Noninvasive coronary angiography by contrast-enhanced electron beam computed tomography

Electron beam computed tomography (EBCT) is a cross-sectional imaging method with high temporal and spatial resolution. So far, it has mainly been applied for the detection of coronary artery calcifications which permit the very sensitive detection of coronary atherosclerosis even in the very early stages. However, after intravenous injection of a contrast agent, EBCT also permits the direct visualization of the coronary artery lumen. For these investigations, a volume data set is acquired that consists of 40 axial cross-sections of the heart (3 mm slice thickness). To evaluate the coronary arteries as to the presence of stenoses and occlusions, various forms of postprocessing, including shaded surface display, maximum intensity projection, and multiplanar reconstruction, are applied. The sensitivities and specificities for the detection of coronary artery stenoses and occlusions are about 90%. Best results are obtained for coronary artery bypass grafts, the left main coronary artery, and the left anterior descending coronary artery, while reduced image quality impairs the results for the right coronary artery and the left circumflex coronary artery.     

电子束CT检测冠状动脉钙化对诊断老年冠心病的价值

目的　探讨电子束CT检测冠状动脉钙化 (CAC)对诊断老年人冠心病的价值。方法　 2 2 9例老年患者行电子束CT检测CAC并计算每例的CAC总积分 ,行选择性冠状动脉造影以确定冠状动脉粥样硬化狭窄的有无及其程度。结果　 (1) 2 2 9例患者中 ,CAC检测阳性 2 2 0例 ,总阳性率 96 .0 7% ;造影显示有 2 13例存在不同程度的冠状动脉狭窄 ,其中 16 8例确诊为冠心病。 (2 )全组CAC诊断老年人冠心病的总体敏感性、特异性、阳性预测值和阴性预测值分别为 99%、13%、76 %和 89% ,诊断老年人冠状动脉粥样硬化的相应指标则分别为 97%、19%、94%和 33%。(3)老年男性组CAC诊断冠心病的敏感性较高特异性较低 ;老年女性则特异性较高而敏感性较低。综合考虑敏感性及特异性 ,对于老年男性 ,以CAC积分为 2 0 0作为诊断冠心病的分值较好 ,而对于老年女性则以 5 0作为诊断分值较佳。结论　电子束CT检测冠状动脉钙化对诊断老年人冠心病具有一定价值 ,但应结合性别和钙化分值进行综合分析。     

Impact of obesity on coronary artery calcification examined by electron beam computed tomographic scan

Aim:  Obesity is highly associated with cardiovascular disease (CVD). The early and non-invasive diagnosis method for asymptomatic obese is desirable. The aim of this study was to examine the impact of obesity on coronary artery calcification (CAC) by electron beam computed tomographic (EBCT) scan.
Methods:  A total of 465 subjects (i) aged between 40 and 65 years, (ii) being Chinese, (iii) without clinical or historical angiographic obstruction or arrhythmia and (iv) without family history of CVD were enrolled in this study. All the subjects were assigned to one of the EBCT CAC score categories according to the quartiles: quartile 1 (<25%), quartile 2 (25–49%), quartile 3 (50–75%) and quartile 4 (>75%), for further assessment and comparison. The main outcome evaluated is the difference in CAC scores between obese [body mass index (BMI): ≥30 kg/m²] and healthy (BMI: 18.5–25.0 g/m²) BMI groups. The trends of the characteristics in CAC quartile groups and the odds ratios (ORs) were also evaluated.
Results:  The mean of CAC scores between the obese and the healthy BMI groups showed significant difference (p = 0.05). The obese subjects had higher ORs (1.0–5.8 times) than those with BMI < 23 kg/m², and male had higher ORs (1.1–3.6 times) than female, to develop the high CAC score quartile group.
Conclusion:  This study demonstrated that the obese BMI group has a higher mean of CAC scores than the healthy BMI group of middle-aged, asymptomatic, Chinese adults. The obese males have higher risk of developing high CAC scores, which might induce CVD.     

Electron beam computed tomography: screening for coronary artery disease.

