Optical Imaging of Steady Flow in a Phantom Model of Iliac Artery Stenosis: Comparison of CFD Simulations with PIV Measurements ∗
04 Mar 2010-Proceedings of SPIE (International Society for Optics and Photonics)-Vol. 7626, Iss: 36, pp 187-194
TL;DR: A flexible flow phantom system was designed and fabricated for validation of CFD models proposed in conjunction with vascular imaging and medical imaging techniques that can produce flow velocities to mimic the blood flow through the human common iliac artery.
Abstract: A flexible flow phantom system was designed and fabricated for the purpose of validation of i) CFD models proposed in conjunction with vascular imaging and ii) medical imaging techniques (such as MRI) that can produce flow velocities. In particular, one of the most challenging flows for both CFD models when modeling flow velocities and imaging techniques when measuring flow velocities are stenotic flows. Particle Image Velocimetry (PIV) is an optical technique for accurate measurement of in-vitro flow velocities and visualization of fluid flow. The fluid is seeded with tracer particles and the motion of the particles, illuminated with a laser light sheet, reveal particle velocities. Particle Image Velocimetry (PIV) was used to measure the flow fields across a Gaussian-shaped 90% area stenosis phantom. The flow parameters were adjusted to the phantom geometry to mimic the blood flow through the human common iliac artery. In addition, Computational Fluid Dynamics (CFD) simulation of the same flow was performed and the results were validated with those from PIV measurements. Steady flow rate of 46.9 ml/s was used, which corresponds to a Reynolds number of 188 and 595 at the inlet and stenosis throat, respectively. A maximum discrepancy of 15% in peak velocity was observed between the two techniques.
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TL;DR: To validate conventional phase‐contrast MRI measurements of steady and pulsatile flows through stenotic phantoms with various degrees of narrowing at Reynolds numbers mimicking flows in the human iliac artery using stereoscopic particle image velocimetry (SPIV) as gold standard.
Abstract: Purpose: To validate conventional phase-contrast MRI (PC-MRI) measurements of steady and pulsatile flows through stenotic phantoms with various degrees of narrowing at Reynolds numbers mimicking flows in the human iliac artery using stereoscopic particle image velocimetry (SPIV) as gold standard. Materials and Methods: A series of detailed experiments are reported for validation of MR measurements of steady and pulsatile flows with SPIV and CFD on three different stenotic models with 50%, 74%, and 87% area occlusions at three sites: two diameters proximal to the stenosis, at the throat, and two diameters distal to the stenosis. Results: Agreement between conventional spin-warp PC-MRI with Cartesian read-out and SPIV was demonstrated for both steady and pulsatile flows with mean Reynolds numbers of 130, 160, and 190 at the inlet by evaluating the linear regression between the two methods. The analysis revealed a correlation coefficient of >0.99 and >0.96 for steady and pulsatile flows, respectively. Additionally, it was found that the most accurate measures of flow by the sequence were at the throat of the stenosis (error <5% for both steady and pulsatile mean flows). The flow rate error distal to the stenosis was primarily found to be a function of narrowing severity including dependence on proper Venc selection. Conclusion: SPIV and CFD provide excellent approaches to in vitro validation of new or existing PC-MRI flow measurement techniques.
19 citations
Cites background from "Optical Imaging of Steady Flow in a..."
...More details about the experimental setup may be found in (23,24)....
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11 Nov 2010
TL;DR: Pressure gradient across a Gaussian-shaped 87% area stenosis phantom was estimated by solving the pressure Poisson equation (PPE) for a steady flow mimicking the blood flow through the human iliac artery.
Abstract: Pressure gradient across a Gaussian-shaped 87% area stenosis phantom was estimated by solving the pressure Poisson equation (PPE) for a steady flow mimicking the blood flow through the human iliac artery. The velocity field needed to solve the pressure equation was obtained using particle image velocimetry (PIV). A steady flow rate of 46.9 ml/s was used, which corresponds to a Reynolds number of 188 and 595 at the inlet and stenosis throat, respectively (in the range of mean Reynolds number encountered in-vivo). In addition, computational fluid dynamics (CFD) simulation of the same flow was performed. Pressure drops across the stenosis predicted by PPE/PIV and CFD were compared with those measured by a pressure catheter transducer. RMS errors relative to the measurements were 17% and 10% for PPE/PIV and CFD, respectively.
12 citations
Cites methods from "Optical Imaging of Steady Flow in a..."
...More details of the experimental setup have been described in [7]....
