Indications for Coronary and Cardiac Computed Tomographic Angiography

Cardiovascular disease remains the leading cause of death and disability in the developed world. Over the last several years, many noninvasive imaging techniques have been used to enhance the diagnosis of cardiac disease. One of these advances, multidetector computed tomographic angiography (CTA), has transformed computed tomography from a single-slice transaxial imaging modality to a true 3-dimensional imaging technique with the ability to acquire submillimeter volumetric data. These benefits enable novel applications of CTA for the assessment of cardiac and coronary anatomy that were not previously possible. In this report, we discuss evolving indications for coronary CTA, noncoronary cardiac CTA, and several potential future indications for cardiac CTA.

Two-week treatment with pravastatin improves ventriculo-vascular haemodynamic interactions in young men with type 1 diabetes

Young patients with diabetes but without established vascular disease have altered conduit and resistance artery reactivity. Early endothelial dysfunction is an initial step in atherogenesis: reductions in nitric oxide (NO) production in these vascular beds are implicated. The study aim was two-fold: first, to detect baseline abnormalities in cardiac function, conduit vessels and the microcirculation using applanation tonometry, brachial artery ultrasound and laser Doppler fluximetry, respectively; and second, to investigate any modification in these parameters with the use of pravastatin. Nine young men with diabetes and normoalbuminuria were randomised in a double-blind cross-over fashion to placebo or pravastatin (40 mg) treatment for two weeks. They underwent scans on three separate occasions. Control patients (n=12) underwent a baseline scan but were not given any drug treatment. It was found that patients with diabetes had significantly higher systolic and diastolic blood pressures, heart rate and Buckberg index (propensity to myocardial ischaemia). Brachial artery reactivity and microcirculatory dilation were both reduced. Levels of von Willebrand Factor, a marker of endothelial damage, were also elevated. Pravastatin treatment restored these sub-clinical abnormalities towards normal levels. In conclusion, pravastatin improves vascular abnormalities in young male patients with diabetes through alterations in microcirculation and conduit vessel function, with secondary myocardial effects. This may be of benefit in preventing end-organ injury.

Cardiac CT angiography (CTA) and nuclear myocardial perfusion imaging (MPI)-a comparison in detecting significant coronary artery disease

RATIONALE AND OBJECTIVES

Endowed with sufficient diagnostic accuracy, electron beam computed tomography angiography (CTA) is being increasingly used to evaluate coronary arteries. However, data on direct comparisons with nuclear myocardial perfusion studies are limited. In this study, we sought to compare the accuracies of CTA and myocardial perfusion imaging (MPI) for identifying symptomatic patients with hemodynamically significant obstructive coronary artery disease (CAD).

MATERIALS AND METHODS

In a single-center study, symptomatic outpatients who were scheduled for cardiac catheterization were prospectively enrolled. Only patients with exertional angina or dyspnea were included. After fulfilling the inclusion criteria, 30 patients were enrolled in the study (mean age 54 +/- 9 years and 70% males). Patients underwent MPI, CTA including coronary artery calcification (CAC) measure, and invasive coronary angiography for evaluation of obstructive coronary artery disease. Significant CAD was defined as >50% left main artery stenosis or >70% stenosis of any other epicardial vessel by invasive angiography. The sensitivities, specificities and predictive values of MPI, CAC, and CTA were analyzed per patient

RESULTS

CTA demonstrated significant higher sensitivity than MPI (95% vs. 81%, P < .05). CTA demonstrated significantly higher specificity than both MPI (89% versus 78%, P = .04) and CAC (56%, P = .002). CTA also performed better in a per-vessel analysis (sensitivity 94%, specificity 96%) than both nuclear and CAC. There were no significant differences between the sensitivities and specificities of MPI and CAC.

CONCLUSION

CTA accurately detects obstructive CAD in symptomatic patients and may be more accurate than MPI or CAC assessment. Larger studies in a more diverse population are needed.

Patient acceptance of noninvasive and invasive coronary angiography

BACKGROUND

Noninvasive angiography using multislice computed tomography (MSCT) is superior to magnetic resonance imaging (MRI) for detection of coronary stenoses. We compared patient acceptance of these two noninvasive diagnostic tests and invasive conventional coronary angiography (Angio).

METHODS AND FINDINGS

A total of 111 consecutive patients with suspected coronary artery disease underwent MSCT, MRI, and Angio. Subsequently, patient acceptance of the three tests was evaluated with questionnaires in all patients. The main acceptance variables were preparation and information prior to the test, degree of concern, comfort, degree of helplessness, pain (on visual analog scales), willingness to undergo the test again, and overall satisfaction. Preparation for each test was not rated significantly differently, whereas patients were significantly more concerned about Angio than the two noninvasive tests (p<0.001). No pain during MSCT, MRI, and Angio as assessed on visual analog scales (0 to 100) was reported by 99, 93, and 31 patients, respectively. Among the 82 patients who felt pain during at least one procedure, both CT (0.9+/-4.5) and MRI (5.2+/-16.6) were significantly less painful than Angio (24.6+/-23.4, both p<0.001). MSCT was considered significantly more comfortable (1.49+/-0.64) than MRI (1.75+/-0.81, p<0.001). In both the no-revascularization (55 patients) and the revascularization group (56 patients), the majority of the patients (73 and 71%) would prefer MSCT to MRI and Angio for future imaging of the coronary arteries. None of the patients indicated to be unwilling to undergo MSCT again. The major advantages patients attributed to MSCT were its fast, uncomplicated, noninvasive, and painless nature.

CONCLUSIONS

Noninvasive coronary angiography with MSCT is considered more comfortable than MRI and both MSCT and MRI are less painful than Angio. Patient preference for MSCT might tip the scales in favor of this test provided that the diagnostic accuracy of MSCT can be shown to be high enough for clinical application.

Coronary anomalies by cardiac computed tomographic angiography

BACKGROUND

Early identification of an anomalous coronary anatomy is quite relevant because of the increased incidence of sudden cardiac death or related symptoms of myocardial ischemia in the patients. Invasive coronary angiography (ICA) is not only invasive, but expensive, and cannot always adequately provide the required information about the abnormal coronary anatomy. Cardiac computed tomographic angiography (CTA) is a robust noninvasive imaging modality that has several clinical applications and is now being used increasingly in practices across the nation. It not only provides high-resolution anatomical information of the coronary artery tree but also helps define other aspects of the cardiovascular anatomy, be it normal or abnormal.

HYPOTHESIS

This study sought to determine the clinical role played by CTA in the evaluation of different types of coronary arterial anomalies by reviewing CTA studies since 1997.

METHODS

We reviewed 6,089 case studies of contrast CTA conducted at our institution. There were 53 coronary anomalies in 39 patients (0.64%).

RESULTS

Computed tomographic angiography correctly identified the course of coronary arteries in all cases.

CONCLUSION

The results of this study support the use of CTA as a safe and effective noninvasive imaging modality for defining coronary arterial anomalies in an appropriate clinical setting, providing detailed three-dimensional anatomic information that may be difficult to obtain with invasive angiography.

