The Experts below are selected from a list of 41925 Experts worldwide ranked by ideXlab platform
George R Sutherland - One of the best experts on this subject based on the ideXlab platform.
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are changes in myocardial integrated backscatter restricted to the ischemic zone in acute induced ischemia an in vivo animal study
Journal of The American Society of Echocardiography, 2000Co-Authors: Bart Bijnens, Jan Dhooge, Maarten Schrooten, Sorin V Pislaru, C Pislaru, Bruno De Man, Johan Nuyts, Paul Suetens, Frans Van De Werf, George R SutherlandAbstract:Integrated backscatter (IB) from a myocardial region, calculated from radiofrequency echocardiographic data, has been proposed as a useful parameter for investigating changes in myocardial tissue induced by ischemia. In 10 closed-chest dogs, 5 minutes of myocardial ischemia was induced by either a proximal occlusion of the circumflex coronary artery (CX) (5 dogs), resulting in extensive ischemia in the posterior wall, or by occluding the distal CX vessel (5 dogs) to produce a small localized ischemic zone in the posterior wall. High-resolution digital radiofrequency data from the whole left ventricular myocardium, in the imaging plane during one complete Heart Cycle, were acquired with a whole-image real-time acquisition approach. Regions in the septum and posterior wall (both ischemic tissue and, in the case of distal occlusions, tissue surrounding the ischemic zone) were chosen for analysis, and IB and cyclic variation (CV) of IB were calculated. Post occlusion, an increase in mean IB values was found in the ischemic segment. However, an increase in CV was also observed in the peri-ischemic zone for the distal CX occlusion and in the septum after proximal CX occlusion. These findings show that changes in CV are not restricted to the ischemic zone but may also occur in distal myocardium. This may be explained by changes in the regional contractile state and loading conditions of the "normal" myocardium, which are altered in response to the distal ischemia.
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how accurate is visual assessment of synchronicity in myocardial motion an in vitro study with computer simulated regional delay in myocardial motion clinical implications for rest and stress echocardiography studies
Journal of The American Society of Echocardiography, 1999Co-Authors: Johnpeder Escobar Kvitting, Lars Wigstrom, Jorg M Strotmann, George R SutherlandAbstract:Asynchronicity in echocardiographic images is normally assessed visually. No prior quantitative studies have determined the limitations of this approach. To quantify visual recognition of myocardial asynchronicity in echocardiographic images, computer-simulated delay phantom loops were generated from a 3.3 MHz digital image data from a normal left ventricular short-axis Heart Cycle acquired at 55 frames per second. Six expert observers visually assessed 30 abnormal and 3 normal loops with differing computer-induced delay patterns on 3 occasions and in this optimally simulated environment could recognize only single delays of 89 ms or more. This was improved to 71 ms or more by use of side-by-side (normal versus abnormal) comparative review. Thus visual assessment of clinically important regional delay in rest or stress echo images is limited.
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how accurate is visual assessment of synchronicity in myocardial motion an in vitro study with computer simulated regional delay in myocardial motion clinical implications for rest and stress echocardiography studies
Journal of The American Society of Echocardiography, 1999Co-Authors: Johnpeder Escobar Kvitting, Lars Wigstrom, Jorg M Strotmann, George R SutherlandAbstract:Abstract Asynchronicity in echocardiographic images is normally assessed visually. No prior quantitative studies have determined the limitations of this approach. To quantify visual recognition of myocardial asynchronicity in echocardiographic images, computer-simulated delay phantom loops were generated from a 3.3 MHz digital image data from a normal left ventricular short-axis Heart Cycle acquired at 55 frames per second. Six expert observers visually assessed 30 abnormal and 3 normal loops with differing computer-induced delay patterns on 3 occasions and in this optimally simulated environment could recognize only single delays of 89 ms or more. This was improved to 71 ms or more by use of side-by-side (normal versus abnormal) comparative review. Thus visual assessment of clinically important regional delay in rest or stress echo images is limited. (J Am Soc Echocardiogr 1999;12:698-705.)
Tino Ebbers - One of the best experts on this subject based on the ideXlab platform.
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comprehensive 4d velocity mapping of the Heart and great vessels by cardiovascular magnetic resonance
Journal of Cardiovascular Magnetic Resonance, 2011Co-Authors: Michael Markl, Philip J Kilner, Tino EbbersAbstract:Phase contrast cardiovascular magnetic resonance (CMR) is able to measure all three directional components of the velocities of blood flow relative to the three spatial dimensions and the time course of the Heart Cycle. In this article, methods used for the acquisition, visualization, and quantification of such datasets are reviewed and illustrated. Currently, the acquisition of 3D cine (4D) phase contrast velocity data, synchronized relative to both cardiac and respiratory movements takes about ten minutes or more, even when using parallel imaging and optimized pulse sequence design. The large resulting datasets need appropriate post processing for the visualization of multidirectional flow, for example as vector fields, pathlines or streamlines, or for retrospective volumetric quantification. Multidirectional velocity acquisitions have provided 3D visualization of large scale flow features of the healthy Heart and great vessels, and have shown altered patterns of flow in abnormal chambers and vessels. Clinically relevant examples include retrograde streams in atheromatous descending aortas as potential thrombo-embolic pathways in patients with cryptogenic stroke and marked variations of flow visualized in common aortic pathologies. Compared to standard clinical tools, 4D velocity mapping offers the potential for retrospective quantification of flow and other hemodynamic parameters. Multidirectional, 3D cine velocity acquisitions are contributing to the understanding of normal and pathologically altered blood flow features. Although more rapid and user-friendly strategies for acquisition and analysis may be needed before 4D velocity acquisitions come to be adopted in routine clinical CMR, their capacity to measure multidirectional flows throughout a study volume has contributed novel insights into cardiovascular fluid dynamics in health and disease.
