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Research paper thumbnail of Automatic Calculation of the Reflection Site Distance: In the Internal Carotid

Journal of Mechanics in Medicine and Biology

Purpose: The objective of this study is to estimate, in vivo, the effective reflected site of the... more Purpose: The objective of this study is to estimate, in vivo, the effective reflected site of the internal carotid wall (ICA) from the noninvasive determination of the local arterial wave speed (c). Materials: c was calculated in our previous work that uses the measurement of the instantaneous blood velocity at two sites by contrast magnetic resonance, the study having been conducted on 20 healthy subjects. The determination of the effective reflection distance (ERD) requires the measurement of the arrival time of the reflected wave. We have found that the major reflection site in the internal carotid artery was located in the proximity of the measurement site to the circle of Willis. To validate the method proposed in this work, we compared it to the results obtained by using the return time of the foot of the wave. The foot of the wave was determined from the tangent of the abrupt rise of the velocity signal wavefront. Results: A positive correlation between ERD obtained by using ...

Research paper thumbnail of Noninvasive determination of propagation parameters in the carotid artery

Journal of Mechanics in Medicine and Biology, Sep 23, 2022

Research paper thumbnail of Comparison Between Two Noninvasive Methods Used to Estimate Biomechanical Properties of the Internal Carotid Artery

Journal of Mechanics in Medicine and Biology

Background: Many cardiovascular diseases modified the arterial wall stiffness. Objectives: This w... more Background: Many cardiovascular diseases modified the arterial wall stiffness. Objectives: This work focuses on the quantification of the elastic biomechanical properties of the internal carotid (ICA) wall by applying the cepstral analysis on healthy volunteers aged from 22 to 86 years old. The purpose of this study is to compare two methods of measurement of arterial compliance ([Formula: see text], arterial distensibility ([Formula: see text], arterial elastance (Eh), and Young’s modulus ([Formula: see text]. Material and methods: First, arterial compliance and arterial distensibility were measured in function of wave speed ([Formula: see text], which is measured in our previous works by using two methods. Second, elastance Eh was estimated through the ratio between diastolic radius ([Formula: see text] and [Formula: see text]. Finally, [Formula: see text] was estimated from a statistical study from the literature on h due to the difficulty of measuring wall thickness ([Formula: s...

Research paper thumbnail of A Novel Method for Determining the Arrival Time of Reflected Wave at Single Site: Validation Using Phase Contrast Magnetic Resonance Data

Journal of Mechanics in Medicine and Biology, 2022

Characterization of the wave reflection and mainly its return time has significant clinical value... more Characterization of the wave reflection and mainly its return time has significant clinical value in detecting cardiovascular and cerebrovascular diseases. Indeed, the return time is an indicator which is used to evaluate the performance of peripheral perfusion and the propagation speed for arterial stiffness measurement. The study is aimed at implementing a novel model based on cepstral analysis for estimation of the arrival time of reflected wave ([Formula: see text]. The proposed method is specially based on cepstral analysis of the simulated blood velocity wave by using the Matlab software. To achieve this aim, we used a theoretical bidimensional model to simulate blood flow velocity, and we combined this model with clinical data acquired in two healthy subjects using phase contrast magnetic resonance imaging (PCMRI). Values of the arrival time of reflected wave measured are similar to the theoretical values. The suggested model is validated in vivo. We can conclude that the nov...

Research paper thumbnail of Non invasive measurement of velocity Profile in the carotid artery

Research paper thumbnail of Estimation of tansfer function in carotid artery

2018 IEEE 4th Middle East Conference on Biomedical Engineering (MECBME)

Research paper thumbnail of Comparative Study for Wave Speed Estimation at a Single and Two Measurement Points

Journal of Mechanics in Medicine and Biology

Local wave speed is a prognostic detector that allows the analysis of cardiovascular function. Ob... more Local wave speed is a prognostic detector that allows the analysis of cardiovascular function. Objectives: This study compared wave speed ([Formula: see text] measurements at single-point and two-point techniques. Material and methods: [Formula: see text] were determined from the cepstral analysis of the blood flow velocities, which identified the arrivals times of reflected waves. The blood velocities waveforms were measured by using phase-contrast magnetic resonance (PCMR) for 20 subjects on young and old healthy subjects. Local wave speed was estimated through the arrivals time of reflections waves ([Formula: see text] and the distance separating the measurement site to reflection area ([Formula: see text] or the distance separating the two measurement sites. Results: Our obtained results were in total agreement with reference values reported in the literature. Moreover, the detected results show that there is a high correlation ([Formula: see text]) between the two methods. Con...

