Pim de Feyter

Coronary angiography with multi-slice computed tomography

BACKGROUNDnA new generation of subsecond multi-slice computed tomography (MSCT) scanners, which allow complete coronary coverage, are becoming widely available. We investigated the potential value of MSCT angiography in a range of coronary disorders.nnnMETHODSnWe studied 35 patients, including 11 who had undergone percutaneous transluminal coronary angioplasty and four who had had coronary-artery bypass grafts, by both MSCT and conventional coronary angiography. After intravenous injection of a non-ionic contrast medium with high iodine content, the entire heart was scanned within a single breath-hold. The total examination time was no more than 20 min. The retrospective electrocardiographically gated reconstruction source images and three-dimensional reconstructed volumes were analysed by two investigators, unaware of the results of conventional angiography.nnnFINDINGSnIn the 31 patients without previous coronary surgery, 173 (73%) of the 237 proximal and middle coronary segments were assessable. In the assessable segments, 17 of 21 significant stenoses (>50% reduction of vessel diameter) were correctly diagnosed. The non-assessable segments included four lesions. Misinterpretations were mainly the result of severe calcification of the vessel wall. Segments with implanted stents were poorly visualised, but stent patency could be assessed in all cases. Of the 17 segments of bypass grafts, 15 were assessable and four of five graft lesions were detected. Two cases of anomalous coronary anatomy could be visualised well.nnnINTERPRETATIONnThese preliminary data suggest that MSCT allows non-invasive imaging of coronary-artery stenoses and has potential to develop into a reliable clinical technique.

Quantitative coronary angiography in clinical practice

Foreword. Introduction. Part I: Validation of QCA: In vitro and in vivo, off-line and on-line studies. Part II: The QCA Core Laboratory: practical lessons learned and application to clinical practice. Part III: Physiological applications of QCA, correlation with intracoronary physiological measurements obtained by alternative methodology. Part IV: QCA in the study of vasomotion. Part V: QCA in the setting of acute coronary syndromes, evaluation of the role of thrombolysis and balloon angioplasty. Part VI: QCA applied to the evaluation of immediate and long term outcome following coronary balloon angioplasty: experiences emerging from large multicentre restenosis prevention trials. Part VII: Evaluation of new devices and comparison with balloon angioplasty using QCA. Part VIII: QCA applied to the natural history of atherosclerosis. Part IX: Intravascular ultrasound and QCA. Index.

Plaque and Shear Stress Distribution in Human Coronary Bifurcations: a Multi-Slice Computed Tomography Study

Aims: Early atherosclerosis is located in low wall shear-stress (WSS) regions, however plaques are also found in the high WSS sensing flowdivider walls of coronary bifurcations. We assessed the plaque distribution and morphology near bifurcations non-invasively with 64 slice computed tomography (MSCT) in relation to the WSS distribution. Methods and results: We inspected 65 cross-sections near coronary bifurcations for the presence of plaque. Cross-sections were divided into four equal parts, which we numbered according to expected levels of WSS, with part I the lowest WSS (outer wall) and increasing WSS’s in part II (inner bend), III (outer bend) and IV (flowdivider). Of the cross-sections 88% had plaque. Of all parts I, 72% contained plaque. This was 62%, 38% and 31% in parts II, III and IV. In cross-sections with only 1 or 2 parts inflicted, plaque was found in part I and/or II in 94%. In 93% of the cross-sections with the flowdivider inflicted, parts I and/or II were also inflicted. Plaque was never found exclusively in the flowdivider part IV. Conclusions: We demonstrated that plaque is mostly present in low WSS regions, whereas plaque in high WSS regions is accompanied by plaque in adjacent low WSS regions. It is therefore plausible that plaque grows from the outer wall (low WSS) of the bifurcation towards the flowdivider (high WSS).

Towards complete assessment of progression/regression of coronary atherosclerosis: Implications for intervention trials

Visual assessment of serial angiograms has always been the standard method to study progression/regression of coronary atherosclerosis. Visual assessment is subjective and suffers from the large intra- and interobserver variability. This stimulated the development of quantitative coronary angiography, employing computer based edge-finding detection techniques, which are currently applied and now considered as the new’ standard’.

