Noninvasive visualization of coronary arteries using contrast-enhanced multidetector CT: influence of heart rate on image quality and stenosis detection

Efficacy and Safety of Iodixanol in Computed Coronary Tomographic Angiography and Cardiac Catheterization

Iodixanol is an iso-osmolar non-ionic dimeric hydrophilic contrast agent with a higher viscosity than the monomeric agents. It is the only Food and Drug Administration (FDA)-approved iso-osmolar agent in the United States, and it is the only contrast agent with an FDA-approved indication for use in cardiac computed tomographic angiography (CCTA), to assist in the diagnostic evaluation of patients with suspected coronary artery disease. In clinical studies, it has been noted to have fewer side effects and similar image quality when compared to low-osmolar contrast media. This can be attributed to the pharmacological properties of iodixanol. These contrast agents are used for coronary computed tomography angiography and cardiac catheterization. In this article, the use, tolerability, and efficacy of iodixanol are reviewed, specifically evaluating the use of CCTA and coronary angiography, including outcome studies, randomized trials, and comparisons to other contrast agents.

Topological recovery for non-rigid 2D/3D registration of coronary artery models

BACKGROUND AND OBJECTIVE

Intra-operative X-ray angiography, the current standard method for visualizing and diagnosing cardiovascular disease, is limited in its ability to provide essential 3D information. These limitations are disadvantages in treating patients. For example, it is a cause of lowering the success rate of interventional procedures. Here, we propose a novel 2D-3D non-rigid registration method to understand vascular geometry during percutaneous coronary intervention.

METHODS

The proposed method uses the local bijection pair distance as a cost function to minimize the effect of inconsistencies from center-line extraction. Moreover, novel cage-based 3D deformation and multi-threaded particle swarm optimization are utilized to implement real-time registration. We evaluated the proposed method for 154 examinations from 10 anonymous patients by coverage percentage, comparing the average distance of the 2D extracted center-line with that of the registered 3D center-line.

RESULTS

The proposed 2D-3D non-rigid registration method achieved an average distance of 1.98 mm with a 0.54 s computation time. Additionally, in aiming to reduce the uncertainty of XA images, we used the proposed method to retrospectively visualize the connections between 2D vascular segments and the distal part of occlusions.

CONCLUSIONS

Ultimately, the proposed 2D/3D non-rigid registration method can successfully register the 3D center-line of coronary arteries with corresponding 2D XA images, and is computationally sufficient for online usage. Therefore, this method can improve the success rate of such procedures as a percutaneous coronary intervention and provide the information necessary to diagnose cardiovascular diseases better.

State of the art of coronary computed tomography angiography

OBJECTIVES

The aim of this paper is to evaluate contrast media (CM) bolus geometry and opacification patterns in the coronary arteries with particular focus on patient, scanner and safety considerations during coronary computed tomography angiography (CCTA).

KEY FINDINGS

The rapid evolution of computed tomography (CT) technology has seen this imaging modality challenge conventional coronary angiography in the evaluation of coronary artery disease. Increases in spatial and temporal resolutions have enabled CCTA to become the modality of choice when evaluating the coronary vascular tree as an alternative in the diagnostic algorithm for acute chest pain. However, these new technologic improvements in scanner technology have imposed new challenges for the optimisation of CM delivery and image acquisition strategies.

CONCLUSION

Understanding basic CM-imaging principles is essential for designing optimal injection protocols according to each specific clinical scenario, independently of scanner technology.

IMPLICATIONS FOR PRACTICE

With rapid advances in CT scanner technology including faster scan acquisitions, the risk of poor opacification of coronary vasculature increases significantly. Therefore, awareness of CM delivery protocols is paramount to consistently provide optimal image quality at a low radiation dose.

Incidental myocardial perfusion defect detected on ECG-gated CT aortogram

We report the case of a 49-year-old man with a history of diabetes and hypertension who presented to the emergency room with intermittent chest pain radiating to the back for one day. An electrocardiogram-gated CT aortogram excluded the emergency department's primary consideration of aortic dissection, but incidentally revealed a myocardial perfusion defect and corresponding coronary artery stenosis. Cardiac catheterization performed the following day confirmed the CT findings and the patient underwent angioplasty and stent placement. We show that despite a different protocol than coronary CTA or myocardial perfusion CT, a gated CTA for dissection (CT aortogram) is capable of detecting resting perfusion abnormalities in patients presenting to the emergency room with chest pain.

Multidetector computed tomography for detecting left atrial/left atrial appendage thrombus: a meta-analysis

BACKGROUND

The diagnostic accuracy of multidetector computed tomography (MDCT) in the detection of left atrial/left atrial appendage (LA/LAA) thrombus had been tested in many studies; however, the results are controversial.

AIM

The aim of the present study was to evaluate synthetically the diagnostic accuracy of MDCT in LA/LAA thrombus.

METHODS

PubMed and Embase were searched for published prospective studies which compared computed tomography with transoesophageal echocardiography (TEE) in detecting LA/LAA thrombus prior to March 2014. Descriptive and quantitative information was extracted and MetaDiSc 1.4 was used to perform a meta-analysis.

RESULTS

Fifteen prospective clinical controlled trials with 2540 patients fulfilled the inclusion criteria. The pooled sensitivities (SEN): 0.957; pooled specificities (SPE): 0.917; pooled positive likelihood ratio (PLR): 22.017; pooled negative likelihood ratio (NLR): 0.060; pooled diagnostic odds ratio (DOR): 437.43; the area under the curve (AUC): 0.9883; Q*-value: 0.9544. However, in the abovementioned indexes, the heterogeneities were statistically significant between studies (P < 0.05, inconsistency index (I(2) ) > 50%). In a sub-analysis of studies in which delayed imaging, electrocardiogram (ECG) gating and heart rate control were performed, not only the diagnostic accuracy, but also the heterogeneities were significantly improved (pooled SEN 0.991; pooled SPE 0.989; pooled PLR 60.768; pooled NLR 0.034; pooled DOR 2561.7; AUC 0.9972; Q*-value 0.9806; all the indexes' P-value were greater than 0.05 and the I(2) were 0%, except for SPE, I(2) = 54.6%).

CONCLUSION

For patients with TEE intolerance or contraindications, MDCT may be an alternative method, especially when the delayed imaging, ECG gating and heart rate control were performed.

