16层螺旋CT冠状动脉血管成像技术临床应用

目的:探讨16层螺旋CT冠状动脉成像技术临床应用价值。方法:对45例临床诊断或可疑冠心病的住院患者行16层螺旋CT冠状动脉回顾性心电门控平扫及增强扫描。将增强扫描图像传送到Wizard图像工作站进行最大密度投影(MIP)、多平面重组(MPR)、曲面重组(CPR)、容积再现技术(VRT)及平带多平面重组(RMPR)。并将VRT及MIP重组像为参照,用平扫图像对冠状动脉各支段进行钙化积分。结果:左冠状动脉主干(LM)、左前降支近中段(LAD1、LAD2)、第一对角支(D1)、左回旋支(LCX)及右冠状动脉近段(RCA1)显示均45例(100%),左前降支远段(LAD3)23例(51%),第二对角支(D2)30例(67%),第三对角支(D3)24例(53%),第一左缘支(M1)36例(80%),第二缘支(M2)28例(62%),右冠状动脉中段(RCA2)41例(91%),右冠状动脉远段(RCA3)43例(96%)及后降支(PDA)34例(76%)。左冠状动脉主干钙化12例(27%),左前降支近中段钙化有29例(64%),左回旋支钙化例数22例(49%),右冠状动脉近中段钙化有24例(53%)。结论:16层螺旋CT可对冠状动脉进行钙化积分并准确显影,是冠状动脉粥样硬化疾病筛选和诊断的首选方法。     

Evaluation of the optimal image reconstruction interval for coronary artery imaging using 64-slice computed tomography

BACKGROUND: Cardiac computed tomography (CT) has become an established complement in cardiac imaging. Thus, optimized image quality is diagnostically crucial. PURPOSE: To prospectively evaluate whether, by using 64-slice CT, a specific reconstruction interval can be identified providing best image quality for all coronary artery segments and each individual coronary artery. MATERIAL AND METHODS: 311 coronary segments of 14 men and seven women were analyzed using 64-slice CT. Data reconstruction was performed in 5% increments from 5-100% of the R-R interval. Four experienced observers independently evaluated image quality of the coronary arteries according to the AHA classification. A three-point ranking scale was applied: 1, very poor, no evaluation possible; 2, diagnostically sufficient quality; 3, highest image quality, no artifacts. RESULTS: The best reconstruction point for all segments was found to be 65% of the R-R interval (mean value 2.4+/-0.5; P<0.05). On a per-artery basis, best image quality was again achieved at 65% of the R-R interval: RCA 2.2+/-0.4, LCA 2.4+/-0.5, LM 2.5+/-0.2, LAD 2.3+/-0.4, LCX 2.3+/-0.5. CONCLUSION: By using 64-slice CT, the need for adjusting the reconstruction point to each coronary segment might be overcome. Best image quality was achieved with image reconstruction at 65% of the R-R interval for all coronary segments as well as each coronary artery.     

关于16层螺旋CT冠状动脉成像最佳重建相位窗选择的探讨

目的探讨16层螺旋CT冠状动脉造影的最佳重建相位窗。方法32例健康受检者行16层CT冠状动脉成像检查,在6个相位窗（心动周期的R波后40％、50％、60％、70％、80％、90％）上对冠状动脉进行CT图像重组,对这6个时相的薄层图像进行最大密度投影、二维曲面重建、多平面重建和容积再现重建。结果每位受检者的4条冠状动脉分支（左冠状动脉主干、左前降支、左回旋支、右冠状动脉）分别用于图像质量分析。左主干在6个R—R时相均显示良好,左前降支、左回旋支在70％相位窗的图像质量最佳,右冠状动脉在80％相位窗的图像质量最佳,整体图像在70％相位窗的重组图像质量最佳。结论16层螺旋CT冠状动脉成像,应首先选择70％相位窗。选择最佳相位窗进行图像重建可以明显提高图像质量和工作效率。     

心率对16层螺旋CT冠状动脉造影图像质量的影响

目的探讨心率对16层螺旋CT冠状动脉造影图像质量的影响。方法80例健康体检者行16层螺旋CT回顾性心电门控条件下冠状动脉造影。每位患者的4条冠状动脉分支(左冠状动脉主干、左前降支、左回旋支、右冠状动脉)分别用于图像质量分析。结果心率≤65次/m in有89.3%(100/112支)的图像可用于诊断;心率66~80次/m in有81.1%(198/244支)的图像可用于诊断;心率>80次/m in有64.3%(36/56支)的图像可用于诊断;心律不齐或前后波动>5次/m in有25%(8/32支)的血管可用于诊断。结论MSCTCA图像质量受心率影响,并与之呈负相关。     

