Noninvasive simultaneous assessment of wall shear rate and wall distension in carotid arteries (original) (raw)
Related papers
A noninvasive method to estimate wall shear rate using ultrasound
Ultrasound in Medicine & Biology, 1995
Wall shear stress (blood viscosity X wall shear rate), imposed by the flowing blood, and blood pressure are tbe main mechanical forces acting on a blood vessel wall. Accurate measurement of wall shear stress is important when investigating the development of vascular disease, since both high and low wall shear stresses have been cited as factors leading to vessel wall anomalies. Furthermore, in vi&o studies have shown that endothelial cells, which play a key role in the function of the underlying arterial wall, undergo a variety of structural and functional changes in response to imposed shear stress. However, there is practically no knowledge about the influence of wall shear stress on the arterial wall in vivo because of the difficulty in measuring this stress in terms of magnitude and time variation. The method presented in this article to measure the time-dependent wall shear rate in the main arteries is based on the evaluation of velocity profiles determhuxl by means of ultrasound, using off-line signal processing. Pulsed ultrasound is well suited for this application since it is noninvasive. The processing performed in the radio-frequency (RF) domain consists of a mean frequency estimator preceded by an adaptive vessel wall filter. In a pilot study (30 measurements in the carotid artery of five healthy volunteers) we investigated the reproducibiity of our method to estimate wall shear rate as compared with the reproducibility of the measurement of blood flow velocity in the middle of the vessel. The coefficient of variation was on the order of 9% for blood flow velmity estimation, and for wall shear rate estimation on the order of 5%.
A simplified approach for real-time detection of arterial wall velocity and distension
IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 2001
Arterial stiffness is known to increase with age and with many vascular diseases, but its noninvasive assessment in patients still represents a difficult task. The measurement of diameter change during the cardiac cycle (distension) has been proposed as a means to estimate arterial compliance and stiffness. Therefore, we have developed a simple PC-based device and algorithm for noninvasive quantification of vessel wall motion and diameter change in humans. This goal is achieved in real-time by processing the base-band signals from a commercial ultrasound Doppler system. Real-time operation is of crucial importance, because it allows a rapid achievement of optimal measurement conditions. The system was evaluated in a laboratory using a string phantom and was tested on the carotid arteries of 10 volunteers. Wall velocities from 0.05 to 600 mm/s and displacements lower than 2 microns were detected with phantoms. The measured carotid diameter change in the volunteers ranged from 7.5 to 11.8% (mean = 9.8%) and agrees closely with values reported in the literature. The difference between values taken one hour apart ranged from 0.2 to 0.5%. We conclude that the new system provides rapid, accurate, and repeatable measurements of vessel distension in humans.
Ultrasound in Medicine & Biology, 2005
Mechanical properties of human large arteries result from the interaction between blood pressure, wall distensibility and shear stress. Both the arterial diameter changes through the cardiac cycle (distension) and blood flow velocities can be noninvasively investigated through Doppler ultrasound approaches. Recently, an integrated system processing in real-time all the echo signals produced along an M-line has been developed. This system has been so far demonstrated to be suitable for accurate hemodynamic studies through the detection of blood velocity profiles. This paper reports on the extension of its processing capabilities to the real-time measurement of arterial distension. Tissue motion estimation is based on a modified 2-D autocorrelation algorithm. A novel adaptive approach to track wall position over time using the sum of the high-pass filtered displacement waveform and the low-pass filtered wall position is described. By observing the blood velocity profile, a rapid and accurate positioning of the ultrasound probe and an inherent check on perpendicular observation are provided. First clinical results obtained by measuring the distension of common carotid arteries in a group of 41 volunteers are reported and measurements are validated against those provided by a dedicated wall-track reference system. Average measured distension and diameter were 499 ؎ 188 m and 6.90 ؎ 0.66 mm and intraobserver intrasession reproducibility tests showed coefficients of variability of 8.5% and 5.9%, respectively. The agreement between the proposed system and the reference system, expressed as bias ؎ 2 SD of the differences, was ؊34 ؎ 141 m for distension and 0.05 ؎ 1.07 mm for diameter. (E-mail: piero.tortoli@unifi.it) © 2005 World Federation for Ultrasound in Medicine & Biology.