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Comprehensive 4D velocity mapping of the Heart and great vessels by cardiovascular magnetic resonance
Journal of Cardiovascular Magnetic Resonance, 2011Co-Authors: Michael Markl, Philip J Kilner, Tino EbbersAbstract:Background Phase contrast cardiovascular magnetic resonance (CMR) is able to measure all three directional components of the velocities of blood flow relative to the three spatial dimensions and the time course of the Heart Cycle. In this article, methods used for the acquisition, visualization, and quantification of such datasets are reviewed and illustrated. Methods Currently, the acquisition of 3D cine (4D) phase contrast velocity data, synchronized relative to both cardiac and respiratory movements takes about ten minutes or more, even when using parallel imaging and optimized pulse sequence design. The large resulting datasets need appropriate post processing for the visualization of multidirectional flow, for example as vector fields, pathlines or streamlines, or for retrospective volumetric quantification. Applications Multidirectional velocity acquisitions have provided 3D visualization of large scale flow features of the healthy Heart and great vessels, and have shown altered patterns of flow in abnormal chambers and vessels. Clinically relevant examples include retrograde streams in atheromatous descending aortas as potential thrombo-embolic pathways in patients with cryptogenic stroke and marked variations of flow visualized in common aortic pathologies. Compared to standard clinical tools, 4D velocity mapping offers the potential for retrospective quantification of flow and other hemodynamic parameters. Conclusions Multidirectional, 3D cine velocity acquisitions are contributing to the understanding of normal and pathologically altered blood flow features. Although more rapid and user-friendly strategies for acquisition and analysis may be needed before 4D velocity acquisitions come to be adopted in routine clinical CMR, their capacity to measure multidirectional flows throughout a study volume has contributed novel insights into cardiovascular fluid dynamics in health and disease.
Lars Wigstrom - One of the best experts on this subject based on the ideXlab platform.
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towards cardiac c arm computed tomography
IEEE Transactions on Medical Imaging, 2006Co-Authors: Guenter Lauritsch, Jan Dr Boese, Lars Wigstrom, H Kemeth, Rebecca FahrigAbstract:Cardiac interventional procedures would benefit tremendously from sophisticated three-dimensional image guidance. Such procedures are typically performed with C-arm angiography systems, and tomographic imaging is currently available only by using preprocedural computed tomography (CT) or magnetic resonance imaging (MRI) scans. Recent developments in C-arm CT (Angiographic CT) allow three-dimensional (3-D) imaging of low contrast details with angiography imaging systems for noncardiac applications. We propose a new approach for cardiac imaging that takes advantage of this improved contrast resolution and is based on intravenous contrast injection. The method is an analogue to multisegment reconstruction in cardiac CT adapted to the much slower rotational speed of C-arm CT. Motion of the Heart is considered in the reconstruction process by retrospective electrocardiogram (ECG)-gating, using only projections acquired at a similar Heart phase. A series of N almost identical rotational acquisitions is performed at different Heart phases to obtain a complete data set at a minimum temporal resolution of 1/N of the Heart Cycle time. First results in simulation, using an experimental phantom, and in preclinical in vivo studies showed that excellent image quality can be achieved
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how accurate is visual assessment of synchronicity in myocardial motion an in vitro study with computer simulated regional delay in myocardial motion clinical implications for rest and stress echocardiography studies
Journal of The American Society of Echocardiography, 1999Co-Authors: Johnpeder Escobar Kvitting, Lars Wigstrom, Jorg M Strotmann, George R SutherlandAbstract:Asynchronicity in echocardiographic images is normally assessed visually. No prior quantitative studies have determined the limitations of this approach. To quantify visual recognition of myocardial asynchronicity in echocardiographic images, computer-simulated delay phantom loops were generated from a 3.3 MHz digital image data from a normal left ventricular short-axis Heart Cycle acquired at 55 frames per second. Six expert observers visually assessed 30 abnormal and 3 normal loops with differing computer-induced delay patterns on 3 occasions and in this optimally simulated environment could recognize only single delays of 89 ms or more. This was improved to 71 ms or more by use of side-by-side (normal versus abnormal) comparative review. Thus visual assessment of clinically important regional delay in rest or stress echo images is limited.