Quantitative parameters to compare image quality of non-invasive coronary angiography with 16-slice, 64-slice and dual-source computed tomography

Multi-slice computed tomography (MSCT) is a non-invasive modality to visualize coronary arteries with an overall good image quality. Improved spatial and temporal resolution of 64-slice and dual-source computed tomography (DSCT) scanners are supposed to have a positive impact on diagnostic accuracy and image quality. However, quantitative parameters to compare image quality of 16-slice, 64-slice MSCT and DSCT are missing. A total of 256 CT examinations were evaluated (Siemens, Sensation 16: n = 90; Siemens Sensation 64: n = 91; Siemens Definition: n = 75). Mean Hounsfield units (HU) were measured in the cavum of the left ventricle (LV), the ascending aorta (Ao), the left ventricular myocardium (My) and the proximal part of the left main (LM), the left anterior descending artery (LAD), the right coronary artery (RCA) and the circumflex artery (CX). Moreover, the ratio of intraluminal attenuation (HU) to myocardial attenuation was assessed for all coronary arteries. Clinical data [body mass index (BMI), gender, heart rate] were accessible for all patients. Mean attenuation (CA) of the coronary arteries was significantly higher for DSCT in comparison to 64- and 16-slice MSCT within the RCA [347 ± 13 vs. 254 ± 14 (64-MSCT) vs. 233 ± 11 (16-MSCT) HU], LM (362 ± 11/275 ± 12/262 ± 9), LAD (332 ± 17/248 ± 19/219 ± 14) and LCX (310 ± 12/210 ± 13/221 ± 10, all p < 0.05), whereas there was no significant difference between DSCT and 64-MSCT for the LV, the Ao and My. Heart rate had a significant impact on CA ratio in 16-slice and 64-slice CT only (p < 0.05). BMI had no impact on the CA ratio in DSCT only (p < 0.001). Improved spatial and temporal resolution of dual-source CT is associated with better opacification of the coronary arteries and a better contrast with the myocardium, which is independent of heart rate. In comparison to MSCT, opacification of the coronary arteries at DSCT is not affected by BMI. The main advantage of DSCT lies with the heart rate independency, which might have a positive impact on the diagnostic accuracy. Christof Burgstahler and Anja Reimann contributed equally to this work     

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。     

16层螺旋CT冠状动脉成像最佳重建时相探讨

目的：探讨16层螺旋CT冠状动脉成像的最佳重建时相。方法：对40例临床诊断或拟诊冠心病的患者行16层螺旋CT冠状动脉成像检查，利用原始数据分别在每个R波前300ms、400ms、500ms、600ms处进行图像重建，得出不同重建时相的横断面图像，然后在工作站进行最大密度投影(MIP)、多平面重建(MPR)、容积再现技术(VRT)等方法的重建，评价不同重建时相冠状动脉各主要分支的图像质量等级及显示的节段数。结果：左冠状动脉主干在各个时相均显示良好，左前降支最佳重建时相为R波前400ms及500ms处，左回旋支及右冠状动脉最佳重建时相为R波前400ms处。结论：选择最佳时相进行图像重建可以最大限度减轻心脏运动伪影，提高图像质量。     

ECG-gated reconstructed multi-detector row CT coronary angiography: effect of varying trigger delay on image quality

PURPOSE: To evaluate the effectiveness of electrocardiographically (ECG)-gated retrospective image reconstruction for multi-detector row computed tomographic (CT) coronary angiography in reducing cardiac motion artifacts and to evaluate the influence of heart rate on cardiac image quality. MATERIALS AND METHODS: Sixty-five patients with different heart rates underwent coronary CT angiography. Raw helical CT data and ECG tracings were combined to retrospectively reconstruct at the defined consecutive z position with a temporal resolution of 250 msec per section. The starting points of the reconstruction were chosen between 30% and 80% of the R-R intervals. The relationships between heart rate, trigger delay, and image quality were analyzed. RESULTS: Optimal image quality was achieved with a 50% trigger delay for the right coronary artery and 60% for the left circumflex coronary artery. Optimal image quality for the left anterior descending coronary artery was equally obtained at 50% and 60% triggering. A significant negative correlation was observed between heart rate and image quality (P <.05). The best image quality was achieved when the heart rate was less than 74.5 beats per minute. CONCLUSION: To achieve high image quality, the heart rate should be sufficiently slow. Selection of appropriate trigger delays and a decreasing heart rate are effective to reduce cardiac motion artifacts.     

