Shear wave transmissivity measurement by color Doppler shear wave imaging

Abstract

Shear wave elastography is a useful method for evaluating tissue stiffness. We have proposed a novel shear wave imaging method (color Doppler shear wave imaging: CD SWI), which utilizes a signal processing unit in ultrasound color flow imaging in order to detect the shear wave wavefront in real time. Shear wave velocity is adopted to characterize tissue stiffness; however, it is difficult to measure tissue stiffness with high spatial resolution because of the artifact produced by shear wave diffraction. Spatial average processing in the image reconstruction method also degrades the spatial resolution. In this paper, we propose a novel measurement method for the shear wave transmissivity of a tissue boundary. Shear wave wavefront maps are acquired by changing the displacement amplitude of the shear wave and the transmissivity of the shear wave, which gives the difference in shear wave velocity between two mediums separated by the boundary, is measured from the ratio of two threshold voltages required to form the shear wave wavefronts in the two mediums. From this method, a high-resolution shear wave amplitude imaging method that reconstructs a tissue boundary is proposed.

Ultrasonic inspection method for billet using time-of-flight deviation of bottom echo and its performance evaluation in numerical simulations

“…For nondestructive inspection, various ultrasonic methods are studied. [7][8][9][10][11][12][13][14][15] For billet inspection, the pulse echo method is commonly used in a production line. 16,17) Although this method is simple and fast, defects near the surface of a billet cannot be detected because echoes from these defects are received with pulse signals and bottom echoes at the same time.…”

Measurement of shear wave absorption with correction of the diffraction effect for viscoelasticity characterization of soft tissues

“…[18][19][20][21][22] The advantage of such a method is that it avoids the direct measurement of α S , which is rather challenging to measure precisely since the reflections and diffraction of SW within a specimen could deform SW waveforms observed, resulting in the measurement error of v S and α S . [23][24][25][26][27] However, the dispersion method requires multiple measurements at different frequencies to determine the v S dispersion unless using an impulse SW having a broad frequency bandwidth with a high framerate ultrasound imaging system. 15,20) We have proposed a SW measurement method of v S by using a conventional B-mode scan of focused ultrasound with a single external SW vibration source.…”

CaBi4Ti4O15-based lead-free sol–gel composites for high-temperature application

“…An ultrasonic measurement technique has been applied for nondestructive testing (NDT), and the improvement of piezoelectric ultrasonic transducers has been investigated by many researchers since it uses ultrasonic transducers as a transmitter and=or a receiver. [1][2][3][4][5][6][7][8][9][10] NDT at high temperatures has been desired for industrial fields such as power plants and manufacturing industries to detect failures in the early stage of operation. [11][12][13] However, conventional piezoelectric transducers have a backing material with high attenuation to achieve a broad bandwidth characteristic 1,14) and this allows them to be used at elevated temperatures owing to the low thermal durability of the backing material and thermal expansion coefficient difference between the backing material and piezoelectric materials.…”