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how accurate is visual assessment of synchronicity in myocardial motion an in vitro study with computer simulated regional delay in myocardial motion clinical implications for rest and stress echocardiography studies
Journal of The American Society of Echocardiography, 1999Co-Authors: Johnpeder Escobar Kvitting, Lars Wigstrom, Jorg M Strotmann, George R SutherlandAbstract:Abstract Asynchronicity in echocardiographic images is normally assessed visually. No prior quantitative studies have determined the limitations of this approach. To quantify visual recognition of myocardial asynchronicity in echocardiographic images, computer-simulated delay phantom loops were generated from a 3.3 MHz digital image data from a normal left ventricular short-axis Heart Cycle acquired at 55 frames per second. Six expert observers visually assessed 30 abnormal and 3 normal loops with differing computer-induced delay patterns on 3 occasions and in this optimally simulated environment could recognize only single delays of 89 ms or more. This was improved to 71 ms or more by use of side-by-side (normal versus abnormal) comparative review. Thus visual assessment of clinically important regional delay in rest or stress echo images is limited. (J Am Soc Echocardiogr 1999;12:698-705.)
Otto A Smiseth - One of the best experts on this subject based on the ideXlab platform.
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mean strain throughout the Heart Cycle by longitudinal two dimensional speckle tracking echocardiography enables early prediction of infarct size
Journal of The American Society of Echocardiography, 2011Co-Authors: Bjornar Grenne, Christian Eek, Benthe Sjoli, Thomas Dahlslett, Per Kristian Hol, Stein Orn, Helge Skulstad, Otto A SmisethAbstract:Background Early prediction of infarct size directs therapy in patients with acute myocardial infarction (AMI). Global strain by echocardiography describes myocardial deformation and correlates with infarct size. However, peak strain measures deformation at a single time point, whereas ischemia and necrosis influence deformation throughout the Heart Cycle. It was hypothesized that the measurement of myocardial deformation throughout the Heart Cycle by mean strain is a more comprehensive expression of myocardial deformation. The aim of this study was to assess the ability of mean strain to predict infarct size and to identify large infarctions at admission and after revascularization in patients with AMI. Methods Seventy-six patients with AMI were included. Echocardiographic measurements were performed at admission and after revascularization. Myocardial strain was calculated using speckle-tracking echocardiography. Infarct size was measured using contrast-enhanced magnetic resonance imaging ≥3 months after revascularization. Results There were significant correlations between infarct size and longitudinal global mean strain, longitudinal global strain, and left ventricular ejection fraction ( P Conclusions Longitudinal global mean strain provides improved early prediction of infarct size in patients with AMI compared with longitudinal global strain and left ventricular ejection fraction.
Johnpeder Escobar Kvitting - One of the best experts on this subject based on the ideXlab platform.
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how accurate is visual assessment of synchronicity in myocardial motion an in vitro study with computer simulated regional delay in myocardial motion clinical implications for rest and stress echocardiography studies
Journal of The American Society of Echocardiography, 1999Co-Authors: Johnpeder Escobar Kvitting, Lars Wigstrom, Jorg M Strotmann, George R SutherlandAbstract:Asynchronicity in echocardiographic images is normally assessed visually. No prior quantitative studies have determined the limitations of this approach. To quantify visual recognition of myocardial asynchronicity in echocardiographic images, computer-simulated delay phantom loops were generated from a 3.3 MHz digital image data from a normal left ventricular short-axis Heart Cycle acquired at 55 frames per second. Six expert observers visually assessed 30 abnormal and 3 normal loops with differing computer-induced delay patterns on 3 occasions and in this optimally simulated environment could recognize only single delays of 89 ms or more. This was improved to 71 ms or more by use of side-by-side (normal versus abnormal) comparative review. Thus visual assessment of clinically important regional delay in rest or stress echo images is limited.
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how accurate is visual assessment of synchronicity in myocardial motion an in vitro study with computer simulated regional delay in myocardial motion clinical implications for rest and stress echocardiography studies
Journal of The American Society of Echocardiography, 1999Co-Authors: Johnpeder Escobar Kvitting, Lars Wigstrom, Jorg M Strotmann, George R SutherlandAbstract:Abstract Asynchronicity in echocardiographic images is normally assessed visually. No prior quantitative studies have determined the limitations of this approach. To quantify visual recognition of myocardial asynchronicity in echocardiographic images, computer-simulated delay phantom loops were generated from a 3.3 MHz digital image data from a normal left ventricular short-axis Heart Cycle acquired at 55 frames per second. Six expert observers visually assessed 30 abnormal and 3 normal loops with differing computer-induced delay patterns on 3 occasions and in this optimally simulated environment could recognize only single delays of 89 ms or more. This was improved to 71 ms or more by use of side-by-side (normal versus abnormal) comparative review. Thus visual assessment of clinically important regional delay in rest or stress echo images is limited. (J Am Soc Echocardiogr 1999;12:698-705.)