Optimal image reconstruction intervals for non-invasive coronary angiography with 64-slice CT

The reconstruction intervals providing best image quality for non-invasive coronary angiography with 64-slice computed tomography (CT) were evaluated. Contrast-enhanced, retrospectively electrocardiography (ECG)-gated 64-slice CT coronary angiography was performed in 80 patients (47 male, 33 female; mean age 62.1±10.6 years). Thirteen data sets were reconstructed in 5% increments from 20 to 80% of the R-R interval. Depending on the average heart rate during scanning, patients were grouped as <65 bpm (n=49) and ≥65 bpm (n=31). Two blinded and independent readers assessed the image quality of each coronary segment with a diameter ≥1.5 mm using the following scores: 1, no motion artifacts; 2, minor artifacts; 3, moderate artifacts; 4, severe artifacts; and 5, not evaluative. The average heart rate was 63.3±13.1 bpm (range 38–102). Acceptable image quality (scores 1–3) was achieved in 99.1% of all coronary segments (1,162/1,172; mean image quality score 1.55±0.77) in the best reconstruction interval. Best image quality was found at 60% and 65% of the R-R interval for all patients and for each heart rate subgroup, whereas motion artifacts occurred significantly more often (P<0.01) at other reconstruction intervals. At heart rates <65 bpm, acceptable image quality was found in all coronary segments at 60%. At heart rates ≥65 bpm, the whole coronary artery tree could be visualized with acceptable image quality in 87% (27/31) of the patients at 60%, while ten segments in four patients were rated as non-diagnostic (scores 4–5) at any reconstruction interval. In conclusion, 64-slice CT coronary angiography provides best overall image quality in mid-diastole. At heart rates <65 bpm, diagnostic image quality of all coronary segments can be obtained at a single reconstruction interval of 60%.     

Improvement of image quality with beta-blocker premedication on ECG-gated 16-MDCT coronary angiography

OBJECTIVE: The objective of our study was to assess the effect of beta-blockers on image quality of ECG-gated 16-MDCT coronary angiography. MATERIALS AND METHODS: Coronary CT angiography was performed in two groups: group 1, 24 volunteers (mean age, 50 years; mean heart rate, 69 beats per minute [bpm]; range, 47-97 bpm); and group 2, 15 patients with current ischemic heart disease (mean age, 54 years; mean heart rate, 54 bpm; range, 48-69 bpm) who were premedicated with 20-40 mg of oral propranolol 1 hr before the study. CT scans were obtained on a 16-MDCT scanner with a 12 x 0.75 mm collimation and 420-msec rotation using nonionic contrast material (80 mL; injection rate, 4 ml/sec). Images were reconstructed at 30-80% of the cardiac cycle in increments of 5%. Image quality of the following eight coronary segments was assessed by two radiologists in consensus: left main coronary artery; proximal and middle segments of the left anterior descending (LAD) and left circumflex (LCX) coronary arteries; and the proximal, middle, and distal segments of the right coronary artery (RCA). Image quality was assessed, using a 5-point grading scale, as grades 1-5. Images assessed as grade 4 or 5 were considered to be of diagnostically acceptable quality. RESULTS: In group 1, grade 4 or 5 image quality was achieved for visualization of 92% of the left main coronary arteries; 96% of the proximal LAD coronary arteries; 88% of the middle LAD, proximal LCX, and middle LCX coronary arteries; 83% of the proximal RCAs; 58% of the middle RCAs; and 96% of the distal RCAs. In group 2, this level of image quality was achieved in 100% of the left main coronary arteries, proximal and middle LAD arteries, and proximal LCX arteries; 87% of the middle LCX arteries; and 93% of the proximal, middle, and distal RCAs. CONCLUSION: Reduction of heart rates with beta-blocker premedication improves the image quality of CT coronary angiography, especially in terms of the visualization of the right coronary artery.     