Coronary stent patency and in-stent restenosis: determination with 64-section multidetector CT coronary angiography--initial experience

PURPOSE

To prospectively assess the diagnostic performance of 64-section multidetector computed tomography (CT) for the evaluation of coronary stent stenosis and occlusion by using conventional coronary angiography as the reference standard.

MATERIALS AND METHODS

Institutional review board approval and informed consent were obtained. Thirty patients (27 men, three women; mean age, 58.2 years; range, 42-67 years) with 39 coronary stents were examined with 64-section multidetector CT. Scanning was retrospectively electrocardiographically gated, and an automatic bolus-tracking method was used. For image reconstruction, an edge-enhancing kernel (B46f) was chosen. Evaluations were performed by two radiologists who were blinded to the results of conventional coronary angiography performed within 2-3 days after CT. Sensitivity, specificity, and positive and negative predictive values were calculated.

RESULTS

At conventional angiography, nine of the 39 stents were shown to be totally occluded. All of the occluded stents were correctly diagnosed with CT angiography. Nineteen of 20 patent stents were correctly demonstrated with CT angiography. Ten stents had in-stent restenosis; eight were correctly diagnosed with CT. The sensitivity, specificity, and positive and negative predictive values of 64-section multidetector CT were 89% (17 of 19), 95% (19 of 20), 94% (17 of 18), and 90% (19 of 21), respectively, for in-stent restenosis and occlusion. With the McNemar test, no significant difference was found between 64-section multidetector CT and conventional coronary angiography for the detection of coronary in-stent restenosis and occlusion.

CONCLUSION

Sixty-four-section multidetector CT coronary angiography is a promising method for the noninvasive diagnosis of in-stent restenosis and occlusion.

Multislice computed tomography in an asymptomatic high-risk population

Approximately 50% of all acute coronary syndromes occur in previously asymptomatic patients. This study evaluated the value of multislice computed tomography for early detection of significant coronary artery disease (CAD) in high-risk asymptomatic subjects. One hundred sixty-eight asymptomatic subjects with >or=1 major risk factor (hypertension, diabetes, hypercholesterolemia, family history, or smoking) and an inconclusive or unfeasible noninvasive stress test result (stress electrocardiography, echocardiography, or nuclear scintigraphy) were evaluated in an outpatient setting. After clinical examination and laboratory risk analysis, all patients underwent multislice computed tomographic (MSCT) coronary angiography within 1 week. In all subjects, conventional coronary angiography was also carried out. Multislice computed tomography displayed single-vessel CAD in 16% of patients, 2-vessel CAD in 7%, and 3-vessel CAD in 4%. Selective coronary angiography confirmed the results of multislice computed tomography in 99% of all patients. Sensitivity and specificity of MSCT coronary angiography were 100% and 98%, respectively, with a positive predictive value of 95% and a negative predictive value of 100%. In conclusion, MSCT coronary angiography is an excellent noninvasive technique for early identification of significant CAD in high-risk asymptomatic patients with inconclusive or unfeasible noninvasive stress test results.

Coronary Plaque Vulnerability in Metabolic Syndrome Assessment of Carotid Artery Morphology in Acute Coronary Syndrome

BACKGROUND

The aim of the present study was to investigate the clinical implication of metabolic syndrome and carotid artery morphologies on coronary plaque vulnerability in Japanese men with acute coronary syndrome (ACS).

METHODS AND RESULTS

Consecutive ACS Japanese men (n=225) underwent emergent coronary angiography and B-mode ultrasonography within 1 week of the acute coronary event. With a 11.3-MHz linear array transducer, the morphologies of common carotid artery were examined. Common carotid arteries with an intima-media thickness>1.1 mm and interadventitial diameter>8.0 mm were considered to be undergoing carotid artery remodeling. Patients were divided into 2 groups based on the number of complex plaques identified by coronary angiography. Abdominal obesity, low level of high-density lipoprotein and carotid artery remodeling were more often observed in patients with multiple, complex coronary plaques than in patients with a single, complex plaque (p<0.03, p<0.03 and p=0.0001, respectively). Metabolic syndrome and carotid artery remodeling were independent predictors of multiple, complex coronary plaques (odds ratio 1.86, p<0.05; odds ratio 5.96, p<0.0001).

CONCLUSION

Metabolic syndrome and carotid artery remodeling might be useful indicators to assess the efficacy of aggressive treatments for secondary prevention of cardiovascular events in ACS Japanese men.

[64 MDCT imaging of the heart]

In the investigation of ischemic heart disease, cardiac CT imaging is the most effective non-invasive technique for exploration of the coronary arteries now. Thanks to its volume acquisition, cardiac CT is acknowledged to be the best technique for reproducible out-patient exploration not only of the coronary arteries but of all cardiac structures. Over the last 4 years, after a period of technical development and clinical validation, cardiac CT imaging has become a routine examination that is progressively finding a place alongside other types of cardiac exploration. The latest generation of faster, high-resolution devices has pushed back the limits of this technique. Not only coronography but also other modes of imaging in an increasing number of indications are progessively reduced by this complementary examination. We presented our first experiences which we had got through examinatinon of 70 patients.

Coronary artery anatomy in children with congenital heart disease by computed tomography

AIMS

To evaluate electron beam computed tomography (EBCT) for recognition of coronary artery patterns in children with congenital heart diseases.

METHODS

Institutional review board approval was obtained; informed consents were not required. A total of 226 children diagnosed with Tetralogy of Fallot (n=122), double outlet right ventricle (n=52), transposition of the great arteries (n=34), and congenitally corrected transposition (n=18) who had undergone cardiac EBCT at our institution between 1995 and 2002 were identified. Iodinated contrast medium was injected with arterial phase acquisition. The two radiologists and one pediatric cardiologist that interpreted the EBCT images and cardiac angiograms, respectively, were blinded to each other's results. Surgical and cardiac angiogram findings were compared to the EBCT results. Descriptive statistics were used to compare efficacy.

RESULTS

Numerous aberrant patterns were clearly identified on the EBCT images. Pattern IX occurred in most patients with Tetralogy of Fallot or double outlet right ventricle. Patterns I and 0 are the most common coronary artery types in transposition of the great arteries and congenitally corrected transposition, respectively. Overall diagnostic accuracy for all disease groups was 82.7%. The diagnostic accuracy of the coronary arterial anatomy by EBCT increased with older age, and was more than 90% in individuals aged over 3 months.

CONCLUSION

EBCT is effective for identification of the coronary anatomy of children with specific congenital heart diseases, except for neonates and small infants less than 3 months of age.

Plaque stabilization: Can we turn theory into evidence?