Research paper thumbnail of A Non-invasive Method for Determining Biomechanical Properties of the Internal Carotid Artery

IRBM

Abstract Objectives Mechanical properties of the carotid artery play an important role in the pro... more Abstract Objectives Mechanical properties of the carotid artery play an important role in the progression of arterial disease such as atherosclerosis. An early change in the mechanical properties of the arteries can be introduced as a novel risk factor for cardiovascular events. The aim of this study is to estimate, in vivo, the elastic biomechanical properties of the internal carotid wall (ICA), from the noninvasive determination of the local arterial wave speed (c). Material and methods To achieve this objective, c was determined from a mathematical and physical model developed in our previous work that uses the measurement of the instantaneous blood velocity at two sites by contrast magnetic resonance (PCMR), the study having been conducted on 20 healthy, young and old subjects. The determination of Young's modulus (E) requiring the measurement of the arterial radius (R) and the wall thickness (h), we first estimated the arterial compliance (C). Then from a segmentation of the PCMR image, we evaluated R and thus the elastance given by the product Eh. Finally, in front of the difficulty of measuring h, E was estimated from a statistical study on h. Results Our method is sensitive to a variation of the parietal elasticity as it is the case with the age. A statistical test showed that there is a very significant difference between younger and older subjects in terms of speed wave, elastance, compliance, and Young's modulus (p Conclusion Thus, the in vivo application of this technique shows its potential for clinical evaluation of arterial stiffness ICA as it is fully quantitative, non-invasive and can be performed in real time.

Research paper thumbnail of Numerical simulation of non-invasive determination of the propagation coefficient in arterial system using two measurements sites

The European Physical Journal Applied Physics, 2007

Literature shows a lack of works based on non-invasive methods for computing the propagation coef... more Literature shows a lack of works based on non-invasive methods for computing the propagation coefficient γ, a complex number related to dynamic vascular properties. Its imaginary part is inversely related to the wave speed C through the relationship C = ω/Im(γ), while its real part a, called attenuation, represents loss of pulse energy per unit of length. In this work an expression is derived giving the propagation coefficient when assuming a pulsatile flow through a viscoelastic vessel. The effects of physical and geometrical parameters of the tube are then studied. In particular, the effects of increasing the reflection coefficient, on the determination of the propagation coefficient are investigated in a first step. In a second step, we simulate a variation of tube length under physiological conditions. The method developed here is based on the knowledge of instantaneous velocity and radius values at only two sites. It takes into account the presence of a reflection site of unknown reflection coefficient, localised in the distal end of the vessel. The values of wave speed and attenuation obtained with this method are in a good agreement with the theory. This method has the advantage to be usable for small portions of the arterial tree.

Research paper thumbnail of Influence of the distensibility of large arteries on the longitudinal impedance: application for the development of non-invasive techniques to the diagnosis of arterial diseases

Nonlinear biomedical physics, Jan 16, 2012

This study shows that the arterial longitudinal impedance constitutes a hemodynamic parameter of ... more This study shows that the arterial longitudinal impedance constitutes a hemodynamic parameter of interest for performance characterization of large arteries in normal condition as well as in pathological situations. For this purpose, we solved the Navier-Stokes equations for an incompressible flow using the finite element analysis method and the Arbitrary Lagrangian Eulerian (ALE) formulation. The mathematical model assumes a two-dimensional flow and takes into account the nonlinear terms in the equations of fluid motion that express the convective acceleration, as well as the nonlinear deformation of the arterial wall. Several numerical simulations of the blood flow in large vessels have been performed to study the propagation along an arterial vessel of a pressure gradient pulse and a rate flow pulse. These simulations include various deformations of the wall artery leading to parietal displacements ranging from 0 (rigid wall) to 15% (very elastic wall) in order to consider physio...