Electrocardiogram-independent image reconstruction in cardiac multidetector computed tomography using retrospective motion synchronization

OBJECTIVE: We sought to evaluate an electrocardiogram (ECG)-independent image reconstruction technique for coronary computed tomography (CT)-angiography based on cardiac motion. MATERIALS AND METHODS: The raw data from 20 patients was reconstructed with both an ECG-gated algorithm and a motion-dependent algorithm that calculates the cardiac motion-function directly from the CT raw data using a center of mass technique. Images were reconstructed in 5% steps over the R-R interval and the cardiac motion-cycle. For both approaches multiplanar reformations were created and the set of images with the least motion artifacts was used for the evaluation. Motion artifacts affecting the ascending aorta, the left main coronary artery and the entire course of the LAD, LCX and RCA were scored using a 5-point scale. RESULTS: The mean optimal reconstruction window was at 60% of the R-R interval and 30% of the cardiac motion cycle. A total of 73 of 100 vascular regions showed no motion artifacts in ECG-gated images, with the motion-synchronized algorithm only 41 regions were free of motion artifacts. The mean motion-score was 1.4 (+/-0.6) and 2.4 (+/-1.2) respectively (P < 0.05). CONCLUSION: In the currently implemented form the motion-gated algorithm is inferior to ECG-gated image reconstruction but can be used in patients with an incomplete or corrupt ECG-signal.     

双源CT对先天性心脏病儿童冠状动脉成像效果分析

目的 分析儿童先天性心脏病双源CT(DSCT)扫描对冠状动脉显示的效果.方法 2名放射科医师分别对儿童先天性心脏病DSCT扫描的图像评分,按冠状动脉各分支成像效果评为1～4分,3分以上为成像质量较好,可以用于诊断.采用方差分析比较3个心率水平、3个年龄段下冠状动脉评分差异及4支冠状动脉分支间评分差异.采用多元线性回归分析比较各支冠状动脉评分与年龄、心率、管电压、管电流、螺距、对比剂总量、对比剂流率的关系.结果 共评价72例患儿(平均1.5岁),71.2%(205/288)的冠状动脉分支图像质量较好,可以用于诊断.左主干(3.64±0.49)分、前降支(2.97±0.40)分、右冠状动脉(2.82±0.70)分、回旋支(2.76±0.73)分,各支评分依次降低而不完全相同(F=29.00,P<0.01).<1岁组(2.80±0.65)分、≥1～3岁组(2.81±0.74)分、>3～14岁组(3.58±0.52)分,各组评分依次升高而不完全相同(F=20.16,P<0.01).心率<100次/min(bpm)组(3.54±0.56)分,100～150 bpm组(2.86±0.70)分,>150 bpm组(2.81±0.63)分,各组评分依次降低而不完全相同(F=16.72,P<0.01).多元回归分析显示年龄(r=0.013,P<0.01)和对比剂总量(r=0.292,P=0.011)与左主干评分呈正相关;年龄(r=0.509,P<0.01)、管电压与前降支评分呈正相关(r=0.292,P<0.01),心率与前降支评分呈负相关(r=-0.179,P<0.05);年龄与回旋支评分呈负相关(r=0.063,P<0.01);年龄、管电压与右冠状动脉评分呈正相关(r值分别为0.486、0.220,P值分别<0.01、<0.05).结论 DSCT能够清晰显示3岁以上或心率<100 bpm的先天性心脏病儿童的冠状动脉,限制DSCT成像效果的是患儿的基础心律和年龄.     

Usefulness of 64-slice MDCT for follow-up of young children with coronary artery aneurysm due to Kawasaki disease: initial experience

