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This paper describes an in-vivo pilot study in which the systolic myocardial stiffness of four pigs was measured with various acoustic techniques. We compare the propagation velocity of shear waves in open chest and closed chest experiments, in which the open-chest shear wave was either physiologically induced by aortic valve closure (N=3), or externally induced by acoustic-radiation force (N=1)....
Ultrasonic measurement techniques are widely used for non-destructive detection of material defects. However, material properties, such as Young's modulus, are still mostly determined destructively, especially for materials with high damping or strong anisotropy. One method for non-destructive material characterization creates and detects ultrasonic waves in plate-shaped specimens, so that the material's...
Skin represents a complex structure for the quantification of viscoelastic (VE) properties using shear waves. Wave propagation through skin has been modeled as propagating both as a Lamb wave and as a Rayleigh wave, but both assumptions are limited due to the structure of the skin, which is a multi-layered tissue. This complexity of structure makes it difficult to accurately assess the relative contributions...
Elastography is an efficient alternative to the traditional palpation method of assessing tissue stiffness. Magnetic resonance imaging (MRI) provides a three-dimensional (3D) high-resolution view of the surrounding anatomy during interventions. Therefore, the development of MRI-based elastographic strategies is desirable for multiple clinical applications. In this work, we developed a new transient...
This study describes a new method to determine the stiffness µ0 and viscosity η of viscoelastic materials by observing shear wave propagation following localized, impulsive excitations and measuring the group shear wave speeds Vdisp and Vvel determined using the shear wave displacement and velocity signals, respectively. The stiffness and viscosity are found by analytically solving the equation of...
In this experiment, [100]. [110] and [111] single crystal silicon wafers were interrogated by line focused ultrasonic transducer with large aperture. Lamb waves generated in the wafers were detected by same transducer, and the rf signals, V (t, z) were acquired as varying defocusing distance. Since Lamb wave is dispersive, a numerous modes were mixed in the detected rf signal. A series of signal processing...
This paper proposes a fast calculation method for three dimensional photoacoustic reconstruction using compressed sensing (CS). It is required for CS to solve photoacoustic forward propagation model from laser induced initial pressure repeatedly. The proposed method can reduce calculation cost of the forward propagation calculation by using integration over a sphere surface on k-space representation...
The purpose of this paper was to demonstrate a noninvasive technique to measure elastic properties of human eyes using ultrasound surface wave elastography (USWE) technique. Twenty eyes of 10 healthy subjects (age 44–63; mean 51 years) were studied. A localized harmonic vibration for 0.1 second at 100 Hz was generated by using a spherically-tipped vibrator (3 mm diameter) placed on the closed eyelid...
A lung ultrasound surface wave elastography (LUSWE) technique is developed to measure superficial lung tissue elastic properties. A small, local, and short 0.1 second harmonic vibration is generated by the indenter of a handheld shaker on the skin of a subject. The ultrasound probe is positioned about 5 mm away from the indenter in the same intercostal space to measure the generated surface wave propagation...
Pulse wave Imaging (PWI) is a noninvasive technique for tracking the propagation of the pulse waves along the arterial wall. Estimation of regional Pulse Wave Velocity (PWV) using 2D long-axis views of arterial vessels assumes propagation parallel to the imaging plane. 3D ultrasound imaging would aid in objectively estimating the PWV vector. The aims of this study were to introduce a novel method...
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