Research paper thumbnail of Influence des effets convectifs sur l'hémodynamique des larges artères dans des conditions normales et pathologiques

Research paper thumbnail of A novel non-invasive method for estimating the local wave speed at a single site in the internal carotid artery

Biomedical Engineering / Biomedizinische Technik

ObjectivesLocal wave speed is a biomarker which provides an objective analysis of the cardiovascu... more ObjectivesLocal wave speed is a biomarker which provides an objective analysis of the cardiovascular function. The aim of this study was to determine the local wave speed in the internal carotid artery by a new non-invasive method that measures blood velocity waveform at only one site.MethodsFor this purpose, the cepstral analysis was employed to determine the arrival time of the reflection wave and the wave speed in the carotid artery. To validate our model, we applied it experimentally in vivo on young and old healthy subjects. The blood velocity waveform was measured by using phase-contrast magnetic resonance for 22 subjects.ResultsOur experimental results correlated with reference values reported in previous studies conducted on the internal arterial carotid usually adopting the invasive method. They also correlated with those obtained by using the foot-to-foot method (R2=0.72). The wave speed obtained by the method developed in this study and that of the foot-to-foot method inc...

Research paper thumbnail of Identification of the reflection wave by its delay time in short artery with cepstral analysis

Computer Methods in Biomechanics and Biomedical Engineering

Research paper thumbnail of A novel non-invasive method for estimating biomechanical properties of the internal carotid

Computer Methods in Biomechanics and Biomedical Engineering

Research paper thumbnail of A New Noninvasive Method for Determining the Local (True) Wave Speed: Application to Internal Carotid Artery

Biophysical Reviews and Letters

Local wave speed plays an interesting role in investigating cardiovascular diseases and arterial ... more Local wave speed plays an interesting role in investigating cardiovascular diseases and arterial wall stiffness. The aim of this study was to implement a novel method based on cepstral analysis for noninvasive determination of local wave speed in the carotid artery. To show the precision of the proposed method, we specially focused on the effect of age. In addition, we intended to compare the obtained results to those obtained by the foot-to-foot method. Our method consists in measuring the instantaneous blood velocity in the internal carotid by using phase-contrast magnetic resonance imaging in 20 healthy subjects distributed as follows: 10 young subjects aged between 22 and 41 years, and 10 old subjects aged between 50 and 86 years. The cepstral analysis was used to determine the arrival time of the reflection wave and the wave speed in the carotid artery. A statistical test analysis was conducted in order to establish the relation between the wave speed and the age in the sample ...

Research paper thumbnail of Determination of cardiovascular parameters from bioimpedance signal

2016 2nd International Conference on Advanced Technologies for Signal and Image Processing (ATSIP), 2016

Research paper thumbnail of Automatic Calculation of the Reflection Site Distance: In the Internal Carotid

Journal of Mechanics in Medicine and Biology

Purpose: The objective of this study is to estimate, in vivo, the effective reflected site of the... more Purpose: The objective of this study is to estimate, in vivo, the effective reflected site of the internal carotid wall (ICA) from the noninvasive determination of the local arterial wave speed (c). Materials: c was calculated in our previous work that uses the measurement of the instantaneous blood velocity at two sites by contrast magnetic resonance, the study having been conducted on 20 healthy subjects. The determination of the effective reflection distance (ERD) requires the measurement of the arrival time of the reflected wave. We have found that the major reflection site in the internal carotid artery was located in the proximity of the measurement site to the circle of Willis. To validate the method proposed in this work, we compared it to the results obtained by using the return time of the foot of the wave. The foot of the wave was determined from the tangent of the abrupt rise of the velocity signal wavefront. Results: A positive correlation between ERD obtained by using ...

Research paper thumbnail of Noninvasive determination of propagation parameters in the carotid artery

Journal of Mechanics in Medicine and Biology, Sep 23, 2022

Research paper thumbnail of Comparison Between Two Noninvasive Methods Used to Estimate Biomechanical Properties of the Internal Carotid Artery

Journal of Mechanics in Medicine and Biology

Background: Many cardiovascular diseases modified the arterial wall stiffness. Objectives: This w... more Background: Many cardiovascular diseases modified the arterial wall stiffness. Objectives: This work focuses on the quantification of the elastic biomechanical properties of the internal carotid (ICA) wall by applying the cepstral analysis on healthy volunteers aged from 22 to 86 years old. The purpose of this study is to compare two methods of measurement of arterial compliance ([Formula: see text], arterial distensibility ([Formula: see text], arterial elastance (Eh), and Young’s modulus ([Formula: see text]. Material and methods: First, arterial compliance and arterial distensibility were measured in function of wave speed ([Formula: see text], which is measured in our previous works by using two methods. Second, elastance Eh was estimated through the ratio between diastolic radius ([Formula: see text] and [Formula: see text]. Finally, [Formula: see text] was estimated from a statistical study from the literature on h due to the difficulty of measuring wall thickness ([Formula: s...

