Results 211 to 220 of about 19,778 (259)

The nonlinear ultrasound needle pulse

The Journal of the Acoustical Society of America, 2018
Recent work has established an analytical formulation of broadband fields which extend in the axial direction and converge to a narrow concentrated line. Those unique (needle) fields have their origins in an angular spectrum configuration in which the forward propagating wavenumber of the field (kz) is constant across any z plane for all of the ...
P, Ted Christopher, Kevin J, Parker
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Nonlinear propagation in doppler ultrasound

Ultrasound in Medicine & Biology, 1993
The nonlinear propagation of ultrasound was demonstrated using Doppler transducers on two commercial duplex machines. The influence of nonlinear propagation on Doppler measurements was studied on both a flow phantom and a string phantom. It was found that although the pulse waveforms showed clearly different degrees of nonlinear distortion, no effect ...
S, Li, W N, McDicken, P R, Hoskins
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Ultrasound coefficient of nonlinearity imaging

IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, 2015
Imaging the acoustical coefficient of nonlinearity, β, is of interest in several healthcare interventional applications. It is an important feature that can be used for discriminating tissues. In this paper, we propose a nonlinearity characterization method with the goal of locally estimating the coefficient of nonlinearity.
Van Sloun, Ruud, Demi, Libertario, Shan, Caifeng, Mischi, Massimo   +3 more
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Nonlinear ultrasound imaging of the microcirculation

The Journal of the Acoustical Society of America, 2023
Blood flow at and near the tissue level is a physiological parameter of significant experimental and clinical importance, as it reflects the adaptive response of organs to their normal biological environment, to disease, trauma, and the malignant progression of cancer.
Matthew Bruce, Jennifer N. Harmon, Anton Arkadevitch, Zin Khaing   +3 more
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Nonlinear intravascular ultrasound contrast imaging

Ultrasound in Medicine & Biology, 2006
Nonlinear contrast agent imaging with intravascular ultrasound (IVUS) is investigated using a prototype IVUS system and an experimental small bubble contrast agent. The IVUS system employed a mechanically scanned single element transducer and was operated at a 20 MHz transmit frequency (F20) for second harmonic imaging (H40), and at a 40 MHz transmit ...
Goertz, David E., Frijlink, Martijn E., de Jong, N., van der Steen, Antonius F.W.   +3 more
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Ultrasound imaging of the coefficient of nonlinearity

The Journal of the Acoustical Society of America, 2015
Cardiac ablation (CA) is increasingly used to treat atrial fibrillation. However, long-term success is relatively low, and the procedure carries serious risks. To this end, we are developing a β (coefficient of nonlinearity) imaging method that may be employed to perform both tissue characterization and real time temperature estimation to respectively ...
Demi, Libertario, van Sloun, Ruud J., Shan, Caifeng, Verweij, Martin D., Mischi, Massimo   +4 more
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Nonlinear acoustics in diagnostic ultrasound

Ultrasound in Medicine & Biology, 2002
The propagation of ultrasonic waves is nonlinear. Phenomena associated with the propagation of diagnostic ultrasound pulses cannot be predicted using linear assumptions alone. These include a progressive distortion in waveform, the generation of frequency harmonics and acoustic shocks, excess deposition of energy and acoustic saturation.
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Nonlinear modeling of therapeutic ultrasound

1995 IEEE Ultrasonics Symposium. Proceedings. An International Symposium, 2002
The authors describe experimental finite element modeling of tissue ablation by focused ultrasound. Emphasis is on nonlinear coupling of high intensity sound temperature, and tissue properties. The numerical basis for modeling nonlinearity is an incrementally linear, time-domain, finite element algorithm solving the electromechanical and bioheat ...
G. Wojcik, J. Mould, N. Abboud, M. Ostromogilsky, D. Vaughan   +4 more
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Nonlinearities in the bioeffects of ultrasound

The Journal of the Acoustical Society of America, 1998
Biological effects of ultrasound involve nonlinear phenomena (1) in the propagation of sound itself, (2) in the generation of acoustic cavitation, and (3) in the biochemistry, physiology, and pathology of the biological system. Most nonthermal bioeffects of interest to users of diagnostic ultrasound require acoustic pressures great enough that the wave
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Nonlinear simulation for contrast ultrasound imaging

The Journal of the Acoustical Society of America
Contrast ultrasound (CUS) has received much interest because of its sensitivity enhancement for blood flow imaging. However, there is still a lack of nonlinear simulation method for CUS, as conventional simulators cannot deal with the microbubble acoustic nonlinearity.
Shuangyi Cheng, Kailiang Xu
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