任何严重不良反应。

  • 2.1.   图像质量

  • 表 1可见,1003例患者所有可诊断血管节段:右冠状动脉图像质量为1分的节段占右冠状动脉节段的99.20% (3968/4000) (图 1)、2分的节段占0.55% (22/4000)、3分的节段占0.25% (10/4000)、不可诊断的血管节段为0;左冠状动脉主干及前降支图像质量为1分的节段占左冠状动脉节段的99.78% (5612/5624)、2分的节段占0.16% (9/5624)、3分的节段占0.05% (3/5624)、不可诊断的血管节段为0;回旋支图像质量为1分的节段占回旋支节段的98.73% (4152/4205)、2分的节段占1.02% (43/4205)、3分的节段占0.17% (7/4205)、不可诊断的血管节段为3段,中间支图像均显示良好。1003例患者中17例患者由于心率变异性较大,导致血管有运动伪影,但结果基本可供诊断,由此可知,影响图像质量的因素主要是心率变异性。

    Figure 1.  CCTA images of patients with suspected coronary heart disease

    节段号 评分/分 合计
    1 2 3 4
    右冠状动脉 1 992 7 4 0 1003
    2 987 10 6 0 1003
    3 997 5 0 0 1002
    4 992 0 0 0 992
    左冠状动脉主干 5 1003 0 0 0 1003
    6 1000 2 1 0 1003
    7 995 6 2 0 1003
    左冠状动脉前降支 8 1002 1 0 0 1003
    9 979 0 0 0 979
    10 633 0 0 0 633
    左冠状动脉回旋支 11 990 11 1 0 1002
    12 799 28 5 3 835
    13 997 4 1 0 1002
    14 391 0 0 0 391
    15 975 0 0 0 975
    16 531 0 0 0 531
    17 415 0 0 0 415
    18 20 0 0 0 20
    注:表中,CCTA:冠状动脉CT成像。

    Table 1.  CCTA coronary image quality score scale for 1003 suspected patients with coronary heart disease

  • 2.2.   CCTA的准确性

  • 70例行CAG检查的患者共显示出冠状动脉节段1014段,典型病例的CAG图像见图 2。基于节段水平分析,CCTA检查显示冠状动脉狭窄病变301段;CAG显示冠状动脉狭窄病变298段。基于节段分析、基于血管分析和基于患者分析,CCTA诊断冠状动脉狭窄的灵敏度、特异度、阳性预测值和阴性预测值的结果见表 2。CCTA与CAG在显示冠状动脉狭窄分级一致性检验上Kappa值为0.932,对Kappa值进行U检验,差异有统计学意义(U=2.4,P=0.008),这说明CCTA与CAG在显示冠状动脉狭窄分级上高度一致(图 3)。

    Figure 2.  Curved planar reformation images and electrocardiogramgating images of patients with suspected coronary heart disease

    Figure 3.  CCTA images and CAG images of patients with coronary artery stenosis were compared and the electrocardiogram-gating images were obtained

    分析部位 结果 统计分析(%)
    真阳性 假阳性 真阴性 假阴性 灵敏度 特异度 阳性预测值 阴性预测值
    基于节段分析(n=1014) 289 12 706 9 97 98.3 96 98.7
    基于血管分析(n=210) 159 7 40 4 97.5 85.1 95.8 90.9
    基于患者分析(n=70) 70 0 0 0 100 100 100 100

    Table 2.  Accuracy of Force CT in the diagnosis of coronary artery stenosis

  • 2.3.   有效辐射剂量结果

  • 1003例患者CCTA的DLP为16.5~78.7 mGy×cm[ (45.0±11.5)mGy×cm],ED为0.43×2.04 mSv[ (1.17±0.29)mSv]。

3.   讨论
  • 我们曾利用第2代双源CT大螺距模式做了不同心率的CCTA研究,结果显示心率≤65次/min且心率稳定的患者扫描成功率高,图像质量好[3-4, 10]。高心率患者采用RR间期的20%~30%采集图像,图像质量好。但前期研究具有一定局限性:①仅用第二代双源CT成像;②所有患者的心率均≤100次/min。本研究在前期研究基础上将样本量扩大为1003例,入选患者扫描时的最高心率达113次/min。

  • 3.1.   图像质量评价

  • 本研究结果显示,影响图像质量的因素有很多,最重要的是心率变异性,其直接影响扫描采集时间窗的选择。当患者心率>70次/min时,采集窗选择在最佳收缩期范围(50%~60%);当心率≤70次/min时,采集窗选择在最佳舒张期范围(20%~30%),有些患者扫描前心率在正常范围,扫描中由于紧张心率突然升高,导致扫描采集时间窗选择有误,采集时间窗落在QRS波峰上,图像质量欠佳。另外,回旋支图像质量相比其他血管显影稍差,不可诊断血管率高,右冠状动脉图像质量较左冠状动脉主干及前降支图像质量稍差,究其原因为右冠状动脉和回旋支行走于房室沟内,由于心房与心室的不同步收缩,导致右冠状动脉运动幅度较大而产生伪影。