Research paper thumbnail of A Novel Method for Determining the Arrival Time of Reflected Wave at Single Site: Validation Using Phase Contrast Magnetic Resonance Data

Journal of Mechanics in Medicine and Biology, 2022

Characterization of the wave reflection and mainly its return time has significant clinical value... more Characterization of the wave reflection and mainly its return time has significant clinical value in detecting cardiovascular and cerebrovascular diseases. Indeed, the return time is an indicator which is used to evaluate the performance of peripheral perfusion and the propagation speed for arterial stiffness measurement. The study is aimed at implementing a novel model based on cepstral analysis for estimation of the arrival time of reflected wave ([Formula: see text]. The proposed method is specially based on cepstral analysis of the simulated blood velocity wave by using the Matlab software. To achieve this aim, we used a theoretical bidimensional model to simulate blood flow velocity, and we combined this model with clinical data acquired in two healthy subjects using phase contrast magnetic resonance imaging (PCMRI). Values of the arrival time of reflected wave measured are similar to the theoretical values. The suggested model is validated in vivo. We can conclude that the nov...

Research paper thumbnail of Non invasive measurement of velocity Profile in the carotid artery

Research paper thumbnail of Estimation of tansfer function in carotid artery

2018 IEEE 4th Middle East Conference on Biomedical Engineering (MECBME)

Research paper thumbnail of Comparative Study for Wave Speed Estimation at a Single and Two Measurement Points

Journal of Mechanics in Medicine and Biology

Local wave speed is a prognostic detector that allows the analysis of cardiovascular function. Ob... more Local wave speed is a prognostic detector that allows the analysis of cardiovascular function. Objectives: This study compared wave speed ([Formula: see text] measurements at single-point and two-point techniques. Material and methods: [Formula: see text] were determined from the cepstral analysis of the blood flow velocities, which identified the arrivals times of reflected waves. The blood velocities waveforms were measured by using phase-contrast magnetic resonance (PCMR) for 20 subjects on young and old healthy subjects. Local wave speed was estimated through the arrivals time of reflections waves ([Formula: see text] and the distance separating the measurement site to reflection area ([Formula: see text] or the distance separating the two measurement sites. Results: Our obtained results were in total agreement with reference values reported in the literature. Moreover, the detected results show that there is a high correlation ([Formula: see text]) between the two methods. Con...

Research paper thumbnail of A Non-invasive Method for Determining Biomechanical Properties of the Internal Carotid Artery

IRBM

Abstract Objectives Mechanical properties of the carotid artery play an important role in the pro... more Abstract Objectives Mechanical properties of the carotid artery play an important role in the progression of arterial disease such as atherosclerosis. An early change in the mechanical properties of the arteries can be introduced as a novel risk factor for cardiovascular events. The aim of this study is to estimate, in vivo, the elastic biomechanical properties of the internal carotid wall (ICA), from the noninvasive determination of the local arterial wave speed (c). Material and methods To achieve this objective, c was determined from a mathematical and physical model developed in our previous work that uses the measurement of the instantaneous blood velocity at two sites by contrast magnetic resonance (PCMR), the study having been conducted on 20 healthy, young and old subjects. The determination of Young's modulus (E) requiring the measurement of the arterial radius (R) and the wall thickness (h), we first estimated the arterial compliance (C). Then from a segmentation of the PCMR image, we evaluated R and thus the elastance given by the product Eh. Finally, in front of the difficulty of measuring h, E was estimated from a statistical study on h. Results Our method is sensitive to a variation of the parietal elasticity as it is the case with the age. A statistical test showed that there is a very significant difference between younger and older subjects in terms of speed wave, elastance, compliance, and Young's modulus (p Conclusion Thus, the in vivo application of this technique shows its potential for clinical evaluation of arterial stiffness ICA as it is fully quantitative, non-invasive and can be performed in real time.

