Full wave 3D inverse scattering transmission ultrasound tomography in the presence of high contrast

Wiskin, James; Malik, Bilal; Borup, D.T.; Pirshafiey, Nasser; Klock, John C.

doi:10.1038/s41598-020-76754-3

“…The equation (5) shows that the reflection point is located at the source-receiver midpoint only when the medium is isotropic (v 1 = v 2 ) or the anisotropy symmetry axis is aligned with our coordinate system (ϕ = 0). For muscle tissue, we expect v 1 > v 2 for ϕ ∈ [−π/4, π/4), i.e., waves propagating faster along than across fiber direction [14].…”

Section: A Reflector-based Experimental Setupmentioning

confidence: 99%

Toward speed-of-sound anisotropy quantification in muscle with pulse-echo ultrasound

Martiartu¹,

Simutė²,

Frauenfelder³

et al. 2022

Preprint

0

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<p> The velocity of ultrasound longitudinal waves (speed of sound) is emerging as a valuable biomarker for a wide range of diseases, including musculoskeletal disorders. Muscles are fiber-rich tissues that exhibit anisotropic behavior, meaning that velocities vary with the wave-propagation direction. Quantifying anisotropy is therefore essential to improve velocity estimates while providing a new metric that relates to both muscle composition and architecture. This work presents a method to estimate longitudinal-wave anisotropy in transversely isotropic tissues. We assume elliptical anisotropy and consider an experimental setup that includes a flat reflector located in front of the linear probe. Moreover, we consider transducers operating multistatically. This setup allows us to measure first-arrival reflection traveltimes. Unknown muscle parameters are the orientation angle of the anisotropy symmetry axis and the velocities along and across this axis. We derive analytical expressions for the relationship between traveltimes and anisotropy parameters, accounting for reflector inclinations. To analyze the structure of this nonlinear forward problem, we formulate the inversion statistically using the Bayesian framework. Solutions are probability density functions useful for quantifying uncertainties in parameter estimates. Using numerical examples, we demonstrate that all parameters can be well constrained when traveltimes from different reflector inclinations are combined. Results from a wide range of acquisition and medium properties show that uncertainties in velocity estimates are substantially lower than expected velocity differences in muscle. Thus, our formulation could provide accurate muscle anisotropy estimates in future clinical applications.</p> p { margin-bottom: 0.25cm; line-height: 115%; background: transparent }

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“…We use the first transducer element as a source with a Ricker wavelet of 2 MHz center frequency and all transducers as receivers. Our approach predicts traveltimes accurately, even though the frequencies of simulated ultrasonic waves are lower than those used commercially (5)(6)(7)(8)(9)(10)(11)(12). The traveltime modelling presented here is based on the ray theory, which assumes infinite frequencies.…”

Section: Validation With Numerical Simulationsmentioning

confidence: 99%

Ultrasound longitudinal-wave anisotropy estimation in muscle tissue

Martiartu¹,

Simutė²,

Rominger³

et al. 2021

Preprint

0

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<p> The velocity of ultrasound longitudinal waves (speed of sound) is emerging as a valuable biomarker for a wide range of diseases, including musculoskeletal disorders. Muscles are fiber-rich tissues that exhibit anisotropic behavior, meaning that velocities vary with the wave-propagation direction. Quantifying anisotropy is therefore essential to improve velocity estimates while providing a new metric that relates to both muscle composition and architecture. This work presents a method to estimate longitudinal-wave anisotropy in transversely isotropic tissues. We assume elliptical anisotropy and consider an experimental setup that includes a flat reflector located in front of the linear probe. Moreover, we consider transducers operating multistatically. This setup allows us to measure first-arrival reflection traveltimes. Unknown muscle parameters are the orientation angle of the anisotropy symmetry axis and the velocities along and across this axis. We derive analytical expressions for the relationship between traveltimes and anisotropy parameters, accounting for reflector inclinations. To analyze the structure of this nonlinear forward problem, we formulate the inversion statistically using the Bayesian framework. Solutions are probability density functions useful for quantifying uncertainties in parameter estimates. Using numerical examples, we demonstrate that all parameters can be well constrained when traveltimes from different reflector inclinations are combined. Results from a wide range of acquisition and medium properties show that uncertainties in velocity estimates are substantially lower than expected velocity differences in muscle. Thus, our formulation could provide accurate muscle anisotropy estimates in future clinical applications.</p> p { margin-bottom: 0.25cm; line-height: 115%; background: transparent }

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“…Under a fluid or acoustic modeling, the effects of attenuation and shear wave propagation are not taken into account. This simplified model is often used in the imaging of soft tissues in order to reduce the complexity of the implementation, 20 but it has also been extended to targets with high impedance contrast such as bone 21–23 obtaining proper quantitative estimates of the tissue characteristics. To go further, the FWI approach have been proposed as suitable method for USCT of high impedance contrast targets, and the results obtained using synthetic data are promising.…”

Section: Introductionmentioning

confidence: 99%

Ultrasonic Imaging of High-contrasted Objects Based on Full-waveform Inversion: Limits under Fluid Modeling

Espinosa

¹

,

Doveri

²

,

Bernard

³

et al. 2021

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Quantitative ultrasound techniques have been previously used to evaluate biological hard tissues, characterized by a large acoustic impedance contrast. Here, we are interested in the imaging of experimental data from different test-targets with high acoustic impedance contrast, using the Full Waveform Inversion (FWI) method to solve the inverse problem. This method is based on high-resolution numerical modeling of the forward problem of interaction between waves and medium, considering the full time series. To reduce the complexity of the numerical implementation, the model considers a fluid medium. Therefore, the aim is to evaluate the precision of the reconstruction under this assumption for materials with a different level of attenuation of shear waves, to study the limits of this hypothesis. Images of the sound speed obtained using the experimental data are presented, and the precision of the reconstruction is evaluated. Future work should include viscoelastic materials.

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Full wave 3D inverse scattering transmission ultrasound tomography in the presence of high contrast

Cited by 64 publications

References 61 publications

Toward speed-of-sound anisotropy quantification in muscle with pulse-echo ultrasound

Toward speed-of-sound anisotropy quantification in muscle with pulse-echo ultrasound

Ultrasound longitudinal-wave anisotropy estimation in muscle tissue

Ultrasonic Imaging of High-contrasted Objects Based on Full-waveform Inversion: Limits under Fluid Modeling

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