The need to detect coronary atherosclerosis early in its course has been well recognized by clinicians and epidemiologists for decades. The ability to identify populations with a greater prevalence of coronary disease prior to manifestation of illness would greatly reduce cardiac morbidity and mortality. Electron beam computed tomography (EBCT) uniquely combines the characteristics of speed and excellent density resolution that have led to a rebirth of interest in detecting coronary calcium as a means of screening asymptomatic populations for coronary atherosclerosis. Electron beam computed tomography is noninvasive and widely applicable. It can both detect and quantitate the presence of coronary atherosclerosis. A positive test has diagnostic and prognostic significance, predicting future cardiac events and the extent of atherosclerosis, including the probability of obstructive coronary artery disease (CAD). Multiple studies demonstrate a 6- to 35-fold increased risk of developing a cardiac event with elevated calcium scores. A negative test is highly predictive for excluding obstructive CAD. The cost ranges from $300 to $400, similar to that of an exercise treadmill test. Moreover, scanning for coronary calcium does not require injection of contrast medium, requiring no patient preparation or exercise; therefore, a CT technician can perform the study without supervision. The entire procedure takes < 10 min to perform. These features make EBCT a potential screening test for occult CAD in symptomatic and asymptomatic persons.     

In vivo assessment of three dimensional coronary anatomy using electron beam computed tomography after intravenous contrast administration

Intravenous coronary angiography with electron beam computed tomography (EBCT) allows for the non-invasive visualisation of coronary arteries. With dedicated computer hardware and software, three dimensional renderings of the coronary arteries can be constructed, starting from the individual transaxial tomograms. This article describes image acquisition, postprocessing techniques, and the results of clinical studies. EBCT coronary angiography is a promising coronary artery imaging technique. Currently it is a reasonably robust technique for the visualisation and assessment of the left main and left anterior descending coronary artery. The right and circumflex coronary arteries can be visualised less consistently. Improvements in image acquisition and postprocessing techniques are expected to improve visualisation and diagnostic accuracy of the technique.


Keywords: electron beam computed tomography; coronary angiography; coronary anatomy; volume rendering     

Contrast enhanced electron beam computed tomography to analyse the coronary arteries in patients after acute myocardial infarction

OBJECTIVE—To evaluate the accuracy of contrast enhanced electron beam computed tomography (EBCT) after acute myocardial infarction in determining patency of the infarct related artery and detecting high grade stenoses and occlusions in the coronary vessels.
DESIGN—Case study using blinded comparison with invasive coronary angiography.
PATIENTS—36 patients (mean age 53 years) 4-70 days after acute myocardial infarction.
INTERVENTIONS—The patients were studied by EBCT and invasive coronary angiography. For EBCT, 50 axial images of the heart (3 mm slice thickness) were acquired. They were triggered by the ECG during breath holding, after intravenous injection of contrast agent. The original images, surface reconstructions, and maximum intensity projections were evaluated for the presence of high grade stenoses and occlusions of the coronary arteries.
MAIN OUTCOME MEASURES—EBCT results were compared with invasive coronary angiography.
RESULTS—Of a total of 144 coronary arteries (left main, left anterior descending, left circumflex, and right coronary artery in 36 patients), 29 (20%) were unevaluable by EBCT. In the remaining arteries, 33 of 36 high grade lesions were correctly detected (92% sensitivity). Specificity was also 92% (73/79). Patency of the infarct related artery was correctly detected in 15 of 16 cases (94%). Five of the 14 occluded infarct related arteries (35%) were mistaken as stenotic but patent, and six could not be assessed.
CONCLUSIONS—EBCT is very accurate in detecting significant coronary artery lesions in patients after acute myocardial infarction, but differentiation between occluded and patent infarct related arteries is currently unreliable.


Keywords: electron beam CT; coronary angiography; myocardial infarction; computed tomography     

Non-invasive assessment of coronary Palmaz-Schatz stents by contrast enhanced electron beam computed tomography

The aim of the study was the evaluation of electron beam computedtomography as a non-invasive method to localize coronary stentsand to document patency in stented vessel segments. METHODS: Twenty-two patients (16m/6f, 58 ± 7·8 years) withcoronary Palmaz-Schatz stents were examined. Contrast enhancedelectron beam computed tomography using an Evolution scanner(Siemens) and coronary angiography were carried out within 7days of each other. Stent localization was performed using thesingle-slice mode of the electron beam computed tomography scanner.Patency of the coronary target segment was assessed using themulti slice mode after peripheral venous injection of a 40 mlbolus of contrast medium (Ultravist 370). Qualitative imageanalysis of a cine loop of 10 consecutive frames and quantitativeanalysis of densitometric curves in a region of interest distalto the stented vessel segment were performed. RESULTS: All stented vessel segments were identified. In 20 patients(91%), qualitative assessment of contrast enhancement patternsenabled stent patency to be evaluated. In 18 patients (90%),contrast medium was visualized distal to the stent. Quantitativecoronary angiography confirmed that the stented vessel segmentswere not stenosed. Densitometric curves obtained in 16 of these18 patients yielded contrast enhancement distal to the stentedvessel segment of 63 ± 6% compared to the aorta. In onepatient, qualitative and quantitative analysis showed prolongedcontrast enhancement of reduced density, which hinted at a stenosisrelated to the stented vessel segment. Coronary angio graphyrevealed subtotal occlusion of the stented vessel directly distalto the stent. In another patient, no contrast visualizationof the vessel distal to the stent was achieved. Coronary angiographyrevealed complete stent occlusion in this case. CONCLUSION: Electron beam computed tomography can reliably localize coronarystents and may become a useful tool for providing informationon stented vessel segment patency. (Eur Heart J 1996; 17: 1546–1553)     

