Arterial waveguide model for shear wave elastography: implementation andin vitrovalidation

Abstract

Arterial stiffness is found to be an early indicator of many cardiovascular diseases. Among various techniques, shear wave elastography has emerged as a promising tool for estimating local arterial stiffness through the observed dispersion of guided waves. In this paper, we develop efficient models for the computational simulation of guided wave dispersion in arterial walls. The models are capable of considering fluid-loaded tubes, immersed in fluid or embedded in a solid, which are encountered in in vitro/ex vivo, and in vivo experiments. The proposed methods are based on judiciously combining Fourier transformation and finite element discretization, leading to a significant reduction in computational cost while fully capturing complex 3D wave propagation. The developed methods are implemented in open-source code, and verified by comparing them with significantly more expensive, fully 3D finite element models. We also validate the models using the shear wave elastography of tissue-mimicking phantoms. The computational efficiency of the developed methods indicates the possibility of being able to estimate arterial stiffness in real time, which would be beneficial in clinical settings.

Toward improved accuracy in shear wave elastography of arteries through controlling the arterial response to ultrasound perturbation in-silico and in phantoms

“…We begin by defining the artery as a cylindrical, fluid-immersed waveguide, as shown in figure 1. This approach was developed during our previous work with Astaneh et al on modeling SWE, detailed in Astaneh et al (2017).…”

“…To reduce the complexity of the inversion, many simplifications and assumptions are made throughout the literature, beginning with the geometry: the artery is commonly treated as a cylinder with constant radius and wall thickness (Takashima et al 2007, Banks and Luke 2008, Bernal et al 2010, Couade et al 2010, Jang et al 2013, Muha and Canić 2013, Alhayani et al 2014. This simplified geometry can be leveraged to treat the artery as a cylindrical waveguide and decompose its motion into combinations of characteristic vibrational modes, allowing for inversion through study of wave dispersion (Armenàkas et al 1969, Royer and Dieulesaint 1999, Fung 2013, Astaneh et al 2017. In their paper validating such a dispersion-based method, Roy et al note that, although most authors treat the arterial motion as being dominated by a single mode, significant contributions from multiple modes are present (Astaneh et al 2017, Roy et al 2021.…”

“…This simplified geometry can be leveraged to treat the artery as a cylindrical waveguide and decompose its motion into combinations of characteristic vibrational modes, allowing for inversion through study of wave dispersion (Armenàkas et al 1969, Royer and Dieulesaint 1999, Fung 2013, Astaneh et al 2017. In their paper validating such a dispersion-based method, Roy et al note that, although most authors treat the arterial motion as being dominated by a single mode, significant contributions from multiple modes are present (Astaneh et al 2017, Roy et al 2021. They find that failing to correctly account for this multimodal nature reduces the accuracy of material property estimates, posing additional challenges for inversion (Roy et al 2021).…”

Advanced Ultrasound Technologies for Diagnosis and Therapy

“…Additionally, in heterogeneous media, the observed wave speed might be determined not only by the average properties of the tissue but also by its boundaries, which can guide the waves and change the observed speed. Proper modeling, such as modeling of arteries as waveguides, allows these effects to be exploited and arterial stiffness characterized on the basis of the observed wave speed (5). In the future, full-wavefield inversion techniques applied to the measured tissue motion might solve this problem, at the cost of increased computational complexity (2).…”

Full waveform inversion for arterial viscoelasticity

“…Many waveguide models have been developed for arterial SWE: immersed plate model (Couade et al 2010, Bernal et al 2011, Nguyen et al 2011, Jang et al 2015, Widman et al 2015, Li et al 2017a, annulus waveguide (Li et al 2017b), hollow tube waveguide (Zhang et al 2005, Flamini et al 2015, fluid-filled tube (Flamini et al 2015, Lin et al 2015, immersed fluid-filled 3D finite element model (Dutta et al 2015), immersed fluid-filled SAFE models (Astaneh et al 2017. These models can be used to estimate modulus from wave propagation measurements.…”