64层螺旋CT冠状动脉图像质量控制研究:最佳重组时相与心率关系

目的量化评估64层螺旋CT冠状动脉各分支不同重组时相图像质量,探讨冠状动脉CT成像最佳重组时相与心率关系。资料与方法102例患者均采用64层螺旋CT回顾性心电门控冠状动脉成像,男68例,女34例,平均年龄(58.1±9.7)岁,平均心率(66.4±11.5)次/min。心率<65次/min(n=43)为Ⅰ组,65～75次/min(n=34)为Ⅱ组,>75次/min(n=25)为Ⅲ组,每例患者的4支冠状动脉(左主干、左前降支、左回旋支、右冠状动脉)共分为12个节段用于图像质量分析。扫描原始数据以间隔5%在20%～80%时相分别回顾性重组冠状动脉图像,采用横断位、曲面重组、容积再现等方法对图像质量综合评分。结果Ⅰ组60%、65%和70%为最佳时相,Ⅱ组60%、65%时相为最佳时相,Ⅲ组右冠状动脉较优时相为35%、40%,左冠状动脉较优时相为60%、65%。结论心率和重组时相的选择是决定冠状动脉图像质量的重要因素。平均心率≤75次/min,冠状动脉各分支图像质量在心脏运动的舒张中期(60%、65%)最佳;>75次/min时,左右冠状动脉分别进行重组能明显提高冠状动脉的成像质量。     

64层探测器CT冠状动脉成像依据不同心率的最佳重建方案

目的:探讨64层螺旋CT冠状动脉成像不同心率下冠状动脉各节段血管的最佳重建时相。方法:对61例患者行64层螺旋CT冠状动脉成像,扫描后原始数据分别按R-R间期30%、35%、40%、45%、50%、60%、70%、75%的相位进行后处理重组,按扫描期间平均心率分组,Ⅰ组30例,心率70次/min;Ⅱ组31例,心率≥70次/min。分析不同心率组不同R-R时相对各支冠状动脉血管的显示情况。结果:Ⅰ组的所有的冠状动脉节段可以在单一的75%相位上获得最佳图像质量;Ⅱ组的所有冠状动脉可以在单一的45%或40%的相位上获得最佳图像质量,多时相重建并不能显著提高图像质量。结论:随着64层螺旋CT时间分辨率的充分发展,所有冠状动脉节段能在一个重建时相得到有诊断价值的图像,多时相重建并不能显著提高图像质量。     

64层CT冠状动脉成像最佳重建时间窗的探讨

目的 :探讨不同心率及不同重建时相对64层CT冠状动脉血管成像图像质量的影响。方法:收集90例临床疑诊冠心病患者的冠状动脉CTA检查资料。按扫描时平均心率分组,对心动周期的R-R相位30%~90%间期,每间隔5%重建后进行血管分析及评分,获得回顾性心电门控最佳重建时相,并评价不同心率时的图像质量。结果:冠状动脉图像质量随心率增加而降低,两者呈负相关。心率70次/min时,冠状动脉最佳重建时间窗为R-R间期的70%~75%;心率70~79次/min时,冠状动脉最佳重建时相为R-R间期的60%~70%;心率80次/min时,冠状动脉最佳重建时相为R-R间期的40%~50%。左前降支在70%和75%R-R重建时相显示最佳,左回旋支在70%R-R时相显示最佳,而右冠状动脉在50%R-R时相显示最佳。结论 :选择最佳重建时相、合理控制心率能够减轻运动伪影,明显提高冠状动脉成像质量,其中准确选择回顾性心电门控最佳重建时相是保证图像质量、准确诊断的重要因素。     