Coronary events often result from thrombi that form because of physical disruption of the atherosclerotic plaque. The dynamic nature of the plaque offers the opportunity to intervene to modify plaque biology with lifestyle changes and, if needed, pharmacologic measures. Inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase (statins) reduce levels of serum cholesterol and decrease the incidence of coronary events, but some of the benefits of statins may not depend on their effects on circulating lipids. Indeed, increasing evidence suggests that statins may also enhance plaque stability. Such evidence includes results of preclinical studies with experimental atherosclerosis as well as imaging data and analyses of proinflammatory and prothrombotic mediators in clinical trials. Currently, however, no studies have demonstrated conclusively the mechanisms underlying the unexpected magnitude and rapidity of statin benefits. This article reviews the evolution of the concept of plaque stabilization and reexamines the evidence for the role of statins in that process.

Comprehensive evaluation of atrial septal defects in individuals undergoing percutaneous repair by 64-detector row computed tomography

Transcatheter atrial septal defect closure is becoming more commonplace as it has been demonstrated to be safe, efficacious and associated with low morbidity. Pre-procedural assessment of individuals has primarily relied upon transesophageal echocardiography. We present four individuals who underwent both transesophageal echocardiography as well as cardiac multidetector computed tomography. In all four cases, multidetector computed tomography added incremental information above the transesophageal echocardiogram. Multidetector computed tomography may play an essential role in individuals with atrial septal defects undergoing percutaneous transcatheter closure.

Identification of the metabolic syndrome and imaging of subclinical coronary artery disease: early markers of cardiovascular risk

The metabolic syndrome and imaging of subclinical coronary artery disease are novel approaches to identify cardiovascular risk at an early disease stage before the onset of complications. The metabolic syndrome is defined as a combination of major and emerging cardiovascular risk factors that are related to underlying insulin resistance. These risk factors accelerate atherosclerotic disease progression and increase the risk for future cardiovascular events. Atherosclerosis imaging visualizes the presence of subclinical disease burden many years before the onset of symptoms. The early identification of asymptomatic persons with increased cardiovascular risk provides the opportunity to prevent of future disease complications. The relationship between the metabolic syndrome and sublinical disease burden is incompletely understood. Although further evaluation of the potential role for the emerging biomarkers and imaging techniques in the setting of the metabolic syndrome is needed, it is obvious that cardiovascular nurses need to develop a heightened awareness of patients at risk for future events.

Three-dimensional CT scanning: a new diagnostic modality in congenital heart disease

New generation multislice CT technology has changed the approach to non-invasive assessment of congenital heart disease, in both paediatric and adult patients. This is mainly because of rapid advances in spatial and temporal resolution and in post-processing capability. At Hôpital Necker-Enfants Malades, CT with multiplanar and three-dimensional reconstruction has become a routine examination in the evaluation of congenital heart disease planning surgery, complex interventional catheterisations and for follow-up. It has proved to be an invaluable diagnostic and decision-aiding methodology in these situations, as a complement to echocardiography and, increasingly, as a substitute for diagnostic angiography (which is usually associated with higher-dose radiation and longer sedation times, as well as occasional morbidity). This review illustrates the current status of 64-slice CT in congenital heart diseases, including assessment of the aorta, the coronary arteries, the pulmonary arteries, the systemic and pulmonary veins, and other intra- and extracardiac malformations.

Thematic review series: Patient-Oriented Research. Imaging atherosclerosis: state of the art

The ability to image obstructive arterial disease brought about a revolution in clinical cardiovascular care; the development of newer technologies that image arterial wall thicknesses, areas, volumes, and composition allows valid imaging of atherosclerosis for the first time. Development of noninvasive imaging of atherosclerosis has further led to a quantum shift in research in the field by enabling the study of asymptomatic populations and thus allowing investigators to focus on preclinical disease without the many biases associated with the study of symptomatic patients. These noninvasive investigations have broad implications for clinical care as well. Coronary angiography, computed tomographic (CT) imaging of coronary calcium, intravascular ultrasound, multidetector CT angiography, B mode ultrasound of the carotid arteries, and MRI of the carotid arteries all have unique strengths and weaknesses for imaging atherosclerosis. Certain of these techniques are extremely useful as outcome variables for clinical trials, and others are uniquely useful as predictors of the risk of cardiovascular disease. All are informative in one way or another with regard to the role of plaque remodeling and composition in disease causation. CT and MRI technology are advancing very rapidly, and research and clinical uses of these imaging modalities promise to further advance our understanding of atherosclerosis and its prevention.

Aortic valve bypass for aortic stenosis: imaging appearances on multidetector CT

OBJECT

Aortic valve bypass is a technique used in high-risk patients with critical aortic stenosis that consists of placement of a conduit from the left ventricular apex to descending aorta. We describe the imaging appearances of this apicoaortic conduit on multidetector CT (MDCT).

METHODS

Each patient underwent retrospective ECG-gated MDCT using a 16-detector-row scanner several days after placement of an apicoaortic conduit. All images were assessed by two radiologists who reviewed the appearance of the apicoaortic conduit and any post-operative complications. Follow-up studies were available for several patients.

RESULTS

Twelve patients (9 men, 3 women, mean age - 78 years) underwent evaluation and the conduit was visible in each. The valve within the conduit was visible in ten (91%) of the 11 patients who received intravenous contrast material. Common findings were periconduit outpouching and hypoperfusion involving the left ventricle. Complications included pericardial hemorrhage, hemothorax and ventricular pseudoaneurysm. Mild to moderate increase in wall thinning was identified in the three patients who underwent follow-up imaging.

CONCLUSION

Aortic valve bypass with an apicoaortic conduit appears to be a feasible alternative to aortic valve replacement in high-risk patients. MDCT is an excellent method to assess the imaging features of such conduits.

Beta-blockers for cardiac CT: a primer for the radiologist

OBJECTIVE

The objective of this article is to describe a protocol for the administration of beta-blockers for cardiac CT. A low and regular heart rate is necessary for optimal visualization of the coronary arteries on CT and can be achieved by the administration of medications.

CONCLUSION

Beta-blockers can be safely given, orally or IV, to most patients to lower the heart rate for cardiac CT. A protocol can be implemented and patients can be screened for certain contraindications to allow successful administration of these medications by radiologists.

Establishing a cardiac imaging rotation in radiology residency

RATIONALE AND OBJECTIVE

The advent of new technologies for cardiac imaging such as magnetic resonance imaging (MRI) and cardiac computed tomography (CT) have added new tools in the armamentarium of noninvasive methods for predicting cardiac disease. However, training in cardiac anatomy and physiology is critical if radiology is to meet the demands of this service.

MATERIALS AND METHODS

We designed a core rotation in cardiac imaging at the Beth Israel Deaconess Medical Center, Harvard Medical School, to train residents in noninvasive cardiac imaging methods, such as cardiac echocardiography, nuclear cardiac imaging, cardiac MRI, and with special emphasis on cardiac CT.

RESULTS

This 1-month block includes cardiac imaging conferences and a lecture series, hands-on training in the use of imaging software, introduction to cardiac catheterization, and clinical cardiology. Residents are provided with a set of research and review articles along with textbooks on coronary imaging to serve as references for this rotation.

CONCLUSION

We believe that this educational exercise will establish a core of young, knowledgeable, and capable physicians who will be able to meet the clinical demand for noninvasive cardiac imaging and maintain a major role in this emerging specialty.

