Coronary CT angiography: How should physicians use it wisely and when do physicians request it appropriately?

Coronary CT angiography has been increasingly used in the diagnosis of coronary artery disease due to rapid technological developments, which are reflected in the improved spatial and temporal resolution of the images. High diagnostic accuracy has been achieved with 64- and more slice CT scanners and in selected patients, coronary CT angiography is regarded as a reliable alternative to invasive coronary angiography. Although the tremendous contributions of coronary CT angiography to cardiac imaging are acknowledged, appropriate use of cardiac CT as the first line technique by physicians has not been well established. Optimal selection of cardiac CT is essential to ensure acquisition of valuable diagnostic information and avoid unnecessary invasive procedures. This is of paramount importance since cardiac CT not only involves patient risk assessment, prediction of major cardiac events, but also impacts physician decision-making on patient management. Applications of CT in cardiac imaging include coronary artery calcium scoring for predicting the patient risk of developing major cardiac events, followed by coronary CT angiography which is commonly used to determine the diagnostic and prognostic accuracy in the coronary artery disease. This review presents an overview of the applications of CT in cardiac imaging in terms of coronary calcium scoring and coronary CT angiography. Judicious use of both cardiac CT tools will be discussed with regard to their value in different patient risk groups with the aim of identifying the appropriate criteria for choosing a cardiac CT modality. An effective diagnostic pathway is finally recommended to physicians for appropriate selection of cardiac CT in clinical practice.     

Value and limits of the computed tomography of the heart

In cardiac diagnosis we can observe an increasing replacement of the conventional invasive examination methods by less invasive or non invasive procedures. Non invasive examination methods are sufficient in the diagnostic work-up of ventricular function in coronary heart disease and cardiomyopathie, cardiac tumours and thrombi, calcifications, assessment of the bypass perfusion, pericardial disease, positional anomalies of the heart and the morphological changes caused by congenital cardiovascular defects. Invasive angiocardiography remains essential in the diagnosis of coronary artery stenoses, abnormal bypass perfusion, septal defects and in congenital cardiovascular defects in combination with intracardiac measurements of pressure and oxygenation.     

Coronary artery bypass grafts and MDCT imaging: what to know and what to look for

Multi-detector row CT (MDCT) scanners with high spatial and temporal resolutions are now available and are increasingly used for non-invasive assessment of vascular disease, including coronary arteries and coronary artery bypass grafts (CABG). Follow-up of patients who have previously undergone surgical revascularization for coronary artery disease is nowadays one of the main applications of MDCT. Thanks to the continuous technical evolution of the CT scanners, it is now possible to scan the heart and the full anatomic extent of grafts with sub-millimeter slice-thickness within a single breath-hold. In the evaluation of these patients, it is important for the radiologist to be familiar with the different types of grafts and surgical techniques to know the main characteristics of each graft type and what to look for in the assessment of a patient who has undergone coronary artery surgical revascularization. This review summarizes some surgical aspects, the biological characteristics of conduits, and the main technical MDCT features, and describes the CABG anatomy together with some typical CT findings.     

64-层螺旋CT在心脏冠状动脉成像中的应用现状与进展

近年来多层螺旋CT(MSCT)特别是64-层CT的临床应用证明,MSCT在心脏冠状动脉成像方面是切实有效的。本文综述了64-层螺旋CT冠状动脉造影的检查技术和临床应用进展。64-层螺旋CT心脏冠状动脉造影在冠心病筛查、冠心病诊断和治疗效果随访中具有重要的临床价值。     

