Torsional Ultrasound Sensor Optimization for Soft Tissue Characterization

Melchor, Juan; Muñoz, Rafael; Rus, Guillermo

doi:10.3390/s17061402

Cited by 15 publications

(15 citation statements)

References 45 publications

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“…To respond to the principles of an optimal design of a torsional wave sensor considering the extraction of biomechanical properties, it is necessary to compute Finite Element Models (FEM) as a first step [ 15 , 29 , 30 ]. Thus, the resonant frequency can be determined for torsional waves for the emitter and the receiver using Finite Element Analysis Program (FEAP) software [ 31 ].…”

Section: Methodsmentioning

confidence: 99%

Performance Study of a Torsional Wave Sensor and Cervical Tissue Characterization

Callejas

Gómez

Melchor

et al. 2017

Sensors

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A novel torsional wave sensor designed to characterize mechanical properties of soft tissues is presented in this work. Elastography is a widely used technique since the 1990s to map tissue stiffness. Moreover, quantitative elastography uses the velocity of shear waves to achieve the shear stiffness. This technique exhibits significant limitations caused by the difficulty of the separation between longitudinal and shear waves and the pressure applied while measuring. To overcome these drawbacks, the proposed torsional wave sensor can isolate a pure shear wave, avoiding the possibility of multiple wave interference. It comprises a rotational actuator disk and a piezoceramic receiver ring circumferentially aligned. Both allow the transmission of shear waves that interact with the tissue before being received. Experimental tests are performed using tissue mimicking phantoms and cervical tissues. One contribution is a sensor sensitivity study that has been conducted to evaluate the robustness of the new proposed torsional wave elastography (TWE) technique. The variables object of the study are both the applied pressure and the angle of incidence sensor–phantom. The other contribution consists of a cervical tissue characterization. To this end, three rheological models have fit the experimental data and a static independent testing method has been performed. The proposed methodology permits the reconstruction of the mechanical constants from the propagated shear wave, providing a proof of principle and warranting further studies to confirm the validity of the results.

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Section: Methodsmentioning

confidence: 99%

Performance Study of a Torsional Wave Sensor and Cervical Tissue Characterization

Callejas

Gómez

Melchor

et al. 2017

Sensors

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“…It is an ambitious goal, yet we have obtained promising results and the technique is being validated through this work and recent work of the group. Torsional wave elastography has been shown to be effective in obtaining biomechanical biomarkers [21,[25][26][27]43].…”

Section: Discussionmentioning

confidence: 99%

“…Dealing with this type of geometry is a challenge for current elastography approaches in small organs such as the uterine cervix, where SWE would generate bounces on the tissue walls and mask the signal received by the receiver. However, TWE technique generates less energy that does not generate rebounds [26]. Torsional waves propagate both radially and in depth, which is very advantageous in the case of multilayer tissue.…”

Section: Discussionmentioning

confidence: 99%

“…The emitter transmitting the waves consists of a PLA (polylactic acid) disk, printed in 3D, whose rotational movement is due to an electromechanical actuator. The receiver is formed by two PLA rings with four slots in the inner face of the ring, where the four ceramic piezoelectric elements are fitted [25][26][27]. This allows the precise interrogation of soft tissue mechanical functionality in cylindrical geometries.…”

Section: Torsional Wave Elastographymentioning

confidence: 99%

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Viscoelastic Biomarkers of Ex Vivo Liver Samples via Torsional Wave Elastography

et al. 2020

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The clinical ultrasound community demands mechanisms to obtain the viscoelastic biomarkers of soft tissue in order to quantify the tissue condition and to be able to track its consistency. Torsional Wave Elastography (TWE) is an emerging technique proposed for interrogating soft tissue mechanical viscoelastic constants. Torsional waves are a particular configuration of shear waves, which propagate asymmetrically in-depth and are radially transmitted by a disc and received by a ring. This configuration is shown to be particularly efficient in minimizing spurious p-waves components and is sensitive to mechanical constants, especially in cylinder-shaped organs. The objective of this work was to validate (TWE) technique against Shear Wave Elasticity Imaging (SWEI) technique through the determination of shear wave velocity, shear moduli, and viscosity of ex vivo chicken liver samples and tissue mimicking hydrogel phantoms. The results of shear moduli for ex vivo liver tissue vary 1.69–4.0kPa using TWE technique and 1.32–4.48kPa using SWEI technique for a range of frequencies from 200 to 800Hz. Kelvin–Voigt viscoelastic parameters reported values of μ = 1.51kPa and η = 0.54Pa·s using TWE and μ = 1.02kPa and η = 0.63Pa·s using SWEI. Preliminary results show that the proposed technique successfully allows reconstructing shear wave velocity, shear moduli, and viscosity mechanical biomarkers from the propagated torsional wave, establishing a proof of principle and warranting further studies.

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“…If two materials with different elasticities (for instance of twice Young’s modulus) are compared in terms of their stiffness and compliance (its inverse), different distances are obtained. Since there is no reason to prefer one over the other, the definition of their distance should be independent of the choice, which can be attained through a logarithmic change of variable [ 30 , 31 ]. This change of variables is completed with a mapping from

to a predefined range of physically reasonable values

, to improve numerical stability, as,

…”

Section: Methodsmentioning

confidence: 99%

Logical Inference Framework for Experimental Design of Mechanical Characterization Procedures

Rus

Melchor

2018

Sensors

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Optimizing an experimental design is a complex task when a model is required for indirect reconstruction of physical parameters from the sensor readings. In this work, a formulation is proposed to unify the probabilistic reconstruction of mechanical parameters and an optimization problem. An information-theoretic framework combined with a new metric of information density is formulated providing several comparative advantages: (i) a straightforward way to extend the formulation to incorporate additional concurrent models, as well as new unknowns such as experimental design parameters in a probabilistic way; (ii) the model causality required by Bayes’ theorem is overridden, allowing generalization of contingent models; and (iii) a simpler formulation that avoids the characteristic complex denominator of Bayes’ theorem when reconstructing model parameters. The first step allows the solving of multiple-model reconstructions. Further extensions could be easily extracted, such as robust model reconstruction, or adding alternative dimensions to the problem to accommodate future needs.

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Torsional Ultrasound Sensor Optimization for Soft Tissue Characterization

Cited by 15 publications

References 45 publications

Performance Study of a Torsional Wave Sensor and Cervical Tissue Characterization

Performance Study of a Torsional Wave Sensor and Cervical Tissue Characterization

Viscoelastic Biomarkers of Ex Vivo Liver Samples via Torsional Wave Elastography

Logical Inference Framework for Experimental Design of Mechanical Characterization Procedures

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