Carotid plaque imaging and the risk of atherosclerotic cardiovascular disease

Carotid artery plaque is a measure of atherosclerosis and is associated with future risk of atherosclerotic cardiovascular disease (ASCVD), which encompasses coronary, cerebrovascular, and peripheral arterial diseases. With advanced imaging techniques, computerized tomography (CT) and magnetic resonance imaging (MRI) have shown their potential superiority to routine ultrasound to detect features of carotid plaque vulnerability, such as intraplaque hemorrhage (IPH), lipid-rich necrotic core (LRNC), fibrous cap (FC), and calcification. The correlation between imaging features and histological changes of carotid plaques has been investigated. Imaging of carotid features has been used to predict the risk of cardiovascular events. Other techniques such as nuclear imaging and intra-vascular ultrasound (IVUS) have also been proposed to better understand the vulnerable carotid plaque features. In this article, we review the studies of imaging specific carotid plaque components and their correlation with risk scores

MRI and CT in the diagnosis of coronary artery disease: indications and applications

In recent years, technical advances and improvements in cardiac computed tomography (CT) and cardiac magnetic resonance imaging (MRI) have provoked increasing interest in the potential clinical role of these techniques in the non-invasive work-up of patients with suspected coronary artery disease (CAD) and correct patient selection for these emerging imaging techniques. In the primary detection or exclusion of significant CAD, e.g. in the patient with unspecific thoracic complaints, and also in patients with known CAD or advanced stages of CAD, both CT and MRI yield specific advantages. In this review, the major aspects of non-invasive MR and CT imaging in the diagnosis of CAD will be discussed. The first part describes the clinical value of contrast-enhanced non-invasive CT coronary angiography (CTCA), including the diagnostic accuracy of CTCA for the exclusion or detection of significant CAD with coronary artery stenoses that may require angioplastic intervention, as well as potentially valuable information on the coronary artery vessel wall. In the second section, the potential of CT for the imaging of myocardial viability and perfusion will be highlighted. In the third and final part, the range of applications of cardiac MRI in CAD patients will be outlined

Validation and application of intravascular ultrasound in the study of percutaneous coronary intervention

Intravascular ultrasound (IVUS) is a relatively new method of imaging coronary arteries which has several advantages over contrast angiography in the accurate quantification of coronary lumen and vessel dimensions and assessment of atherosclerotic plaque. Experimentally, IVUS has so far provided detailed insights into the distribution and composition of atheroma in the coronary circulation and its behaviour when subjected, particularly, to balloon dilatation. The technique is now regarded as a useful adjunct to angiography in the routine assessment of patients with atherosclerotic coronary disease as well as in the guidance of percutaneous coronary interventional techniques such as balloon angioplasty and intracoronary stent implantation. Additionally, the concept of three-dimensional reconstruction of IVUS images has recently been realized providing the opportunity for longitudinal as well as tomographic analysisDespite the wealth of information so far provided by IVUS most in vitro studies require cautious interpretation due to well-recognised limitations of studying animal models of atherosclerosis or human coronary disease in circumstances that do not accurately reflect the clinical setting. This thesis is based upon the development of a pulsatile flow system which is capable of accurately reproducing some of the important physiological properties of in-vivo flow in normal and diseased coronary arteries. Some characteristics of in-vivo coronary blood flow cannot be met, such as the effect of blood viscosity and extrinsic compression of the vessel by the beating heart. However, the system is designed to enable the study of human coronary atherosclerotic disease by IVUS in conditions which closely resemble those seen in the clinical setting. The initial chapters provide an overview of IVUS, including methods and rationale for three-dimensional reconstruction, and describe the development and validation of the flow system. Chapters 3 and 4 assess the qualitative accuracy of IVUS in the assessment of the composition of atherosclerotic plaque and also the reproducibility of IVUS assessments of vessel and lumen dimensions in diseased coronary arteries. There follows a study of coronary balloon angioplasty designed to assess the influence of procedural factors, such as balloon calibre and inflation pressure selection, and IVUS guidance on the initial success of the procedure. In the remaining chapters two studies examine three-dimensional reconstruction of IVUS images and the influence of technical factors, which are inherent in IVUS imaging, on the accuracy of atherosclerotic plaque volume measurement and its use in assessing vascular injury following coronary balloon angioplasty. It should be emphasized that all patient donors died from causes other than cardiovascular disease such that the histopathological studies involved the use of coronary artery specimens which were not required for diagnostic purposes. The studies adhered to strict ethical standards of the day. Harvesting of specimens received ethical approval as part of the overall IVUS research programme being undertaken at the time. All specimens were retained by the Department of Pathology during the study period and disposed of appropriately following the final analysesTaken together these studies have helped to provide further insights into the quantitative and qualitative accuracy of IVUS in the assessment of coronary atherosclerosis and the technical factors which may confound these analyses. Furthermore, the value of IVUS in guiding, and assessing the outcome of, coronary balloon angioplasty is clearly demonstrated. Given the close correlation of the studies to the clinical setting the findings should be expected to influence our approach to clinical IVUS studies and utilize the technique more frequently in the guidance of percutaneous coronary intervention