Diagnostic Accuracy, Image Quality, and Patient Comfort for Coronary CT Angiography Performed Using Iso-Osmolar versus Low-Osmolar Iodinated Contrast: A Prospective International Multicenter Randomized Controlled Trial

RATIONALE AND OBJECTIVES

The impact of iso-osmolar versus low-osmolar iodinated contrast on diagnostic accuracy for coronary computed tomography angiography (CCTA), against the reference standard of invasive coronary angiography (ICA), has not been determined. We sought to compare in an international multicenter randomized controlled trial the impact of iso-osmolar iodixanol versus low-osmolar iopamidol on diagnostic accuracy, image quality, patient symptoms, and heart rate variability.

MATERIALS AND METHODS

Adult patients who were clinically referred for ICA were randomly assigned to receive either iodixanol (n = 133) or iopamidol (n = 133) with an investigational CCTA. CCTA stenosis and image quality were scored by consensus of independent blinded core laboratory readers. Degree of stenosis by ICA was evaluated using quantitative coronary angiography and used to calculate diagnostic accuracy. Heart rate variability and patient-reported symptom questionnaires were compared between the two groups.

RESULTS

A total of 266 subjects underwent both CCTA and ICA (57 ± 11 years, 58% male). The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for detecting coronary artery disease were 86.8%, 93.7%, 84.6%, 94.7%, and 91.7% for iodixanol and 94.7%, 88.4%, 76.6%, 97.7%, and 90.2% for iopamidol, respectively, on a per-patient level. These values were not significantly different between the two groups. There was no significant difference in image quality and heart rate increase or variability. The majority of patients reported symptoms (59.4%), with no differences in the overall or individual rate of any or moderate to severe symptoms between the two groups. Patients receiving iodixanol reported lower incidence of moderate to severe flushing (3.0% vs. 12.8%, P = .005). Lower rates of moderate to severe symptoms were particularly evident for patients with ≥55 years receiving iodixanol versus iopamidol (8.5% vs. 24.6%, P = .01).

CONCLUSIONS

Diagnostic performance and image quality were similar for CCTA performed with iso-osmolar versus low-osmolar iodinated contrast. Indices of patient comfort were improved with iso-osmolar iodinated contrast.

Impact of a motion correction algorithm on quality and diagnostic utility in unselected patients undergoing coronary CT angiography

AIMS

The aims of the study were to investigate the diagnostic utility of motion correction reconstruction algorithm Snapshot Freeze (SSF) compared to the standard reconstruction algorithm (STD) in coronary computed tomography angiography (CCTA) images where a prescan heart-rate-lowering protocol is fully integrated.

METHODS

CCTA was performed in 140 patients. Two independent blinded readers made image evaluation of the SSF and STD images.

RESULTS

SSF reduced the motion artifacts (30% vs. 41%; P<.05) and improved the image quality ("excellent" images: 52% vs. 42%; P=.022), but did not influence diagnostic utility ("nondiagnostic" images: 10% vs. 14%; P=.104).

CONCLUSION

The use of the SSF algorithm reduced the presence of motion artifacts and improved image quality, but did not influence the diagnostic utility.

Impact of an intra-cycle motion correction algorithm on overall evaluability and diagnostic accuracy of computed tomography coronary angiography

OBJECTIVES

The aim of this study was to evaluate the impact of a novel intra-cycle motion correction algorithm (MCA) on overall evaluability and diagnostic accuracy of cardiac computed tomography coronary angiography (CCT).

METHODS

From a cohort of 900 consecutive patients referred for CCT for suspected coronary artery disease (CAD), we enrolled 160 (18 %) patients (mean age 65.3 ± 11.7 years, 101 male) with at least one coronary segment classified as non-evaluable for motion artefacts. The CCT data sets were evaluated using a standard reconstruction algorithm (SRA) and MCA and compared in terms of subjective image quality, evaluability and diagnostic accuracy.

RESULTS

The mean heart rate during the examination was 68.3 ± 9.4 bpm. The MCA showed a higher Likert score (3.1 ± 0.9 vs. 2.5 ± 1.1, p < 0.001) and evaluability (94%vs.79 %, p < 0.001) than the SRA. In a 45-patient subgroup studied by clinically indicated invasive coronary angiography, specificity, positive predictive value and accuracy were higher in MCA vs. SRA in segment-based and vessel-based models, respectively (87%vs.73 %, 50%vs.34 %, 85%vs.73 %, p < 0.001 and 62%vs.28 %, 66%vs.51 % and 75%vs.57 %, p < 0.001). In a patient-based model, MCA showed higher accuracy vs. SCA (93%vs.76 %, p < 0.05).

CONCLUSIONS

MCA can significantly improve subjective image quality, overall evaluability and diagnostic accuracy of CCT.

KEY POINTS

Cardiac computed tomographic coronary angiography (CCT) allows non-invasive evaluation of coronary arteries. Intra-cycle motion correction algorithm (MCA) allows for compensation of coronary motion. An MCA improves image quality, CCT evaluability and diagnostic accuracy.

Optimal reconstruction interval in dual source CT coronary angiography: a single-center experience in 285 patients

PURPOSE

We aimed to evaluate the visibility of coronary arteries and bypass-grafts in patients who underwent dual source computed tomography (DSCT) angiography without heart rate (HR) control and to determine optimal intervals for image reconstruction.

MATERIALS AND METHODS

A total of 285 consecutive cases who underwent coronary (n=255) and bypass-graft (n=30) DSCT angiography at our institution were identified retrospectively. Patients with atrial fibrillation were excluded. Ten datasets in 10% increments were reconstructed in all patients. On each dataset, the visibility of coronary arteries was evaluated using the 15-segment American Heart Association classification by two radiologists in consensus.

RESULTS

Mean HR was 76±16.3 bpm, (range, 46-127 bpm). All coronary segments could be visualized in 277 patients (97.19%). On a segment-basis, 4265 of 4275 (99.77%) coronary artery segments were visible. All segments of 56 bypass-grafts in 30 patients were visible (100%). Total mean segment visibility scores of all coronary arteries were highest at 70%, 40%, and 30% intervals for all HRs. The optimal reconstruction intervals to visualize the segments of all three coronary arteries in descending order were 70%, 60%, 80%, and 30% intervals in patients with a mean HR <70 bpm; 40%, 70%, and 30% intervals in patients with a mean HR 70-100 bpm; and 40%, 50%, and 30% in patients with a mean HR >100 bpm.

CONCLUSION

Without beta-blocker administration, DSCT coronary angiography offers excellent visibility of vascular segments using both end-systolic and mid-late diastolic reconstructions at HRs up to 100 bpm, and only end-systolic reconstructions at HRs over 100 bpm.