Coronary artery disease in Chinese adults with type 2 diabetes mellitus estimated by electron beam computed tomography and electron beam computed tomography angiography

Objective To assess the prevalence and risk of coronary artery disease(CAD) in Chinese adults with type 2 diabetes mellitus(T2DM) using electron beam computed tomography(EBCT) and EBCT angiography(EBCTA) . Methods:Ninety-four cases were enrolled in this study including diabetes(n=28) ,impaired glucose tolerance(IGT,n=30) ,coronary heart disease(CHD,n=11) ,and control(n=25) . Cardiac EBCT plain scanning and EBCTA were performed on all of these subjects to evaluate coronary artery calcifica-tion(CAC) scores,and number of segments of stenosed coronary arteries. Both CAC and/or coronary artery stenosis were defined as patients with coronary artery lesions(CAL) . Results CAC scores were not different with the control,diabetes,IGT,or CHD(P>0.05) groups. Compared to control(0.520±1.295) ,more stenosed coronary arteries segments(P<0.05) were detected in diabetes(2.964± 1.915) ,IGT(2.200±2.024) ,and CHD(2.273±1.679) . Number of stenosed artery segments were correlated with age(r=0.215,P=0.019) ,postprandial glucose(r=0.224,P=0.015) ,total cholesterol(r=0.323,P=0.000) ,and duration of diabetes(r=0.208,P=0.004) . The incidences of CAL in diabetes(96.43%) ,IGT(93.33%) ,and CHD(90.91%) was substantially higher than that in normal control(56.00%,P<0.01) . The odds ratio of CAL associated with having diabetes was estimated to be 7.514(95% CI:1.885-63.778) . Conclusions Coronary artery lesions are prevalent in Chinese adults with type 2 diabetes,implying a high CAD risk. EBCTA holds potential in depicting the details of CAL and can be used to track the progression of CAD in diabetes patients.     

Comparison of vessel diameters in electron beam tomography and quantitative coronary angiography

Electron beam tomography (EBT) has been shown to permit non-invasive imaging of the coronary arteries after intravenous injection of contrast agent and 3-dimensional reconstruction. We compared the vessel diameters in EBT reconstructions to quantitative coronary angiography (QCA). 10 patients were investigated by EBT and QCA. 3-dimensional EBT reconstructions (shaded surface display) were performed after acquisition of 40 axial cross-sections of the heart with 3 mm slice thickness (1 mm overlap) which were obtained triggered to the ECG in breathhold following intravenous injection of 120–160 ml of contrast agent. A fixed lower reconstruction threshold of 80 HU was used to selectively visualize the contrast-enhanced coronary artery lumen. At 60 sites in the coronary artery system, the vessel diameters measured in the EBT reconstructions were compared to the diameters found in quantitative analysis of the patients' coronary angiograms. The correlation coefficient of the vessel diameters in EBT and QCA was 0.83. Mean vessel diameters were not significantly different in EBT and QCA (3.06±0.93 vs. 2.97±0.94 mm). However, very small vessel diameters tended to be underestimated in the EBT reconstructions, which was due to the partial volume effect. If only vessel diameters measured in the left main or left anterior descending coronary artery were compared to QCA, the correlation increased to 0.87, since these vessel segments are less prone to artifacts in the EBT investigation. Vessel diameters in EBT and QCA correlate reasonably well. Due to partial volume effects, the diameter of very small vessels and stenotic segments tends to be underestimated by EBT.     

