Excitation of shear waves inside of rubberlike material by focused ultrasound

1996 ◽  
Vol 100 (4) ◽  
pp. 2647-2647 ◽  
Author(s):  
Valery Andreev ◽  
Yury Pishalnikov ◽  
Oleg Rudenko ◽  
Oleg Sapozhnikov ◽  
Vladimir Dmitriev ◽  
...  
Keyword(s):  
Focused Ultrasound ◽  
Shear Waves ◽  
Rubberlike Material

scholarly journals Estimation of Anisotropic Material Properties of Soft Tissue by MRI of Ultrasound-Induced Shear Waves

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Charlotte A. Guertler ◽  
Ruth J. Okamoto ◽  
Jake A. Ireland ◽  
Christopher P. Pacia ◽  
Joel R. Garbow ◽  
...  
Keyword(s):  
Soft Tissue ◽  
Focused Ultrasound ◽  
Ex Vivo ◽  
Tissue Sample ◽  
Shear Waves ◽  
Chicken Breast ◽  
Fiber Direction ◽  
Fibrous Materials ◽  
Phase Gradient ◽  
Anisotropic Mechanical Properties

Abstract This paper describes a new method for estimating anisotropic mechanical properties of fibrous soft tissue by imaging shear waves induced by focused ultrasound (FUS) and analyzing their direction-dependent speeds. Fibrous materials with a single, dominant fiber direction may exhibit anisotropy in both shear and tensile moduli, reflecting differences in the response of the material when loads are applied in different directions. The speeds of shear waves in such materials depend on the propagation and polarization directions of the waves relative to the dominant fiber direction. In this study, shear waves were induced in muscle tissue (chicken breast) ex vivo by harmonically oscillating the amplitude of an ultrasound beam focused in a cylindrical tissue sample. The orientation of the fiber direction relative to the excitation direction was varied by rotating the sample. Magnetic resonance elastography (MRE) was used to visualize and measure the full 3D displacement field due to the ultrasound-induced shear waves. The phase gradient (PG) of radially propagating “slow” and “fast” shear waves provided local estimates of their respective wave speeds and directions. The equations for the speeds of these waves in an incompressible, transversely isotropic (TI), linear elastic material were fitted to measurements to estimate the shear and tensile moduli of the material. The combination of focused ultrasound and MR imaging allows noninvasive, but comprehensive, characterization of anisotropic soft tissue.

Doppler ultrasound detection of shear waves remotely induced in tissue phantoms by focused ultrasound

2000 ◽  
Vol 108 (5) ◽  
pp. 2549-2550 ◽  
Author(s):  
Evgen A. Barannik ◽  
Sergii A. Girnyk ◽  
Volodymyr V. Tovstiak ◽  
Armen P. Sarvazyan
Keyword(s):  
Doppler Ultrasound ◽  
Focused Ultrasound ◽  
Shear Waves ◽  
Tissue Phantoms

scholarly journals Transcranial Focused Ultrasound Generates Skull-Conducted Shear Waves: Computational Model and Implications for Neuromodulation

2020 ◽  
Author(s):  
Hossein Salahshoor ◽  
Mikhail G. Shapiro ◽  
Michael Ortiz
Keyword(s):  
Focused Ultrasound ◽  
Soft Tissues ◽  
Control Strategies ◽  
Shear Waves ◽  
Element Model ◽  
Potential Method ◽  
Non Invasive ◽  
Auditory Responses ◽  
Shear Compliance ◽  
Established Technique

ABSTRACTFocused ultrasound (FUS) is an established technique for non-invasive surgery and has recently attracted considerable attention as a potential method for non-invasive neuromodulation. While the pressure waves generated by FUS in this context have been extensively studied, the accompanying shear waves are often neglected due to the relatively high shear compliance of soft tissues. However, in bony structures such as the skull, acoustic pressure can also induce significant shear waves that could propagate outside the ultrasound focus. Here, we investigate wave propagation in the human cranium by means of a finite-element model that accounts for the anatomy, elasticity and viscoelasticity of the skull and brain. We show that, when a region on the frontal lobe is subjected to FUS, the skull acts as a wave guide for shear waves, resulting in their propagation to off-target structures such as the cochlea. This effect helps explain the off-target auditory responses observed during neuromodulation experiments and informs the development of mitigation and sham control strategies.

In vivo measurements of muscle elasticity applying shear waves excited with focused ultrasound

2017 ◽  
Vol 141 (5) ◽  
pp. 3613-3613
Author(s):  
Timofey Krit ◽  
Valeriy Andreev ◽  
Igor Demin ◽  
Pavel Rykhtik ◽  
Elena Ryabova
Keyword(s):  
Focused Ultrasound ◽  
Shear Waves ◽  
Muscle Elasticity ◽  
In Vivo Measurements

scholarly journals Mechanics Of Ultrasonic Neuromodulation In A Mouse Subject

2021 ◽  
Author(s):  
Hossein Salahshoor ◽  
Hongsun Guo ◽  
Mikhail G. Shapiro ◽  
Michael Ortiz
Keyword(s):  
Pressure Wave ◽  
Focused Ultrasound ◽  
Shear Waves ◽  
Element Model ◽  
Wave Pattern ◽  
Promising Tool ◽  
Sensory Effects ◽  
The Subject ◽  
Sensory Responses ◽  
The Brain

AbstractUltrasound neuromodulation (UNM), where a region in the brain is targeted by focused ultrasound (FUS), which, in turn, causes excitation or inhibition of neural activity, has recently received considerable attention as a promising tool for neuroscience. Despite its great potential, several aspects of UNM are still unknown. An important question pertains to the off-target sensory effects of UNM and their dependence on stimulation frequency. To understand these effects, we have developed a finite-element model of a mouse, including elasticity and viscoelasticity, and used it to interrogate the response of mouse models to focused ultrasound (FUS). We find that, while some degree of focusing and magnification of the signal is achieved within the brain, the induced pressure-wave pattern is complex and delocalized. In addition, we find that the brain is largely insulated, or ‘cloaked’, from shear waves by the cranium and that the shear waves are largely carried away from the skull by the vertebral column, which acts as a waveguide. We find that, as expected, this waveguide mechanism is strongly frequency dependent, which may contribute to the frequency dependence of UNM effects. Our calculations further suggest that off-target skin locations experience displacements and stresses at levels that, while greatly attenuated from the source, could nevertheless induce sensory responses in the subject.

scholarly journals MR imaging of shear waves generated by focused ultrasound

2000 ◽  
Vol 43 (1) ◽  
pp. 111-115 ◽  
Author(s):  
Tao Wu ◽  
Joel P. Felmlee ◽  
James F. Greenleaf ◽  
Stephen J. Riederer ◽  
Richard L. Ehman
Keyword(s):  
Mr Imaging ◽  
Focused Ultrasound ◽  
Shear Waves

Visuomotor Transformations Are Modulated by Focused Ultrasound over Frontal Eye Field

2020 ◽  
Author(s):  
Kaleb A. Lowe ◽  
Wolf Zinke ◽  
M. Anthony Phipps ◽  
Josh Cosman ◽  
Micala Maddox ◽  
...  
Keyword(s):  
Focused Ultrasound ◽  
Frontal Eye Field ◽  
Visuomotor Transformations ◽  
Eye Field
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