Noninvasive coronary angiography using computed tomography

While noninvasive imaging of the coronary lumen remains challenging, great strides have been made with computed tomography. Two variations of computed tomography are used in the study of the coronary tree: multislice or multidetector computed tomography and electron-beam computed tomography. Both have high spatial and temporal resolutions as well as excellent signal-to-noise ratios, which allows major branches of the coronary tree to be depicted. Impaired image quality, due to dense calcifications and multiple image artifacts including coronary artery motion and breathing artifacts, limits the clinical utility of noninvasive coronary angiography. Early studies with electron-beam angiography demonstrated an overall sensitivity of 85% and specificity of 89% for the detection of obstructive coronary artery disease. With early diastolic imaging, the sensitivity and specificity increases to 92 and 93%, respectively (rather than 80% of the cardiac interbeat interval, where coronary motion is more pronounced). Multidetector computed tomography, with improved spatial resolution but decreased temporal resolution, produces results that vary depending on the equipment. Four-slice scanners have an average sensitivity of only 61%, and only 38% of patients have all four vessels or 15 segments available for analysis, due to both cardiac motion and calcification. Thinner slice collimation with eight and 16 slices have allowed for improved detection. Sensitivity and specificity improve to 80 and 86%, respectively. Furthermore, the number of assessable segments with eight-to 16-slice scanners improves significantly, compared with four-slice scanners (85 vs. 73%; p<0.001). If only assessable segments are included in analysis, sensitivity and specificity for multidetector-row computed tomography improves to nearly 90%. Compared with magnetic resonance imaging, with a reported accuracy of 72% in the only multicenter study, computed tomography has great promise to become the primary method of noninvasive coronary angiography.

Beta-blocker administration protocol for prospectively ECG-triggered coronary CT angiography

The aim of this article is to discuss the protocol of beta-blockers that is commonly used for prospectively ECG-triggered coronary computed tomography angiography (CCTA). It is essential to ensure a low and regular heart rate in patients undergoing prospectively ECG-triggered CCTA for optimal visualization of coronary arteries. Although early generations of computed tomographyscanners are not applicable to be tailored according to patients’ heart rate, a low and regular heart rate is possible to be achieved by the administration of medications according to the beta-blocker protocol. Beta-blocker can be safely administered to reduce patients’ heart rate for CCTA examination if patients are screened for certain contraindications.

Dose-finding study of landiolol hydrochloride: a short-acting β1-blocker for controlling heart rate during coronary computed-tomography angiography in Japan

INTRODUCTION

Coronary computed-tomography angiography (CCTA) has high diagnostic performance, but it sometimes does not allow evaluation because of artifacts. Currently, the use of a β-blocker is recommended to prevent motion artifacts, but the β-blocker (metoprolol, propranolol, etc.) commonly used has a slow onset and long duration of action. Landiolol hydrochloride is an intravenous β1-blocker with a very short half-life. We investigated the efficacy and optimal dose of this drug for reduction of heart rate in patients undergoing CCTA.

METHODS

Eighty-seven subjects with ischemic heart disease were divided into three groups to receive landiolol hydrochloride at a dose of 0.125 (Group L), 0.25 (Group M), or 0.5 mg/kg (Group H). CCTA was performed at 3-7 min after administration, and heart rate, blood pressure, and image quality were assessed.

RESULTS

Heart rate decreased rapidly after completion of landiolol hydrochloride administration in all groups, with a heart rate reduction of 15.55 ± 6.56% in Group L, 16.48 ± 7.80% in Group M, and 21.49 ± 6.13% in Group H (Group L vs Group H, P = 0.0008; Group M vs Group H, P = 0.0109). Since there was no significant difference in heart rate during imaging among the three groups, although there was a significant difference between groups L and H and groups M and H in terms of percent change in heart rate, coronary stenosis was diagnosable in all groups with no significant difference.

CONCLUSION

Landiolol hydrochloride showed a rapid onset and short β-blocking effect, and was most effective at a dose of 0.5 mg/kg. However, the diagnosable proportion had no significant differences among the three groups in CCTA. Therefore, the clinically recommended dose was 0.125 mg/kg or less, considering the heart rate of patients with suspected coronary stenosis during CCTA.

MDCT coronary angiography -- postprocessing, reading, and reporting: last but not least

Significant literature on MDCT coronary angiography (MDCT-CA) has emerged in the last decade concerning patient's selection, technical aspects of different generations of CT equipment, ECG gating, contrast material and beta-blockade administration, acquisition parameters, and radiation dose. However, the literature regarding postprocessing, reading, and reporting is not so extensive. This review highlights the main elements of MDCT-CA data analysis, thereby allowing the radiologist to take full advantage of this technology and enable a structured report to be generated, promoting best practice with high-quality results.

Individual patient data meta-analysis for the clinical assessment of coronary computed tomography angiography: protocol of the Collaborative Meta-Analysis of Cardiac CT (CoMe-CCT)

BACKGROUND

Coronary computed tomography angiography has become the foremost noninvasive imaging modality of the coronary arteries and is used as an alternative to the reference standard, conventional coronary angiography, for direct visualization and detection of coronary artery stenoses in patients with suspected coronary artery disease. Nevertheless, there is considerable debate regarding the optimal target population to maximize clinical performance and patient benefit. The most obvious indication for noninvasive coronary computed tomography angiography in patients with suspected coronary artery disease would be to reliably exclude significant stenosis and, thus, avoid unnecessary invasive conventional coronary angiography. To do this, a test should have, at clinically appropriate pretest likelihoods, minimal false-negative outcomes resulting in a high negative predictive value. However, little is known about the influence of patient characteristics on the clinical predictive values of coronary computed tomography angiography. Previous regular systematic reviews and meta-analyses had to rely on limited summary patient cohort data offered by primary studies. Performing an individual patient data meta-analysis will enable a much more detailed and powerful analysis and thus increase representativeness and generalizability of the results. The individual patient data meta-analysis is registered with the PROSPERO database (CoMe-CCT, CRD42012002780).

METHODS/DESIGN

The analysis will include individual patient data from published and unpublished prospective diagnostic accuracy studies comparing coronary computed tomography angiography with conventional coronary angiography. These studies will be identified performing a systematic search in several electronic databases. Corresponding authors will be contacted and asked to provide obligatory and additional data. Risk factors, previous test results and symptoms of individual patients will be used to estimate the pretest likelihood of coronary artery disease. A bivariate random-effects model will be used to calculate pooled mean negative and positive predictive values as well as sensitivity and specificity. The primary outcome of interest will be positive and negative predictive values of coronary computed tomography angiography for the presence of coronary artery disease as a function of pretest likelihood of coronary artery disease, analyzed by meta-regression. As a secondary endpoint, factors that may influence the diagnostic performance and clinical value of computed tomography, such as heart rate and body mass index of patients, number of detector rows, and administration of beta blockade and nitroglycerin, will be investigated by integrating them as further covariates into the bivariate random-effects model.