European journal of ultrasound : official journal of the European Federation of Societies for Ultrasound in Medicine and Biology, 1999
To integrate methods for non-invasive assessment of vessel wall properties (diastolic diameter, distension waveform and intima-media thickness) and hemodynamic properties (blood flow velocity and shear rate distribution) of large arteries by means of dedicated ultrasound signal processing. we have developed an arterial laboratory (ART-lab) system. ART-lab consists of software running on a standard personal computer, equipped with a data acquisition card for the acquisition of radio frequency (RF) ultrasound signals obtained with a conventional echo scanner. It operates either (1) off-line or (2) in real-time. Real-time operation is restricted to the assessment of vessel wall properties because of limitations in computational power. This paper provides an overview of ART-lab ultrasound radio frequency data acquisition and dedicated RF-signal processing methods. The capabilities of the system are illustrated with some typical applications. ART-lab in real-time mode is a useful tool fo...
Future Medical Engineering Based on Bionanotechnology - Proceedings of the Final Symposium of the Tohoku University 21st Century Center of Excellence Program, 2006
Ultrasound can be used for mechanical property measurements of the arterial wall in addition to imaging of its morphology. This paper describes (1) accurate imaging of the carotid sinus which cannot be assumed to be a straight cylindrical shell, (2) measurement of elasticity and tissue characterization of the arterial wall based on the axial motion estimation, and (3) lateral motion estimation in the carotid artery.
Ultrasound in Medicine & Biology, 1997
A numerically based simulation of pulsed Doppler ultrasound convolution and deconvolution of theoretical hemodynamic velocity profiles yields two major conclusions on performing a deconvolution process. First, the most important parameter to be accounted for is the size of the sample vdume. Second, a deconvolution process with an overestimated sample volume size is revealed by high-frequency noise on the resulting profile. A deconvolution process is presented for in vivo arterial velocity profiles, which has the advantage of being systematic and not needing experimental testing for determining the size or the shape of the sample volume. It is also independent of the observation angle. Fhmlly, an example of an application to in vivo human velocity profiles is given. Evaluation of the wall shear rate from the corrected deconvolved profiles shows a noticeable improvement with respect to that using the directly convolved Doppler profiles.
Physics Procedia, 2015
The detection of changes in the properties of the walls in blood vessels (e.g. modifications in thickness or elasticity) is a promising way for the early diagnosis of cardiovascular diseases (e.g. atherosclerosis), and some attempts have been made using classic ultrasonic images. However, to obtain a reliable non invasive estimation of these changes still presents many challenges that must be overcome, in particular, to achieve an accurate estimation of the vessel wall thickness, which usually is associated to strain and elasticity alterations happening before the cardiovascular disease presents clinical symptom; to solve efficiently these aspects is a very difficult task. In this work, the application to vessels of a recent ultrasonic method developed by the authors for estimating wall thicknesses is described. This method (based on high-resolution power spectral density-PSD) and its algorithmic responses were tested on an arterial phantom under physiological conditions of flow and pressure, and some results are compared to those obtained using a direct-time thickness estimation and with the resolutions related to our alternative cross-correlation option shown in previous papers. A higher spatial resolution is obtained, for experimental multi-pulse ultrasonic echoes, with this PSD method in comparison to those based on conventional echography, cross correlation operators or other spectral options.
