The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
In most studies on vascular shear wave imaging (SWI), longitudinal section is mainly concerned, and the radial motion and reflected waves are not considered in cross section. It is important to investigate the SWI in cross section when evaluating the anisotropy of the vessel wall or the complete plaque composition. In our previous study, a novel method based on coordinate transformation and directional...
Single Track Location Shear Wave Elasticity Imaging (STL-SWEI) creates high resolution shear wave speed maps by comparing the tissue motion at each tracking location between spatially-offset radiation force excitations. While STL-SWEI circumvents the resolution-limiting effects of speckle noise, it requires a series of excitation-tracking ensembles to build up a lateral field of view, increasing the...
Spontaneous preterm birth, the foremost source of neonatal mortality, could potentially be prevented by objectively detecting abnormal changes in the uterine cervix. Shear Wave Elasticity Imaging (SWEI) biomarkers can quantify cervical softening that precedes vaginal delivery. This task can be complicated by biological (i.e., heterogeneity of cervical stiffness and pregnancy history) and experimental...
Shear wave elastography is useful for quantitatively evaluating tissue elasticity by measuring the speed of a shear wave induced within the body by acoustic radiation force. We proposed a pushing-and-tracking sequence, coded push-pulse excitation to increase the signal-to-noise ratio (SNR) of the observed shear wave propagation without increasing measurement time and push-pulse amplitude1). In this...
ARFI displacements have been shown to share an inverse relationship with shear wave speed — based estimates of tissue elasticity. In transthoracic imaging, induced shear waves have been observed during diastole, but only ARFI displacements have been accurately measured through both diastole and systole. We propose here a method for using diastolic shear wave speeds to calibrate ARFI displacement magnitudes,...
Tissue mechanical anisotropy has been shown to be diagnostically relevant in numerous clinical applications. Anisotropy can be assessed using acoustic radiation force-based techniques, including Acoustic Radiation Force Impulse (ARFI) and Viscoelastic Response (VisR) ultrasound. In this work, ARFI peak displacement (PD), as well as VisR relative elasticity (RE) and relative viscosity (RV), were implemented...
While skeletal muscle is often assumed to be structurally transversely isotropic (TI), its mechanical anisotropy is not well characterized in vivo. VisR ultrasound, a technique that provides information about the viscoelastic mechanical response of tissue, can be used for such in vivo characterization. Specifically, VisR-derived Relative Elasticity (RE) provides directionally dependent information...
Tissue elasticity is an important parameter which relates to the pathological state of soft tissue. Fibrotic lesions or malignant tumors are known to be notoriously stiff compared to benign tissue. Shear wave elastography can provide a fully quantitative measure of lesion stiffness by estimating the speed at which acoustically induced shear waves propagate through the material. This speed is in turn...
ARFI displacements have been shown to share an inverse relationship with shear wave speed — based estimates of tissue elasticity. Both ARFI and shear wave elasticity imaging (SWEI) have been used to track the stiffening and softening of myocardium through the cardiac cycle in open-chest, intracardiac, and Langendorff preparations. In transthoracic imaging, induced shear waves have been observed during...
Arrhythmias can be treated by ablating the heart tissue in the regions of abnormal conduction, e.g. activating too early or with a different speed. The key of the treatment then lies in the location of these areas. In current clinical practice, 3-D electroanatomic maps can be created during the procedure by probing the heart with a specific catheter. However, it is a time-consuming and invasive procedure...
Shear Wave Elasticity Imaging is used to assess liver fibrosis, as shear wave speed (SWS) correlates with fibrosis stage. We have previously proposed a group SWS-based method to derive the tissue's stiffness (μ) and viscosity (η) using an analytic solution for the shear wave propagation in a Voigt material which accounts for the source excitation geometry [Rouze et al., IEEE IUS 2016]. However, in...
A method for measurement of the bladder wall nonlinear elasticity is presented. The method is based on acoustoelasticity modeling of the bladder tissue modulus of elasticity changes at different volumetric loading levels. At each loading volume, tissue strain is obtained from the real-time images. Using acoustic radiation force, a transient Lamb wave is excited on the bladder wall and shear elasticity...
Lipid-coated microbubbles are being researched as agents for ultrasound imaging and ultrasound-assisted drug delivery. It is well known that lipid shell composition of a microbubble affects the acoustic response. However, the effect of temperature on lipid shell viscoelasticity has not yet been fully established. The goal of this study was to determine the effect of temperature on the viscoelastic...
Elastography plays a key role in characterizing soft tissue. Although it has found widespread use in clinical diagnostics, nearly all methods require direct physical contact with tissue and can even be invasive. However, for a number of applications (ophthalmic, for instance) physical contact is not desired and may not even be allowed. Recently, we proposed a fundamentally new approach to 4-D dynamic...
Characterization of the viscoelastic properties of tissues at the micro-level has been a challenge for many years. Recently, several micro-elastography techniques have been developed with high frequency ultrasound or optical coherence tomography to improve the spatial resolution. However, most of these techniques did not consider the medium boundary conditions and still used traditional shear wave...
Quantification of local arterial wall elasticity may assist in differentiating lipid rich rupture prone atherosclerotic plaques from stable fibrous plaques. Because lipid cores can be present anywhere along the circumference, we focus on developing a noninvasive shear wave elastography technique for transverse carotid cross-sections. Tracking the induced wave is not trivial because the circular geometry...
Ultrasound shear wave elastography (SWE) has gained wide acceptance as a non-invasive and quantitative clinical diagnostic modality. To realize SWE on low-cost systems, external mechanical vibration (EMV) is rising as an alternative to acoustic radiation force (ARF) for shear wave generation. In this paper, we present simulation, design, and implementation of an EMV-based SWE concept. Multiple EMV...
Cortical bone is an anisotropic material with hierarchical structure whose elastic properties are described at different length scales. At millimeter-scale, the whole set of stiffness tensor can be conveniently measured by resonant ultrasound spectroscopy (RUS). At microscopic-scale, micro-indentation and scanning acoustic microscopy are often used to quantify tissue matrix elastic properties. However,...
Pancreatic cancer is an aggressive disease a 5-year-survival rate less than 7%. To improve the patient overall survival, recent developments in pancreatic cancer research have been targeting various components of the tumor microenvironment such as the extracellular matrix, blood vessels and immune cells. We hypothesize that targeted therapies will affect the biomechanics of the tumor microenvironment...
In Duchenne muscular dystrophy (DMD), muscle fiber necrosis and subsequent progressive replacement of muscle by fibrous tissue and fat impacts the degree of anisotropy (DoA) in mechanical properties. Mechanical DoA can be assessed in skeletal muscle using Viscoelastic Response (VisR) ultrasound. We hypothesize that in vivo VisR DoA measures in the rectus femoris (RF) muscles of boys with DMD statistically...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.