Coronary CT angiography: current status and continuing challenges

Coronary CT angiography has been increasingly used in the diagnosis of coronary artery disease owing to rapid technological developments, which are reflected in the improved spatial and temporal resolution of the images. High diagnostic accuracy has been achieved with multislice CT scanners (64 slice and higher), and in selected patients coronary CT angiography is regarded as a reliable alternative to invasive coronary angiography. With high-quality coronary CT imaging increasingly being performed, patients can benefit from an imaging modality that provides a rapid and accurate diagnosis while avoiding an invasive procedure. Despite the tremendous contributions of coronary CT angiography to cardiac imaging, study results reported in the literature should be interpreted with caution as there are some limitations existing within the study design or related to patient risk factors. In addition, some attention must be given to the potential health risks associated with the ionising radiation received during cardiac CT examinations. Radiation dose associated with coronary CT angiography has raised serious concerns in the literature, as the risk of developing malignancy is not negligible. Various dose-saving strategies have been implemented, with some of the strategies resulting in significant dose reduction. The aim of this review is to present an overview of the role of coronary CT angiography on cardiac imaging, with focus on coronary artery disease in terms of the diagnostic and prognostic value of coronary CT angiography. Various approaches for dose reduction commonly recommended in the literature are discussed. Limitations of coronary CT angiography are identified. Finally, future directions and challenges with the use of coronary CT angiography are highlighted.     

Computed tomography of a broken heart: Chronic left ventricular pseudoaneurysm

The multislice cardiac computed tomography (CT) images of a 77-year-old man with a history of coronary artery bypass grafting and subsequent large left ventricular pseudoaneurysm (LVPA) formation are presented. Survival, as in this case, for several years after pseudoaneurysm formation is unusual without operative intervention. The case highlights the utility of CT in this scenario in allowing accurate assessment of LVPA anatomy, as well as noninvasive assessment of graft vessel patentcy, both vital to surgical planning in such high-risk cases.     

Triage of patients with suspected coronary artery disease using multislice computed tomography

RATIONALE AND OBJECTIVES: Several studies have shown that multislice computed tomography (MSCT) has a high sensitivity and specificity for detecting coronary artery stenoses. The aim of the present study was to investigate whether MSCT can reliably triage patients with suspected coronary artery disease (CAD) to coronary artery bypass grafting (CABG), percutaneous coronary intervention (PCI), or no revascularization. MATERIALS AND METHODS: A total of 123 patients with suspected CAD who were referred for conventional coronary angiography (CATH) additionally underwent MSCT (16*0.5 mm detector collimation). Therapeutic decisions made on the basis of CATH and MSCT strictly following current guidelines for treatment of CAD were compared with decisions made by a cardiac surgeon and an interventional cardiologist. Only MSCTs with at least adequate image quality in all coronary segments were included in the analysis (94/123). RESULTS: Decisions made on the basis of MSCT and CATH according to guidelines did not differ significantly (agreement of 88%, 82 of 94, P = .319). The therapeutic decisions made by the interventional cardiologist and the cardiac surgeon based on CATH differed significantly (overall agreement of 79%, 74 of 94 cases, P < .001; cardiologist: 78% PCI and 22% CABG versus surgeon: 38% PCI and 62% CABG), whereas there was 100% agreement regarding decisions for or against invasive treatment. CONCLUSIONS: MSCT shows good agreement with CATH in triaging patients with suspected CAD to CABG, PCI, or no revascularization. The choice of revascularization procedure is significantly more strongly influenced by whether an interventional cardiologist or a cardiac surgeon makes the decision than by the diagnostic test on which the decision is based.     

Normal anatomy of the vessels of the heart with 16-row multislice computed tomography

Nowadays, cardiac imaging is not part of the clinical routine for the radiologist. Multislice Computed Tomography (MSCT) with 4 rows allowed to start the non invasive evaluation of coronary arteries. The introduction of 16-row MSCT has significantly improved the performance and diagnostic accuracy of this technique, so far that MSCT angiography has been advocated as a potential clinical tool for the study of coronary artery disease. Therefore, it is mandatory to understand normal cardiac and coronary anatomy in order to evaluate the presence and severity of coronary artery disease. The anatomical visualisation provided by MSCT differs from the one of conventional coronary angiography because it is not a simple "lumenology" but it is capable to provide information on the vessel wall, until now only achieved by invasive techniques such as intravascular ultrasound or optical coherence tomography, and on neighbouring structures. Aim of this works is to provide the basics of anatomy of the vessels of the heart applied to MSCT.     