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30 Jan 2014
TL;DR: A digital real time stabilization technique is proposed for compensation of impact of involuntary movements of a finger on results of measurements for measurements of red blood cells velocity in individual capillary of human nailfold.
Abstract: A digital optical system for intravital capillaroscopy has been developed. It implements the particle image velocimetry
(PIV) based approach for measurements of red blood cells velocity in individual capillary of human nailfold. We propose
to use a digital real time stabilization technique for compensation of impact of involuntary movements of a finger on
results of measurements. Image stabilization algorithm is based on correlation of feature tracking. The efficiency of
designed image stabilization algorithm was experimentally demonstrated.
9 citations
01 Jan 2008
TL;DR: In this paper, the authors present the results of sociological research devoted to the analysis of the contemporary youth political consciousness, and define the activity level of the youth political behaviour, also their attitude to the current political events in Russia, to political ideologies, to active state power institutions, state and social structures.
Abstract: This article presents the results of sociological research devoted to the analysis of the contemporary youth political consciousness. As a result it becomes possible to define the activity level of the youth political behaviour, also their attitude to the current political events in Russia, to political ideologies, to active state power institutions, state and social structures.
3 citations
Additional excerpts
...Данная технология была применена для изучения микроциркуляции крови или ее “фантомов” в аорте и их моделей [64,65], и мониторинга кровообращения в мелких кровеносных сосудах человека и животных [66]....
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01 Jan 2012
TL;DR: A series of detailed experiments are reported for the validation of MR measurements of steady and pulsatile flows with stereoscopic particle image velocimetry (SPIV) and blood flow and pressure measurements using phase-contrast MRI.
Abstract: FLOW AND PRESSURE MEASUREMENT USING PHASECONTRAST MRI: EXPERIMENTS IN STENOTIC PHANTOM MODELS Iman Khodarahmi May 29, 2012 Peripheral Arterial Disease (PAD) is a progressive atherosclerotic disorder which is defined as any pathologic process obstructing the blood flow of the arteries supplying the lower extremities. Moderate stenoses mayor may not be hemodynamically significant, and intravascular pressure measurements have been recommended to evaluate whether these lesions are clinically significant. Phase-contrast MRI (PC-MRI) provides a powerful and non-invasive method to acquire spatially registered blood velocity. The velocity field, then, can be used to derive other clinically useful hemodynamic parameters, such as blood flow and blood pressure gradients. Herein, a series of detailed experiments are reported for the validation of MR measurements of steady and pulsatile flows with stereoscopic particle image velocimetry (SPIV).
3 citations
References
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Book•
15 Dec 2001
TL;DR: This renowned work is a guide to the fundamental principles of medical imaging physics, radiation protection and radiation biology, with complex topics presented in the clear and concise manner and style for which these authors are known.
Abstract: This renowned work is derived from the authors' acclaimed national review course ("Physics of Medical Imaging") at the University of California-Davis for radiology residents. The text is a guide to the fundamental principles of medical imaging physics, radiation protection and radiation biology, with complex topics presented in the clear and concise manner and style for which these authors are known. Coverage includes the production, characteristics and interactions of ionizing radiation used in medical imaging and the imaging modalities in which they are used, including radiography, mammography, fluoroscopy, computed tomography and nuclear medicine. Special attention is paid to optimizing patient dose in each of these modalities. Sections of the book address topics common to all forms of diagnostic imaging, including image quality and medical informatics as well as the non-ionizing medical imaging modalities of MRI and ultrasound. The basic science important to nuclear imaging, including the nature and production of radioactivity, internal dosimetry and radiation detection and measurement, are presented clearly and concisely. Current concepts in the fields of radiation biology and radiation protection relevant to medical imaging, and a number of helpful appendices complete this comprehensive textbook. The text is enhanced by numerous full color charts, tables, images and superb illustrations that reinforce central concepts. The book is ideal for medical imaging professionals, and teachers and students in medical physics and biomedical engineering. Radiology residents will find this text especially useful in bolstering their understanding of imaging physics and related topics prior to board exams. Features: new Four-color throughout; new Companion website with fully searchable text and images; basic line drawings help to explain concepts; comprehensive coverage of diagnostic imaging modalities; and superb writing style of the author team helps make a difficult subject approachable and engaging.
1,394 citations
01 Oct 1991
TL;DR: Phase contrast cine magnetic resonance imaging combines the flow-dependent contrast of phase contrast MRI with the ability of cardiac cine imaging to produce images throughout the cardiac cycle, helpful in the diagnosis of aortic dissections, in the study of flow distributions in large vessels such as pulmonary arteries, and in the evaluation of complex anatomical variants.
