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Shear wave-based elasticity methods which quantify shear wave speed, cs, are becoming clinically relevant as many pathological conditions change values of cs in soft tissue. Reliable measurements require shear waves with high signal-to-noise ratio that propagate far enough to measure cs. Push tonebursts must have long duration and/or high intensity, but ultrasound exposure regulations limit deposited...
Renal fibrosis threatens kidney viability and fibrosis has been associated with altered tissue structure affecting the biomechanical properties of the kidney, such as elasticity and viscosity. Although there are limited studies regarding viscoelastic properties of renal tissue, an in vivo renal MRE study suggests that shear elasticity changes as a result of hemodynamic variables. A newly emerging...
Shear wave Dispersion Ultrasound Vibrometry (SDUV), is an acoustic radiation force based technique that measures tissue shear viscoelasticity by characterizing shear wave speed dispersion. One of the potential applications of this technique is the non-invasive measurement of liver viscoelasticity to stage liver fibrosis. In this study, a Philips' iU22 ultrasound system was modified to allow for the...
Composed vibration pulses are developed to generate ultrasound radiation force for stimulating vibrations in a tissue region with preferred spectral distributions and increasing specific vibration harmonics when the peak radiation power is limited. The new vibration sequence has multiple pulses in one fundamental period of the vibration. The pulses are sparsely sampled from an orthogonal frequency...
Shearwave Dispersion Ultrasound Vibrometry (SDUV) measures tissue elasticity and viscosity by quantifying dispersion of shear wave propagation velocity. Long tone bursts of focused ultrasound are transmitted by an array transducer to a push origin at a pulse repetition frequency of fp to produce multi-tone shear waves at fp and its harmonics. Shear waves are monitored by pulse echo ultrasound transmitted...
Shear wave dispersion vibrometry (SDUV) produces motion in tissue using sequential pulses of ultrasound radiation pressure. The resulting motion of the tissue in the form of propagating shear waves can provide information about the material properties of the tissue given the appropriate equations of motion for the geometry of the tissue. An example application of the method is described to measure...
Noninvasive quantification of liver elasticity is a promising alternative to liver biopsy to stage liver fibrosis, a condition afflicting hundreds of millions of patients worldwide. Quantitative measurement of elasticity (in unit of Pascal) is required in this application because liver fibrosis is a diffuse disease where abnormality is not confined to a local region and there is no normal background...
We propose a method using broadband tone burst excitation pulses with non-uniform sampling for Shearwave Dispersion Ultrasound Vibrometry (SDUV). The method allows long excitation pulses with a high PRF of detection pulses to induce a strong tissue motion and obtain strong detection signal. The method also simultaneously estimates all harmonics of tissue motion induced by the broadband excitation...
Shear wave speed measurements are used in elasticity imaging to find the shear elasticity and viscosity of tissue. A technique called shear wave dispersion ultrasound vibrometry (SDUV) has been introduced to use the dispersive nature of shear wave speed to locally estimate the material properties of tissue. Shear waves are created using a multifrequency ultrasound radiation force, and the propagating...
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