Primary prevention for patients with intermediate framingham Risk Scores

Coronary heart disease (CHD) is the leading cause of mortality in the industrialized world. Proper identification of individuals at risk for CHD is challenging. The Framingham Risk Score, the most widely accepted tool for quantifying 10-year risk, fails to identify a great proportion of future CHD. Because of the health and economic consequences of CHD, there is a need to develop better prognostic tools for primary prevention. Coronary artery calcium scoring, C-reactive protein measurement, and heart rate recovery and exercise tolerance during exercise stress test may be useful tools for better risk stratification of intermediate-risk patients.

Diagnostic imaging over the last 50 years: research and development in medical imaging science and technology

Over the last 50 years, diagnostic imaging has grown from a state of infancy to a high level of maturity. Many new imaging modalities have been developed. However, modern medical imaging includes not only image production but also image processing, computer-aided diagnosis (CAD), image recording and storage, and image transmission, most of which are included in a picture archiving and communication system (PACS). The content of this paper includes a short review of research and development in medical imaging science and technology, which covers (a) diagnostic imaging in the 1950s, (b) the importance of image quality and diagnostic performance, (c) MTF, Wiener spectrum, NEQ and DQE, (d) ROC analysis, (e) analogue imaging systems, (f) digital imaging systems, (g) image processing, (h) computer-aided diagnosis, (i) PACS, (j) 3D imaging and (k) future directions. Although some of the modalities are already very sophisticated, further improvements will be made in image quality for MRI, ultrasound and molecular imaging. The infrastructure of PACS is likely to be improved further in terms of its reliability, speed and capacity. However, CAD is currently still in its infancy, and is likely to be a subject of research for a long time.

MDCT Angiography of Acute Chest Pain: Evaluation of ECG-Gated and Nongated Techniques

OBJECTIVE

The objective of our study was to compare MDCT angiography protocols used in patients with acute chest pain caused by vascular, nonvascular, and cardiac abnormalities.

SUBJECTS AND METHODS

In four groups of 20 patients with chest pain each, four MDCT protocols were used based on monitoring vascular attenuation: pulmonary embolism (150 H at pulmonary artery), aortic dissection (200 H at aortic arch), chest pain (200 H at pulmonary artery), and chest pain with ECG gating (150 H at pulmonary artery). Vascular enhancement was assessed by attenuation measurements taken from locations in the pulmonary artery (n = 3) and thoracic aorta (n = 4). The appearance of the coronary artery in regard to opacification and motion was assessed on a scale of 1 to 5 (best).

RESULTS

The mean pulmonary artery and aorta attenuation (372 H and 352 H, respectively) was significantly higher (p < 0.005, Student's t test) and the number of vessel attenuation points measuring less than 200 H (1/140) was significantly smaller (p < 0.001, chi-square test) in the chest pain compared with the dissection (318 H, 310 H; 16/140), gated chest pain (304 H, 286 H; 17/14), and pulmonary embolism (302 H, 220 H; 28/140) groups. The median coronary artery visualization score was 4; the proximal regions received a significantly (p < 0.005, Mann-Whitney test) higher grade compared with the middle and distal regions (medians, 5, 4, and 2, respectively). Artifacts were noted on the gated scans.

CONCLUSION

The chest pain protocol can be used to assess both the pulmonary arteries and the thoracic aorta, whereas the ECG-gating protocol appears to be a promising adjunct for a comprehensive single chest pain protocol.

[Cardiac anatomy and the radiologist]

We report a case of myocardial infarction due to occlusion of the left anterior descending artery seen on a routine chest CT performed in order to exclude aortic dissection. This underscores the need for the radiologist to look at the heart and coronary arteries on each thoracic CT-scan, even if acquired without EKG-gating.

The clinical value of a negative multi-detector computed tomographic angiography in patients suspected of coronary artery disease: A meta-analysis

The aim of this meta-analysis was to calculate the sensitivity of contrast-enhanced multi-detector computed tomography (MDCT) compared with coronary angiography (CAG) in incident patients suspected of coronary artery disease (CAD). We searched PubMed, Embase, bibliographies of original papers and reviews to identify original papers including > or =20 patients. Two independent reviewers selected papers and judged eligible papers on quality. Heterogeneity was assessed and homogeneous subgroups were pooled. Of the 15 included studies, ten provided moderately homogeneous patient-based analyses with absolute diagnostic numbers (n = 630 patients). Pooled sensitivity was 89% (95% confidence interval: 85-92%). Scanners with 16 detectors (n = 4) had higher sensitivities (pooled sensitivity: 91%) than four-detector scanners (n = 6; pooling not possible due to heterogeneity). Seven studies reported sensitivity for a proximal stenosis, but different definitions were used making pooling impossible; sensitivities ranged from 75 to 100%. The sensitivity of four- and 16-detector MDCT is not sufficient to rule out any stenosis in patients suspected of CAD. No conclusions can be drawn with respect to the sensitivity for clinically relevant or proximal stenoses.

Clampless arterial coronary artery bypass grafting with the use of magnetic coupling devices

BACKGROUND

The aim of our study was to evaluate the feasibility of using the Ventrica MVP device to perform proximal anastomoses as part of the clampless off-pump coronary artery bypass (OPCAB) arterial revascularization procedure.

METHODS

We present our preliminary experience of these first nine coronary artery cases performed in the UK from April 2003 to December 2004.

RESULTS

The device was used in eight patients for the proximal anastomosis of a radial artery (n = 8) or right internal thoracic artery (n = 1) graft as a Y-graft from the left internal thoracic artery to the circumflex territories. One patient died in this series although the autopsy showed that the device was intact and free of clots and the reported cause of death was an acute cardiac event due to myocardial ischemia. Anastomotic patency was confirmed in five patients with the use of multidetector row computed tomography coronary angiogram. The anastomosis time in our series was 6.3 +/- 2.1 minutes and the blood loss 814 +/- 245 mL. The mean length of stay was 5.2 +/- 1.2 days. No other significant major morbidity events were observed postoperatively (neurological complications, renal failure, and reopening for bleeding). The assessment of quality of life at 6 months postoperatively using SF-36 questionnaires revealed improvement.

CONCLUSION

The versatile use of Ventrica MVP distal anastomotic device is feasible in clinical practice allowing surgeons to perform proximal anastomoses and arterial OPCAB surgery with short learning curve and without compromising the clinical outcome and quality of life.