DISCUSSION

This collaborative individual patient data meta-analysis should provide answers to the pivotal question of which patients benefit most from noninvasive coronary computed tomography angiography and thus help to adequately select the right patients for this test.

Safety and efficacy of oral ivabradine as a heart rate-reducing agent in patients undergoing CT coronary angiography

OBJECTIVE

To investigate the role of oral ivabradine as a heart rate reducing agent in patients undergoing CT coronary angiography (CTCA). Despite the routine use of β-blockers prior to CTCA studies, it is not uncommon to have patients with heart rates persistently above the target range of 65 bpm. Ivabradine is a selective inhibitor of the I(f) current, which primarily contributes to sinus node pacemaker activity, and has no significant direct cardiovascular effects such as reduction of blood pressure, cardiac contractility or impairment of cardiac conduction.

METHODS

We investigated 100 consecutive patients who had been referred for CTCA for the evaluation of suspected coronary artery disease (CAD). Patients were randomised to receive either of the following two pre-medication protocols: oral metorprolol or oral ivabradine.

RESULTS

Ivabradine was significantly more effective than metorprolol in lowering the heart rate; the mean percentage reduction in heart rate with ivabradine vs metorpolol was 23.89+6.95% vs 15.20+4.50%, respectively (p=0.0001). Metoprolol significantly lowered both systolic and diastolic blood pressure while ivabradine did not. The requirement of additional doses to achieve a target heart rate of <65 beats per min was also significantly more frequent with metoprolol.

CONCLUSION

Ivabradine is a potentially attractive alternative to currently used drugs for reduction of heart rate in patients undergoing CTCA.

Radiation dose and diagnostic accuracy of multidetector computed tomography for the detection of significant coronary artery stenoses: a meta-analysis

We conducted a meta-analysis evaluating the critical ratio between effective radiation dose (ED), feasibility (Fe) and diagnostic accuracy (Ac) of multidetector computed tomography (MDCT) for the detection of significant coronary artery disease. By using our predetermined criteria, we selected human studies published in English in which the ED and raw data of Ac vs. invasive coronary angiography in a segment based model were specified. Data from 31 studies including 3661 patients (mean age 61.9 ± 4.5 years, heart rate 62.5 ± 6.7 bpm) and 50,236 coronary artery segments were analysed and are reported. Overall, Fe, sensitivity, specificity, negative predictive value, positive predictive value, Ac and ED were 95%, 90%, 96%, 99%, 69%, 95% and 10.4 ± 5.4 mSv, respectively. Multivariate analysis showed that prospective ECG-gating (-8.8 mSv CI95% -13.4 to -4.3 mSv, p=0.001), dual-source (-3.7 mSv CI95% -7.9 to 0 mSv, p=0.05) and BMI-adapted scanning protocols (-4.5 mSv CI95% -8.7 to -2.7 mSv, p=0.03) were independent predictors of ED reduction. In patients with low heart rate, the best compromise between ED, Fe and Ac (2.5 mSv, 97% and 98%, respectively) was obtained combining prospective ECG-gating and BMI-adapted scanning protocols, while in patients with high heart rate the strategy associated with the best results (10 mSv, 98% and 97%, respectively) was the use of dual-source MDCT with retrospective ECG gating and modulation dose. In conclusion, careful selection of CT scanning protocols according to the patient's characteristics is critical for keeping the radiation exposure "as low as reasonably achievable" (ALARA) without impairing Fe and Ac.

Congenital anomalies of coronary arteries: Diagnosis with 64 slice multidetector CT

OBJECTIVE

Congenital coronary artery anomalies are generally incidental, uncommon and asymptomatic. Some can cause severe potentially life threatening symptoms. The common mode of studying the coronary arteries is Conventional Coronary Angiogram. ECG-gated-multidetector CT is a non invasive modality. The objective of our study was to identify rare congenital coronary artery anomalies and discuss their clinical significance.

MATERIAL AND METHODS

A total number of 900 MDCT coronary angiograms were carried out at our institution between the period of April 2006 and October 2010. Patients with coronary artery anomaly constituted the subject of study.

RESULTS

The incidence of anomalous anatomical origin and course of the coronary arteries in our study was 1.55%. Hemodynamical significance was seen in five patients. 3 cases of single coronary artery originating from right coronary sinus were seen. 1 case of anomalous left coronary artery arising from main pulmonary artery was seen. 4 cases of anomalous RCA arising from left aortic cusp, 6 cases of absent LMCA with separate origin of LAD and LCX were seen.

CONCLUSION

Multidetector row CT is a noninvasive modality in cardiac imaging. It provides superior resolution of coronary tree and its variant. No projectional vascular overlap is seen. Various postprocessing techniques outclass catheter angiography imaging. Definition of ostia and proximal course of the coronary arteries by Multidetector CT is better than catheter angiography.

Safety, efficacy, and indications of beta-adrenergic receptor blockade to reduce heart rate prior to coronary CT angiography

For selected indications, coronary computed tomographic (CT) angiography is an established clinical technology for evaluation in patients suspected of having or known to have coronary artery disease. In coronary CT angiography, image quality is highly dependent on heart rate, with heart rate reduction to less than 60 beats per minute being important for both image quality and radiation dose reduction, especially when single-source CT scanners are used. β-Blockers are the first-line option for short-term reduction of heart rate prior to coronary CT angiography. In recent years, multiple β-blocker administration protocols with oral and/or intravenous application have been proposed. This review article provides an overview of the indications, efficacy, and safety of β-blockade protocols prior to coronary CT angiography with respect to different scanner techniques. Moreover, implications for radiation exposure and left ventricular function analysis are discussed.

Testing of low-risk patients presenting to the emergency department with chest pain: a scientific statement from the American Heart Association

The management of low-risk patients presenting to emergency departments is a common and challenging clinical problem entailing 8 million emergency department visits annually. Although a majority of these patients do not have a life-threatening condition, the clinician must distinguish between those who require urgent treatment of a serious problem and those with more benign entities who do not require admission. Inadvertent discharge of patients with acute coronary syndrome from the emergency department is associated with increased mortality and liability, whereas inappropriate admission of patients without serious disease is neither indicated nor cost-effective. Clinical judgment and basic clinical tools (history, physical examination, and electrocardiogram) remain primary in meeting this challenge and affording early identification of low-risk patients with chest pain. Additionally, established and newer diagnostic methods have extended clinicians' diagnostic capacity in this setting. Low-risk patients presenting with chest pain are increasingly managed in chest pain units in which accelerated diagnostic protocols are performed, comprising serial electrocardiograms and cardiac injury markers to exclude acute coronary syndrome. Patients with negative findings usually complete the accelerated diagnostic protocol with a confirmatory test to exclude ischemia. This is typically an exercise treadmill test or a cardiac imaging study if the exercise treadmill test is not applicable. Rest myocardial perfusion imaging has assumed an important role in this setting. Computed tomography coronary angiography has also shown promise in this setting. A negative accelerated diagnostic protocol evaluation allows discharge, whereas patients with positive findings are admitted. This approach has been found to be safe, accurate, and cost-effective in low-risk patients presenting with chest pain.

