AN ASSESSMENT OF THE ACCURACY OF MAGENTIC RESONANCE PHASE VELOCITY MAPPING IN TURBULENT FLOW THROUGH ORIFICES

Bibliographic Details
Main Author:	Pidaparthi, Sahitya
Language:	English
Published:	Cleveland State University / OhioLINK 2011
Subjects:	Biomedical Engineering MRPVM Orifice Signal loss
Online Access:	http://rave.ohiolink.edu/etdc/view?acc_num=csu1297396841

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spelling	ndltd-OhioLink-oai-etd.ohiolink.edu-csu12973968412021-08-03T05:35:19Z AN ASSESSMENT OF THE ACCURACY OF MAGENTIC RESONANCE PHASE VELOCITY MAPPING IN TURBULENT FLOW THROUGH ORIFICES Pidaparthi, Sahitya Biomedical Engineering MRPVM Orifice Signal loss <p>Magnetic resonance phase velocity mapping (MRPVM) is an established clinical technique to measure blood flow. The acquired information can be used to diagnose a variety of cardiovascular disease. One of the main limitations of MRPVM is that it cannot quantify the flow under turbulent flow conditions. Such conditions develop in certain cases such as in heart valve stenosis and arterial stenosis. Specifically, heart valve stenosis is a serious disease in which the valve does not open as much as necessary for blood to pass through. As a result, the heart has to overwork to overcome the increased resistance. If untreated, the disease can lead to death. One of the diagnostic problems related to stenosis is that the flow through the stenotic orifice becomes turbulent, associated with velocity fluctuations, flow separation and recirculation downstream of the stenosis. Clinically, it is difficult to quantify turbulent flow. Especially in the case of MRPVM, turbulent flow leads to signal loss in the images, resulting in loss of valuable diagnostic information. This study aimed at investigating the effects of imaging parameters on the ability of MRPVM for turbulent flow quantification. Two orifice models were used, one with a 75% area reduction and another with a 94% area reduction. Axial MRPVM acquisitions were performed (flow rate: 1.2-10.5 L/min; upstream Re: 1271-11124, orifice Re: 2542–44497) inside a 1.5 Tesla whole-body clinical MRI scanner. Three in-plane spatial resolutions (0.9 x 0.9, 1.5 x 1.5, and 2.0 x 2.0 mm2) and five echo times (2.65, 3.5, 5.0, 7.5, 10.0 msec) were studied. Images were acquired in both models at five locations: 6.0 cm upstream from the orifice; at the orifice; 1.0 cm downstream from the orifice; 3.0 cm downstream from the orifice; and 5.0 cm downstream from the orifice. The MRPVM-measured flow rates were compared with the true flow rates known from rotameters to determine the accuracy. </p><p> The results confirmed that MRPVM is highly accurate under laminar flow conditions, but under turbulent flow conditions, the accuracy was reduced. Signal loss caused an underestimation in the flow rate which was higher in the 94% area reduction orifice model as compared to the 75% model. As Re increased, the signal loss and the underestimation in the flow rate increased. Overall, increasing the spatial resolution and shortening the echo time had an effect on improving the accuracy of the measurements, although the effect of resolution was smaller when compared to that of the echo time. Further in vitro studies using additional geometries and a larger range of Re as well as clinical studies are necessary to further investigate ways to improve the ability of MRPVM under turbulent flow conditions.</p> 2011-02-17 English text Cleveland State University / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=csu1297396841 http://rave.ohiolink.edu/etdc/view?acc_num=csu1297396841 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.
collection	NDLTD
language	English
sources	NDLTD
topic	Biomedical Engineering MRPVM Orifice Signal loss
spellingShingle	Biomedical Engineering MRPVM Orifice Signal loss Pidaparthi, Sahitya AN ASSESSMENT OF THE ACCURACY OF MAGENTIC RESONANCE PHASE VELOCITY MAPPING IN TURBULENT FLOW THROUGH ORIFICES
author	Pidaparthi, Sahitya
author_facet	Pidaparthi, Sahitya
author_sort	Pidaparthi, Sahitya
title	AN ASSESSMENT OF THE ACCURACY OF MAGENTIC RESONANCE PHASE VELOCITY MAPPING IN TURBULENT FLOW THROUGH ORIFICES
title_short	AN ASSESSMENT OF THE ACCURACY OF MAGENTIC RESONANCE PHASE VELOCITY MAPPING IN TURBULENT FLOW THROUGH ORIFICES
title_full	AN ASSESSMENT OF THE ACCURACY OF MAGENTIC RESONANCE PHASE VELOCITY MAPPING IN TURBULENT FLOW THROUGH ORIFICES
title_fullStr	AN ASSESSMENT OF THE ACCURACY OF MAGENTIC RESONANCE PHASE VELOCITY MAPPING IN TURBULENT FLOW THROUGH ORIFICES
title_full_unstemmed	AN ASSESSMENT OF THE ACCURACY OF MAGENTIC RESONANCE PHASE VELOCITY MAPPING IN TURBULENT FLOW THROUGH ORIFICES
title_sort	assessment of the accuracy of magentic resonance phase velocity mapping in turbulent flow through orifices
publisher	Cleveland State University / OhioLINK
publishDate	2011
url	http://rave.ohiolink.edu/etdc/view?acc_num=csu1297396841
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AN ASSESSMENT OF THE ACCURACY OF MAGENTIC RESONANCE PHASE VELOCITY MAPPING IN TURBULENT FLOW THROUGH ORIFICES

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