Noninvasive detection of coronary artery stenosis using 16-slice spiral CT: A comparison with selective X-ray coronary angiography

The role of 16-slice spiral CT was evaluated in the diagnosis of coronary stenosis, with selective X-ray coronary angiography (SCA) serving as the reference standard. Sixty-five patients who were suspected of having coronary heart disease, without percutaneous transluminal coronary angioplasty or coronary bypass-grafting, were investigated using 16-slice CT. Eight patients with pre-scan heart rate of more than 80 beats/min were given beta-blockers. After the retrospectively ECG-gated axial imaging reconstruction, volume redering (VR), multi-planar reconstruction (MPR), curved MPR and maximum intensity projection (MIP) were used to reconstruct. Every segment of coronary artery with a diameter > or = 1.5 mm was assessed, and the presence on CT with a stenosis exceeding 50% diameter reduction was compared with that on SCA. The reasons which lead to some segments unevaluable were analysed. Compared with SCA, 93% coronary segments and 94% main branches were evaluable. Residual cardiac motion artifacts, severe calcification and poor opacification made 58%, 28% and 14% of the remaining 60 segments unevaluable respectively. Without routine administration of beta-blockers, good coronary imaging quality can be acquired using 16-slice spiral CT. It is a reliable noninvasive method for detection of obstructive coronary artery disease.

Coronary artery imaging with multidetector computed tomography: a call for an evidence-based, multidisciplinary approach

Modern multidetector computed tomography systems are capable of a comprehensive assessment of the cardiovascular system, including noninvasive assessment of coronary anatomy. Multidetector computed tomography is expected to advance the role of noninvasive imaging for coronary artery disease, but clinical experience is still limited. Clinical guidelines are necessary to standardize scanner technology and appropriate clinical applications for coronary computed tomographic angiography. Further evaluation of this evolving technology will benefit from cooperation between different medical specialties, imaging scientists, and manufacturers of multidetector computed tomography systems, supporting multidisciplinary teams focused on the diagnosis and treatment of early and advanced stages of coronary artery disease. This cooperation will provide the necessary education, training, and guidelines for physicians and technologists assuring standard of care for their patients.

Dedicated calibration formulas permit correction of differences between measurements by different IVUS devices as demonstrated in atherosclerotic human coronary arteries in vitro

Serial intravascular ultrasound (IVUS) measurements of coronary vessel dimensions are major endpoints of studies focusing on pharmacological interventions, efficiency of drug eluting stents, and vascular remodeling. In serial studies measurement variability among different IVUS devices may cause substantial misinterpretation and error. We analyzed 33 human coronary plaques in vitro using two different IVUS systems (mechanical IVUS system with a 40 MHz Atlantis SR catheter; solid-state electronic IVUS system with a 20 MHz Invision catheter) and repeatedly measured the total vessel, lumen, and plaque + media cross-sectional area and plaque burden (plaque + media area divided by total vessel area). Between the "raw" measurements made by the two devices, there was a significant difference for both plaque + media area (2.35+/-1.86 mm(2), P < 0.01) and plaque burden (5.39+/-3.68%, P < 0.05). Measurements were then corrected by use of recently introduced calibration formulas; as a result the differences decreased significantly for all IVUS parameters measured ( P < 0.0001). After correction, the remaining differences between the corrected mechanical and solid-state IVUS measurements similar to differences between repeated measurements with the same IVUS device (i.e., the intraobserver variability). Thus, in serial studies the use of different IVUS devices at index and follow-up procedure may introduce a substantial error as a result of system-related differences. The application of dedicated calibration formulas allows for correction for these differences by decreasing such differences to the level of intraobserver variability.

Direct cone-beam cardiac reconstruction algorithm with cardiac banding artifact correction

Multislice helical computed tomography (CT) is a promising noninvasive technique for coronary artery imaging. Various factors can cause inconsistencies in cardiac CT data, which can result in degraded image quality. These inconsistencies may be the result of the patient physiology (e.g., heart rate variations), the nature of the data (e.g., cone-angle), or the reconstruction algorithm itself. An algorithm which provides the best temporal resolution for each slice, for example, often provides suboptimal image quality for the entire volume since the cardiac temporal resolution (TRc) changes from slice to slice. Such variations in TRc can generate strong banding artifacts in multiplanar reconstruction images or three-dimensional images. Discontinuous heart walls and coronary arteries may compromise the accuracy of the diagnosis. A beta-blocker is often used to reduce and stabilize patients' heart rate but cannot eliminate the variation. In order to obtain robust and optimal image quality, a software solution that increases the temporal resolution and decreases the effect of heart rate is highly desirable. This paper proposes an ECG-correlated direct cone-beam reconstruction algorithm (TCOT-EGR) with cardiac banding artifact correction (CBC) and disconnected projections redundancy compensation technique (DIRECT). First the theory and analytical model of the cardiac temporal resolution is outlined. Next, the performance of the proposed algorithms is evaluated by using computer simulations as well as patient data. It will be shown that the proposed algorithms enhance the robustness of the image quality against inconsistencies by guaranteeing smooth transition of heart cycles used in reconstruction.

Influence of different lipid-lowering strategies on plaque volume and plaque composition in patients with coronary artery disease: role of intravascular ultrasound imaging

Lipid-lowering therapy has a significant impact on the prognosis and clinical course of coronary artery disease (CAD). Slowdown of plaque progression and plaque stabilization are the major cardiac goals of any lipid-lowering strategy. Until now, intravascular ultrasound imaging (IVUS) has been the only in vivo imaging modality which allows serial analysis of plaque burden and plaque composition on a volumetric basis. Several serial IVUS studies have shown that chronic statin therapy could decrease or even halt plaque growth. Moreover, aggressive lipid-lowering therapy using statins changes plaque composition over time. There is evidence that changes in plaque composition might explain the positive prognostic impact of statin therapy in patients with CAD. Beyond clinical endpoint studies, serial volumetric IVUS studies will become the standard to prove the efficacy of new lipid-lowering strategies in the future.

Nontraumatic Thoracic Emergencies

Acute chest pain is one of the most common complaints of patients who present to an emergency department, and accounts for up to 5% of all visits. It also is one of the most complex issues in an emergency setting because, although clinical signs and symptoms often are nonspecific, rapid diagnosis and therapy are of great importance. The chest radiograph remains an important component of the evaluation of chest pain, and usually is the first examination to be obtained. Nevertheless, cross-sectional imaging has added greatly to the ability to characterize the wide constellation of clinical findings into a distinct etiology. This article reviews how the various entities that can present as nontraumatic chest pain can manifest radiographically.

Correlation between image noise and body weight in coronary CTA with 16-row MDCT

RATIONALE AND OBJECTIVES

To evaluate the correlation between image noise and body weight (BW) or body mass index (BMI) in coronary computed tomography angiography (CTA) as a potential parameter for reducing radiation dose in coronary CTA.

MATERIALS AND METHODS

Thirty-six patients who underwent electrocardiogram-gated cardiac CT were analyzed in this study. The patients included 26 men and 10 women with a mean age of 60 years (range 43-79 years). All patients were imaged on a 16-row multidetector CT scanner. Mean value of BW and BMI was 83.5 kg and 28.1, respectively. Image noise was defined as standard deviation (SD) of the attenuation values measured by using 1 cm2 circular region of interest in the ascending aorta at the level of the right main pulmonary artery. The SD values were plotted against BW and BMI. The correlations were examined using a linear regression method. A P value of less than .05 was considered significant.