  • 3.2.   准确性评价

  • 本研究结果显示,采用第3代双源CT Turbo Flash模式进行CCTA诊断冠状动脉狭窄的灵敏度为97.0%、特异度为98.3%、阳性预测值为96.0%、阴性预测值为98.7%。Zheng等[11]报道,第2代双源CT前瞻性心电门控大螺距模式诊断冠状动脉病变的灵敏度、特异度、阳性预测值和阴性预测值分别为72%、91%、88%和78%;Sato等[12]同样利用第2代双源CT大螺距模式行CCTA,灵敏度、特异度、阳性预测值和阴性预测值分别为92.2%、87.5%、69.6%和97.3%;Mangold等[13]利用第3代双源CT Turbo Flash模式行CCTA,灵敏度、特异度、阳性预测值和阴性预测值分别为96.0%、95.5%、93.9%和97.7%。与以上研究结果比较,本研究利用第3代双源CT Turbo Flash模式行CCTA的准确性较高。影响CCTA诊断准确率的因素有多种,在本研究的病例中,分析CCTA造成的假阴性、假阳性的21个血管节段中,11个节段由冠状动脉钙化引起,冠状动脉钙化严重时,病变处真实管腔被钙化遮盖,致使对狭窄程度的评估有误;6个节段由冠状动脉闭塞引起;4个节段由心肌桥造成。

  • 3.3.   辐射剂量评价

  • 本研究结果显示,有效辐射剂量的ED为(1.17±0.29)mSv,低于64排CT的12.29 mSv[14]及第2代双源CT的1.2 mSv[15]。Gordic等[16]报道,第3代双源CT行CCTA的有效辐射剂量为(0.4±0.1)mSv。Meyer等[17]用第3代双源CT行CCTA的有效辐射剂量为(0.44±0.1)mSv。Hell等[18]用第3代双源CT行CCTA的有效辐射剂量为(0.3±0.03)mSv。本研究结果与之相比,辐射剂量稍高,分析原因可能为本地区患者的身体质量指数相对较高,对部分患者我们采用了提高管电压的方法行CCTA,因此辐射剂量相对较高。另外,本研究k值参照的是Trattner等[9]的研究,心脏k=0.026 mSv·mGy-1·cm-1,而以往研究心脏k值均参照欧盟委员会关于CT的质量标准指南[19],利用胸部k=0.014 mSv·mGy-1·cm-1来计算有效辐射剂量。

  • 3.4.   本研究技术的关键点

  • 心率:本研究低心率患者(心率≤70次/min)扫描时间窗采用舒张期成像(50%~60%);高心率患者(心率>70次/min)采用收缩期成像(20%~30%)。除了严重心律不齐的患者,本研究用第3代双源CT行CCTA检查,基本做到了检查前无需对患者心率进行人工干预便可直接进行检查。1003例患者的心率为45~113 (76±14)次/min,心率>70次/min者618例,这些患者扫描前均未服用β受体阻滞剂等药物降低心率,采集的图像未因心率过快而影响图像质量,有17例因为心率变异性较大而导致右冠状动脉出现伪影,但结果基本可供诊断。Zheng等[11]采用第3代双源CT回顾性评估胸腹主动脉CCTA图像质量,入选病例仅50例,扫描前未服用β受体阻滞剂等控制心率,结果有14%的患者冠状动脉成像图像质量不佳,不能供临床诊断,冠状动脉成像的最高心率为70次/min。本研究的所有患者均采用Turbo Flash模式进行冠状动脉成像,不可诊断的血管节段仅3个节段,最高心率达113次/min。本研究结果显示,利用第3代双源CT行CCTA检查虽然对心率的快慢无明显要求,但心率变异性大的患者冠状动脉成像图像质量稍差,心律不齐的患者冠状动脉成像检查受限。

    呼吸:本研究的另外一个优势是患者可以在自然呼吸下进行冠状动脉成像。传统的螺旋CT,为了得到没有呼吸伪影的图像,需要屏气才能完成CCTA检查。在实际工作中,我们经常遇到不能配合呼吸命令的患者,如小儿、听力受损、危重或需急救、肺功能不好的老年人、严重的心肺或神经系统疾病引起的并发症或痴呆等患者,从而导致CCTA检查的失败。第3代双源CT的螺距达到3.2,使用Turbo Flash模式扫描可以在0.13 s内完成CCTA的检查,从而克服屏气对冠状动脉的影响。本研究的1003例患者CCTA检查均在没有呼吸的指令下完成的,结果显示,冠状动脉没有出现呼吸及心脏运动产生的伪影。

    综上所述,第3代双源CT Turbo Flash模式CCTA评价冠状动脉狭窄的图像质量好,准确性高,有效辐射剂量低;可在自然呼吸下和无心率干预下对患者进行检查,检查结果基本可供临床诊断。不足之处:本研究没有对存在病变的患者冠状动脉斑块性质及危险因素进行分析,未能对患者进行长期跟踪随访,这些将在日后的研究工作中进一步改善。

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