Abstract: Phase contrast cine magnetic resonance imaging (MRI) combines the flow-dependent contrast of phase contrast MRI with the ability of cardiac cine imaging to produce images throughout the cardiac cycle. Two pulse sequence types are used for sensitivity to flow in one direction, whereas four are needed for sensitivity in all directions. Several alternatives for synchronization of the data to the cardiac cycle exist. Retrospectively interpolated methods can image the entire cardiac cycle efficiently. Rapid interleaving of the various sequence types ensures immunity to motion misregistration. The technique produces images in which contrast is related to flow velocity as well as magnitude images such as those of conventional cine MRI. The data can be interpreted qualitatively to demonstrate the presence, magnitude, and direction of flow, and quantitatively to provide estimates of flow velocity, volume flow rate, and displaced volumes. Phase contrast cine MRI is helpful in the diagnosis of aortic dissections, in the study of flow distributions in large vessels such as pulmonary arteries, as well as in smaller vessels such as carotid and basilar arteries, and in the evaluation of complex anatomical variants. Future developments are expected to reduce imaging time and expand the quantitative applications.
586 citations
TL;DR: This renowned work is derived from the authors' acclaimed national review course (“Physics of Medical Imaging") at the University of California-Davis for radiology residents and addresses topics common to all forms of diagnostic imaging, including image quality and medical informatics.
Abstract: This renowned work is derived from the authors' acclaimed national review course (“Physics of Medical Imaging\") at the University of California-Davis for radiology residents. Coverage includes the production, characteristics and interactions of ionizing radiation used in medical imaging and the imaging modalities in which they are used, including radiography, mammography, fluoroscopy, computed tomography and nuclear medicine. Special attention is paid to optimizing patient dose in each of these modalities. Sections of the book address topics common to all forms of diagnostic imaging, including image quality and medical informatics as well as the non-ionizing medical imaging modalities of MRI and ultrasound.
563 citations
TL;DR: In this article, the authors review progress made largely within the last five years towards the routine use of anatomically realistic CFD models, derived from in vivo medical imaging, to elucidate the role of local hemodynamics in the development and progression of atherosclerosis in large arteries.
Abstract: Local hemodynamics are an important factor in atherosclerosis, from the development of early lesions, to the assessment of stroke risk, to determining the ultimate fate of a mature plaque. Until recently, our understanding of arterial fluid dynamics and their relationship to atherosclerosis was limited by the use of idealized or averaged artery models. Recent advances in medical imaging, computerized image processing, and computational fluid dynamics (CFD) now make it possible to computationally reconstruct the time-varying, three-dimensional blood flow patterns in anatomically realistic models. In this paper we review progress, made largely within the last five years, towards the routine use of anatomically realistic CFD models, derived from in vivo medical imaging, to elucidate the role of local hemodynamics in the development and progression of atherosclerosis in large arteries. In addition to describing various image-based CFD studies carried out to date, we review the medical imaging and image processing techniques available to acquire the necessary geometric and functional boundary conditions. Issues related to accuracy, precision, and modeling assumptions are also discussed. © 2002 Biomedical Engineering Society.
380 citations
TL;DR: Experimental and computational methods for quantifying blood flow velocity and pressure fields in human arteries are reviewed, with particular emphasis on providing an introduction to the physics and applications of magnetic resonance imaging techniques.
Abstract: ▪ AbstractThe characterization of blood flow is important for understanding the function of the cardiovascular system under normal and diseased conditions, designing cardiovascular devices, and diagnosing and treating congenital and acquired cardiovascular disease. Experimental methods, especially magnetic resonance imaging techniques can be used to noninvasively quantify blood flow for diagnosing cardiovascular disease, researching disease mechanisms, and validating assumptions and predictions of mathematical models. Computational methods can be used to simulate blood flow and vessel dynamics, test hypotheses of disease formation under controlled conditions, and evaluate devices that have not yet been built and treatments that have not yet been implemented. In this article we review experimental and computational methods for quantifying blood flow velocity and pressure fields in human arteries. We place particular emphasis on providing an introduction to the physics and applications of magnetic resonance...
282 citations
"Optical Imaging of Steady Flow in a..." refers background in this paper
...Additionally, there has been a great deal of interest in Computational Fluid Dynamics (CFD) simulations of blood flow with geometries derived from volumetric medical imaging techniques such as MRI and CT, and producing flow velocities through-out the vascular domain.(4,13,14)...
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