RESULTS

The r value of linear regression between noise and BW was 0.90 (P < .001). The r value of linear regression between noise and BMI was 0.74 (P = .015).

CONCLUSIONS

Excellent correlation was observed between noise and BW in coronary CTA. These data may be used as potential parameters for customized radiation dose modification to reduce radiation dose in coronary CT examinations.

Mutidetector-row CT and quantitative gated SPECT for the assessment of left ventricular function in small hearts: the cardiac physical phantom study using a combined SPECT/CT system

The aim of this study was to compare results of left ventricular (LV) function obtained by quantitative gated single-photon emission tomography (QGS) and multidetector-row spiral computed tomography (MDCT) with reference parameters using an electrocardiogram-gated cardiac physical phantom. The phantom study was performed using a combined SPECT/CT system. Flexible membranes formed the inner and outer walls of the simulated LV. The stroke volume was adjusted (45 mL or 58 mL) and the fixed 42-mL end-systolic volume (ESV) produced two different volume combinations. The LV function parameters were estimated by means of MDCT and QGS. Differences in true and measured volumes were compared among CT with a reconstructed image thickness of 2.5 mm and 5.0 mm and QGS volumetric values. Each scan was repeated three-times. The estimation of LV volumes using both QGS and MDCT analyses were reproducible very well. QGS overestimated ejection fraction (EF) by approximately 20%; MDCT volumetry overestimated EF by approximately 5% in each volume setting. The differences in true and measured values for EF and ESV obtained with QGS were significantly greater than obtained with MDCT.

CONCLUSION

MDCT provides a reliable estimation of functional LV parameters, whereas QGS tends to significantly overestimate the EF in small hearts.

Early detection of progressive renal dysfunction in patients with coronary artery disease

BACKGROUND

An association between renal hemodynamic dysfunction and coronary artery disease (CAD) has been documented in chronic renal failure; however, no information is available in CAD patients with normal glomerular filtration rate (GFR). This study was aimed at evaluating early abnormalities and outcome of renal function in CAD patients.

METHODS

In 15 nondiabetic patients with normal renal function and no significant stenoses in renal arteries, and having undergone coronary arteriography, we studied systemic and renal hemodynamics before and after a vasodilating stimulus induced by aminoacid (AA) infusion. A control group (C) consisted of 15 sex- and age-matched kidney donors. The statistical adequacy of the sample size was preliminarily verified. Renal clearances were repeated after two years.

RESULTS

At baseline, GFR (mL/min/1.73 m2) averaged 81.4 +/- 3.8 in CAD and 83.7 +/- 1.4 in C (P= NS); RPF (mL/min/1.73 m2) was 297 +/- 22 in CAD and 456 +/- 15 in C (P < 0.0001); filtration fraction was higher in CAD (P < 0.001). Plasma renin activity was higher in CAD (P < 0.005). The number of coronary stenoses was inversely correlated with RPF but not with GFR. In CAD, at variance with C, AA did not induce any increment of GFR, while RPF increased without achieving the unstimulated value of C. Blood pressure was comparable in CAD and C at baseline and not modified by AA. After two years, a significant decrease in GFR (-14%, P < 0.001) and RPF (-15%, P < 0.001) occurred only in CAD, and in either group, the response to AA did not differ from that detected at baseline.

CONCLUSION

In CAD patients with normal GFR, reduction in renal perfusion and absence of renal functional reserve likely represent early markers of progressive renal dysfunction.

Towards patient specific thermal modelling of the prostate

The application of thermal modelling for hyperthermia and thermal ablation is severely hampered by lack of information about perfusion and vasculature. However, recently, with the advent of sophisticated angiography and dynamic contrast enhanced (DCE) imaging techniques, it has become possible to image small vessels and blood perfusion bringing the ultimate goal of patient specific thermal modelling closer within reach. In this study dynamic contrast enhanced multi-slice CT imaging techniques are employed to investigate the feasibility of this concept for regional hyperthermia treatment of the prostate. The results are retrospectively compared with clinical thermometry data of a patient group from an earlier trial. Furthermore, the role of the prostate vasculature in the establishment of the prostate temperature distribution is studied. Quantitative 3D perfusion maps of the prostate were constructed for five patients using a distributed-parameter tracer kinetics model to analyse dynamic CT data. CT angiography was applied to construct a discrete vessel model of the pelvis. Additionally, a discrete vessel model of the prostate vasculature was constructed of a prostate taken from a human corpse. Three thermal modelling schemes with increasing inclusion of the patient specific physiological information were used to simulate the temperature distribution of the prostate during regional hyperthermia. Prostate perfusion was found to be heterogeneous and T3 prostate carcinomas are often characterized by a strongly elevated tumour perfusion (up to 70-80 ml 100 g(-1) min(-1)). This elevated tumour perfusion leads to 1-2 degrees C lower tumour temperatures than thermal simulations based on a homogeneous prostate perfusion. Furthermore, the comparison has shown that the simulations with the measured perfusion maps result in consistently lower prostate temperatures than clinically achieved. The simulations with the discrete vessel model indicate that significant pre-heating takes place in the prostate capsule vasculature which forms a possible explanation for the discrepancy. Pre-heating in the larger pelvic vessels is very moderate, approximately 0.1-0.3 degrees C. In conclusion, perfusion imaging provides important input for thermal modelling and can be used to obtain a lower limit on the prostate and tumour temperature in regional hyperthermia. However, it is not sufficient to calculate in detail the prostate temperature distribution in individual patients. The prostate vasculature plays such a crucial role that a patient specific discrete vessel model of the prostate vasculature is required.

[Evaluation of change in the optimal image reconstruction phase in retrospective ECG-gated reconstruction]

The purpose of this study was to optimize the reconstruction phase in order to improve depiction of the coronary artery in the relative delay method of the retrospective electrocardiogram (ECG)-gated reconstruction technique using a multi-slice computed tomography (MSCT) scanner with four channels. The following items were evaluated; 1) image quality of the coronary arteriogram, 2) degree of difference between the standard phase corresponding to the diastasis period and the selected phase, which was determined in each case to obtain the best image, and 3) the factors causing the phase difference. The image quality in the selected phase was better than that in the standard phase. A positive correlation was observed between the degree of phase difference and the median value and standard deviation of the heart rate. The degradation of image quality was remarkable in cases showing a large degree of phase difference. A negative correlation was observed between image quality in the selected phase and the degree of phase difference. Individualizing the reconstruction phase is required to improve the image quality of coronary arteriograms with MSCT. It should be noted that the condition of a low and stable heart rate results in reduction in the degree of phase difference, which is useful for the acquisition of better images.