多层螺旋CT冠状动脉造影的扫描技术及临床应用

目的：探讨多层螺旋CT冠状动脉造影的成像技术及临床应用价值。方法：对68例[包括40例无明显心脏疾患的志愿者，25例冠心病患者，2例经皮冠冠状动脉成形术（PTCA）术后5个月和1例主动脉瓣膜置换术后的患者]进行了多层螺旋CT冠状动脉造影（multi-slice spiral CT coronary angiography,MSSCTCA)并行冠状动脉三维重建，其中25例冠心病患者并进行了选择性冠状动脉造影检查，以此为金标准，比较MSSCTCA对冠状动脉病变的检出率（未作冠状动脉造影的，只是用于评价多层螺旋CT对冠脉各支的显示能力，如显示哪几支、显示长度，示涉及有否冠状动脉疾患的显示）。结果：MSSCTCA对冠状动脉近中段显示清晰，显示率可达90％以上；对冠状动脉狭窄检出率为87．5％。结论：MSSCTCA可作为冠状动脉粥样硬化疾患的筛选手段及冠状动脉术后复查的首选方法。     

Integrated PET/CT for the assessment of coronary artery disease: a feasibility study.

An accurate, noninvasive technique for the diagnosis of coronary artery disease (CAD) should provide complementary information on coronary anatomy and pathophysiologic lesion severity. We present, what is to our knowledge, the first clinical evaluation of integrated PET/CT for combined acquisition of coronary anatomy and perfusion. METHODS: On an integrated PET/CT scanner, contrast-enhanced CT angiography (CTA) and rest/adenosine-stress myocardial perfusion scanning with (13)N-ammonia were performed on 25 patients with CAD documented by coronary angiography. Contrast-enhanced CTA was performed with retrospective electrocardiography gating after injection of 150 mL of intravenous contrast medium. Decisions on whether to treat with revascularization (anatomic lesion plus ischemia) or conservatively (no lesion or no ischemia) based on PET/CT were compared with those based on PET plus coronary angiography. RESULTS: Of the 100 coronary artery segments (left main, left anterior descending, left circumflex, and right in 25 patients), 7 (in 5 patients) were considered impossible to evaluate by CT because of rapid vessel movement but were correctly categorized by PET alone. In the remaining 93 segments, the sensitivity and specificity of PET/CT versus PET plus coronary angiography were 90% and 98%, respectively. Positive and negative predictive values were 82% and 99%, and accuracy was 97%. CONCLUSION: The data of this preliminary study suggest that PET/CT allows accurate noninvasive clinical decision making about CAD. Because of its high negative predictive value, PET/CT may play an important role in noninvasive selection of CAD patients for revascularization. Integration of higher-performance multislice spiral CT scanners into PET/CT hybrids will accelerate the clinical implementation of this technique.     

电子束CT血管造影对冠状动脉疾病的诊断与随访

目的评价电子束CT血管造影(EBA)及其三维血管成像技术对冠状动脉疾病的诊断与随访价值. 资料与方法 87例经EBA检查的患者,其中支架置入术后随访16例,搭桥术后随访9例.除9例搭桥患者外,其余78例均有冠状动脉造影(CAG)结果证实. 结果 EBA可评价的冠状动脉中,对左主干和前降支的诊断敏感性、特异性最高,尤其是近段,其次为右冠,对回旋支的诊断敏感性和特异性则较低;16例支架置入术后患者共放置支架47枚,EBA准确定位45枚(95.7%),对支架内开通诊断的符合率为74.5%;9例冠状动脉搭桥术后的患者,共搭建冠状动脉桥血管27支,EBA对桥血管开通与否诊断的符合率为81.5%. 结论 EBA对冠状动脉狭窄的诊断具有较高的术前筛选价值,对术后的随访也有较大的潜力,是一项很有优势的无创性冠心病检查方法.     

