Evaluation of computed tomography coronary angiography in patients with a high heart rate using 16-slice spiral computed tomography with 0.37-s gantry rotation time

The aim of our study is to evaluate computed tomography (CT) coronary angiography in patients with a high heart rate using 16-slice spiral CT with 0.37-s gantry rotation time. We compare the image quality of patients whose heart rates were over 70 beats per minute (bpm) with that of patients whose heart rates were 70 bpm or less. Sixty patients with various heart rates underwent retrospectively ECG-gated multislice spiral CT (MSCT) coronary angiography. Two experienced observers who were blind to the heart rates of the patients evaluated all the MSCT coronary angiographic images and calculated the assessable segments. A total of 620 out of 891 (69.6%) segments were satisfactorily visualized. On average, 10.3 coronary artery segments per patient could be evaluated. In 36 patients whose heart rates were below 70 bpm [mean 62.2 bpm±5.32 (standard deviation, SD)], the number of assessable segments was 10.72±2.02 (SD). In the other 24 patients whose heart rates were above 70 bpm [mean 78.6 bpm±8.24 (SD)], the corresponding number was 9.75±1.74 (SD). No statistically significant difference was found in these two subgroups t test, P>0.05. The new generation of 16-slice spiral CT with 0.37-s rotation time can satisfactorily evaluate the coronary arteries of patients with high heart rates (above 70 bpm, up to 102 bpm).     

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冠状动脉血管成像与冠脉造影结果对照研究

目的:评价多层螺旋CT(MSCT)冠状动脉血管成像方法显示管腔≥50%狭窄的准确性,分析改善成像质量的方法.方法:对72例临床诊断或可疑冠心病的患者在心电门控下采用64层螺旋CT进行冠状动脉血管成像.其中56例在2周内行导管法冠状动脉造影.结果:本组56例与冠状动脉造影结果相对照,冠状动脉血管成像诊断≥50%血管狭窄的敏感性为91.5%,特异性为97.5%,阳性预测值为82.3%,阴性预测值为98.9%.结论:64层螺旋CT冠状动脉血管成像具有较高的敏感性和特异性,同时具有无创和简便的特点,可以作为临床对高危人群筛查的首选方法.     

Quantitative parameters of image quality in 64-slice computed tomography angiography of the coronary arteries

We explored quantitative parameters of image quality in consecutive patients undergoing 64-slice multi-detector computed tomography (MDCT) coronary angiography for clinical reasons. Forty-two patients (36 men, mean age 61 +/- 11 years, mean heart rate 63 +/- 10 bpm) underwent contrast-enhanced MDCT coronary angiography with a 64-slice scanner (Siemens Sensation 64, 64 mm x 0.6 mm collimation, 330 ms tube rotation, 850 mAs, 120 kV). Two independent observers measured the overall visualized vessel length and the length of the coronary arteries visualized without motion artifacts in curved multiplanar reformatted images. Contrast-to-noise ratio was measured in the proximal and distal segments of the coronary arteries. The mean length of visualized coronary arteries was: left main 12 +/- 6 mm, left anterior descending 149 +/- 25 mm, left circumflex 89 +/- 30 mm, and right coronary artery 161 +/- 38 mm. On average, 97 +/- 5% of the total visualized vessel length was depicted without motion artifacts (left main 100 +/- 0%, left anterior descending 97 +/- 6%, left circumflex 98 +/- 5%, and right coronary artery 95 +/- 6%). In 27 patients with a heart rate < or = 65 bpm, 98 +/- 4% of the overall visualized vessel length was imaged without motion artifacts, whereas 96+/-6% of the overall visualized vessel length was imaged without motion artifacts in 15 patients with a heart rate > 65 bpm (p < 0.001). The mean contrast-to-noise ratio in all measured coronary arteries was 14.6 +/- 4.7 (proximal coronary segments: range 15.1 +/- 4.4 to 16.1 +/- 5.0, distal coronary segments: range 11.4 +/- 4.2 to 15.9 +/- 4.9). In conclusion, 64-slice MDCT permits reliable visualization of the coronary arteries with minimal motion artifacts and high CNR in consecutive patients referred for non-invasive MDCT coronary angiography. Low heart rate is an important prerequisite for excellent image quality.     