Japanese Journal of Applied Physics, 2004
We have developed the phased tracking method [H. Kanai, M. Sato, Y. Koiwa and N. Chubachi: IEEE Trans. UFFC 43 (1996) 791.] for measuring the minute change in thickness during one heartbeat and the elasticity of the arterial wall with transcutaneous ultrasound. When this method is applied to a plane perpendicular to the axis of the artery (short-axis plane) using a linear-type probe, only an ultrasonic beam which passes through the center of the artery coincides with the direction of the change in thickness. At other beam positions, the wall motion cannot be accurately tracked because the direction of wall expansion slips off the beam. To obtain the cross-sectional image of elasticity in the short-axis plane using transcutaneous ultrasound, in this paper, the directions of ultrasonic beams are designed so that each beam always passes through the center of the artery; thus, they always coincide with the direction of the wall expansion. In basic experiments, the accuracy in elasticity measurement was evaluated using a silicone rubber tube. In in vivo experiments, the minute change in wall thickness was measured along each ultrasonic beam, and the cross-sectional image of elasticity was obtained in the short-axis plane with transcutaneous ultrasound.
A noninvasive method to estimate pulse wave velocity in arteries locally by means of ultrasound
Ultrasound in Medicine & Biology, 1998
Noninvasive evaluation of vessel wall properties in humans is hampered by the absence of methods to assess directly local distensibility, compliance, and Young's modulus. Contemporary ultrasound methods are capable of assessing end-diastolic artery diameter, the local change in artery diameter as a function of time, and local wall thickness. However, to assess vessel wall properties of the carotid artery, for example, the pulse pressure in the brachial artery still must be used as a substitute for local pulse pressure. The assessment of local pulse wave velocity as described in the present article provides a direct estimate of local vessel wall properties (distensibility, compliance, and Young's modulus) and, in combination with the relative change in artery cross-sectional area, an estimate of the local pulse pressure. The local pulse wave velocity is obtained by processing radio frequency ultrasound signals acquired simultaneously along two M-lines spaced at a known distance along the artery. A full derivation and mathematical description of the method to assess local pulse wave velocity, using the temporal and longitudinal gradients of the change in diameter, are presented. A performance evaluation of the method was carried out by means of experiments in an elastic tube under pulsatile pressure conditions. It is concluded that, in a phantom set-up, the assessed local pulse wave velocity provides reliable estimates for local distensibility. © 1998 World Federation for Ultrasound in Medicine & Biology.
HAL (Le Centre pour la Communication Scientifique Directe), 2020
This study aims to investigate the clinical feasibility of simultaneous extraction of vessel wall motion and vectorial blood flow at high frame rates for extraction of clinical markers. If available in the clinic, such a technique would allow better estimation of plaque vulnerability and evaluation of overall arterial health of patients. In this study, both healthy and patient volunteers were recruited and scanned using a plane-wave acquisition scheme that provided a dataset of 43 carotid recordings in total. The vessel wall motion is extracted based on the complex autocorrelation of the signals received, while the vector flow is extracted using the transverse oscillation technique. Wall motion and vector flow are extracted at high frame rates, which allows visual appreciation of tissue movement and blood flow simultaneously and with fine temporal resolution. Several clinical markers are extracted, along with p-values. From all of the potential markers, young healthy volunteers have smaller artery diameter (7.32 mm) compared to diseased patients (9.56 mm), 66 % of diseased patients have backflow, a carotid with a pulse wave velocity extracted from the wall velocity that is greater than 7 m/s is always a diseased vessel, and the peak wall shear rate decreases as the risk increases. Based on both the pathological markers and the visual inspection of tissue motion and vector flow, we conclude that the clinical feasibility of this approach is demonstrated. Larger and more disease-specific studies using such an approach will lead to better understanding and evaluation of vessels, which can translate to future use in the clinic. Index Terms-vessel wall motion, vectorial flow, arterial properties, high frame rate, clinical study, carotid I. INTRODUCTION U LTRASOUND has been used with Doppler to assess cardiovascular properties since the 1950s [1], and more broadly through the 1970s [2]. Nowadays, ultrasound imaging is widely used with Doppler for routine checkups and for evaluation of vessel disease, such as atherosclerosis