Is it possible to predict heart rate and range during enhanced cardiac CT scan from previous non-enhanced cardiac CT?

The effect of heart rate and variation during cardiac computed tomography (CT) on the examination quality. The purpose of this study is to investigate whether it is possible to predict heart rate and range during enhanced cardiac computed CT scan from previous non-enhanced cardiac CT scan. Electrocardiograph (ECG) files from 112 patients on three types of cardiac 64-slice CT (non-enhanced, prospective ECG-triggered and retrospective ECG-gated enhanced scans) were recorded. The mean heart rate, range (defined as difference between maximal and minimal heart rates) and the range ratio (defined as maximal heart rate divided by minimal heart rate) during the scans were compared. Scan time was 4.8, 4.6, and 7.3 s on non-enhanced, prospective ECG-triggered and retrospective ECG-gated scans, respectively (p < 0.0001). The heart rates were not significantly different (60 ± 9 beats per minute (bpm), 60 ± 9 and 61 ± 10 bpm; p = 0.64). Heart rate on the enhanced scan markedly correlated with that of the non-enhanced scan (r = 0.78 and 0.74). In contrast, the ranges of heart rate were 2 ± 5, 4 ± 8, and 8 ± 21 bpm, with different range ratios (1.04, 1.07, and 1.14; p < 0.0001). Correlation of heart rate ranges between non-enhanced scan versus prospective ECG-triggered scan was low (r = 0.27) and that between non-enhanced scan versus retrospective ECG-gated scan negligible (r = -0.027).Heart rate on enhanced cardiac CT, in most cases, can be predicted from a non-enhanced scan. Heart rate range on enhanced cardiac CT, however, is hard to predict from the non-enhanced scan.

Evaluation of reperfused myocardial infarction by low-dose multidetector computed tomography using prospective electrocardiography (ECG)-triggering: comparison with magnetic resonance imaging

PURPOSE

To evaluate the potential of prospective electrocardiography (ECG)- gated 64-slice multidetector computed tomography (MDCT) for evaluation of myocardial enhancement, infarct size, and stent patency after percutaneous coronary intervention (PCI) with stenting in patients with myocardial infarction.

MATERIALS AND METHODS

Seventeen patients who were admitted with acute myocardial infarction were examined with prospective ECG-gated 64-slice cardiac MDCT and magnetic resonance (MR) imaging after reperfusion using PCI with stenting. Cardiac MDCT was performed with two different phases: arterial and delayed phases. We evaluated the stent patency on the arterial phase, and nonviable myocardium on the delayed phase of computed tomography (CT) image, and they were compared with the results from the delayed MR images.

RESULTS

Total mean radiation dose was 7.7 +/- 0.5 mSv on the two phases of CT images. All patients except one showed good patency of the stent at the culprit lesion on the arterial phase CT images. All patients had hyperenhanced area on the delayed phase CT images, which correlated well with those on the delayed phase MR images, with a mean difference of 1.6% (20 +/- 10% vs. 22 +/- 10%, r = 0.935, p = 0.10). Delayed MR images had a better contrast-to-noise ratio (CNR) than delayed CT images (27.1 +/- 17.8% vs. 4.3 +/- 2.1%, p < 0.001).

CONCLUSION

Prospective ECG-gated 64-slice MDCT provides the potential to evaluate myocardial viability on delayed phase as well as for stent patency on arterial phase with an acceptable radiation dose after PCI with stenting in patients with myocardial infarction.

Evaluation of the patient with acute chest pain

The past decade has brought rapid advances in CT technology, which allows increasingly precise application to the study of coronary arteries and acute chest pain. The literature has expanded to lend quantifiable justification to the intuitive appeal of a rapid, reproducible, 3D study of the heart and vasculature. More complete analysis of efficacy and costs on broader populations will further refine our understanding of how best to implement what may become the new gold standard. Meanwhile, evolving technology promises to further challenge radiologists and clinicians to optimize approach and diagnosis to acute chest pain.

Coronary computed tomographic angiography (CCTA) in community hospitals: "current and emerging role"

Coronary computed tomographic angiography (CCTA) is a rapidly evolving test for diagnosis of coronary artery disease. Although invasive coronary angiography is the gold standard for coronary artery disease (CAD), CCTA is an excellent noninvasive tool for evaluation of chest pain. There is ample evidence to support the cost-effective use of CCTA in the early triage process of patients presenting with chest pain in the emergency room. CCTA plays a critical role in the diagnosis of chest pain etiology as one of potentially fatal conditions, aortic dissection, pulmonary embolism, and myocardial infarction. This 'triple rule out' protocol is becoming an increasingly practicable and popular diagnostic tool in ERs across the country. In addition to a quick triage of chest pain patients, it may improve quality of care, decrease cost, and prevent medico-legal risk for missing potentially lethal conditions presenting as chest pain. CCTA is also helpful in the detection of subclinical and vulnerable coronary plaques. The major limitations for wide spread acceptance of this test include radiation exposure, motion artifacts, and its suboptimal imaging with increased body mass index.

Quantitative assessment of image quality in 64-slice-computed tomography of coronary arteries in subjects undergoing screening for coronary artery disease

Accurate and consistent visualization of the entire coronary system with high-grade imaging quality is crucial for routine applications of multi-detector-computed tomography (MDCT) coronary angiography. To determine the imaging quality of 64-slice-MDCT coronary angiography, we respectively explored the quantitative parameters of imaging quality in 105 consecutive subjects (71 men, 34 women; aged 58.66 +/- 10.62 years) who underwent 64-slice-MDCT coronary angiography to screen for coronary disease. The interobserver agreement for semi-quantitative image quality, visible length, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the coronary arteries was good. The SNR and CNR of the proximal segments of the coronary arteries were superior to that of the distal segments of coronary arteries (p < 0.001). The visible length of the stenosed right coronary artery was significantly shorter than that of the non-stenosed right coronary artery (p = 0.03). The SNR and CNR of the stenosed and non-stenosed coronary arteries revealed no significant difference (p > 0.05). Body weight and body mass index were inversely related to the SNR and CNR of the aorta (p < 0.001). In conclusion, 64-slice-MDCT coronary angiography can provide excellent imaging quality of coronary arteries in subjects undergoing screening for coronary disease, although the SNR and CNR were relatively low at the distal segments of coronary arteries.