Noninvasive coronary angiography using 64-slice spiral computed tomography in an unselected patient collective: effect of heart rate, heart rate variability and coronary calcifications on image quality and diagnostic accuracy

OBJECTIVE: The aim of this study was to assess the impact of heart rate, heart rate variability and calcification on image quality and diagnostic accuracy in an unselected patient collective. SUBJECTS AND METHODS: One hundred and two consecutive patients with known or suspected coronary artery disease underwent both 64-MSCT and invasive coronary angiography. Image quality (IQ) was assessed by independent observers using a 4-point scale from excellent (1) to non-diagnostic (4). Accuracy of MSCT regarding detection or exclusion of significant stenosis (>50%) was evaluated on a per segment basis in a modified AHA 13-segment model. Effects of heart rate, heart rate variability, calcification and body mass index (BMI) on IQ and accuracy were evaluated by multivariate regression. IQ and accuracy were further analysed in subgroups of significant predictor variables and simple regression performed to calculate thresholds for adequate IQ. RESULTS: Mean heart rate was 68.2+/-13.3 bpm, mean heart rate variability 11.5+/-16.0 beats per CT-examination (bpct) and median Agatston score 226.5. Average IQ score was 2+/-0.6 whilst diagnostic quality was obtained in 89% of segments. Overall sensitivity, specificity, PPV or NPV was 91.2%, 99.2%, 95.3% or 98.3%. According to multivariate regression, overall IQ was significantly related to heart rate and calcification (P=0.0038; P<0.0001). The effect of heart rate variability was limited to IQ of RCA segments (P=0.018); BMI was not related to IQ (P=0.52). Calcification was the only predictor variable with significant effect on the number of non-diagnostic segments (P<0.0001). In a multivariate regression, calcification was also the single factor with impact on diagnostic accuracy (P=0.0049). CONCLUSION: Whilst heart rate, heart rate variability and calcification all show an inverse correlation to IQ, severe calcium burden remains the single factor with translation of such effect into decrease of diagnostic accuracy.     

Radiation dose and cancer risk estimates in 16-slice computed tomography coronary angiography

Background  Recent advances have led to a rapid increase in the number of computed tomography coronary angiography (CTCA) studies performed. Whereas several studies have reported the effective dose, there are no data available on cancer risk for current CTCA protocols. Methods and Results  Effective and organ doses were estimated, by use of scanner-derived parameters and Monte Carlo methods, for 50 patients having 16-slice CTCA performed for clinical indications. Lifetime attributable risks were estimated with models developed in the National Academies’ Biological Effects of Ionizing Radiation VII report. The effective dose of a complete CTCA averaged 9.5 mSv, whereas that of a complete study, including calcium scoring when indicated, averaged 11.7 mSv. Calcium scoring increased effective dose by 25%, whereas tube current modulation reduced it by 34% and was more effective at lower heart rates. Organ doses to the lungs and female breast were highest. The lifetime attributable risk of cancer incidence from CTCA averaged approximately 1 in 1,600 but varied widely among patients, being highest in younger women. For all patients, the greatest risk was from lung cancer. Conclusions  CTCA is associated with non-negligible risk of malignancy. Doses can be reduced by careful attention to scanning protocol. This study was presented in part at the American College of Cardiology 55th Annual Scientific Session, Atlanta, Ga, March 13, 2006. This work was supported in part by a National Institutes of Health/National Center for Research Resources Clinical and Translational Science Award (1 UL1 RR-24156-01).     

影响16层螺旋CT冠状动脉成像质量技术因素的探讨

目的:探讨16层螺旋CT冠状动脉血管成像技术。方法:272例受检者行16层螺旋CT冠状动脉血管成像检查,采用电影扫描序列,层厚为1.25mm或0.625mm,螺距为0.275:1,对比剂1.5~2ml/kg,注射速率3~4ml/s,采用容积再现(VR)、多平面重建(MPR)、曲面重建(CPR)和仿真内窥镜(VE)进行图像后处理重建,显示冠状动脉主干及其主要分支。结果:心率对图像质量的影响较大(χ2=23.936,P<0.01),心率平稳,心率在55~75次/min,MSCT对冠状动脉主干及主要分支显示率80.3%达到诊断要求,心率大于90次/分时,冠状动脉的主要分支显示不清;重建相位窗在55%、65%和75%之间显示一、二级高质量冠状动脉图像的例数无显著性差异(χ2=1.980,P>0.05),选择重建相位窗为75%可提高工作效率;采用扫描层厚为0.625mm或1.25mm(重建间隔为0.625)所得到的图像质量可满足影像及临床诊断需要(χ2=0.833,P>0.05),选择扫描层厚1.25mm所获得图像的信噪比及移动伪影明显减少;采用3.5ml/s或4ml/s注射速率图像重建后达到一、二级水平的图像质量基本接近(χ2=0.268,P>0.05),使用注射速率为3.5ml/s,显示冠状动脉清晰且受腔静脉伪影少。结论:心率平稳且小于75次/min,使用合适的重建相位窗、对比剂及扫描参数,MSCT可满意显示冠状动脉主干及主要分支,可作为冠状动脉粥样硬化疾患的筛选,对血管搭桥和内支架放置术后复查的评价有较高临床价值。     