Non-invasive coronary bypass graft imaging

Coronary artery bypass grafting (CABG) is the most commonly performed revascularization procedure for coronary multi-vessel disease. Clinical outcome depends mainly on bypass graft patency. The gold standard for the assessment of graft patency is angiography. This is invasive and has a significant X-ray exposure and there is a need for contrast. A minimally or non-invasive imaging method of evaluating early and late postoperative graft patency is desirable. Several new minimally invasive imaging techniques have potential value in demonstrating coronary graft patency. This review article will focus on three techniques: (spiral) computed tomography (SCT), electron beam computed tomography (EBCT), and magnetic resonance angiography (MRA). Both SCT and EBCT have comparable diagnostic power. EBCT offers the advantages of electrocardiographically triggered data acquisition and simultaneous quantitation of coronary calcification, as well as a myocardial perfusion modality. EBCT may have superior potential for visualizing graft stenoses. The rapid development of a subsecond SCT technique may provide similar advantages with a much higher spatial resolution. The main disadvantages of CT techniques remain exposure to ionizing radiation and contrast. The application of MRA for graft analysis, particularly using the recently developed fast contrast enhanced sequences, is another promising tool. Good accuracy is combined with no X-ray exposure. Moreover, MRA may be combined with MR perfusion imaging along with anatomical and functional MR imaging, thereby providing a comprehensive cardiac evaluation.{copy}     

Multislice computed tomography cardiac imaging: current status

Non-invasive CT coronary artery imaging has previously had little relevance to most UK radiologists due to the limited availability of electron beam CT scanners. Major advances in CT technology have promoted new applications for helical CT, which include cardiac imaging. Widespread installation of 'multislice' helical CT scanners will make CT coronary artery imaging available for the first time in many UK hospitals. The technical advances and early clinical trial data are reviewed and multislice helical CT cardiac imaging in general is discussed.     

Comprehensive cardiac CT study: Evaluation of coronary arteries,left ventricular function,and myocardial perfusion—Is it possible?

With advances in multidetector computed tomography (MDCT) technology, the new generation of 64-slice MDCT scanners with submillimeter collimation and a faster gantry ratation allows imaging of the entire heart in a single breath-hold with excellent temporal and spatial resolution. This potentially permits a comprehensive assessment of coronary anatomy, left ventricular function, and myocardial perfusion. As will be seen in this review of the current literature regarding 16- and 64-slice MDCT, there is great promise for a comprehensive cardiac computed tomography (CT) study. The available data support the notion that CT coronary angiography may be an alternative to invasive coronary angiography in symptomatic patients with a low to intermediate likelihood of having coronary artery disease. By use of the same data acquired for CT coronary angiography, evaluation of global and regional left ventricular function and myocardial perfusion can be added to the MDCT evaluation without additional exposure to contrast medium or radiation and may provide a more conclusive cardiac workup in these patients. The potential applications and limitations of coronary stenosis detection, global and regional left ventricular function, and myocardial perfusion assessment by MDCT will be reviewed. The full potential of cardiac MDCT is just beginning to be realized.     

Myocardial perfusion imaging after coronary revascularization: a clinical appraisal

Revascularization procedures, including percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG), are performed in many patients with coronary artery disease. Despite the effectiveness of these procedures, different follow-up strategies need to be considered for the management of patients after revascularization. Stress myocardial perfusion single-photon emission computed tomography (MPS) is a suitable imaging method for the evaluation of patients who have undergone PCI or CABG, and it has been used in the follow-up of such patients. Radionuclide imaging is included in the follow-up strategies after PCI and CABG in patients with symptoms, but guidelines warn against routine testing of all asymptomatic patients after revascularization. After PCI, in the absence of symptoms, radionuclide imaging is recommended and indicated as appropriate after incomplete or suboptimal revascularization and in specific asymptomatic patient subsets. On the other hand, the value of MPS late after CABG in risk stratification has been demonstrated even in the absence of symptoms. Thus, given the adverse outcome associated with silent ischaemia, it can be speculated that all patients regardless of clinical status should undergo stress testing late after revascularization. Larger prospective studies are needed to assess whether stress MPS will have an impact on the outcome in asymptomatic patients after revascularization.     