Validation of minimally invasive measurement of myocardial perfusion using electron beam computed tomography and application in human volunteers

OBJECTIVES: To measure myocardial perfusion using an estimate of intramyocardial vascular volume obtained by electron beam computed tomography (EBCT) in an animal model; to assess the feasibility and validity of measuring regional myocardial perfusion in human volunteers using the techniques developed and validated in the animal studies. METHODS: Measurements of myocardial perfusion with EBCT employing intravenous contrast injections were compared with radioactive microsphere measurements (flow 57 to 346 ml/100 g/min) in seven closed chest dogs. Fourteen human volunteers then underwent EBCT scans using intravenous contrast injections. RESULTS: Mean (SEM) global intramyocardial vascular volume by EBCT was 7.6 (1.1)%. The correlation between global EBCT (y) and microsphere (x) perfusion was y = 0.59x + 15.56 (r = 0.86) before, and y = 0.72x + 6. 06 (r = 0.88) after correcting for intramyocardial vascular volume. Regional perfusion correlation was y = 0.75x + 23.84 (r = 0.82). Corresponding improvements in agreement between the two techniques were also seen using Bland-Altman plots. In the human subjects, mean resting global myocardial flow was 98 (6) ml/100 g/min, with homogeneous flow across all regions. In 10 of these subjects, perfusion was studied during coronary vasodilatation using intravenous adenosine. Global flow increased from 93 (5) ml/100 g/min at rest to 250 (19) ml/100 g/min during adenosine (p < 0.001), with an average perfusion reserve ratio of 2.8 (0.2). Similar changes in regional perfusion were observed and were uniform throughout all regions, with a mean regional perfusion reserve ratio of 2.8 (0.3). CONCLUSIONS: Accounting for intramyocardial vascular volume improves the accuracy of EBCT measurements of myocardial perfusion when using intravenous contrast injections. The feasibility of providing accurate measurements of global and regional myocardial perfusion and perfusion reserve in people using this minimally invasive technique has also been demonstrated.     

冠状动脉瘤样扩张与冠心病患者电子束CT冠状动脉钙化的比较研究

目的　比较粥样硬化性冠状动脉瘤样扩张 (CAE)与冠心病 (CHD)患者电子束CT(EBCT)冠状动脉钙化的差异。方法　经选择性冠状动脉造影确诊的 2 4例CAE与 2 4例年龄、性别和病变程度匹配的无瘤样扩张CHD患者行EBCT检查以计算钙化积分 ,分析CAE与CHD患者冠状动脉钙化程度的差异。结果　 (1)两组患者的临床基线资料、狭窄病变程度及病变部位差异均无显著性。 (2 )CAE组钙化积分显著低于CHD组 ,其自然对数转换值 (LN[CS 1])的均数分别为 3 4 1±2 4 4和 4 88± 2 4 8(P <0 0 5 )。 (3)瘤样扩张冠状动脉的钙化程度与病变类型有关 ,弥漫性扩张血管LN[CS 1]显著低于局限性扩张动脉 (1 2 6± 1 85比 2 6 7± 1 93,P <0 0 5 )。 (4)单纯瘤样扩张动脉及瘤样扩张并狭窄血管的钙化阳性率和LN[CS 1]均显著低于单纯狭窄病变动脉 (P <0 0 1或0 0 5 )。结论　粥样硬化性冠状动脉瘤样扩张患者的冠状动脉钙化轻于无瘤样扩张的冠心病患者 ,且钙化程度与病变类型有关 ,提示斑块钙化程度可能与瘤样扩张形成和血管重塑有一定关系。     

螺旋CT检测冠状动脉钙化的临床应用

目的：研究螺旋CT检测冠状动脉钙化(CAC)在冠心病诊断中的应用价值。方法：27例既往确诊为冠心病或经心电图负荷试验和／或冠状动脉造影临床确诊的冠心病患(冠心病组)和35例非冠心病患(对照组)分别进行螺旋CT检查。结果：受检随着年龄的增长钙化率逐渐增高，冠心病组冠状动脉钙化率比对照组明显增高，但随年龄的增长冠心病组钙化的特异性降低(降至11．12％)。钙化血管以累及一支血管最常见，多为左前降支(LAD)，三支血管钙化主要见于60岁以上。结论：螺旋CT检测冠状动脉钙化对早期诊断冠心病和预测冠心病事件有与病理相符的临床价值。     

Congenital coronary anomalies in adults: comparison of anatomic course visualization by catheter angiography and electron beam CT.

The objective of this study was to compare the anatomic course of anomalous coronary arteries by axial and three-dimensional volume-rendered electron beam computed tomography (EBCT) angiography and X-ray catheter angiography (CAG). We performed a blinded study where patients who previously underwent CAG with (n = 14) and without (n = 14; age- and gender-matched controls) anomalous coronary anatomy were studied with EBCT coronary angiography. Forty to 50 EKG-triggered 3 mm overlapping axial slices were acquired with 2 mm table movement within one breath hold during the i.v. injection of 140 cc of nonionic iodinated contrast (4 ml/sec). The axial source images and volume-rendered three-dimensional reconstructions were evaluated for the presence, type, and course of coronary anomalies and the results were compared to those of CAG. All normal and anomalous coronary arteries were identified by both modalities in all subjects. Identified anomalies include single coronary artery (n = 3), left-sided right coronary artery (n = 3), right-sided left main coronary artery (n = 3), anterior descending coronary artery (n = 2), circumflex coronary artery (n = 2), and separate left-sided ostia for left anterior descending and circumflex coronary arteries (n = 1). In five cases, there was discrepancy in the course of the anomalous vessels between the two modalities. Consensus reading among cardiologist and radiologists favored the interpretation of EBCT over catheter angiography. Noninvasive EBCT coronary angiography compares well with CAG in identifying anomalous coronary arteries and may provide confirmatory evaluation of their precise anatomic relationships to the heart and great vessels.     