Flat-panel detector computed tomography for the assessment of coronary artery stents: phantom study in comparison with 16-slice spiral computed tomography

PURPOSE: The evaluation of coronary artery stents is a major limitation of cardiac multislice spiral computed tomography (MSCT). The development of flat-panel detector computed tomography (FPCT) with truly isotropic spatial resolution may overcome this limitation. Thus, we evaluated the use of FPCT in comparison to MSCT for the assessment of coronary artery stents. MATERIAL AND METHODS: Eight different coronary artery stents with a diameter of 3 mm each were placed in a static chest phantom. The phantom was positioned in the CT gantry at angles of 0 degrees , 45 degrees , and 90 degrees toward the z-axis and examined with the prototype of a FPCT (Siemens, Forchheim, Germany) and a commercially available 16-detector row MSCT (Sensation 16, Siemens). Slice thickness was 0.25 mm with FPCT whereas for MSCT, an effective slice thickness of 1 mm with a reconstruction increment of 0.5 mm was used. Image quality was assessed visually using a 5-point grading scale. Stent diameters were measured and compared using a repeated-measures analysis of variance. RESULTS: When compared with MSCT, artificial lumen reduction was significantly less using FPCT. On average the visible stent lumen was reduced by 16.1% with FPCT, whereas the mean of the lumen reduction was 47.2% with 16-detector row MSCT. Visible lumen diameter as well as image noise significantly increased using FPCT (P < 0.001). With FPCT delineation of the different stent struts became possible. CONCLUSION: FPCT proved to be superior when compared with 16-detector row MSCT for the in vitro assessment of coronary artery stents. Improved spatial resolution allows for a detailed assessment of the coronary artery stent lumen.     

16层螺旋CT冠状动脉成像的临床应用

目的:探讨16层螺旋CT冠状动脉(简称冠脉)成像在冠心病诊断中的临床价值。方法:选取50例临床诊断或可疑冠心病患者行16层螺旋CT冠状动脉造影检查(MSCTCA),先行冠脉钙化积分平扫,然后行冠脉增强扫描,选取一组质量最佳的薄层图像行冠脉三维重建,分析MSCTCA对冠状动脉狭窄性病变的显示能力,并对冠脉支架显示及通畅性进行评价。结果:冠脉钙化积分与其狭窄程度呈正相关,中度以上狭窄的冠脉钙化积分值明显高于轻度狭窄,其间有统计学显著性差异(P<0.001)。MSCTCA对诊断有临床意义的冠脉中度以上狭窄的敏感度、特异度、诊断准确率、阳性预测值、阴性预测值分别约89.6%、93.9%、92.6%、86.7%、95.4%。MSCTCA对冠脉支架显示良好,检出5例9根支架,其中2根支架不通畅,出现支架内再狭窄。结论:16层螺旋CT冠脉成像安全、无创,对评价冠状动脉狭窄、支架开放及通畅性等方面有着较高的临床应用价值,可作为冠心病筛查的有效手段以及介入和手术治疗后的随访手段。     

16层螺旋CT冠状动脉成像的技术与应用

目的:探讨多层螺旋CT冠状动脉造影(multislice spiral CT coromary angiography,MSCTCA)的成像技术和临床应用价值。方法:37例患者行MSCTCA检查,利用多种方法进行重建,分析影响冠状动脉图像质量的重要因素,MSCTCA对冠状动脉的显示能力,冠状动脉狭窄程度的评价,冠状动脉斑块性质的判断,冠状动脉的解剖变异,并了解桥血管和支架的通畅性。结果:容积再现图像最佳的显示相位窗为75%,左主干、左前降支重建的最佳相位为75%,右冠和左回旋支为50%~70%。MSCTCA能显示的管腔最小径1.5mm。对冠状动脉的解剖变异、冠状动脉狭窄的程度、斑块的性质及桥血管和内支架显示良好。结论:MSCTCA可作为冠心病介入治疗前的筛选,能能评价斑块的性质,在血运重建后的复查中也有很高的应用价值,并能提供冠状动脉其他病变的信息。     

Screening for carotid injury in trauma patients: image quality of 16-detector-row computed tomography angiography

Background: The introduction of multidetector-row computed tomography (MDCT) has revolutionized the initial management of multiply injured patients. This technology has the potential to improve the imaging of traumatic vascular injuries.

