Research Article Open Access Youssef and Budoff, Angiol 2013, 1:2 DOI: 10.4172/2329-9495.1000111 Review Article Open Access Volume 1 • Issue 2 • 1000111 Angiol, an open access journal ISSN: 2329-9495 Angiology: Open Access A n g i o l o g y : O p e n A c c e s s ISSN: 2329-9495 Introduction Atherosclerotic cardiovascular diseases are still the leading cause of deaths in industrialized Countries and Coronary Artery Disease (CAD) accounts for the majority of this toll [1]. Cardiac events are typically caused by disruption of coronary plaques where plaque rupture occurs in about two thirds of cases, while the remaining third of cases are caused by plaque erosion with subsequent formation of occluding thrombus [2]. Tus, a clinically relevant definition of a rupture-prone (or what has been termed the “vulnerable”) plaque, is a lesion that places a patient at risk for future major adverse cardiac events, including death, myocardial infarction, or progressive angina. On the other hand, the histopathological features that have been associated with vulnerable plaques and defned them, include: 1) A large eccentric necrotic lipid core, occupying approximately one-quarter of the plaque area [3], 2) A thin fbrous cap (<65 µm thick) [4], 3) Heavy infltration by large number of infammatory cells (macrophages and T cells) particularly at the shoulder region of the plaque [5], 4) Spotty calcifcation, 5) Neovascularization due to proliferation of the vasa vasora and formation of immature and leaky microvessels, with subsequent rupture and intra-plaque hemorrhage [6], fnally, 6) In contrast to eroded plaques, rupture-prone plaquesusually are non- or mildly obstructive, yet the size of the plaque may be substantial due to the phenomenon of positive remodeling [7]. Yet, some of these aforementioned features, namely calcifcation and positive remodeling are still controversial about their actual role in plaque stability. Invasive coronary angiography, though presumably considered as the gold standard for the diagnosis of CAD, is a mere luminogram that focuses mainly on the stenosis severity rather than plaque characteristics. Moreover, other traditional non-invasive stress tests as stress echocardiography or myocardial perfusion imaging only help detect hemodynamically signifcant lesions rather than non-obstructive potentially vulnerable plaques. Obstacles in detection of vulnerable plaques include their small size and being localized within the rapidly moving coronary arteries. In addition, plaque vulnerability is a dynamic process, a plaque that appears rupture-prone today could rather be stable tomorrow, even ruptured plaques do not always lead to coronary events as many ruptures occur and heal silently. Terefore, there has been a growing interest for detection and characterization of coronary atherosclerotic plaques. Te aim of the present review paper is to shed some light on diferent diagnostic modalities used for the assessment of plaque vulnerability, with specifc focus on the Multi-Detector Computed Tomography (MDCT) as an evolving tool in that feld with all its strengths and limitations. Imaging Modalities used for Assessment of Vulnerable Plaques Direct visualization of atherosclerotic plaques in vivo is the only way forward for studying the natural history of atherosclerotic disease. Te imaging techniques currently used are generally able to provide adequate information on the lumen diameter reduction or its functional signifcance. So, diferent imaging techniques; both invasive and non- invasive, have been developed to reliably evaluate plaque composition and identify its vulnerable features, thereby allow implementation of treatment strategies to prevent adverse coronary events. Table 1 lists diferent invasive and non-invasive imaging modalities with main strengths and limitations. In addition to being expensive and in need for specially trained personnel, invasive techniques by their very nature, have a lower level of patient acceptability than non-invasive modalities which may provide a good alternative. Collectively, factors that characterize an ideal non-invasive technique would include; patient-related factors: 1) wide range of clinical indications, 2) absence of ionizing radiation, 3) unnecessary administration of contrast media and 4) not precluded by metallic devices or leads, and technical factors: 1) Rapid image acquisition, 2) high temporal, spatial and contrast resolution, 3) ability to provide both anatomic and metabolic information, and 4) accurate and reproducible [26]. *Corresponding author: George Youssef, Los Angeles Biomedical Research Institute, Harbor UCLA, 1124 West Carson Street, Torrance CA 90503, USA, Tel: 310-222-4107; Fax: 310-782-9652; E-mail: george.youssef@yahoo.com Received May 25, 2013; Accepted July 26, 2013; Published July 28, 2013 Citation: Youssef G, Budoff M (2013) Role of Computed Tomography Coronary Angiography in the Detection of Vulnerable Plaque, Where Does it Stand Among Others? Angiol 1: 111. doi: 10.4172/2329-9495.1000111 Copyright: © 2013 Youssef G, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract Recently, there has been a growing interest in identifcation of coronary “vulnerable plaques” that are prone to rupture; this potentially would help identify patients with higher risk of development of cardiac events. Recent advances in cardiac imaging modalities have been successful in studying various plaque vulnerability features to variable degrees, strengths and limitations. Computed Tomography Coronary Angiography (CTCA) has gained an increasing popularity in studying plaque anatomy, morphology and composition by the virtue of its widespread availability and non-invasiveness. CTCA has been validated against histology and IVUS with reasonable correlation; moreover, some follow-up studies have shown a signifcant association to the development of acute coronary syndromes. Nevertheless, attention should be paid to the whole patient big picture that includes other factors operating on other extra-coronary axes that involve infammation, immunity, coagulation and neuroendocrine systems. Role of Computed Tomography Coronary Angiography in the Detection of Vulnerable Plaque, Where Does it Stand Among Others? George Youssef* and Matthew Budoff Los Angeles Biomedical Research Institute, Harbor UCLA Medical Center, California, USA