不同心率下双源CT冠状动脉成像最佳相位窗的研究

目的探讨双源CT冠状动脉成像在不同心率下最佳相位窗的选择。方法对100例临床怀疑冠心病或冠状动脉病变患者进行双源CT冠状动脉回顾性心电门控成像扫描,扫描后数据分别按R-R间期10%、20%、30%、40%、50%、60%、70%、80%、90%的相位进行后处理重组,图像行MPR、MIP、容积再现技术（VRT）重组,利用Inspace软件及Circulation软件分析,将图像质量分为4级,按冠状动脉分段标准评价各个节段的图像质量。扫描时记录心率,100例患者心率小于等于60次/min为1组,心率大于60次/min而小于等于80次/min为2组,心率大于80/min而小于等于100次/min为3组,心率大于100次/min为4组。分析观察不同心率组的各时相冠状动脉评分趋势。结果 1、2组70%相位图像质量最好,3、4组40%相位图像质量较好。冠状动脉的图像质量评分与心率有一定的相关性。结论心率越慢图像质量越好,心率越快图像质量越差。最佳时相的选择可以提高诊断冠心病的准确率。     

心率与螺距匹配与否对双源CT冠状动脉成像质量的影响

目的 分析螺距对双源CT冠状动脉成像的影响,以提高图像质量.方法 80例患者按心率与螺距是否相适应分为2组,第1组60例(心率与螺距相适应),再按心率分成3组,每组20例,依次为A组(心率≤70次/min),B组(70次/min<心率≤90次/min),C组(心率>90次/min).第2组20例(D组,心率与螺距不相适应).对各组图像进行质量评分,冠状动脉节段显示率和最佳重建期相分析.结果 C组的心率显著高于D组,分别是(105.15±11.45)次/min,(89.75±13.79)次/min,P<0.05;2组图像质量评分有差异性,分别是1.31±0.28,1.63±0.42,P<0.05.C组,D组冠状动脉节段显示率分别为96.9%和84.2%,P<0.05.A组最佳期相在60%～80%RR间期,B组最佳期相在30%～80%RR间期,C组最佳期相在30%～60%RR间期内.结论 心率与螺距匹配,双源CT能够在相当宽的心率范围内取得优良的冠状动脉图像质量;对心率变化者,心率与螺距不匹配,通过调整螺距适应心率,双源CT也能获得良好的冠状动脉图像质量,有很高的临床应用价值.     

64层螺旋CT冠状动脉血管成像最佳重建时相与心率关系

【摘要】目的：探讨回顾性心电门控64排螺旋CT冠脉血管成像心率与最佳重建时相的关系,并评价心率对最佳重建时相下图像质量及可诊断率的影响。方法：104例患者行64排螺旋CT（GE Optima 680）冠状动脉血管成像,回顾性重建R-R间期10%~90%期相,间隔5%。按心率分为3组(A组≤65次/分,B组65~80次/分,C组≥80次/分）。由两位医师独立对冠状动脉三大主要分支图像质量按5个等级进行评分。结果：心率≤65次/分,右冠状动脉（RCA）、左冠状动脉前降支（LAD）和左冠状动脉回旋支（LCX）的最佳重建时相为65%~75% R-R间期;65<心率<80次/分,RCA、LAD和LCX的最佳重建时相分别为45% R-R间期、75% R-R间期、45%或75% R-R间期;心率≥80次/分,RCA、LAD和LCX最佳重建时相为45%或50%或55% R-R间期。除A、B组间LAD和LCX的可诊断率无显著性差异外,其余任意两组间的可诊断率和图像质量评分均有显著性差异。结论：不同心率水平,回顾性心电门控64排螺旋CT冠脉血管成像RCA、LCX和LAD有不同的最佳重建时相。随着心率的增加,最佳重建时相下的图像质量及可诊断率降低。     