Patient characteristics as predictors of image quality and diagnostic accuracy of MDCT compared with conventional coronary angiography for detecting coronary artery stenoses: CORE-64 Multicenter International Trial

OBJECTIVE

The purpose of the study was to investigate patient characteristics associated with image quality and their impact on the diagnostic accuracy of MDCT for the detection of coronary artery stenosis.

MATERIALS AND METHODS

Two hundred ninety-one patients with a coronary artery calcification (CAC) score of <or=600 Agatston units (214 men and 77 women; mean age, 59.3+/-10.0 years [SD]) were analyzed. An overall image quality score was derived using an ordinal scale. The accuracy of quantitative MDCT to detect significant (>or=50%) stenoses was assessed using quantitative coronary angiography (QCA) per patient and per vessel using a modified 19-segment model. The effect of CAC, obesity, heart rate, and heart rate variability on image quality and accuracy were evaluated by multiple logistic regression. Image quality and accuracy were further analyzed in subgroups of significant predictor variables. Diagnostic analysis was determined for image quality strata using receiver operating characteristic (ROC) curves.

RESULTS

Increasing body mass index (BMI) (odds ratio [OR]=0.89, p<0.001), increasing heart rate (OR=0.90, p<0.001), and the presence of breathing artifact (OR=4.97, p<or=0.001) were associated with poorer image quality whereas sex, CAC score, and heart rate variability were not. Compared with examinations of white patients, studies of black patients had significantly poorer image quality (OR=0.58, p=0.04). At a vessel level, CAC score (10 Agatston units) (OR=1.03, p=0.012) and patient age (OR=1.02, p=0.04) were significantly associated with the diagnostic accuracy of quantitative MDCT compared with QCA. A trend was observed in differences in the areas under the ROC curves across image quality strata at the vessel level (p=0.08).

CONCLUSION

Image quality is significantly associated with patient ethnicity, BMI, mean scan heart rate, and the presence of breathing artifact but not with CAC score at a patient level. At a vessel level, CAC score and age were associated with reduced diagnostic accuracy.

Image quality of coronary 320-MDCT in patients with atrial fibrillation: initial experience

OBJECTIVE

Noninvasive coronary angiography has generally been contraindicated in patients with atrial fibrillation because of the difficulty in synchronizing an irregular heartbeat with table gantry movement. The objective of this study was to evaluate and compare the quality of 320-MDCT images obtained in patients with atrial fibrillation and in a control group of patients in sinus rhythm.

MATERIALS AND METHODS

Two reviewers were blinded to the patient groups and evaluated images of 15 coronary artery segments for each patient using 320-MDCT. The images were printed on glossy paper and scored subjectively as 1 or 2, meaning of diagnostic quality, or 3, meaning poor quality.

RESULTS

No statistical difference between the groups was noted in patient age: The mean age of the patients with atrial fibrillation was 67 years (age range, 52-82 years) and that of the patients in sinus rhythm was 59 years (36-86 years) (p = 0.3). Scores of 1 and 2 (diagnostic quality) were assigned to 100% in sinus rhythm and 96% in atrial fibrillation (p < 0.05). Scores of 3 were seen only in the atrial fibrillation group (7/175, 4%). Segment 15, the distal circumflex artery, was the segment that was most frequently assigned a score of 3 (2/7, 28.6%). A discrepancy in the two reviewers' scores was seen in 25 segments (7%), requiring joint consensus. The segments that most frequently required consensus reading were segments 12 and 15. The overall mean image quality score for all three coronary arteries in atrial fibrillation was 1.25 +/- 0.47 (SD) and 1.08 +/- 0.26 in sinus rhythm (p < 0.001). The median effective dose was 19.28 and 13.55 mSv in the atrial fibrillation and sinus rhythm groups, respectively.

CONCLUSION

The analysis of our initial experience shows that imaging in patients with atrial fibrillation is possible using 320-MDCT, with images of most segments obtained being of diagnostic quality. Segment 15 was the most difficult to see on 320-MDCT because of the small caliber of the vessel; poor visualization of that segment mostly occurred in the setting of a dominant right coronary arterial system.

Comparison of image quality of 64-slice multidetector CT coronary CT angiography using automated and manual multiphase methods for the determination of optimal phases for image reconstruction in patients with various mean heart rates

This study aimed to compare the effects of the automated and manual methods for determining the optimal phase of image reconstruction with the use of 64-slice coronary CT angiography (CCTA). In 63 patients, the optimal trigger delay was determined using an automated technique (PhaseXact) and by manual phase selection from the images reconstructed at a 10 ms and 1% increment of the R-R interval. The image quality was evaluated using four-step grading. The mean heart rate in all the patients was 70 +/- 10.1 bpm (range: 52-98 bpm). The frequency of obtaining diagnostic quality images was highest with the manual absolute timing method (97.6% of 753 segments), while it was 94.7% with manual relative timing and 91.9% with an automated method. The mean image quality score (1.3 +/- 0.2) based on the manual absolute timing was significantly better (P = 0.002, one-way ANOVA; P < 0.05, Scheffe's test) than the scores determined with the use of the other two techniques (manual relative timing, 1.4 +/- 0.3; automated method, 1.5 +/- 0.4). The best quality coronary CT images were obtained using image reconstruction with manual absolute timing for the ECG-trigger delay, while an automated method and manual relative timing provided diagnostic quality images in most of the segments.

The diagnostic value of multislice computed tomography postprocessing images in coronary artery stenosis

OBJECTIVE

To investigate the clinical application value of various multislice computed tomography (MSCT) postprocessing images in moderate coronary artery stenosis (defined as >50% stenosis).

METHODS

Sixty patients with high risk factors, whether they had suspected or confirmed coronary heart disease, underwent MSCT coronary angiography before undergoing selective coronary angiography (CAG).The transverse images obtained from the MSCT scan were compared, as well as various post-processing images (eg, multiplanar reformation [MPR], maximum-intensity projection [MIP], volume rendering technique [VRT], as well as virtual endoscopy [VE]), with CAG to evaluate the clinical significance of various MSCT postprocessing images in moderate coronary artery stenosis

RESULTS

Among the various MSCT postprocessing images, MPR had the highest sensitivity, specificity, positive predictive value, and negative predictive value in the diagnosis of moderate coronary artery stenosis, followed by VRT, VE, and with MIP having the lowest

CONCLUSION

In the diagnosis of moderate coronary artery stenosis, a comprehensive evaluation should be made by associating axial images, using MPR mainly with VRT, and using VE and MIP as supplements in order to increase the accuracy of diagnosis.

