64-slice Coronary Computed Tomography Research Articles

Measurement of epicardial fat thickness by transthoracic echocardiography for predicting high-risk coronary artery plaques.

Epicardial adipose tissue (EAT) volume is reported to be associated with coronary plaques. We evaluated whether non-invasive measurement of EAT thickness by echocardiography can predict high-risk coronary plaque characteristics determined independently by coronary computed tomography (CT) angiography. We enrolled 406 patients (mean age 63years, 57% male) referred for 64-slice CT. EAT was measured on the right ventricle free wall from a parasternal long-axis view at the end of systole. High-risk coronary plaques were defined as low-density plaques (<30Hounsfield units) with positive remodeling (remodeling index >1.05). Patients were divided into thin or thick EAT groups using a cutoff value derived from receiver operator characteristic curve analysis for discriminating high-risk plaques. The receiver operator characteristic cutoff value was 5.8mm with a sensitivity of 83% and specificity of 64% (area under the curve 0.77, 95% confidence interval 0.70-0.83, p<0.01). Compared with the thin EAT group, the thick EAT group had a high prevalence of low-density plaques (4 vs. 24%, p<0.01), positive remodeling (39 vs. 60%, p<0.01), and high-risk plaques (3 vs. 17%, p<0.01). Multiple logistic analysis revealed that thick EAT was a significant predictor of high-risk plaques (odds ratio 7.98, 95% confidence interval 2.77-22.98, p<0.01) after adjustment for covariates, including conventional risk factors, visceral adipose tissue area, and medications. The measurement of EAT thickness by echocardiography may provide a non-invasive option for predicting high-risk coronary plaques.

Evaluation of the Optimal Image Reconstruction Interval for Noninvasive Coronary 64-Slice Computed Tomography Venography

Objective: We investigated the appropriate reconstruction interval required to generate optimal quality images of the coronary veins and to evaluate the size of each vein at the systolic and diastolic phases using coronary computed tomography (CT) venography. Methods: Coronary CT venograms obtained from 30 patients using 64-slice CT were reconstructed at 0% to 90% of the cardiac cycle in 10% increments. Two radiologists assessed the image quality of the anterior interventricular vein (AIV), the great cardiac vein (GCV), the posterior vein of the left ventricle (PVLV), the posterior interventricular vein (PIV), the coronary sinus (CS) and the small cardiac vein (SCV). We determined the sizes of measurable CS (n = 16) and GCV (n = 12) at the end systolic and mid diastolic phases. Results: The most appropriate reconstruction point for all coronary veins turned out to be at the mid-diastolic phase. The size of the CS and GCV was greater at a 30% than that at a 70% R-R interval (p Conclusions: Image quality was optimal at the mid-diastolic phase for each coronary vein, but the sizes of the coronary veins varied during the cardiac cycle. The cardiac cycle must be considered when measuring the sizes of cardiac veins.

Radiation dose in coronary CT angiography associated with prospective ECG-triggering technique: comparisons with different CT generations

A retrospective analysis was performed in patients undergoing prospective ECG-triggered coronary computed tomography (CT) angiography (CCTA) with the single-source 64-slice CT (SSCT), dual-source 64-slice CT (DSCT), dual-source 128-slice CT and 320-slice CT with the aim of comparing the radiation dose associated with different CT generations. A total of 164 patients undergoing prospective ECG-triggered CCTA with different types of CT scanners were studied with the mean effective doses estimated at 6.8 ± 3.2, 4.2 ± 1.9, 4.1±0.6 and 3.8 ± 1.4 mSv corresponding to the 128-slice DSCT, 64-slice DSCT, 64-slice SSCT and 320-slice CT scanners. In this study a positive relationship was found between the effective dose and the body mass index (BMI). A low radiation dose is achieved in prospective ECG-triggered CCTA, regardless of the CT scanner generation. BMI is identified as the major factor that has a direct impact on the effective dose associated with prospective ECG-triggered CCTA.

A systematic review of radiation dose associated with different generations of multidetector CT coronary angiography