64层螺旋CT冠状动脉成像:不同心率下最优相位窗的探讨

目的:探讨64层螺旋CT冠状动脉成像在不同心率下最优成像相位窗.方法:对112例病例行64层螺旋CT冠状动脉成像,扫描后数据分别按R-R间期10%、20%、30%、40%、50%、60%、70%、80%及90%的相位进行后处理重组,对后处理图像按5级评分,记录扫描期间心率,112例患者心率＜60次/min者为Ⅰ组,60～69次/min为Ⅱ组,70～79次/min为Ⅲ组,≥80次/min为Ⅳ组,绘制不同心率组的冠状动脉成像质量评分随时相位变化的线图,分析观察不同心率组的各时相冠状动脉评分趋势.结果:Ⅰ、Ⅱ、Ⅲ组80%相位图像质量最优,Ⅳ组RCA最优的相位窗为50%相位,LMA、LAD、LCX最优的相位窗为40%,Pearson相关分析在R-R 40%相位,冠状动脉的图像质量评分与心率无显著相关性.结论:在不同心率下,64层螺旋CT冠状动脉成像各相位的图像质量有差别,高心率下,可用40%、50%相位的图像来用于诊断.     

双源CT冠状动脉成像在心房纤颤患者中的应用体会

目的:探讨应用双源CT时心房纤颤(AF)患者进行冠状动脉成像的可行性及心率对图像质量和重建时相的影响.方法:对29例临床可疑冠心病的AF患者进行双源CT增强扫描.29例患者按扫描时平均心率分成2组,慢心率组(＜80次/分)12人,快心率组(≥80次/分)17例.利用回顾性心电门控重建图像,以4级记分评价图像质量.比较慢心率组与快心率组的图像质量评分采用t检验.结果:慢心率组和快心率组的图像质量评分分别为(1.26±0.55)和(1.49±0.77)分,差异有统计学意义(t=-3.433,P＜0.01).慢心率组的最佳重建时相约一半出现在舒张期,快心率组的最佳重建时相多出现在收缩期.总体上29例患者97.4%的冠状动脉节段可以评价.结论:拥有高时间分辨力的双源CT能够为大部分房颤患者提供可评价的图像,心率对图像质量和重建时相有影响.     

房颤患者的64层CTCA:平均心率对图像质量和最佳重建期相的影响

目的:评价房颤患者64层螺旋CT冠状动脉成像中平均心率对最佳图像重建时相和图像质量的影响.方法:58例房颤患者行64层螺旋CT冠状动脉成像,扫描前均未服用美托洛尔.血管图像质量分为好、中等和差.分析平均心率和患者总体图像质量之间的相关性,采用判别分析法计算获得总体图像质量为好和中等的平均心率阈值和最佳重建时相在收缩末期的平均心率阈值.结果:平均心率和患者总体图像质量之间呈负相关(r=-0.43,P=0.001);患者总体图像质量为好和中等的平均心率阈值分别为80次/min和95次/min;最佳重建时相在收缩末期的平均心率阈值为85次/min.结论:控制患者平均心率在一定阈值以下并结合舒张中期蕈建.能保证房颤患者64层螺旋CT冠状动脉成像获得较高的图像质量.     

自适应前瞻性心电门控双源CT冠状动脉成像的初步研究

目的 探讨双源CT自适应前瞻性心电门控技术冠状动脉成像的可行性.方法 对31例患者行双源CT前瞻性心电门控技术冠状动脉成像.将患者分为2组:A组心率≤75次/min,选择R-R间期的70%扫描;B组心率＞75次/min,选择R-R间期的40%扫描.2名有经验的放射医师,利用双盲法、以4分法评定系统对冠状动脉15支分支血管成像质量进行评分,统计方法采用独立样本t检验.计算2组总CT剂量指数(CTDIvol)及有效剂量(ED)均值.结果 31例患者,共纳入分析的血管节段为437段,共有408支(93.4%)冠状动脉节段可满足影像学评价,29支(6.6%)冠状动脉节段不能满足影像学评价,其中A组共226个节段,12个节段(5.3%)不能评价,B组共211个节段,17个节段(8.1%)不能评价;31例患者冠状动脉均分3.57±0.64;其中A组冠状动脉均分(3.65±0.39)与B组冠状动脉均分(3.41±0.43)之间差异无统计学意义(t=1.62,P=0.12);在A、B 2组各段冠状动脉图像质量对照时,只有第10段2组图像质量差异有统计学意义(t=3.8,P＜0.05).CTDIvol均值为(18.88±5.04) mGy,有效剂量为(4.31±1.05) mSv.结论 双源CT自适应前瞻性心电门控冠状动脉成像技术在无需控制心率情况下可得到满足临床诊断的冠状动脉图像,加之低的辐射剂量有望成为冠状动脉CT成像常规的检查方法.     