To evaluate the initial application and value of 64-slice multidetector computed tomography as an alternative diagnostic modality in the follow-up of young children with coronary artery aneurysm due to Kawasaki disease. Twelve boys (mean age 5.1 years, range 1.8-7.8 years) for follow-up (time range from 1.1 to 5.1 years) of known Kawasaki disease and coronary artery aneurysm underwent 64-slice MDCT ECG-gated coronary angiography. All data were acquired without breath holding. Two pediatric radiologists independently assessed image quality and the diameter of all coronary segments were measured for each patient. The number, position, shape and size of each coronary artery aneurysm were observed and compared with those of ECHO performed previously. A total of 118/156 segments permitted visualization with diagnostic image quality, the CT measurements showed good inter-observer and intra-observer reliability, coefficients were 0.93 and 0.88, respectively. A total of 30 coronary artery aneurysms were identified with measured mean of 7.5+/-3.8 mm in diameter, and of 12.4+/-9.1 mm in longitudinal lengths.10 tumors were small, 8 tumors were medium and 12 tumors were giant aneurysm. The affected segments included LM7/12(58.3%), 9/12(75%) of LAD1, 4/12(33.3%) of LAD2, 2/12(16.7%) of LCX1; 6/12(50%) of RCA1, 9/12(75%) of RCA2 and 4/12(33.3%) of RCA3, including affected two segments in 9 tumors and three segments in 1 tumor. Calcifications were found in 5 aneurysms and 3/5 with thrombosis; six stenotic segments were found. ECHO failed to detect 8 tumors with 2/8 in LAD, 1/8 in LCX and 5/8 in RCA, and those included 4 small aneurysms. The use of 64-slice MDCT angiography proved valuable for monitoring young children with Kawasaki disease. However, further study is necessary to specify the sensitivity and specificity of MDCT in the follow-up.     

Comparison of radiation dose,contrast enhancement and image quality of prospective ECG-Gated CT coronary angiography: Single versus dual source CT

IntroductionThe updated National Institute of Clinical Excellence (NICE) guidelines of 2017 state that new generation cardiac CT scanners (Aquilion ONE, Brilliance iCT, Discovery CT750 HD and Somatom Definition Flash) are recommended as an option for first-line imaging of the coronary arteries in people with suspected stable coronary artery disease (with an estimated likelihood of coronary artery disease of 10–29%) in whom imaging with earlier generation CT scanners is difficult. New generation cardiac CT scanners are also recommended as an option for first-line evaluation of disease progression, to establish need for revascularisation in people with known coronary artery disease in whom imaging with earlier generation CT scanners is difficult. CT scanning might not be necessary in situations in which immediate revascularisation is being considered. The European Society of Cardiology 2019 clinical practice guidelines recommend non-invasive functional imaging for myocardial ischaemia or coronary CT angiography (CTA) as the initial test to diagnose CAD in symptomatic patients in whom obstructive CAD cannot be excluded by clinical assessment alone. Given increased computed tomography coronary angiogram (CTCA) utilisation, radiation dose, contrast enhancement and image quality of prospective ECG-gated CTCA between 256-slice single-source and 192x2-slice dual-source CT scanners were retrospectively evaluated.MethodsProspectively gated CTCA data from 63 patients on a 256-slice CT (group A) and 71 patients on a 192x2-slice dual source CT (group B) from January to December 2016 were retrospectively evaluated respectively. Scanner-reported dose length product values were used with a conversion factor (k = 0.014 mSv/mGy x cm) to estimate effective dose. Contrast enhancement was assessed with mean CT attenuation at selected regions of interest on axial coronary images. Image quality of the coronary arteries was assessed by a 4-point grading score (1 = non-diagnostic, 4 = excellent image quality).ResultsThe radiation doses in group B were significantly lower than group A (3.68 + 2.13 mSv versus 4.81 + 1.56 mSv, p < 0.001). There were no significant differences in contrast enhancement in the left coronary artery, proximal right coronary artery and left ventricular wall for both groups. Vessel image quality scores for group B were higher than group A (right coronary artery (RCA): 3.2 + 0.7 versus 2.4 + 0.7, p < 0.001; left anterior descending (LAD) artery: 3.0 + 0.8 vs 2.5 + 0.6, p < 0.001; left circumflex (LCx) artery: 3.3 + 0.7 vs 2.6 + 0.6, p < 0.001). Coronary artery contour scores for group B were significantly higher than group A (RCA: 3.2 + 0.8 versus 2.3 + 0.7, p < 0.001; LAD: 3.0 + 0.7 versus 2.4 + 0.6, p < 0.001; LCx: 3.3 + 0.6 versus 2.5 + 0.6, p < 0.001).ConclusionProspective ECG-gated CTCA performed on 192x2-slice CT results in better image quality and lower radiation dose than 256-slice CT. There were no significant differences in contrast enhancement in left main coronary artery (LMCA), proximal RCA and left ventricular wall in both groups.Implications for practiceIn institutions with both 256-slice and 192x2-slice CT scanners, we recommend that CTCAs be preferentially performed using the 192x2-slice CT scanner.     