64-MDCT coronary angiography of patients with atrial fibrillation: influence of heart rate on image quality and efficacy in evaluation of coronary artery disease

OBJECTIVE

The purpose of this study was to prospectively evaluate the effects of mean heart rate and heart rate variability on image quality at coronary 64-MDCT angiography of patients with atrial fibrillation and to determine the efficacy of coronary 64-MDCT angiography in the detection of significant (> 50%) coronary artery stenosis in patients with atrial fibrillation.

SUBJECTS AND METHODS

Sixty patients (37 women, 23 men; mean age, 58.7 years) underwent both coronary 64-MDCT angiography and conventional coronary angiography. Heart rate variability was calculated as the SD from the mean heart rate during scanning. Image quality (good, moderate, or poor) and the presence of significant (> 50%) stenosis at coronary CT angiography were evaluated by two radiologists blinded to the results of conventional coronary angiography. The sensitivity, specificity, positive predictive value, and negative predictive value of coronary CT angiography were calculated with conventional angiography as the reference standard. Pearson's correlation analysis and chi-square tests were performed to compare image quality with mean heart rate and heart rate variability in each patient. Differences in detection of coronary artery stenosis between coronary 64-MDCT angiography and conventional coronary angiography were evaluated with McNemar's test, and agreement between techniques was calculated with kappa statistics.

RESULTS

The mean heart rate was 90 +/- 13.1 beats/min with variability of 19.35 +/- 6.95 beats/min. Of 803 segments evaluated, 26 (3%) were considered to have poor image quality. Highly significant correlation was found between mean heart rate and image quality for all segments in each patient (r = 0.51, p < 0.001), for the right coronary artery (r = 0.43, p = 0.001), and for the distal portion of the coronary arteries (r = 0.50, p < 0.001). Heart rate variability also correlated in a highly significant way with image quality in all segments (r = 0.57, p < 0.001), the right coronary artery (r = 0.46, p < 0.001), and the middle (r = 0.44, p = 0.001) and distal (r = 0.41, p = 0.001) portions of the coronary arteries. The best diagnostic image quality was obtained in end systole (200-400 milliseconds). Image quality decreased significantly with a mean heart rate greater than 100 beats/min or with an SD of heart rate greater than 24 beats/min. The overall sensitivity, specificity, positive predictive value, and negative predictive value per segment level were 86.4%, 99.3%, 79.2%, and 99.6%. No significant difference was found between coronary 64-MDCT angiography and conventional coronary angiography in detection of significant stenosis. Excellent agreement between techniques was found.

CONCLUSION

Coronary 64-MDCT angiography has diagnostic image quality within a wide range of heart rates and in patients with atrial fibrillation. Reducing average heart rate and heart rate variability in patients with atrial fibrillation is beneficial in improving image quality.

Dose reduction in spiral CT coronary angiography with dual-source equipment. Part I. A phantom study applying different prospective tube current modulation algorithms

PURPOSE

The authors sought to compare different algorithms for dose reduction in retrospectively echocardiographically (ECG)-gated dual-source computed tomography (CT) coronary angiography (DSCT-CA) in a phantom model.

MATERIALS AND METHODS

Weighted CT dose index (CTDI) was measured by using an anthropomorphic phantom in spiral cardiac mode (retrospective ECG gating) at five pitch values adapted with two heart-rate-adaptive ECG pulsing windows using four algorithms: narrow pulsing window, with tube current reduction to 20% (A) and 4% (B) of peak current outside the pulsing window; wide pulsing window, with tube current reduction to 20% (C) and 4% (D). Each algorithm was applied at different heart rates (45, 60, 75, 90, 120 bpm).

RESULTS

Mean CTDI volume (CTDIvol) was 36.9+/-9.7 mGy, 23.9+/-5.6 mGy, 49.7+/-16.2 mGy and 38.5+/-12.3 mGy for A, B, C and D, respectively. Consistent dose reduction was observed with protocols applying the 4% tube current reduction (B and D). Using the conversion coefficient for the chest, the mean effective dose was the highest for C (9.6 mSv) and the lowest for B (4.6 mSv). Heart-ratedependent pitch values (pitch=0.2, 0.26, 0.34, 0.43, 0.5) and the use of heart-rate-adaptive ECG pulsing windows provided a significant decrease in the CTDIvol with progressively higher heart rates (45, 60, 75, 90, 120 bpm), despite using wider pulsing windows.

CONCLUSIONS

Radiation exposure with DSCT-CA using a narrow pulsing window significantly decreases when compared with a wider pulsing window. When using a protocol with reduced tube current to 4%, the radiation dose is significantly lower.

Clinical value of 16‐slice multi‐detector CT compared to invasive coronary angiography

BACKGROUND

Multi-detector row spiral CT (MDCT) can be applied as a noninvasive tool for the assessment of coronary artery stenoses. Few, confounding reports have been published using 16 detector rows. The aim of the present study was to determine the accuracy of 16-detector row MDCT for the detection of significant stenoses in the coronary arteries, in comparison to conventional invasive coronary angiography.

METHODS

Twenty-two patients with suspected coronary artery disease, were prospectively evaluated by 16-slice retrospectively ECG-gated CT coronary angiography and quantitative invasive coronary angiography. The findings were compared for the detection of significant coronary artery stenoses (>50%) in all segments with diameter >1.5 mm.

RESULTS

MDCT correctly classified all 14 patients (100%) that were found to have significant coronary artery disease on conventional angiography. Overall, 288 segments were included in the analysis, regardless of their image quality. Significant stenoses were detected in 24 segments by CT and in 28 segments by conventional angiography. Out of 260 segments that were negative for significant stenoses on conventional angiography, 255 were correctly identified on CT. The sensitivity, specificity, positive and negative predictive values were 86, 98, 83 and 98%, respectively. MDCT also revealed supplementary findings that invasive angiography was unable to visualize, including anomalous vessel course, the course of vessels filling via collaterals, intramyocardial course of vessels and non-stenotic plaques.

CONCLUSIONS

MDCT coronary angiography utilizing 16-detector rows shows promising results for reliable detection of coronary artery stenoses and particularly for ruling out significant disease.

[ECG-gated chest CT angiography: value for atypical chest pain evaluation]

PURPOSE

The aim of this study was to evaluate ECG-gated whole chest CTA as a routine triage tool for patients with acute chest pain.

MATERIAL AND METHODS

Whole chest CTA with retrospective ECG-gating was performed in 30 patients with acute atypical chest pain. The ten main segments of the coronary arteries, the pulmonary arteries, the aorta, and the myocardium (function, morphology) were independently analyzed by a resident and two senior radiologists. The inter-observer agreement between resident and senior radiologists was calculated. A final diagnosis was determined by consensus.