Image quality, motion artifacts, and reconstruction timing of 64-slice coronary computed tomography angiography with 0.33-second rotation speed

OBJECTIVES: We sought to evaluate the impact of patients' heart rate (HR) on coronary CTA image quality (IQ) and motion artifacts using a 64-slice scanner with 0.33/360 degrees rotation. MATERIALS AND METHODS: Coronary CTA data sets of 32 patients (HR 65 bpm to 75 bpm, n = 7) examined on a 64-slice scanner (Sensation 64, Siemens Medical Solutions, Forchheim, Germany) with 0.33s/360 degrees gantry rotation speed were analyzed. All patients had suspicion of coronary artery disease. Data acquisition was performed using 64 x 0.6-mm collimation, and contrast enhancement was provided by injection of 80 mL of iopromide (5 mL/s + NaCl). Images were reconstructed throughout the RR interval using half-scan and dual-segment reconstruction. IQ was rated by 2 observers using a 3-point scale from excellent (1) to nondiagnostic (3) for coronary segments. Quality was correlated to the HR, time point of optimal IQ analyzed, and the benefit of dual-segment reconstruction evaluated. RESULTS: Overall mean IQ was 1.31 +/- 0.32 for all HR, with IQ being 1.08 +/- 0.12 for HR 65 bpm 75 bpm (P = 0.0003). Dual-segment reconstruction did not significantly improve IQ in any HR group (P = NS). Mean IQ was significantly better for LAD than for RCA (P < 0.0001) and LCX (P < 0.01). A total of 3.5% (11/318) of coronary artery segments were rated nondiagnostic by at least one reader based on motion artifacts. Although in HR < 65 bpm, the best IQ was predominately in diastole (93%), in HR > 75 bpm, the best IQ shifted to systole in most cases (86%). CONCLUSIONS: Temporal resolution at 0.33-second rotation allows for diagnostic IQ within a wide range of HR using half-scan reconstruction. With increasing HR the time point of best IQ shifts from mid-diastole to systole.     

Dual-source CT coronary angiography in patients with atrial fibrillation: Comparison with single-source CT

Objective

To evaluate the performance of dual-source computed tomography (DSCT) for the visualization of the coronary arteries in a population with atrial fibrillation (AF) compared to single-source CT (SSCT) and to explore the impact of patients’ heart rate (HR) on image quality (IQ) and reconstruction timing.

Methods

Thirty consecutive patients (11 male, 19 female; 69.0 ± 9.2 years old) with suspected coronary artery disease and permanent AF were examined on a DSCT scanner (120 kV, 400 mAs/rot, 0.33 s rotation time, 64 × 0.6 mm collimation, pitch 0.20–0.28, Siemens Somatom Definition). Patients were divided into two groups: low and medium HR group (HR ≤ 80 bpm, n = 14) and high HR group (HR > 80 bpm, n = 16). Five of the patients also underwent conventional coronary angiography (CAG). The raw data from both tube detector arrays were reconstructed as DSCT data using a routine algorithm (temporal resolution of 83 ms). The raw data from one tube detector array was reconstructed separately on the same system using a routine single source algorithm (temporal resolution of 83–165 ms) and defined as virtual SSCT data. Image quality was assessed using a four-point grading scale from excellent (1) to non-assessable (4).