The purpose of this paper is to perform a systematic review on radiation dose reduction in coronary computed tomography (CT) angiography that is done using different generations of multidetector CT (MDCT) scanners ranging from four-slice to 320-slice CTs, and have different dose-saving techniques. The method followed was to search for references on coronary CT angiography (CTA) that had been published in English between 1998 and February 2011. The effective radiation dose reported in each study based on different generations of MDCT scanners was analysed and compared between the types of scanners, gender, exposure factors and scanning protocols. Sixty-six studies were eligible for inclusion in this analysis. The mean effective dose (ED) for MDCT angiography with retrospective electrocardiogram (ECG) gating without use of any dose-saving protocol was 6.0 ± 2.8, 10.4 ± 4.90 and 11.8 ± 5.9 mSv for four-slice, 16-slice and 64-slice CTs, respectively. More dose-saving strategies were applied in recent CT generations including prospective ECG-gating protocols, application of lower tube voltage and tube current modulation to achieve a noteworthy dose reduction. Prospective ECG-gating protocol was increasingly used in 64, 125, 256 and 320 slices with corresponding ED of 4.1 ± 1.7, 3.6 ± 0.4, 3.0 ± 1.9 and 7.6 ± 1.6 mSv, respectively. Lower tube voltage and tube current modulation were widely applied in 64-slice CT and resulted in significant dose reduction (P < 0.05). This analysis has shown that dose-saving strategies can substantially reduce the radiation dose in CT coronary angiography. The fact that more and more clinicians are opting for dose-saving strategies in CT coronary angiography indicates an increased awareness of risks associated with high radiation doses among them.

Impact of 64-slice coronary CT on the management of patients presenting with acute chest pain: results of a prospective two-centre study

Our two-centre prospective study evaluates the usefulness of 64-slice coronary computed tomography (CCT) to rule out significant coronary artery stenosis in patients admitted in emergency departments (ED) for acute coronary syndromes (ACS) with low-to-intermediate risk score. Patients (175) admitted for acute chest pain (ACP), unmodified electrocardiogram and first troponin measurement within normal ranges were included. A second troponin measurement and a 64-slice CCT within 24 h were performed. Major adverse cardiac events (MACE) were recorded during follow-up (6 months ± 2). 64-slice CCT was either normal or showed non-significant coronary stenosis in the majority of patients (78%). 64-slice CCT depicted significant stenosis (>50% diameter) in 22% of patient whereas initial clinical and biological evaluation was reassuring. For negative CCTs, elevated troponin at second measurement did not modify the strategy or treatment of patients. No MACEs were noted during follow up. In 12% of patients CCT identified unsuspected non-coronary abnormalities. Our study confirms 64-slice CCT utility to rule out significant coronary artery stenosis in 8/10 patients admitted in ED with ACP or ACS with low-to-intermediate risk score. Early discharge with a negative 64-slice CCT is associated with very low risk of cardiac events at 6 months. • 64-slice coronary computed tomography (CCT) offers a critical role in acute chest pain. • 64-slice CCT allows differentiation between significant and non-significant coronary artery stenosis. • Normal 64-slice CCT allows rapid discharge of patients with ACP. • 64-slice CCT helps make appropriate therapeutic decision in patients with ACP.

Coronary computed tomography angiography in coronary artery disease.

To investigate the research directions of coronary computed tomography (CT) angiography in the diagnosis of coronary artery disease (CAD) based on a systematic review of the literature. A search of articles on coronary CT angiography in the diagnosis of CAD was performed during a 6-year-period between 2005 and 2010 from five main radiology journals namely, Radiology, American Journal of Roentgenology, European Radiology, European Journal of Radiology and British Journal of Radiology. Analysis of the references was focused on the research directions of coronary CT angiography with regard to the type of studies in terms of diagnostic value, application of dose-reduction strategies and resultant effective radiation doses with use of these techniques. One hundred and forty two studies were identified which met the selection criteria and were included in the analysis. 64-slice CT (single source and dual-source CT) dominated 78% of the coronary CT angiography studies. Prior to 2007, research was focused on the diagnostic value of coronary CT angiography, but since 2008 more attention has been paid to radiation dose reduction. Radiation dose was reported in 64 studies, representing 45% of total studies published in the five radiology journals. Various dose-saving strategies have been implemented and prospective electrocardiography-triggering and high pitch techniques were found to be the most effective approaches for radiation dose reduction, with the corresponding mean effective dose being 3.5 ± 1.9 mSv and 1.7 ± 0.6 mSv, respectively. This review shows that the current research in coronary CT angiography has shifted from the previous focus on diagnostic accuracy in CAD to more emphasis on radiation dose reduction.

