VFI in Healthy Vessels

Study Overview
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Brief Summary
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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.

Official Title
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Vector Flow Imaging in Healthy Vessels

Conditions
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Carotid Artery Stenosis, Superficial Femoral Artery Stenosis

Intervention / Treatment
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* Diagnostic Test: Blood speckle tracking
* Diagnostic Test: Ultrasound particle Imaging Velocimetry
* Diagnostic Test: 4D flow MRI
* Diagnostic Test: Conventional duplex


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy male or female, without cardiovascular and pulmonary medical history and without the use of medication for cardiovascular risk factors Age between 20-30 year or 65-75 years old Willingness to undergo a 4D flow MRI scan and US examinations Informed consent form understood and signed, and agrees to the hospital visit Exclusion Criteria: Hypersensitivity to the active substance(s) or any of the excipients in Sonovue Pregnancy MRI exclusion criteria (such as presence of pacemaker, cerebral vascular clips, claustrophobia)

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 75 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Young volunteers<br>Volunteers with age between 20-30 years | Diagnostic Test: Blood speckle tracking<br>* Blood speckle tracking measurements will be acquired of the carotid artery and superficial femoral artery<br>Diagnostic Test: Ultrasound particle Imaging Velocimetry<br>* Ultrasound particle imaging velocimetry will be acquired of the carotid artery and superficial femoral artery<br>Diagnostic Test: 4D flow MRI<br>* 4D flow MRI will be acquired of the carotid artery and superficial femoral artery<br>Diagnostic Test: Conventional duplex<br>* Conventional duplex measurements will be acquired of the carotid artery and superficial femoral artery<br>|
| Old volunteers<br>Volunteers with age between 65-75 years | Diagnostic Test: Blood speckle tracking<br>* Blood speckle tracking measurements will be acquired of the carotid artery and superficial femoral artery<br>Diagnostic Test: Ultrasound particle Imaging Velocimetry<br>* Ultrasound particle imaging velocimetry will be acquired of the carotid artery and superficial femoral artery<br>Diagnostic Test: 4D flow MRI<br>* 4D flow MRI will be acquired of the carotid artery and superficial femoral artery<br>Diagnostic Test: Conventional duplex<br>* Conventional duplex measurements will be acquired of the carotid artery and superficial femoral artery<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| 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 | 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 | 1 day (no follow-up) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| 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 | 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. | 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. | 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. | 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. | 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. | 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. | 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. | 1 day (no follow-up) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Vector Flow Imaging, Ultrasound Particle Image Velocimetry, Blood Speckle Tracking, 4D flow MR