Results

IQ of the DSCT data was significantly better than that of the virtual SSCT data (mean score 1.33 ± 0.61 vs. 1.80 ± 1.02; Z = −8.755, P = 0.000). 98.6% of the segments shown in DSCT were diagnostic, compared with 89.9% of the segments in virtual SSCT, χ² = 32.595, P = 0.000. In DSCT group, IQ of low HR group was also better than that of high HR group, although the difference was not as big (mean score 1.25 ± 0.52 vs. 1.38 ± 0.66; Z = −2.227, P = 0.026). The mean HR of low HR group and high HR group were 67.4 ± 8.5 beats per minute (bpm) and 94.2 ± 8.8 bpm (t = −8.499, P = 0.000). The range of the variation of HR was higher in high HR group than in low HR group (mean difference between maximum and minimum HR 79.5 ± 21.0 vs. 49.9 ± 21.1 bpm; t = −3.845, P = 0.001). In 23 (77%) patients optimal IQ was achieved within one phase for all three main arteries. In low HR group, the optimal phase was distributed evenly between diastole and systole; but in high HR group, the optimal phase shifted to systole in most cases (92%). In five cases these results were compared to CAG results to look for the ability to identify stenosis with a diameter reduction of more than 50% of the lumen. With DSCT it was possible to diagnose 20 of 21 stenosis and 48 of 49 non-stenosed vessel segments correctly. With SSCT 19 of 21 stenosis and 45 of 49 non-stenosed vessel segments were diagnosed correctly according to CAG.

Conclusion

Due to its high temporal resolution, DSCT provides images of full diagnostic image quality in patients with AF, which otherwise would be excluded from CT examinations. The number of assessable segments for DSCT is still somewhat less than in non-AF patients, but in opposition to SSCT still valid for routine diagnostic imaging. Patients’ HR had impact on IQ and reconstruction timing.     

双源CT冠状动脉成像在早搏患者中应用的初步体会

目的 探讨应用双源CT对早搏患者进行冠状动脉成像的可行性.方法 对70例临床可疑冠心病的早搏患者进行双源CT增强扫描.利用回顾性心电门控重建心电图编辑前后的图像,以4级记分评价图像质量.比较心电图编辑前后的图像质量采用配对t检验.结果 70例中28例患者的心率波动范围较小[(41.0±18.4)次/min],无需心电图编辑可获得诊断级图像;其余42例患者的心率波动范围较大[(71.4±28.7)次/min],心电图编辑前后的冠状动脉图像质量评分分别为(2.09±1.27)和(1.50±0.79)分,差异有统计学意义(t=13.764,P＜0.01);不可评价的冠状动脉节段比例从24.8%(154/620)降至3.4%(21/620).差异有统计学意义(X2=121.846,P＜0.01).70例患者98.0%(1014/1035)的冠状动脉节段可以评价.结论 拥有高时间分辨率的双源CT能够为早搏患者提供可评价的图像;对于心率波动范围大的患者,心电图编辑能够显著改善图像质量.     

Image quality and reconstruction intervals of dual-source CT coronary angiography: recommendations for ECG-pulsing windowing

PURPOSE: To evaluate reconstruction intervals and image quality in dual-source computed tomography (DSCT) coronary angiography for optimal placement of the ECG-pulsing window. MATERIALS AND METHODS: DSCT coronary angiography was performed in 60 patients. Thirteen datasets were reconstructed in 5% increments from 20-80%. Two readers independently assessed image quality of each segment in each percentage-interval, using scores ranging from 1 (no motion artifacts) to 4 (nonevaluable). RESULTS: Mean heart rate (HR) was 69.0 +/- 18.9 beats per minute (bpm) (range, 35-117 bpm). Diagnostic image quality (scores 1-3) was found in 97.8% of all segments (763 of 780). The 70% RR-interval provided best image quality in all patients and all HRs. The narrowest reconstruction window providing diagnostic image quality was 60-70% for HR <60 bpm, 60-80% for 60-70 bpm, 55-80% for 70-80 bpm, and 30-80% for HR >80 bpm. CONCLUSIONS: DSCT coronary angiography provides best image quality for various HRs at 70%. The ECG-pulsing window can be adapted according to the HR while maintaining diagnostic image quality.     

