There is a wealth of evidence implicating the important role of blood flow throughout all stages of the process of atherogenesis. Two locations along the vascular tree at which atherosclerotic plaques are typically found are the carotid artery (CA) and the superficial femoral artery (SFA). Nowadays, ultrasound is the technique of choice for assessing the vascular condition in the CA and SFA. However, clinically used ultrasound techniques show a large variability in estimating the blood flow velocity, due to multiple limitations. With the advent of ultrafast ultrasound imaging, (almost) all elements of the transducer can be activated simultaneously. These so-called plane wave acquisition acquires thousands of images per second and makes continuous tracking of blood flow velocities in all directions in the field of view possible. This high-frame-rate acquisition opened up new possibilities for blood flow imaging at the CA and SFA, such as blood Speckle Tracking (bST) and ultrasound Particle Image Velocimetry (echoPIV). Both these vector flow imaging (VFI) techniques enable the quantification of 2D blood flow velocity profiles, where bST uses no contrast agents compared to echoPIV. Beside these novel ultrasound based techniques, 4D Phase Contrast Magnetic Resonance Imaging (4D flow MRI) enables a non-invasive quantification of the 4D blood flow velocity profiles (3D + time) and can be used as reference standard for blood flow assessments in-vivo. We therefore aim to evaluate the performance of both VFI techniques in comparison to 4D flow MRI measurements in the CA and SFA of healthy volunteers.
Study Type
OBSERVATIONAL
Enrollment
20
Blood speckle tracking measurements will be acquired of the carotid artery and superficial femoral artery
Ultrasound particle imaging velocimetry will be acquired of the carotid artery and superficial femoral artery
4D flow MRI will be acquired of the carotid artery and superficial femoral artery
Conventional duplex measurements will be acquired of the carotid artery and superficial femoral artery
Rijnstate Hospital
Arnhem, Gelderland, Netherlands
Validation VFI with MRI (echoPIV)
Two-dimensional vector velocity fields derived from VFI (echoPIV) and 4D flow MRI will be used to calculate the spatiotemporal blood flow velocity profiles in artery
Time frame: 1 day (no follow-up)
Validation VFI with MRI (bST)
Two-dimensional vector velocity fields derived from VFI (bST) and 4D flow MRI will be used to calculate the spatiotemporal blood flow velocity profiles in artery
Time frame: 1 day (no follow-up)
Correlation VFI techniques (bST vs echoPIV)
Two-dimensional vector velocity fields derived from echoPIV and bST will be used to calculate the spatiotemporal blood flow velocity profiles in the artery
Time frame: 1 day (no follow-up)
Flow derived parameters (WSS)
Two-dimensional vector velocity fields derived from VFI and 4D flow MRI will be used to calculate the flow derived parameters in the artery. Multiple flow derived parameters will be derived from the vector velocity data. One of the flow derived parameters is wall shear stress (WSS), which defines the amount of friction of the blood on the vessel wall.
Time frame: 1 day (no follow-up)
Flow derived parameters (vorticity)
Two-dimensional vector velocity fields derived from VFI and 4D flow MRI will be used to calculate the flow derived parameters in the artery. Multiple flow derived parameters will be derived from the vector velocity data. One of the flow derived parameters is the vorticity, or the curl of the velocity. The vorticity represents the rotation of particles inside the flow field. This measure can potentially be used to define regions with disturbed blood flow, as a high value (in rad/s) indicates the occurence of a recirculation.
Time frame: 1 day (no follow-up)
Flow derived parameters (vector complexity)
Two-dimensional vector velocity fields derived from VFI and 4D flow MRI will be used to calculate the flow derived parameters in the artery. Multiple flow derived parameters will be derived from the vector velocity data. One of the flow derived parameters is vector complexity, which is a measure of multi-directional flow, ranging from 0 till 1. a value of 1 means complex flow with all velocity vectors pointing in all directions, whereas a value of 0 means laminar flow with all velocity vectors pointing in the same direction. This measure can potentially be used to indicate regions with disturbed blood flow.
Time frame: 1 day (no follow-up)
Old versus young (blood flow velocity profiles)
Two-dimensional vector velocity fields derived from VFI and 4D flow MRI will be used to calculate the spatiotemporal blood flow velocity profiles between young and old volunteers.
Time frame: 1 day (no follow-up)
Old versus young (WSS)
Two-dimensional vector velocity fields derived from VFI and 4D flow MRI will be used to calculate different flow derived parameters between young and old volunteers. One of the parameters is WSS.
Time frame: 1 day (no follow-up)
Old versus young (vector complexity)
Two-dimensional vector velocity fields derived from VFI and 4D flow MRI will be used to calculate different flow derived parameters between young and old volunteers. One of the parameters is vector complexity.
Time frame: 1 day (no follow-up)
Old versus young (vorticity)
Two-dimensional vector velocity fields derived from VFI and 4D flow MRI will be used to calculate different flow derived parameters between young and old volunteers. One of the parameters is vorticity.
Time frame: 1 day (no follow-up)
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