Toward an accurate estimation of wall shear stress from 4D flow magnetic resonance downstream of a severe stenosis
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Date
2021-09
Publication Type
Journal Article
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Abstract
Purpose
First, to investigate the agreement between velocity, velocity gradient, and Reynolds stress obtained from four-dimensional flow magnetic resonance (4D flow MRI) measurements and direct numerical simulation (DNS). Second, to propose and optimize based on DNS, 2 alternative methods for the accurate estimation of wall shear stress (WSS) when the resolution of the flow measurements is limited. Thirdly, to validate the 2 methods based on 4D flow MRI data.
Methods
In vitro 4D MRI has been conducted in a realistic rigid stenosed aorta model under a constant flow rate of 12 L/min. A DNS of transitional stenotic flow has been performed using the same geometry and boundary conditions.
Results
Time-averaged velocity and Reynolds stresses are in good agreement between in vitro 4D MRI data and DNS (errors between 2% and 8% of the reference downsampled data). WSS estimation based on the 2 proposed methods applied to MRI data provide good agreement with DNS for slice-averaged values (maximum error is less than 15% of the mean reference WSS for the first method and 25% for the second method). The performance of both models is not strongly sensitive to spatial resolution up to 1.5 mm voxel size. While the performance of model 1 deteriorates appreciably at low signal-to-noise ratios, model 2 remains robust.
Conclusions
The 2 methods for WSS magnitude give an overall better agreement than the standard approach used in the literature based on direct calculation of the velocity gradient close to the wall (relative error of 84%). © 2021 International Society for Magnetic Resonance in Medicine
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published
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Journal / series
Volume
86 (3)
Pages / Article No.
1531 - 1543
Publisher
Wiley
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Subject
4D Flow MRI; Direct numerical simulation; Reynolds stress; Stenotic transitional flow; Wall shear stress
Organisational unit
09548 - Kozerke, Sebastian / Kozerke, Sebastian