Kelvin-Voigt Parameters Reconstruction of Cervical Tissue-Mimicking Phantoms Using Torsional Wave Elastography.

Antonio Callejas,Antonio Gomez,Guillermo Rus,Inas H. Faris,Juan Melchor

doi:10.3390/s19153281

Antonio Callejas, Antonio Gomez + Show 3 more

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https://doi.org/10.3390/s19153281

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Abstract

The reconstruction of viscous properties of soft tissues, and more specifically, of cervical tissue is a challenging problem. In this paper, a new method is proposed to reconstruct the viscoelastic parameters of cervical tissue-mimicking phantoms by a Torsional Wave Elastography (TWE) technique. The reconstruction method, based on a Probabilistic Inverse Problem (PIP) approach, is presented and experimentally validated against Shear Wave Elastography (SWE). The anatomy of the cervical tissue has been mimicked by means of a two-layer gelatine phantom that simulates the epithelial and connective layers. Five ad hoc oil-in-gelatine phantoms were fabricated at different proportion to test the new reconstruction technique. The PIP approach was used for reconstructing the Kelvin-Voigt (KV) viscoelastic parameters by comparing the measurements obtained from the TWE technique with the synthetic signals from a Finite Difference Time Domain (FDTD) KV wave propagation model. Additionally, SWE tests were realized in order to characterize the viscoelastic properties of each batch of gelatine. Finally, validation was carried out by comparing the KV parameters inferred from the PIP with those reconstructed from the shear wave dispersion curve obtained from the SWE measurements. In order to test the degree of agreement between both techniques, a Student’s T-test and a Pearson’s correlation study were performed. The results indicate that the proposed method is able to reconstruct the KV viscoelastic properties of the cervical tissue, for both the epithelial and connective layers, as well as the thickness of the first layer with acceptable accuracy.

Highlights

The cervix is a muscular part of the female reproductive system located at the lower end of the uterus
By the obtained results from the T-test and the Pearson’s correlation study, it can be concluded that the viscoelastic parameters reconstructed by the Torsional Wave Elastography (TWE) technique in conjunction with the new inversion approach are similar to those provided by the Shear Wave Elastography (SWE) technique
The results of a new method based on a Probabilistic Inverse Problem (PIP) for the reconstruction of the viscoelastic parameters of cervical tissue-mimicking phantoms by the TWE

Summary

Introduction

The cervix is a muscular part of the female reproductive system located at the lower end of the uterus. The cervix plays a crucial role during the gestation, acting as a gatekeeper, supporting the fetus inside the uterus and keeping it safe from external hazard [1]. From the moment of conception biological transformations in the cervix happen until the childbirth. These transformations, triggered by mechanical and chemical processes, have an impact in the physiology of the cervical tissue to the point of altering its mechanical properties [2]. The mechanical transformation during gestation consists in a decrease of stiffness of the cervix [2,4,5].

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