The impact of the menopause on coronary artery calcification examined by multislice computed tomography scanning

Background and aimsTo examine whether there is a difference in coronary artery calcification (CAC) scores between males and females aged above 50 years.Methods and resultsA total of 479 subjects aged between 40 and 70 years with no clinical or family history of cardiovascular disease (CVD) were enrolled for this study. All subjects were assessed by multislice CT scanning (MCTS), and the CAC scores obtained were assigned to one of four quartiles for further assessment and comparison. The main outcome evaluated was the percentage of high CAC scores and mean CAC scores, comparing males and females of different age groups.This study found that the percentage of high CAC scores increased markedly from 5% (40–49 age group) to 21.2% (50–59 age group) among females. The increase was significantly less when comparing males from different age groups (from 25% in the 40–49 age group to 31.2% in the 50–59 age group). Females had higher odds ratios (ORs) postmenopausally (4.3 in the 50–59 age group) than males in the same age group (1.6).ConclusionsThese initial findings seem to indicate that above 50 years of age, CAC is more dependent on age in females than in males, which might be due to the effect of the menopause.     

急性心肌梗死与稳定性心绞痛患者电子束CT冠状动脉钙化的比较研究

目的　比较急性心肌梗死 (AMI)与稳定性心绞痛 (SAP)患者电子束CT冠状动脉钙化(CAC)的不同模式。方法　 5 5例AMI患者与 6 7例SAP患者分别行选择性冠状动脉造影以检测粥样硬化狭窄的程度 ,行电子束CT检查以计算CAC积分 ,分析SAP与AMI患者CAC积分的差异及其与年龄的关系。结果　 (1)就心脏整体而言 ,SAP组CAC检测阳性率为 87 7% ,而AMI组阳性率为5 5 9% ;SAP组心脏整体和冠状动脉分支的CAC阳性率均显著高于AMI组 (P <0 0 1)。 (2 )SAP组CAC积分显著高于AMI组 ,其自然对数转换值 [LN(钙化积分 +1) ]的均数按心脏整体计算为 5 2±1 7对 2 4± 1 8(P <0 0 1) ,按冠状动脉分支计算为 3 3± 2 1对 1 2± 1 4 (P <0 0 1)。 (3)SAP组CAC程度随年龄增加而加重的趋势较AMI组更为明显 ;在每一相同的年龄段内比较 ,SAP组的CAC程度均较AMI组明显增高。 (4)SAP组重度狭窄的冠状动脉多发生重度或中度钙化 ,而AMI组梗死相关动脉则多数无钙化或仅有轻度钙化。结论　SAP患者CAC大多较为严重 ,而AMI患者多数钙化程度较轻 ,且大多发生于无或轻微钙化的冠状动脉。     

A simple single slice method for measurement of left and right ventricular enlargement by electron beam tomography

Rationale and objective:We devised to test the feasibility of measuring the left and right ventricular sizes by non-contrast electron beam tomographic images. Methods:Ventricular sizes consist of the sum of the intracavitary cavity and myocardial mass for each ventricle. A total of 50 image studies from subjects undergoing contrast-enhanced studies were used to develop the measurement methodology. About 20 contrast studies were used to test the measure. The methodology was then prospectively tested on 75 patients with non-contrast studies to estimate the intra-observer, inter-observer and inter-study reproducibility. Results:Multiple linear regression analysis was completed and the correct regression formulas to calculate ventricular volumes were acquired by using the area and span from the contrast studies. There was excellent correlation between the estimate of LV (r > 0.97, p < 0.001) and RV (r > 0.93, p < 0.001) sizes between measured and calculated (contrast, single slice) left and right ventricular volumes. The intra-observer, inter-observer and inter-study reproducibility demonstrated excellent results with <7% difference in absolute values and a high correlation (r > 0.89, p < 0.001). Conclusion:We conclude that the left and right ventricular sizes can be accurately estimated from a single mid-ventricular slice on non-contrast electron beam tomographic images.