Purpose: To evaluate the quality of multidetector-row computed tomography angiography (MDCTA) of the carotid arteries in the setting of a routine whole-body trauma scan.

Material and Methods: 87 trauma patients underwent a routine whole-body CT scan in a 16-detector-row scanner including an MDCTA with a reconstructed axial slice thickness of 3 mm. Images were reviewed by three experienced radiologists with emphasis on image quality. Contrast density, severity, and origin of artifacts and the occurrence of vessel lesions were assessed for different vessel segments.

Results: 3642 separate vessel segments were evaluated. Contrast density was rated good or sufficient for diagnosis in 99.8%. A total of 67.3% of vessel segments were free of artifacts, while 27.9% of vessel segments showed minor artifacts not impairing diagnostic evaluation. Clinically relevant artifacts obscuring a vessel segment occurred in 4.7% and were mostly caused by dental hardware. Four dissections of the internal carotid artery were diagnosed by all three radiologists.

Conclusion: As a rapid screening test for blunt carotid artery injury, integration of MDCTA in the routine imaging workup of trauma patients utilizing a whole-body CT trauma scan is possible and practicable. Image quality is mostly sufficient for diagnosis, but impaired in a few cases by artifacts deriving primarily from dental hardware.     

Diagnostic accuracy of 64-slice computed tomography coronary angiography in patients with low-to-intermediate risk

PURPOSE: Our aim was to evaluate the diagnostic accuracy of 64-slice computed tomography coronary angiography (MSCT-CA) for detecting significant stenosis (>or=50% lumen reduction) in a population of patients at low to intermediate risk. MATERIALS AND METHODS: We studied 72 patients (38 men, 34 women, mean age 53.9+/-8.0 years) with atypical or typical chest pain and stratified in the low-to intermediate risk category. MSCT-CA (Sensation 64 Cardiac, Siemens, Germany) was performed after IV administration of 100 ml of iodinated contrast material (Iomeprol 400 mgI/ml, Bracco, Italy). Two observers, blinded to the results of conventional coronary angiography (CAG), assessed the MSCT-CA scans in consensus. Diagnostic accuracy for detecting significant stenosis was calculated. RESULTS: CAG demonstrated the absence of significant disease in 70.1% of patients (51/72). No patient was excluded from MSCT-CA. There were 37 significant lesions on 1,098 available coronary segments. Sensitivity, specificity and positive and negative predictive value of MSCT-CA for detecting significant coronary artery on a per-segment basis were 100%, 98.6%, 71.2% and 100%, respectively. All patients with at least one significant lesion were correctly identified by MSCT-CA. MSCT-CA scored 15 false positives on a per-segment base, which affected only marginally the per-patient performance (only one false positive). CONCLUSIONS: We concluded that 64-slice CT-CA is a diagnostic modality with high sensitivity and negative predictive value in patients at low to intermediate risk.     

心率对64层螺旋CT冠状动脉造影图像质量的影响及对策

目的：评价心率对64层螺旋CT冠状动脉造影图像质量的影响及解决方案。方法：：将112例冠心病按心率快慢分为4组：A组≤60次／min，B组（61～74）次／min，C组（75～89）次／min，D组≥90次／min。分别对重建图像进行定量评分，比较组间差异。结果：A组与B组间、C组与D组间无统计学差异，而A组与C、D组及B组与C、D组间有统计学差异。结论：心率是64层螺旋CT冠脉造影成像质量影响因素之一，当心率≥75次／min时对冠状动脉造影图像质量产生影响。     