Coronary artery imaging during preoperative CT staging: preliminary experience with 64-slice multidetector CT in 99 consecutive patients

The purpose of this study was to evaluate the clinical feasibility of coronary artery imaging during routine preoperative 64-slice MDCT scans of the chest. Ninety-nine consecutive patients in sinus rhythm underwent a biphasic multidetector-row spiral CT examination of the chest without the administration of beta-blockers, including an ECG-gated acquisition over the cardiac cavities, followed by a non-gated examination of the upper third of the thorax. Data were reconstructed to evaluate coronary arteries and to obtain presurgical staging of the underlying disease. The percentage of assessable segments ranged from 65.4% (972/1,485) when considering all coronary artery segments to 88% (613/693) for the proximal and mid segments, reaching 98% (387/396) for proximal coronary artery segments. The 387 interpretable proximal segments included 97 (97%) LM, 99 (100%) LAD, 96 (97%) LCX and 95 (96%) RCA with a mean attenuation of 280.70±52.93 HU. The mean percentage of assessable segments was significantly higher in patients with a heart rate ≤80 bpm (n=48) than in patients with a heart rate greater than 80 bpm (n=35) (80±11% vs. 72±13%; P=0.0008). Diagnostic image quality was achieved in all patients for preoperative staging of the underlying disorder. The mean estimated effective dose was 12.06±3.25 mSv for ECG-gated scans and 13.88±3.49 mSv for complete chest examinations. Proximal and mid-coronary artery segments can be adequately evaluated during presurgical CT examinations of the chest obtained with 64-slice MDCT without the administration of β-blockers.     

64层螺旋CT冠状动脉血管成像诊断心肌桥-壁冠状动脉的价值

目的：探讨64层螺旋CT冠状动脉成像对心肌桥-壁冠状动脉的诊断价值。方法：2006年8月-2008年7月我院行64层螺旋CT冠状动脉成像432例,将原始数据传至工作站,行多平面重建（MPR）、容积重建（VR）、最大密度投影（MIP）和曲面重建（CPR）等后处理并进行分析。结果：432例行64层螺旋CT冠状动脉血管成像中发现心肌桥-壁冠状动脉72例,检出率为16.7%（72/432）。其中,63例发生于左冠状动脉前降支及其分支,10例发生在第一对角支,2例发生于第二对角支,8例发生在钝缘支,1例发生于回旋支,2例发生于右冠状动脉及其分支,另外,7例为多支病变。结论：64层螺旋CT冠状动脉成像对心肌桥-壁冠状动脉检出率高,是确诊心肌桥-壁冠状动脉并与冠心病相鉴别的有效方法。     

Clinical application of 64-slice spiral CT in the diagnosis of the Tetralogy of Fallot

OBJECTIVE: To explore the clinical application of 64-slice spiral CT in the diagnosis of the Tetralogy of Fallot. METHODS: Eighteen patients with diagnosed Tetralogy of Fallot underwent cardiac CT angiography with 64-slice CT (CTA). Two- and three-dimensional images were used for diagnosing in all cases by means of MPR (coronal, sagital and oblique), cMPR, MIP and VRT. RESULTS: All patients had ventricular septal defect, pulmonary stenosis and hypertrophy of right ventricle. The morphologic features of Tetralogy of Fallot were equal to echocardiography. Patent ductus arteriosus (PDA) were detected on eight patients. Main coronary artery branches and partial sub-branches were visualized in all patients. Abnormal coronary arteries were found in seven cases: both left and right main coronary artery arising from the right aortic sinus one case, right main coronary artery and circumflex (CX) arising from the right aortic sinus one case, left anterior descending (LAD) and CX arising from left aortic sinus directly one case, left and right coronary artery arising from back and front of the aortic sinus, respectively, three cases. Pulmonary artery branch stenosis was found in 12 cases and branch pulmonary artery dilation noticed in 1 case. Double superior vena cava was also found in one case. According to the surgery the diagnostic accuracy of CT and Echocardiography was 95.45 and 83.33%, respectively. CONCLUSION: Two- and three-dimensional 64-slice CTA not only show the overall anatomical structure of the heart, but also show coronary and pulmonary arteries. With these results, evaluation of coronary anomalies and pulmonary artery stenosis with 64-MSCT is extremely valuable for planning the operative procedure on the patients with Tetralogy of Fallot.     