RESULTS

Thirty patients were included. The coronary artery segments, myocardium and pulmonary arteries were considered analyzable in 84%, 90% and 97% of cases respectively. A final diagnosis for the cause of pain was retained in 19 patients: significant coronary artery stenosis (5), pulmonary embolus (5), aortic dissection (1), hypokinetic cardiomyopathy (2), lung parenchymal abnormalities (5), and hiatus hernia (1). Inter-observer agreement ranged from 0.76 to 1 between senior radiologists and from 0.76 to 1 between resident and senior radiologists. The average time of image interpretation ranged from 14 to 15 minutes.

CONCLUSION

ECG-gated whole chest CT angiography appears as a promising tool for the evaluation of acute chest pain. Combined evaluation of appearance and function of the myocardium can reveal additional interesting information.

Effect of heart rate and coronary calcification on the diagnostic accuracy of the dual-source CT coronary angiography in patients with suspected coronary artery disease

OBJECTIVE

To evaluate the diagnostic accuracy of a dual-source computed tomography (DSCT) coronary angiography, with a particular focus on the effect of heart rate and calcifications.

MATERIALS AND METHODS

One hundred and nine patients with suspected coronary disease were divided into 2 groups according to a mean heart rate (< 70 bpm and >or= 70 bpm) and into 3 groups according to the mean Agatston calcium scores (<or= 100, 101-400, and > 400). Next, the effect of heart rate and calcification on the accuracy of coronary artery stenosis detection was analyzed by using an invasive coronary angiography as a reference standard. Coronary segments of less than 1.5 mm in diameter in an American Heart Association (AHA) 15-segment model were independently assessed.

RESULTS

The mean heart rate during the scan was 71.8 bpm, whereas the mean Agatston score was 226.5. Of the 1,588 segments examined, 1,533 (97%) were assessable. A total of 17 patients had calcium scores above 400 Agatston U, whereas 50 had heart rates >or= 70 bpm. Overall the sensitivity, specificity, positive predictive values (PPV) and negative predictive values (NPV) for significant stenoses were: 95%, 91%, 65%, and 99% (by segment), respectively and 97%, 90%, 81%, and 91% (by artery), respectively (n = 475). Heart rate showed no significant impact on lesion detection; however, vessel calcification did show a significant impact on accuracy of assessment for coronary segments. The specificity, PPV and accuracy were 96%, 80%, and 96% (by segment), respectively for an Agatston score less than 100% and 99%, 96% and 98% (by artery). For an Agatston score of greater to or equal to 400 the specificity, PPV and accuracy were reduced to 79%, 55%, and 83% (by segment), respectively and to 79%, 69%, and 85% (by artery), respectively.

CONCLUSION

The DSCT provides a high rate of accuracy for the detection of significant coronary artery disease, even in patients with high heart rates and evidence of coronary calcification. However, patients with severe coronary calcification (> 400 U) remain a challenge to diagnose.

A comprehensive electrocardiogram-gated 64-slice multidetector computed tomography imaging protocol to visualize the coronary arteries, thoracic aorta, and pulmonary vasculature in a single breath hold

OBJECTIVES

Advances in computed tomography technology may permit the evaluation of coronary disease, aortic dissection, and pulmonary embolism with a single contrast bolus and breath hold. We sought to determine whether 64-slice computed tomography angiography (CTA) allows for simultaneous visualization of the coronary arteries, thoracic aorta, and pulmonary arteries (coronary, aorta, pulmonary [CAP]) with image quality comparable to routine CTA protocols.

MATERIALS AND METHODS

We prospectively enrolled 20 patients who underwent CAP CTA. Image quality of CAP CTA was assessed qualitatively and quantitatively and compared with dedicated coronary (n = 20) and pulmonary (n = 10) CTA data sets using matched controls.

RESULTS

The mean amount of contrast and radiation dose was 132 +/- 10 mL and 17.8 +/- 1.8 mSv, 78 +/- 9 mL and 13.7 +/- 3.4 mSv, and 135 mL and 11.9 +/- 1.5 mSv for CAP CTA, coronary CTA, and pulmonary CTA, respectively (P = 0.001). There was no difference in overall image quality (P = 0.88), presence of motion artifacts (P = 0.40), or enhancement of the proximal coronary arteries (median [interquartile range for contrast-noise ratio was 12.5 9.9-15.2 vs 13.1 10.3-16.9; P = 0.17]) or thoracic aorta (264 [113-326] vs 245 [107-295]; P = 0.34) between CAP CTA and the dedicated coronary CTA, respectively. However, contrast attenuation was higher in the pulmonary arteries with CAP CTA (363 [253-424]) versus the standard pulmonary CTA protocol (235 [182-269]; P = 0.0001).

CONCLUSIONS

: Using an individually tailored single contrast injection, CAP CTA permits simultaneous visualization of the coronary arteries, thoracic aorta, and pulmonary arteries with excellent image quality. Further research is necessary to determine whether this protocol may enhance triage of patients with undifferentiated acute chest pain.

[Dual-source CT coronary angiography: image quality and optimal reconstruction interval]

OBJECTIVE

To evaluate the effect of average heart rate on the quality of images of the coronary arteries and to determine the optimal reconstruction interval in nonselected patients undergoing DSCT coronary imaging.

MATERIALS AND METHODS

We studied 28 consecutive subjects (26 men, 2 women; mean age 60+/-12 years) undergoing contrast-enhanced DSCT (Somatom Definition, Siemens) coronary angiography. Data sets were reconstructed in 5% steps from 30% to 80% of the R-R interval. Two blinded independent readers assessed the image quality of the whole coronary tree and of each coronary artery using a four-point scale (1: impossible to evaluate, 4: excellent quality).

RESULTS

Mean heart rate during scanning was 73.1+/-14.8 bpm (range, 49-107 bpm). In the best reconstruction interval, excellent diagnostic image quality (score 4) was achieved for 98.8% (83/84) of coronary arteries. Very good interobserver agreement was observed for image quality rating (kappa=0.77) and for selection of the optimal reconstruction interval (kappa=0.86). Mean image quality score for the whole coronary tree was 2.84+/-0.31. No significant correlation was found between the average heart rate and the mean quality scores (r=0.108). No significant differences were found in the quality of images of the coronary arteries in systolic and diastolic reconstructions in each patient.

CONCLUSIONS

DSCT makes it possible to obtain excellent coronary angiograms independent of the heart rate. Reconstructions can be obtained in either the diastolic or systolic phase without significant differences in image quality, even at high heart rates.