前门控在256层螺旋CT冠脉成像中应用的探讨

目的通过分析冠脉CTA图像质量及辐射量探讨前门控对冠心病的临床应用价值。方法选取行冠脉CTA检查患者500例,心率≤70次／min者124例;心率〉70次／min者376例,前者随机分为前后门控两组,后者均为后门控扫描。结果心率≤70次／min者,前后门控两组图像质量评分分别为4．14±0．87和4．15±0．83,差异无统计学意义（P〉O．05）;有效辐射量分别为（1．89±0．57）mSv和（15．01±4．13）mSv,差异有统计学意义（P〈0．05）。心率〉70次／min者：71～85次／min者优质图像所在R—R间期百分比具有不确定性;心率〉85次／rain者100％在40％～50％R—R间期。结论心率≤70次／min时,前后门控冠脉成像图像质量具有一致性,前门控明显降低了辐射量;心率〉70次／min者也可以应用前门控技术扫描。     

Image quality and diagnostic accuracy of 16-slice multidetector spiral computed tomography for the detection of coronary artery disease in elderly patients

OBJECTIVES: To determine the image quality and diagnostic accuracy of cardiac multislice spiral computed tomography (MSCT) in elderly patients (>65 years old) in comparison to younger patients, this retrospective analysis was performed. METHODS: The catheter-controlled MSCT results from patients older than 65 years of age were compared with the results of younger patients in a cohort of 117 patients with regard to sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and image quality. Fifty-three patients were older than 65 years of age (group 1: 31 men, age range: 72.2 +/- 4.1 years, number of risk factors: 2.6 +/- 1.3, Agatston score: 866 +/- 1090) and 64 were younger (group 2: 45 men, age range: 57.4 +/- 6.1 years, number of risk factors: 2.6 +/- 1.0, Agatston score: 765 +/- 1013). All patients were examined by MSCT (Sensation 16 Speed 4 D; Siemens, Forchheim, Germany, with a gantry rotation time of 375 milliseconds) and invasive coronary angiography. The MSCT results were compared blinded with the results of the coronary angiography with regard to the presence or absence of significant stenosis (>50%) in a 13-segment model. Image quality was assessed on a qualitative scale between 1 (very good) and 5 (insufficient image quality) for each segment. RESULTS: Sensitivity, specificity, PPV, and NPP were not different statistically in both groups (group 1: 0.80/0.96/0.89/0.93 and group 2: 0.89/0.98/0.93/0.97). Three patients (all <65 years old) had to be excluded from analysis because of technical problems. Image quality was significantly better in group 2. Gender, body mass index, number of risk factors, and mean heart rate were not significantly different in either group. CONCLUSIONS: Age has an impact on MSCT image quality but did not hamper diagnostic accuracy. Thus, MSCT is a noninvasive method to detect or rule out coronary artery disease independently of age. These retrospective data have to be confirmed in larger prospective trials.     

Influence of cardiac function on image quality in coronary computed tomography angiography

PurposeTo evaluate the correlation between cardiac functional parameters and image quality in coronary computed tomography angiography (CCTA).Material and methodsSixty-six patients who underwent both CCTA and echocardiography were included. The coronary artery attenuation values and contrast-to-noise ratios (CNR) were measured in the proximal right coronary arteries (RCA) and left main (LM) trunk. Then, the averages of the mean values derived from RCA and LM were calculated. The cardiac output (CO), left atrial (LA) volume, and early mitral inflow velocity to mitral annular early diastolic velocity ratio (E/e′) were measured by echocardiography. The relationship of cardiac parameters with arterial attenuation and CNR were assessed by Pearson's correlation, Spearman's rank correlation and multivariable linear regression analysis adjusted for age, gender, body surface area and heart rate.ResultsThe coronary artery attenuation value was negatively correlated with CO (r = −0.30, p = 0.01) and LA volume (r = −0.37, p = 0.002). CNR was negatively correlated with LA volume (r = −0.4, p = 0.001) and E/e′ (r = −0.27, p = 0.03). These associations remained significant in the multivariable analysis.ConclusionCO and diastolic function had an impact on image quality of CCTA. Adjusting CCTA protocol may improve image quality in patients with known diastolic dysfunction or reduced cardiac output.     