Examination of the optimal temporal resolution required for computed tomography coronary angiography

Sub-second multidetector-row computed tomography systems provide great potential for the further improvement of CT coronary angiography (CTCA). However, because the temporal resolution (TR) of such CT systems is insufficient, blurring and artifacts produced by fast cardiac motion remain as unresolved issues. Previous TR investigations of CTCA were based on the retrospective electrocardiogram-gated multisegment reconstruction technique. However, the results obtained may not necessarily be correct because the TR of multisegment reconstruction may not be substantial due to the insufficient periodicity of cardiac motion. The optimal TR required for better CTCA images was evaluated with use of a dual-source CT system, which has various substantial TR modes (83, 125, and 165 ms). CTCA images of 147 patients with heart rates (HRs) ranging from 36 to 117 beats/minute (bpm) were evaluated visually on a 4-point scale. Our results revealed not only that the 165-ms TR is sufficient for low HRs (≤60 bpm), but also that the 83- and 125-ms TRs are unnecessary for such HRs. The image quality with the 125-ms TR mode was acceptable for the left anterior descending artery, left circumflex artery, and right coronary artery at low to intermediate HRs (≤70 bpm). At high HRs (>70 bpm), the 83-ms TR mode resulted in an excellent image quality for all cases except those with very rapid RCA motion. Adequate TRs for a wide range of heart rates (52–106 bpm) are thus clarified.     

双源CT全时相间隔重建四维模式对冠状动脉成像质量影响的初步观察

目的 利用双源CT全时相间隔重建并Inspace软件中的四维(4D)模式,评价双源CT对冠状动脉的多时相成像能力,并探讨冠状动脉CT成像(CTA)的质量随时相变化的规律及其形成原因.方法 对50例患者进行双源CT冠状动脉CTA检查,并作10%～100%(间隔10%)全时相重建,然后在后处理工作站上,利用Inspace软件中的4D模式,由2名有经验的放射科医师对各个时相的冠状动脉3支主要分支血管的成像质量进行评级(评分).结果 冠状动脉3支主要血管所有10个时相的平均成像质量评分分别为:右冠状动脉(RCA)1.71分,左前降支(LAD)2.57分,左回旋支(LCX)2.03分(最低为1分,最高为3分).在开始于心脏R-R问期的30%、40%和70%的重组时相窗上,冠状动脉的3支主要分支血管的成像质量平均评分均达到2.0以上.有41例(82%)3支主要血管在收缩期(10%～40%)和舒张期(50%～100%)内同时能找到1个或1个以上的时相其成像质量达到1级(3分).25例(50%)其前降支每一时相的成像质量均达到2级(2分)以上,其中5例(10%)每一时相的成像质量均达到1级.结论 双源CT初步具备了对冠状动脉收缩期和舒张期双期成像的能力,其成像质量存在2个高峰期,1个是收缩中晚期(30%～40%),1个是舒张中期(70%左右);但要达到全时相高质量成像还需进一步提高时间分辨率.     

64-slice computed tomography assessment of coronary artery stents: a phantom study

Purpose: To compare the use of a new 64-slice computed tomography (CT) scanner with 16-slice CT in the visualization of coronary artery stent lumen.

Material and Methods: Eight different coronary artery stents, each with a diameter of 3 mm, were placed in a static chest phantom. The phantom was positioned in the CT gantry at an angle of 0° and 45° towards the z-axis and examined with both a 64-slice and a 16-slice CT scanner. Effective slice thickness was 0.6 mm with 64-slice CT and 1 mm with 16-slice CT. A reconstruction increment of 0.3 mm was applied in both scanners. Image quality was assessed visually using a 5-point grading scale. Stent diameters were measured and compared using paired Wilcoxon tests.

Results: Artificial lumen reduction was significantly less with 64-slice than with 16-slice CT. Average visible stent lumen was 53.4% using 64-slice CT and 47.5% with 16-slice MSCT. Most severe artifacts were seen in stents with radiopaque markers. Using 64-slice CT, image noise increased by approximately 30% due to thinner slice thickness.

Conclusion: Improved spatial resolution of 64-slice CT resulted in superior assessment of coronary artery stent lumen compared to 16-slice CT. However, a relevant part of the stent lumen is still not assessable with multi-slice CT.