Usefulness of multidetector computed tomography for noninvasive evaluation of coronary arteries in asymptomatic patients

This editorial addresses the capabilities, limitations, and potential of multidetector computed tomography (MDCT) for the noninvasive evaluation of coronary arteries in asymptomatic patients. The quantification of coronary calcium with MDCT correlates highly with that obtained by electron-beam computed tomography, but to date, neither has the capability of assessing the distribution of various morphologic patterns of calcium and their relation to other "soft" plaque components. Although MDCT can assess the thickness of the atherosclerotic wall and can readily identify calcific deposits, further plaque characterization (e.g., lipid pools and fibrous tissue), a prerequisite for the identification of most vulnerable lesions, is not yet a workable reality, even with the 64-slice machines in their current configuration. The noninvasive identification by MDCT of plaque components subtending vulnerable lesions will require additional improvement in the primary instrumentation, the use of hybrid constructs (e.g., with positron emission tomography and magnetic resonance imaging), the development of novel methods of post-acquisitional analysis to extract latent images of plaque components (e.g., signal analysis based on 3-dimensional wavelets), or the adaptation of molecular imaging techniques at the cell and gene levels to computed tomography. Such unique approaches may soon contribute a long list of additional parameters that could be evaluated on a noninvasive basis as predictors of acute coronary syndromes and overall patient vulnerability.

Clinical utility of coronary CT angiography: Coronary stenosis detection and prognosis in ambulatory patients

INTRODUCTION

Multislice CT coronary angiography (MSCTA) accurately detects stenosis in patients undergoing coronary arteriography, but its accuracy in clinical outpatients is less certain. This study retrospectively analyzed MSCTA performance in a large outpatient cohort and examined 6-month clinical follow-up in those without invasive CA.

METHODS

Patients underwent MSCTA for clinical indications including symptoms or noninvasive results being either equivocal or suspected as incorrect by referring clinicians. Standard 16-slice CT scanner techniques were used, and results were analyzed on the basis of both patient and vessel. Patients were treated medically or sent to invasive angiography on the basis of MSCTA results and judgment of referring clinicians. All invasive angiograms were analyzed using quantitative coronary angiography. Six-month clinical follow-up was determined in patients without CA.

RESULTS

One thousand fifty-three consecutive patients were referred for MSCTA, resulting in 994 interpretable scans. Mean age was 58+/-13 years, 55% were male, 50% had prior noninvasive testing, and 90% had symptoms. Invasive angiography was performed in 160 patients, with significant stenoses present in 69%. MSCTA demonstrated 87% and 89% accuracy by patient- and vessel-based analysis, respectively, and was most accurate in the left main and right coronary arteries. Only two patients not referred for angiography had significant stenosis in those undergoing 6-month follow-up.

CONCLUSIONS

MSCTA accurately detects obstructive coronary stenosis in clinical patients with possible cardiac symptoms, and effectively triages them for invasive angiography. Negative results are highly accurate in ruling out obstructive disease. Six-month prognosis is excellent in patients without significant disease determined by MSCT.

Novel Use of a Magnetic Coupling Device to Repair Damage of the Internal Thoracic Artery

At present, there is limited reported literature on the use of the magnetic anastomotic device Ventrica MVP in the coronary artery bypass surgery setting. The device has been primarily used to perform distal coronary anastomoses. We report for the first time the novel use of this magnetic coupling device as a technique to repair iatrogenic injury of the left internal thoracic artery conduit. Technical issues, advantages, disadvantages, and the use of computer tomography angiogram for assessment of the anastomosis are discussed.

Initial experience with X-ray CT based attenuation correction in myocardial perfusion SPECT imaging using a combined SPECT/CT system

OBJECTIVE

Attenuation artifacts adversely affect the diagnostic accuracy of myocardial perfusion imaging. We assessed the clinical usefulness of X-ray CT based attenuation correction (AC) in patients undergoing myocardial perfusion imaging by comparing their myocardial AC- and non-corrected (NC) SPECT images with the coronary angiography (CAG).

METHODS

We retrospectively reviewed the myocardial SPECT images of 30 patients (18 men, 12 women; mean age 68 years). Thirteen of 30 patients with coronary artery disease (CAD) and 17 without CAD were confirmed by CAG. They underwent sequential CT and myocardial SPECT imaging with thallium-201 (111 MBq) under an exercise or pharmacological stress protocol using our combined SPECT/ CT system. Two readers reviewed the myocardial SPECT images for the presence of CAD on a 4-point scale where 1 = normal, 2 = probably normal, 3 = probably abnormal, and 4 = abnormal. Two reading sessions were held. First, non-corrected (NC)-SPECT and second, AC-SPECT images using X-ray CT images were interpreted. Interobserver variability was assessed with kappa statistics. Diagnostic performance (accuracy) of coronary arterial stenosis was compared between AC- and NC-images.

RESULTS

Interobserver agreement for visual assessment was substantial or almost perfect. For AC-images, the observer consensus for analysis was 0.84 for the LAD-, 0.87 for the LCX-, and 0.71 for the RCA-territory. For NC-images, it was 0.91, 0.71, and 0.78. AC resulted in statistically significant improvements in overall diagnostic accuracy (sensitivity/ specificity/accuracy = 76%/93%/89%, 67%/86%/81%, respectively, for AC- and NC-images).

CONCLUSIONS

Because of an increase in the specificity, diagnostic accuracy was significantly increased on AC-images. These preliminary data suggest that X-ray CT based AC in myocardial SPECT imaging has the potential to develop into a reliable clinical technique.

Diagnosis and Screening of Coronary Artery Disease

Diagnostic testing for CAD is aided by the calculation of the pretest probability using either the Diamond-Forrester score or the Morise score. Patients who have a low risk of CAD should not undergo testing. Exercise ECG testing should be reserved for patients who have pretest probabilities lower than 20%, because a negative test does not adequately reduce the posttest probability of significant CAD. For patients who are at intermediate risk, either nuclear perfusion imaging or stress echocardiography is an acceptable choice depending on local availability and practice. Due to its low specificity, CAC scoring is currently limited in its usefulness for the diagnosis of CAD in symptomatic patients. Currently, screening for CAD among patients at low risk should not extend beyond screening for traditional risk factors. Physicians should use the Framingham Risk Score to stratify patients into levels of 10-year risk for cardiac events. Due to its high rate of false positive tests and low sensitivity, exercise ECG is of limited value in screening. Among patients with higher levels of risk, in whom further risk stratification would be of use in making decisions about risk factor management, measurement of CAC either with EBCT or multidetector row CT scanning is a promising option, but more research is required before its use should become widespread. Measures of endothelial function are in development but lack data to support their widespread use currently.

Clinical application of normal saline flush in multi-detector CT photography on portal vein

AIM: To evaluate the clinical application of normal saline flush technique in improving the three-dimensional image quality of multi-detector helical CT-photography obtained by maximum intensity projection (MIP).

METHODS: Fifty-eight patients were randomly divided into two groups. Patients in the two groups were both injected with 2.0 mL/kg contrast material (300 gI/L), and patients in group A were also treated with 30 mL saline flush (3 mL/s). The injection of the contrast material lasted 33 s in both groups. The scanning was performed 45 s after injection. The scanning started at the level of the diaphragm and covered the entire liver and spleen. The acquired raw data were reconstructed at an interval of 1 mm. The CT values of the right hepatic lobe (RHL), main portal vein (MPV), right portal vein (RPV), and abdominal aorta were assessed. MIP images of 3D-CTP were visually graded by the four point-scoring system.