前瞻性心电门控双源CT冠状动脉成像在高心率患者中应用的可行性研究

目的 探讨心率不低于91次/分(bpm)患者回顾性心电门控双源CT(DSCT)冠状动脉成像R-R间期的最佳重建时相,从扫描时相选择的角度分析前瞻性心电门控(简称前门控)应用的可行性.方法 分析232例行回顾性心电门控DSCT冠状动脉成像患者(体质量指数23～25 kg/m2,心率≥91 bpm)的图像,根据扫描过程中患者屏气时心电监控记录到的心率将其分为3组(A～C组),A组83例,心率91～95 bpm,B组68例,心率96～100 bpm,C组81例,心率≥101 bpm.每隔3%重建1个时相,分别由2名医师独立对横断面图像、薄层MIP、CPR、VRT图像质量采用5分法进行综合评估,按照15段分段法,选出每个节段的R-R间期的最佳重建时相及范围.采用Kappa检验,评价2名医师对冠状动脉图像评分的一致性.结果 232例患者中,可评价冠状动脉节段共3343个,其图像最佳重建时相范围集中在81%～61%和51%～31%.3组冠状动脉节段与之相对应的节段数百分比:A组(91～95 bpm,83例的1183个节段)分别为5.49%、94.51%;B组(96-100 bpm,68例986个节段)分别为0.20%、99.80%;C组(≥101 bpm,81例1174个节段)分别为0.17%、99.83%.232例患者的3343个冠状动脉节段中3274个节段(97.94%)最佳重建时相范围集中在以41%为中心的51%～31%R-R间期范围内.2名医师对232例患者的3343个冠状动脉节段图像质量的评分结果得到了较高的一致性(Kappa值=0.883,P<0.05).结论 具有稳定的窦性心律,且屏气时平均心率≥91 bpm患者,冠状动脉节段的最佳重建时相集中于以R-R间期41%为中心的51%～31%,从扫描时相选择的角度考虑,可以对稳定高心率(≥91 bpm)患者行前门控横断面扫描,并且预设41%为曝光时间窗,成功把握较大.     

双源CT前瞻性心电门控对较高心率患者冠状动脉成像的准确性研究

目的 评价双源CT(DSCT)前瞻性心电门控对较高心率(HR)冠状动脉成像图像质量及诊断冠心病(CAD)的准确性.方法 回顾性分析103例连续患者的有创冠状动脉造影(ICA)和DSCT前瞻性心电门控冠状动脉成像资料,根据患者DSCT扫描时的心率分成3组,低心率组[<60次/min(bpm)]34例、中等心率组(60-70 bpm)36例和较高心率组(HR>70 bpm)33例.分析各组DSCT冠状动脉成像的图像质量(1～4分),以ICA为金标准,评价不同心率下DSCT前瞻性心电门控诊断CAD(狭窄≥50%)的敏感度和特异度,差异性用x2检验.结果 共1648个冠状动脉节段中的1580个(95.9%)能够满足诊断的图像质量要求,低、中、较高心率3组图像质量评分分别为(3.1±0.3)、(3.1±0.3)和(3.0±0.4)分(x2=2.80,P>0.05).各组诊断CAD的敏感度、特异度分别为82.8%(77/93)和98.4%(428/435),88.3%(91/103)和98.7%(442/448),80.3%(57/71)和98.6%(424/430)(x2值分别为0.69和0.13,P值均>0.05).总体ROC曲线下面积为0.94(95%可信区间为0.92～0.96),平均有效辐射剂量为(3.60±1.60)mSv.结论 DSCT前瞻性心电门控能够用于较高心率患者的冠状动脉成像,与较低心率组在诊断CAD时差异无统计学意义.

