Viscoelastic Biomarkers of Ex Vivo Liver Samples via TorsionalWave Elastography
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AuthorFaris, Inas; Melchor Rodríguez, Juan Manuel; Callejas Zafra, Antonio Manuel; Torres, Jorge; Rus Carlborg, Guillermo
Shear Wave Elastography ImagingTorsional Wave ElastographyMechanical biomarkersTissue biomarkersKelvin–Voigt viscoelasticity
Faris, I.H.; Melchor, J.; Callejas, A.; Torres, J.; Rus, G. Viscoelastic Biomarkers of Ex Vivo Liver Samples via Torsional Wave Elastography. Diagnostics 2020, 10, 111.[doi:10.3390/diagnostics10020111]
SponsorshipThis research was funded by the Ministry of Education grant numbers DPI2017-83859-R, DPI2014-51870-R, and UNGR15-CE-3664; Ministry of Health grant numbers DTS15/00093 and PI16/00339 Carlos III Instituto de Salud y Fondos Feder; and Junta de Andalucía grant numbers, PI-0107-2017 and PIN-0030-2017. Juan de la Cierva Incorporación IJC2018-037167-I.
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.