RESULTS: The mean CT attenuation values of MPV, RPV, and RPV-RHL were higher in group A. The differences between the two groups were 25.0, 19.7, and 17.6 Hu (P = 0.006, 0.047, and 0.042, respectively). The rates of the excellent or good MIP images were 60.7% (17/28) in group A, and 33.3% (10/30) in group B. The mean score of the differences was 0.59, which was significant between the two groups (P = 0.040).

CONCLUSION: The saline flush technique can increase the CT attenuation value of portal vein as well as improve the quality of its MIP images.

Coronary artery bypass graft imaging using ECG-gated multislice computed tomography: Comparison with catheter angiography

AIM

To compare the value of multislice computerized tomography (MSCT) in imaging coronary artery bypass grafts (CABGs) by direct quantitative comparison with standard invasive angiography.

METHODS

Using MSCT, 50 consecutive patients who had previously undergone CABG surgery and had recently undergone invasive angiography for recurrent angina pectoris, were studied further using MSCT after intravenous injection of non-ionic contrast agent; cardiac imaging was performed during a single breath-hold. Graft anatomy was quantified, using both quantitative coronary angiography (QCA) and MSCT, by different investigators blinded to each other. Reproducibility was quantified using the standard error of the measurement expressed as a percentage in log-transformed values (CV%) and intraclass correlation (ICC).

RESULTS

All 150 grafts were imaged using MSCT; only 4 patent grafts were not imaged using selective angiography. Good agreement was achieved between MSCT and QCA on assessment of proximal anastomoses (CV% 25.2, ICC 0.84), mid-vessel luminal diameter (CV% 15.5, ICC 0.91) and aneurysmal dilations (CV% 14.3). Reasonable agreement was reached on assessment of distal anastomoses (CV% 26.7, ICC 0.66) and categorization of distal run-off (ICC 0.73). Good agreement was observed for stenoses of over 50% luminal loss (CV% 8.7, ICC 0.97) but agreement on assessment of less severe lesions was poor (CV% 208.7, ICC 0.51).

CONCLUSION

This study demonstrates that CABGs can be quantitatively evaluated using MSCT, and that significant lesions present in all CABG segments can be reliably identified. Agreement between MSCT and QCA for lesions of less than 50% luminal loss was poor.

Visibility of the origin and proximal course of coronary arteries on non-ECG-gated heart CT in patients with congenital heart disease

BACKGROUND

There is little information on the ability of non-ECG-gated cardiac CT to demonstrate the coronary arteries of children.

OBJECTIVE

To evaluate the visibility of the origin and proximal course of coronary arteries on non-ECG-gated cardiac CT, in which the coronary artery was not of primary diagnostic concern, in children with congenital heart disease.

MATERIALS AND METHODS

From December 2002 to March 2004, 126 cardiac CT examinations from 104 children (median age 11 months; age range 1 day to 15 years) were evaluated. All patients had ventriculo-arterial concordance and no malformations of the great arteries; those with coronary artery anomalies were excluded. Contrast-enhanced 16-slice spiral CT was performed without ECG-gating and multiplanar images for coronary arteries were obtained. The visibility of coronary artery origins was graded on a three-point scale, while nine segments of the arteries were graded on a four-point scale. CT images in which it was possible to trace the coronary arteries were considered diagnostic. The visibility of each whole coronary artery and the origins and proximal four segments of coronary arteries were calculated. The visibility of coronary arteries was also correlated with patient age.

RESULTS

The percentage of CT images of diagnostic quality was 49.3% for the whole coronary artery and 81.7% for the origins and proximal four segments. There was a significant positive correlation between the visibility of coronary arteries and age.

CONCLUSIONS

Non-ECG-gated cardiac CT, in which the coronary artery is not of primary diagnostic concern, is frequently able to visualize the origin and proximal course of coronary arteries and may be helpful in detecting coronary artery anomalies in children with congenital heart disease.

Chest Pain Evaluation in the Emergency Department: Can MDCT Provide a Comprehensive Evaluation?

OBJECTIVE

The purpose of our study was to determine whether MDCT can provide a comprehensive assessment of cardiac and noncardiac causes of chest pain in stable emergency department patients.

SUBJECTS AND METHODS

Patients with chest pain who presented to the emergency department without definitive findings of acute myocardial infarction based on history, physical examination, and ECG were recruited immediately after the initial clinical assessment. For each patient, the emergency department physician was asked whether a CT scan would normally have been ordered on clinical grounds (e.g., to exclude pulmonary embolism). Each consenting patient underwent enhanced ECG-gated 16-MDCT. Ten cardiac phases were reconstructed. The images were evaluated for cardiac (coronary calcium and stenosis, ejection fraction, and wall motion and perfusion) and significant noncardiac (pulmonary embolism, dissection, pneumonia, and so forth) causes of chest pain. Correlation was made between the presence of significant cardiac and noncardiac findings on CT and the final clinical diagnosis based on history, examination, and any subsequent cardiac workup at the 1-month follow-up by a consensus of three physicians.

RESULTS

Sixty-nine patients met all criteria for enrollment in the study, of whom 45 (65%) would not otherwise have undergone CT. Fifty-two patients (75%) had no significant CT findings and a final diagnosis of clinically insignificant chest pain. Thirteen patients (19%) had significant CT findings (cardiac, 10; noncardiac, 3) concordant with the final diagnosis. CT failed to suggest a diagnosis in two patients (3%), both of whom proved to have clinically significant coronary artery stenoses. In two patients (3%), CT overdiagnosed a coronary stenosis. Sensitivity and specificity for the establishment of a cardiac cause of chest pain were 83% and 96%, respectively. Overall sensitivity and specificity for all other cardiac and noncardiac causes were 87% and 96%, respectively.

CONCLUSION

ECG-gated MDCT appears to be logistically feasible and shows promise as a comprehensive method for evaluating cardiac and noncardiac chest pain in stable emergency department patients. Further hardware and software improvements will be necessary for adoption of this paradigm in clinical practice.

Atherosclerosis in childhood and adolescent type 1 diabetes: early disease, early treatment?

Autopsy studies have shown that atherosclerosis begins in adolescence in otherwise healthy individuals, and imaging techniques have shown that atherosclerosis develops earlier and is more prevalent in children with diabetes than in age-matched healthy controls. Cardiovascular disease has now overtaken diabetic nephropathy as the leading cause of premature mortality in young adults with diabetes, and the emphasis on disease prevention has accordingly shifted to a younger age group. The majority of children and adolescents with diabetes have suboptimal blood glucose control, and this contributes to accelerated arterial disease in this age group. Other conventional risk factors for coronary heart disease also need to be considered and treated aggressively. Effective early prevention of cardiovascular disease will involve lifestyle modification and full implementation of existing treatment guidelines, and large-scale prospective studies will be needed to establish the risks and benefits of early pharmacological intervention in children and adolescents.