Abstract：

Objective To evaluate the diagnostic accuracy of dual-source CT(DSCT)prospective ECG-triggering coronary angiography in patients with different heart rate(HR).Methods One hundred and three patients with suspected coronary artery disease underwent DSCT prospective ECG-triggered coronary angiography and invasive coronary angiography(ICA).The patients were grouped by HR during CT scans:low HR(<60 bpm,n=34),medium HR(60-70 bpm,n=36)and high HR(>70 bpm,n=33).Image quality was scored using a 4-point scale.The sensitivity and specificity of DSCT in detecting≥50%stenosis were compared among subgroups where ICA was the gold standard.The differences were compared by using the X2 test of contingency on a per-segment and per-vessel basis.Results Image quality of 1580 coronary artery segments in 1648(95.9%)met the requirements for diagnosis.The image quality scores were(3.1±0.3),(3.1±0.3)and(3.0±0.4)point for subgroups(X2=2.80,P>0.05).Sensitivity and specificity were 82.8%(77/93)and 98.4%(428/435),88.3%(91/103)and 98.7%(442/448),and 80.3%(57/71)and 98.6%(424/430)for different subgroups(X2 were 0.69 and 0.13,all P>0.05).The overall area under the receiver operating characteristic(ROC)curve was 0.94(95%CI=0.92-0.96).The average effective radiation dose was(3.60±1.60)mSv.Conclusion DSCT coronary angiography with prospective ECG-triggering could be used for patients with high HR.And the diagnostic accuracy was not statistical significant between the patients with low HR and patients with medium to high HR.     

中低心率患者在双源CT低管电压冠状动脉成像中的图像质量及辐射剂量

目的 探讨中低心率对双源CT低管电压冠状动脉成像的图像质量及辐射剂量的影响.方法 对85例体质量指数(BMI)为17.51～30.00 kg/m2、心率在91次/min(bpm)以下的可疑冠心病患者进行双源CT低管电压(100 kVp)回顾性心电门控冠状动脉成像增强扫描,检查前不使用β受体阻滞剂控制心率.按患者扫描时的心率进行分组,≤59 bpm为A组(27例),60～69 bpm为B组(29例),≥70 bpm为C组(29例).评价各组的最佳重建时相图像,记录各组的增强扫描序列的螺距、CT容积剂量指数(CTDvol)、剂量长度乘积(DLP)及有效剂量(ED)值.应用单因素方差分析比较3组患者的扫描螺距、图像质量评分和辐射剂量值等.分析心率对冠状动脉成像图像质量及辐射剂量的影响.结果 A、B、C组螺距分别为0.241±0.025、0.286±0.034、0.335±0.036;3组图像质量评分分别为(4.78±0.26)、(4.66±0.56)、(4.70±0.46)分;CTDIvol值分别为(18.06±5.16)、(19.62±7.15)和(17.50±7.13)mGy,ED值分别为(4.23±1.16)、(4.59±1.75)、(4.12±1.39)mSv.3组的螺距差异有统计学意义(F=60.00,P=0.00);3组间的图像质量评分差异无统计学意义(F=0.53,P=0.59);3组间CTDIvol差异无统计学意义(F=0.83,P=0.44),ED差异也无统计学意义(F=0.86,P=0.43).结论 中低心率对双源CT低管电压冠状动脉成像的图像质量影响很小,在自动心电门控剂量窗时,对辐射剂量的影响也很小.

Abstract：

Objective To evaluate the imaging quality and radiation doses of dual-source computed tomography (DSCT) coronary angiography at a low tube voltage in patients with medium and low heart rate.Methods Eighty-five patients[heart rate (HR) ＜ 91 beats per minute (bpm); body mass index (BMI) 17. 51-30. 00 kg/m2]suspected of coronary artery disease received retrospectively ECG-gating coronary angiography with dual-source CT scanner (Somatom Definition, Siemens) at a tube voltage of 100 kVp. For all patients, no beta-blocker was used before CT scan. According to the HR, the patients were divided into three groups: Group A, HR ≤ 59 bpm, n = 27; Group B, HR 60-69 bpm, n = 29; Group C,HR ≥70 bpm, n = 29. All images were transferred to a workstation for postprocessing. The best R-R interval reconstruction images of all groups were evaluated. The value of pitch, CT volume dosage index (CTDIvol), dose length product (DLP)and effective dose (ED)were recorded. The pitch, the score of imaging quality of coronary artery segments and the radiation dose were compared with one-way ANOVA. The influence of HR on image quality and radiation doses of coronary artery was analyzed. Results The value of pitch in Group A, Group B and Group C was 0. 241 ± 0. 025, 0. 286 ± 0. 034 and 0. 335 ± 0. 036,respectively. The mean score of imaging quality of coronary artery segments in Group A, Group B and Group C was 4. 78 ± 0. 26, 4. 66 ± 0. 56 and 4. 70 ± 0. 46, respectively. The value of CTDIvol in Group A,Group B and Group C was (18.06 ±5. 16), (19. 62 ±7. 15) and (17. 50 ±7. 13) mGy, respectively. The value of ED in group A, Group B and Group C was (4.23 ± 1.76), (4.59 ± 1.75) and (4.12 ±1.39) mSv, respectively. There was statistical difference in value of pitch among the three groups (F =60. 00, P= 0. 00). There were no statistical difference in score of imaging quality, CTDIvol and value of ED among the three groups (F = 0. 53, P = 0. 59; F = 0. 83, P = 0. 44 ; F = 0. 86, P = 0. 43). Conclusion Medium and low HR have little influences on image quality of dual-source CT coronary angiography at a low tube voltage. When the auto ECG-gating is selected, there is little influence on radiation dosage as well.     