含服硝酸甘油对64层螺旋CT冠状动脉成像质量影响的分析

目的 定量评估64层CT在冠状动脉成像中含服和不含服硝酸甘油对冠状动脉显示的差异.方法 分别在相对时段中对含服硝酸甘油(A组)和不含服硝酸甘油(B组)的各100例患者进行64层CT冠状动脉检查,2组受检者均采用回顾性后门控智能mA扫描技术.分别选取左、右冠状动脉的最佳期相进行MPR、MIP、CPR、VR重组.对2组图像分别进行冠状动脉10个测量点管径的测量,并对右冠状动脉、前降支、回旋支3支冠状动脉显示的分支数目进行统计,然后对2组图像管径测量值和分支数目采用完全随机的两样本均数t检验进行统计学比较.结果 右冠状动脉近、中、远段管径A组比B组分别增加0.29、0.17、0.11mm,扩张率分别为8.0%、5.0%、4.0%;前降支分别增加0.40、0.23、0.10 mm,扩张率分别为11.0%、8.0%、4.7%;回旋支分别增加0.42、0.35、0.12 mm,扩张率分别为13.5%、12.5%、5.5%;左主干增加0.31 mm,扩张率7.8%.A组较B组分支数目增加率,右冠状动脉、前降支、回旋支分别为83%、80%、113%.A、B 2组冠状动脉10个血管节段中,右冠状动脉近段、左主干、前降支近、中段、回旋支近、中段差异有统计学意义(t值分别为3.86、3.74、5.35、3.58、5.29、4.64,P值均＜0.01);右冠状动脉中、远段、前降支远段、回旋支远段差异亦有统计学意义(t值分别为2.13、2.58、2.35、2.14,P值均＜0.05).结论 服用硝酸甘油能有效扩张冠状动脉并能有效增加冠状动脉分支的显示,从而提高64层CT冠状动脉成像质量.     

Coronary computed tomography angiography using 128-slice dual-source computed tomography in patients with severe calcification

Purpose

To compare coronary computed tomography angiography (CTA) and coronary angiography (CAG) with regard to luminal graphic definition of calcified segments using 128-slice dual-source computed tomography (DSCT), specifically for patients with an Agatston score >400.

Materials and methods

Of 1148 consecutive patients who underwent coronary CTA using a 128-slice DSCT, 132 subjects had severe calcification with an Agatston score >400. Thirty-nine of the 132 patients who had undergone CAG within 3 months before or after coronary CTA were included. We investigated the distribution of calcification, and we visually evaluated significant stenosis in the calcified and all segments. Results were compared with CAG.

Results

The target group in this study had a very high mean Agatston score of 1771 ± 1724. Results for sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 247 calcified vs all 325 segments were as follows: sensitivity 93.2 vs 92.2%, specificity 83.9 vs 87.5%, PPV 70.8 vs 69.6%, and NPV 96.7 vs 97.3%, respectively.

Conclusion

128-slice DSCT has potential for evaluation of calcified segments in the lumen, even in patients whose Agatston score exceeds 400.

     

How image quality can be improved: our experience with multidetector computed tomography coronary angiography

PURPOSE: The objective of this study was to investigate the factors that may influence image quality on multidetector computed tomography (MDCT) coronary angiography (CA). MATERIALS AND METHODS: Two hundred twenty-four consecutive patients (161 men and 63 women; mean age, 52 years; age range, 34-76 years) evaluated with MDCT CA were included in the study. The evaluation of the quality of the patients' images was mainly based on the contrast material phase (early phase, optimal phase, or late phase) and the level of stepladder artifact (none, acceptable, or unacceptable). In addition, factors such as patient selection, patient preparation, scanning, processing, and steps of analysis, which may be affecting the quality of a final image, were examined independently. RESULTS: Patients who could not achieve sufficient breath-holding despite multiple breath exercises, those with a calcium score of 500 or higher, those with a heart rate greater than 90 bpm after metoprolol administration (because of shortening of the diastolic phase in the most still period), and those whose scanning was not completed were excluded from the study. The results for the remaining 224 patients were evaluated. Based on the contrast phase, there were 66 (29.5%) patients in the first group (early), 93 (41.5%) in the second group (optimal), and 65 (29%) in the third group (late). Among the 224 patients, the images of 152 (67.9%) had no stepladder artifact, those of 67 (29.9%) were of acceptable image quality, and those of 5 (2.2%) were of unacceptable image quality. CONCLUSION: It is important to obtain high-quality images to achieve correct interpretation with coronary artery CT angiography. This study aimed to describe a technique performed on 224 patients based on an array of factors ranging from patient selection to postprocessing. The results show that patient selection, cooperation with the patient, and breath-holding exercises play a very important role in obtaining the best images. In addition, a proper scanning technique (e.g., placement of electrocardiographic electrodes and contrast material phase) and postprocessing (e.g., reconstruction interval) may also contribute to obtaining high-quality images.