Research paper thumbnail of Numerical simulation of non-invasive determination of the propagation coefficient in arterial system using two measurements sites

The European Physical Journal Applied Physics, 2007

Literature shows a lack of works based on non-invasive methods for computing the propagation coef... more Literature shows a lack of works based on non-invasive methods for computing the propagation coefficient γ, a complex number related to dynamic vascular properties. Its imaginary part is inversely related to the wave speed C through the relationship C = ω/Im(γ), while its real part a, called attenuation, represents loss of pulse energy per unit of length. In this work an expression is derived giving the propagation coefficient when assuming a pulsatile flow through a viscoelastic vessel. The effects of physical and geometrical parameters of the tube are then studied. In particular, the effects of increasing the reflection coefficient, on the determination of the propagation coefficient are investigated in a first step. In a second step, we simulate a variation of tube length under physiological conditions. The method developed here is based on the knowledge of instantaneous velocity and radius values at only two sites. It takes into account the presence of a reflection site of unknown reflection coefficient, localised in the distal end of the vessel. The values of wave speed and attenuation obtained with this method are in a good agreement with the theory. This method has the advantage to be usable for small portions of the arterial tree.

Research paper thumbnail of Influence of the distensibility of large arteries on the longitudinal impedance: application for the development of non-invasive techniques to the diagnosis of arterial diseases

Nonlinear biomedical physics, Jan 16, 2012

This study shows that the arterial longitudinal impedance constitutes a hemodynamic parameter of ... more This study shows that the arterial longitudinal impedance constitutes a hemodynamic parameter of interest for performance characterization of large arteries in normal condition as well as in pathological situations. For this purpose, we solved the Navier-Stokes equations for an incompressible flow using the finite element analysis method and the Arbitrary Lagrangian Eulerian (ALE) formulation. The mathematical model assumes a two-dimensional flow and takes into account the nonlinear terms in the equations of fluid motion that express the convective acceleration, as well as the nonlinear deformation of the arterial wall. Several numerical simulations of the blood flow in large vessels have been performed to study the propagation along an arterial vessel of a pressure gradient pulse and a rate flow pulse. These simulations include various deformations of the wall artery leading to parietal displacements ranging from 0 (rigid wall) to 15% (very elastic wall) in order to consider physio...

Research paper thumbnail of Influence des effets convectifs sur l'hémodynamique des larges artères dans des conditions normales et pathologiques

Research paper thumbnail of A novel non-invasive method for estimating the local wave speed at a single site in the internal carotid artery

Biomedical Engineering / Biomedizinische Technik

ObjectivesLocal wave speed is a biomarker which provides an objective analysis of the cardiovascu... more ObjectivesLocal wave speed is a biomarker which provides an objective analysis of the cardiovascular function. The aim of this study was to determine the local wave speed in the internal carotid artery by a new non-invasive method that measures blood velocity waveform at only one site.MethodsFor this purpose, the cepstral analysis was employed to determine the arrival time of the reflection wave and the wave speed in the carotid artery. To validate our model, we applied it experimentally in vivo on young and old healthy subjects. The blood velocity waveform was measured by using phase-contrast magnetic resonance for 22 subjects.ResultsOur experimental results correlated with reference values reported in previous studies conducted on the internal arterial carotid usually adopting the invasive method. They also correlated with those obtained by using the foot-to-foot method (R2=0.72). The wave speed obtained by the method developed in this study and that of the foot-to-foot method inc...

Research paper thumbnail of Identification of the reflection wave by its delay time in short artery with cepstral analysis

Computer Methods in Biomechanics and Biomedical Engineering

Research paper thumbnail of A novel non-invasive method for estimating biomechanical properties of the internal carotid

Computer Methods in Biomechanics and Biomedical Engineering

Research paper thumbnail of A New Noninvasive Method for Determining the Local (True) Wave Speed: Application to Internal Carotid Artery

Biophysical Reviews and Letters

Local wave speed plays an interesting role in investigating cardiovascular diseases and arterial ... more Local wave speed plays an interesting role in investigating cardiovascular diseases and arterial wall stiffness. The aim of this study was to implement a novel method based on cepstral analysis for noninvasive determination of local wave speed in the carotid artery. To show the precision of the proposed method, we specially focused on the effect of age. In addition, we intended to compare the obtained results to those obtained by the foot-to-foot method. Our method consists in measuring the instantaneous blood velocity in the internal carotid by using phase-contrast magnetic resonance imaging in 20 healthy subjects distributed as follows: 10 young subjects aged between 22 and 41 years, and 10 old subjects aged between 50 and 86 years. The cepstral analysis was used to determine the arrival time of the reflection wave and the wave speed in the carotid artery. A statistical test analysis was conducted in order to establish the relation between the wave speed and the age in the sample ...

Research paper thumbnail of Determination of cardiovascular parameters from bioimpedance signal

2016 2nd International Conference on Advanced Technologies for Signal and Image Processing (ATSIP), 2016