第二代双源CT冠状动脉成像前门控大螺距扫描的初步经验

目的:初步分析第二代双源CT前瞻性心电触发大螺距扫描(Flash模式)行心脏冠状动脉成像的图像质量,同时观察扫描的辐射剂量.方法:回顾性分析了87例第二代双源CT使用Flash扫描模式(前瞻性心电触发选在60% R-R间期,螺距3.4)行冠脉成像患者的图像质量.分别由2名医师采用4级法进行综合评估,1～3级图像为可评估,能用于影像诊断,4级为不可评估; 根据美国心脏学会冠脉16段分段法,对各段图像质量进行分级评估;再根据扫描心率,分成≤65次/min和＞65次/min 2组病例,比较2组间图像质量的差异;统计分析此种扫描模式的平均辐射剂量.结果:共评价冠脉1 047段,可用于诊断的节段占97.3%,不可评价节段占2.7%;平均心率≤65次/min组可评价血管节段为99.5%,平均心率＞65次/min 组可评价血管节段是89.1%,2组图像质量差异有统计学意义(P＜0.05).平均每例扫描辐射剂量为(1.25±0.45)mSv.结论:使用Flash模式行冠脉CTA扫描图像质量较高;对于心律较整齐患者,影响其图像质量的主要因素是心率,在60%R-R间期采集时,扫描时心率≤65次/min图像质量较心率＞65次/min可评价比例明显提高;此种模式较其他扫描模式辐射剂量显著降低.     

Image quality on dual-source computed-tomographic coronary angiography

Multi-detector CT reliably permits visualization of coronary arteries, but due to the occurrence of motion artefacts at heart rates >65 bpm caused by a temporal resolution of 165 ms, its utilisation has so far been limited to patients with a preferably low heart rate. We investigated the assessment of image quality on computed tomography of coronary arteries in a large series of patients without additional heart rate control using dual-source computed tomography (DSCT). DSCT (Siemens Somatom Definition, 83-ms temporal resolution) was performed in 165 consecutive patients (mean age 64 +/- 11.4 years) after injection of 60-80 ml of contrast. Data sets were reconstructed in 5% intervals of the cardiac cycle and evaluated by two readers in consensus concerning evaluability of the coronary arteries and presence of motion and beam-hardening artefacts using the AHA 16-segment coronary model. Mean heart rate during CT was 65 +/- 10.5 bpm; visualisation without artefacts was possible in 98.7% of 2,541 coronary segments. Only two segments were considered unevaluable due to cardiac motion; 30 segments were unassessable due to poor signal-to-noise ratio or coronary calcifications (both n = 15). Data reconstruction at 65-70% of the cardiac cycle provided for the best image quality. For heart rates >85 bpm, a systolic reconstruction at 45% revealed satisfactory results. Compared with earlier CT generations, DSCT provides for non-invasive coronary angiography with diagnostic image quality even at heart rates >65 bpm and thus may broaden the spectrum of patients that can be investigated non-invasively.