Coronary sinus fistula: A reason not to implant a transvenous left ventricular lead

A 40-year-old woman referred for biventricular implantable cardioverter-defibrillator (ICD) implantation with an ejection fraction of 30%, New York Heart Association class III symptoms, and left bundle branch block QRS duration of 160 ms (patient had nonischemic cardiomyopathy and no evidence of occlusive coronary artery disease by nuclear perfusion imaging). Occlusive venography (Figure 1) demonstrated a coronary artery‐to‐coronary venous fistula. The left anterior descending artery is seen anteriorly (along the interventricular septal region) in the right anterior oblique image. There is no evidence of coronary sinus dilation, and the proximal coronary sinus was a relatively narrow vessel with no significant lateral branches. A shunt assessment demonstrated no significant left-to-right shunt. Based on the findings, the decision was made not to place a coronary sinus lead due to risk of thrombus formation and embolization to the coronary arteries. Additionally, there was a lack of suitable lateral branches to provide an optimal pacing vector. A decision to consider a surgically implanted lead was made. A follow-up coronary computed tomography (CT) scan interestingly did not document a fistula, likely because the image resolution of the 64-slice CT was not sufficient to visualize a small fistula.

Assessment of left ventricular function at rest using rubidium-82 myocardial perfusion PET: comparison of four software algorithms with simultaneous 64-slice coronary CT angiography

Left ventricular function is prognostically important. Our aim was to validate different algorithms' measurements with rubidium-82 PET, using computed tomography (CT) acquired simultaneously on hybrid imaging. Fifty patients (33 men, 17 women, mean age 59 years SD 12) referred for coronary artery disease evaluation underwent rubidium-82 PET myocardial perfusion scintigraphy and 64-slice CT coronary angiography simultaneously on hybrid PET/CT. Left ventricular ejection fraction, end-systolic volume and end-diastolic volume from quantitative gated PET at rest, were calculated using quantitative gated single-photon emission computed tomography (QGS), Emory Cardiac Toolbox (ECT), Myometrix and CardIQ Physio software and then compared with CT. The paired t-test and Bland-Altman plots were used for analysis. There was no significant difference between CT and both QGS and ECT for calculating ESV. Otherwise there were significant differences (t-test, P<0.05) between CT coronary angiography and all other software algorithms in calculating systolic and diastolic volumes. Bland-Altman analysis revealed a bias towards underestimating end-diastolic volume with mean differences of 32.3, 34.8, 42.6 and 35.7 ml for QGS, ECT, Myometrix and CardIQ Physio, respectively. The limits of agreement (mean bias+/-1.96 SD) for left ventricular ejection fraction (%) were 8.5+/-21.0, 12.9+/-21.0, 3.5+/-18.9 and 5.6+/-17.1, for QGS, ECT, Myometrix and CardIQ Physio, respectively. The systematic error (or mean bias) of the Myometrix algorithm is the smallest, and CardIQ Physio shows the least statistical error (or limits of agreement) when calculating ejection fraction from rubidium-82 myocardial perfusion PET, compared with QGS and ECT. The wide limits of agreement between the different algorithms mean that they are not interchangeable.

Predictors of image quality of coronary computed tomography in the acute care setting of patients with chest pain

Objective We aimed to determine predictors of image quality in consecutive patients who underwent coronary computed tomography (CT) for the evaluation of acute chest pain. Method and materials We prospectively enrolled patients who presented with chest pain to the emergency department. All subjects underwent contrast-enhanced 64-slice coronary multi-detector CT. Two experienced readers determined overall image quality on a per-patient basis and the prevalence and characteristics of non-evaluable coronary segments on a per-segment basis. Results Among 378 subjects (143 women, age: 52.9 ± 11.8 years), 345 (91%) had acceptable overall image quality, while 33 (9%) had poor image quality or were unreadable. In adjusted analysis, patients with diabetes, hypertension and a higher heart rate during the scan were more likely to have exams graded as poor or unreadable (odds ratio [OR]: 2.94, p = 0.02; OR: 2.62, p = 0.03; OR: 1.43, p = 0.02; respectively). Of 6253 coronary segments, 257 (4%) were non-evaluable, most due to severe calcification in combination with motion (35%). The presence of non-evaluable coronary segments was associated with age (OR: 1.08 annually, 95%-confidence interval [CI]: 1.05–1.12, p < 0.001), baseline heart rate (OR: 1.35 per 10 beats/min, 95%-CI: 1.11–1.67, p = 0.003), diabetes, hypertension, and history of coronary artery disease (OR: 4.43, 95%-CI: 1.93–10.17, p < 0.001; OR: 2.27, 95-CI: 1.01–4.73, p = 0.03; OR: 5.12, 95%-CI: 2.0–13.06, p < 0.001; respectively). Conclusion Coronary CT permits acceptable image quality in more than 90% of patients with chest pain. Patients with multiple risk factors are more likely to have impaired image quality or non-evaluable coronary segments. These patients may require careful patient preparation and optimization of CT scanning protocols.

