Abstract
Although recent advances of four-dimensional (4D) flow magnetic resonance imaging (MRI) has introduced a new way to measure Reynolds stress tensor (RST) in turbulent flows, its measurement accuracy and possible bias have remained to be revealed. The purpose of this study was to compare the turbulent flow measurement of 4D flow MRI and particle image velocimetry (PIV) in terms of velocity and turbulence quantification. Two difference flow rates of 10 and 20 L/min through a 50% stenosis were measured with both PIV and 4D flow MRI. Not only velocity through the stenosis but also the turbulence parameters such as turbulence kinetic energy and turbulence production were quantitatively compared. Results shows that 4D flow MRI velocity measurement well agreed with the that of PIV, showing the linear regression slopes of two methods are 0.94 and 0.89, respectively. Although turbulence mapping of 4D flow MRI was qualitatively agreed with that of PIV, the quantitative comparison shows that the 4D flow MRI overestimates RST showing the linear regression slopes of 1.44 and 1.66, respectively. In this study, we demonstrate that the 4D flow MRI visualize and quantify not only flow velocity and also turbulence tensor. However, further optimization of 4D flow MRI for better accuracy might be remained.
Highlights
Turbulence in blood flow is known to create irregular fluid motion and chaotic changes in pressure and velocity
Experimental measurements were conducted using the 4D flow magnetic resonance imaging (MRI) on an in-vitro flow phantom under various scan conditions to analyze the robustness of ICOSA6 for turbulence quantification
J/m sensitivity of the total were reduced but the results showed the same trend of show used, the sensitivity of the total turbulence production (TP) and Turbulence kinetic energy (TKE)
Summary
Turbulence in blood flow is known to create irregular fluid motion and chaotic changes in pressure and velocity. While blood flow mostly exists as laminar flow state, high flow rate through the heart valve or pulsatility of aortic flow locally develop turbulent blood flow. Local vascular obstructions due to atherosclerosis and a stenotic heart valve are widely known pathophysiological conditions developing turbulent blood flow [1]. Turbulent blood flows in humans and animals have been postulated to contribute to a variety of pathological conditions. Turbulent flow is associated with high oscillatory shear stresses which can damage the endothelial layer and red blood cells [2,3]. The abnormal level of turbulence in the blood flow has been considered as a fluid-dynamic biomarker for early diagnosis of vascular diseases
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