Quantitative imaging in cardiovascular CT angiography

In de afgelopen decennia is computertomografie (CT) een prominente niet-invasieve modaliteit om hart- en vaatziekten te evalueren geworden. Dit proefschrift heeft als doel de rol van CT in de therapeutische behandeling van coronaire hartziekte (CAD) en klepaandoeningen te onderzoeken.De relatie tussen kransslagadergeometrie (statisch en dynamisch) en aanwezigheid en omvang van CAD met CT werd onderzocht. De resultaten suggereren dat de statische geometrie van de kransslagader significant gerelateerd is aan de aanwezigheid van plaque en stenose. Er was echter geen verband tussen dynamische verandering van de coronaire arterie-geometrie en de ernst van CAD. Een algoritme om de invloed van intraluminair contrastmiddel op niet-verkalkte atherosclerotische plaque Hounsfield-Unit-waarden te corrigeren werd gepresenteerd en gevalideerd met behulp van fantomen.Diagnose en operatieplanning kunnen cruciale gevolgen hebben voor de klinische uitkomst van chirurgische ingrepen. In dit proefschrift wordt beschreven dat halfautomatische softwareprogramma’s het kwantificeren van het aortaklepgebied betere reproduceerbare resultaten toonden in vergelijking met handmatige metingen, en vergelijkbare resultaten met de huidige gouden standaard, de echocardiografie. Een systematische review over het dynamische gedrag van de aorta-annulus toont aan dat de vorm van de aorta-annulus tijdens de hartcyclus verandert, wat impliceert dat er bij het bepalen van een prothese rekening moet worden gehouden met meerdere fasen. Een andere review beschrijft het gebruik van 3D-printen in de chirurgische planning samen met andere toepassingen voor de behandeling van hartklepaandoeningen.CT is de belangrijkste beeldvormingsmodaliteit in deze onderzoeken, die gericht waren op de therapeutische behandeling van hart- en vaatziekten, van vroege risicobepaling tot diagnose en chirurgische planning.In the recent decades computed tomography (CT) has emerged as a dominant non-invasive modality to evaluate cardiovascular diseases. This thesis aimed to explore the role of CT in the therapeutic management of coronary artery disease (CAD) and valvular diseases.The relationship between both static and dynamic coronary artery geometry and presence and extent of CAD using CT was investigated. The results suggest that the static coronary artery geometry is significantly related to presence of plaque and significant stenosis. However, there were no such relationship between dynamic change of coronary artery geometry and severity of CAD. As part of this thesis an algorithm to correct the influence of lumen contrast enhancement on non-calcified atherosclerotic plaque Hounsfield-Unit values was presented. The algorithm was validated using phantoms. The diagnosis and surgical planning may have crucial impact on clinical outcome. Semi-automatic software for aortic valve area quantification presented in this thesis was proven to be more repeatable and similar to gold standard echocardiography in comparison to manual measurements. The systematic review regarding the dynamic behavior of aortic annulus revealed that aortic annulus geometry changes throughout the cardiac cycle which implies that multiple phases should be taken into account for prosthesis sizing. Another review in this thesis discusses the use of 3D printing in the surgical planning along with other applications for the treatment of valvular diseases.CT is the main imaging modality in these studies which were focused on the therapeutic management of cardiovascular diseases from early risk determination to diagnosis and surgical planning