Computed Tomography of the Coronary Arteries, Second Edition

Updated to reflect the notable advances in cardiac computed tomography (CT) imaging, the Second Edition of the best-selling Computed Tomography of the Coronary Arteries provides cardiologists and radiologists with a practical text that explains the basic principles and applications of CT. Written by renowned international experts in the field, this accessible resource clearly presents the fundamentals of the new technology of 64-slice imaging through the use of high quality illustrations, references, and tables. Contents include: • image post-processing • coronary imaging for normal coronary arteries • coronary pathology and coronary imaging • coronary stenosis • coronary plaque imaging and calcification • chronic total occlusion • an assessment of coronary stents • coronary artery anomalies in adults • coronary collaterals and bypass grafts • cardiac masses, intracardiac thrombi, and pericardial abnormalities • great thoracic vessels • noncardiac findings on CT calcium screening • left ventricular function • artefacts • the future of cardiac CT imaging • contrast-enhancement for coronary angiography.

Vascular Remodeling During Atherosclerotic Plaque Build Up Is Controlled by the Plaque Free Part of the Vessel Wall

Glagov et al. observed that positive, compensatory vascular remodeling during plaque build up prevents lumen narrowing until plaque burden, this is the relative plaque area to media bounded area, exceeds a threshold of 40% [1]. Until now it is not clear what mechanism controls the compensatory vascular remodeling during the atherosclerotic plaque build up and what determines absence or limits compensatory vascular remodeling. Plaque burden does not seem to reflect a parameter, which could serve as a limiting step in the known control process in the vascular system. For instance, healthy arteries control vascular remodeling by fluid flow induced shear stress via a number of endothelium dependent pathways [2]. The endothelium at the atherosclerotic plaque side is considered to be dysfunctional [2] and might thereby limit the remodeling process. Since plaques are mostly eccentric, we hypothesize that the healthy part of the artery (or plaque free wall) will respond to changes in shear stress and will determine the capacity of the arteries to remodel up till the moment of complete circumferential involvement of the disease. We investigated whether the size of the plaque free wall contributes to vascular remodeling over a 3 year period using serial intravascular ultrasound measurements by determining 1) the frequency of positive remodeling in segments with varying size of plaque free vessel wall 2) the degree of vascular remodeling for segments with varying size of plaque free vessel wall.Copyright

Multi-Dimensional Computed Coronary Visualization

Contemporary medical imaging modalities such as magnetic resonance imaging (MRI), electron beam computed tomography (EBCT), and multi-detector computed tomography (MDCT) are able to provide the clinician with a wealth of information. To be able to evaluate and diagnose the (projection and volumetric) data from modern non-invasive and invasive imaging modalities, new visualization techniques (both for image rendering and image processing) are increasingly used. These visualization techniques have been described frequently both for coronary imaging (Nakanishi et al. 1997; Chen and Carroll 1998; Oijen et al. 1997) and for other applications in medicine (Rankin 1999; Kirchgeorg and Prokop 1998; Calhoun et al. 1999).

Magnetic resonance and electron beam tomography coronary angiography

Recently, two non-invasive techniques Magnetic Resonance (MR) and Electron Beam Tomography (EBT) have been developed that are able to visualize the proximal and mid segments of the coronary arteries.

Intracoronary imaging with ultrasound

Although intravascular ultrasound transducers were first developed and tested in the early seventies [1] it wasn’t until the advent of catheter based coronary interventional techniques that a major impetus was given to their development. Because intracoronary ultrasound allows direct visualisation of the atherosclerotic plaque [2, 3], it may assist in the choice of intervention, guidance during the procedure and assessment of the results and any complications. Furthermore, direct real time visualisation of arterial wall morphology offers unique opportunities for the in vivo assessment of arterial pathophysiology and dynamics on a beat-to-beat basis.

Methodologic Aspects of Quantitative Coronary Angiography (QCA) in Interventional Cardiology

Quantitative Coronary Angiography (QCA) has had a tremendous impact in the field of interventional cardiology. It has supplanted visual and handheld caliper assessments of coronary arteriography due to its superior interobserver and intraobserver variability [1–3]. Currently it is the gold standard to assess the coronary tree for research purposes although it has not gained widespread appeal for routine clinical use because of expense and time constraints. It has been particularly useful in interventional cardiology as the only reliable means to assess the short and long term effects of coronary interventions. In particular, the phenomenon of restenosis has been primarily described and researched most extensively on the basis of sequential QCA studies. At the Thoraxcenter in Rotterdam, we have been advocating the importance of QCA since the first publication by our group in 1982 [4]. The system developed at the Thoraxcenter by Johan Reiber and colleagues, the Coronary Angiographic Analysis System (CAAS), has been extensively and rigorously validated [5–7]. In our database, we have now collected information from over 1700 patients who have undergone several different forms of non-operative coronary revascularization (Fig. 1). We have had to adapt the principles of QCA, which were initially designed for diagnostic studies to assess the extent of coronary artery disease, to more complicated and complex situations related to either the device or the effect of the intervention on the angiographic appearance of a damaged vessel.