CT-SYNTAX评分在复杂冠状动脉疾病心肌血运重建决策中的应用进展

复杂冠状动脉疾病（CAD）心肌血运重建治疗策略的选择是临床医师关注的问题,基于有创冠状动脉造影（ICA）的SYNTAX评分是当前重要的临床指导依据。随着冠状动脉CT血管成像（CCTA）的普及,基于CCTA的SYNTAX评分（CT-SYNTAX）成为研究热点。基于CCTA的血流储备分数（FFR_CT）可提供CAD的功能学信息,实现了CT-SYNTAX评分从解剖学向功能学的提升。就CT-SYNTAX评分在复杂CAD病人治疗策略中应用的研究进展予以综述。     

16层螺旋CT冠状动脉成像的技术与应用

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

Coronary CT angiography for acute chest pain in the emergency department

Acute chest pain in the emergency department (ED) is a common and costly public health challenge. The traditional strategy of evaluating acute chest pain by hospital or ED observation over a period of several hours, serial electrocardiography and cardiac biomarkers, and subsequent diagnostic testing such as physiologic stress testing is safe and effective. Yet this approach has been criticized for being time intensive and costly. This review evaluates the current medical evidence which has demonstrated the potential for coronary CT angiography (CTA) assessment of acute chest pain to safely reduce ED cost, time to discharge, and rate of hospital admission. These benefits must be weighed against the risk of ionizing radiation exposure and the influence of ED testing on rates of downstream coronary angiography and revascularization. Efforts at radiation minimization have quickly evolved, implementing technology such as prospective electrocardiographic gating and high pitch acquisition to significantly reduce radiation exposure over just a few years. CTA in the ED has demonstrated accuracy, safety, and the ability to reduce ED cost and crowding although its big-picture effect on total hospital and health care system cost extends far beyond the ED. The net effect of CTA is dependent also on the prevalence of coronary artery disease (CAD) in the population where CTA is used, which significantly influences rates of post-CTA invasive procedures such as angiography and coronary revascularization. These potential costs and benefits will warrant careful consideration and prospective monitoring as additional hospitals continue to implement this important technology into their diagnostic regimen.     

What does the clinical cardiologist need from noninvasive cardiac imaging: Is it time to adjust practices to meet evolving demands?

With the recent emergence of multidetector computed tomography angiography, coronary anatomy can now be assessed noninvasively. Until this advancement, functional noninvasive imaging used to serve as a gatekeeper that governed access to invasive diagnosis by coronary angiography and subsequent therapy. In the current era the threshold for access to coronary anatomy will be lowered. Functional nonin vasive imaging will often come second, while anatomy is known already. If appropriate use of revascularization procedures is to be promoted, functional evaluation shall play an even greater role than before as a guide for selection of therapy. In subjects screened while the atherosclerotic disease is still at a preclinical stage, the ability to image plaque activity in the absence of flow-limiting stenosis will be essential in our attempts to prevent sudden ischemic cardiac death and unheralded myocardial infarction. In patients with advanced age and extensive obstructive disease, the diagnostic performance of functional testing will have to be raised by shifting from “per-patient” to “per-vessel” accuracy. Reengineering of currently available methods or the development of novel technologies that provide an integrative evaluation of anatomy and function will be necessary. With the availability of an increasing number of imaging options, it is anticipated that the emphasis will be placed more than ever on cost-effectiveness on a population basis, as well as on segmental predictive accuracy in the individual subject. This review summarizes a keynote lecture presented at ASNC2006 (11th Annual Scientific Session of the American Society of Nuclear Cardiology); Sept 9, 2006; Montreal, Quebec, Canada.     

CT imaging of myocardial perfusion: Possibilities and perspectives

Functional imaging in patients with suspected or known coronary artery disease (CAD) is crucial for the identification of patients who could benefit from coronary revascularization. Several studies demonstrated the high diagnostic accuracy of Single-photon-emission computed tomography myocardial perfusion imaging, stress perfusion magnetic resonance imaging, and of invasive FFR measurements for the detection of hemodynamic relevant stenosis. Cardiac computed tomography (CT) used to be limited to coronary angiography (CTA); current guidelines recommend CTA only for the exclusion of CAD. Technological advances now offer the possibility to assess myocardial perfusion by computed tomography (CT-MPI). Though different acquisition protocols and post-processing algorithms still have to be evaluated, initial clinical studies could already show a diagnostic accuracy comparable to the established imaging modalities. Thus, cardiac CT may offer a combined approach of anatomical and functional imaging. Beside the need for further studies, especially on the prognostic value of CT-MPI to stratify future cardiovascular events, the comparatively high radiation exposure and additional administration of contrast agent has to be taken in account.