Randomized Comparison of 64-Slice Single- and Dual-Source Computed Tomography Coronary Angiography for the Detection of Coronary Artery Disease

The purpose of this study was to analyze the influence of a systematic approach to lower heart rate for coronary computed tomography (CT) angiography on diagnostic accuracy of 64-slice single- and dual-source CT. Coronary CT angiography is often impaired by motion artifacts, so that routine lowering of heart rate is usually recommended. This is often conceived as a major limitation of the technique. It is expected that higher temporal resolution, such as with dual-source 64-slice CT, would allow diagnostic imaging even without systematic pre-treatment for lowering the heart rate. Two hundred patients with suspected coronary artery disease were first randomized to either 64-slice single-source CT (n = 100) or dual-source CT (n = 100) for contrast-enhanced coronary artery evaluation. In each group, patients were further randomized to either receive systematic heart rate control (oral and intravenous beta-blockade for a target heart rate < or =60 beats/min) or receive no premedication. Evaluability of datasets and diagnostic accuracy were compared between groups against the results obtained from invasive angiography. Systematic pre-treatment lowered heart rate during CT coronary angiography by 10 beats/min. Heart rate control significantly improved evaluability in single-source CT (93% vs. 69% on a per-patient basis, p = 0.005), whereas it did not in dual-source CT (96% vs. 98%). In evaluable patients, sensitivity to detect the presence of at least 1 coronary stenosis by single-source CT was 86% and 79%, respectively, with and without heart rate control (p = NS). For dual-source CT, it was 100% and 95%, respectively (p = NS). The rate of correctly classified patients, defined as evaluable and correct classification as to the presence or absence of at least 1 coronary artery stenosis, was significantly improved by heart rate control in single-source CT (78% vs. 57%, p = 0.04), whereas there was no such influence in dual-source CT (87% vs. 93%). Systematic heart rate control significantly improves image quality for coronary visualization by 64-slice single-source CT, whereas image quality and diagnostic accuracy remain unaffected in dual-source CT angiography. Improved temporal resolution obviates the need for heart rate control.

Prevalence of Noncalcified Coronary Plaques by 64-Slice Computed Tomography in Patients With an Intermediate Risk for Significant Coronary Artery Disease

In this prospective study, we investigated the prevalence and characteristics of clearly discernible noncalcified coronary plaques in a patient population with suspected significant coronary artery disease (CAD) by using 64-slice computed tomography (CT). The assessment of noncalcified coronary plaques by noninvasive strategies may be important to improve cardiovascular risk stratification. To rule out significant stenosis, high-resolution 64-slice coronary CT (0.6-mm collimation, 330-ms gantry rotation time) was performed in 161 consecutive patients with an intermediate risk for having CAD. Computed tomography data sets were evaluated for presence of coronary calcifications, noncalcified plaques, and/or lumen narrowing. Noncalcified coronary plaques were detected in 48 (29.8%) of 161 enrolled patients. Although noncalcified plaques together with coronary calcifications were present in 38 of 161 (23.6%) patients, the prevalence of noncalcified plaques as the only manifestation of CAD was 6.2% (10 of 161 patients). Patients with noncalcified plaques were characterized by significantly higher total cholesterol, low-density lipoprotein, and C-reactive protein levels as well as a trend for more diabetes mellitus. The majority of noncalcified plaques resulted in lumen narrowing of <50%. Of the remaining 113 patients, CAD and coronary calcifications were ruled out in 53 of 161 (32.9%) patients, whereas 60 of 161 (37.3%) patients presented with calcifications in the absence of noncalcified plaque. With the use of 64-slice CT, clearly discernible noncalcified atherosclerotic coronary plaques can be detected in a large group of patients with an intermediate risk for having CAD. The assessment of these plaques by CT angiography may allow for improved cardiovascular risk stratification.

New imaging techniques for diagnosing coronary artery disease

New tomographic cardiovascular imaging tests, such as intravascular ultrasonography (IVUS), coronary computed tomography (CT) angiography and magnetic resonance imaging (MRI), can be used to assess atherosclerotic plaques for the characterization and early staging of coronary artery disease (CAD). Although IVUS images have very high resolution capable of revealing very early preclinical CAD, it is an invasive technique used clinically only in conjunction with a coronary intervention. Multiple-slice coronary CT angiography, which is noninvasive, shows promise as a diagnostic method for CAD. New 64-slice cardiac CT technology has high accuracy for the detection of lesions obstructing more than 50% of the lumen, with sensitivity, specificity, and positive and negative predictive values all better than 90% in patients without known CAD. Cardiac MRI is also improving accuracy in coronary plaque detection and offers a better opportunity for plaque characterization. With further advances in tomographic imaging of coronary atheromas, the goal will be to detect plaques earlier in the development of CAD and to characterize the plaques most likely to generate a clinical event.