Ultrasound Elastography for Biomedical Applications and Medicine

27 Application of Guided Waves for Quantifying Elasticity and Viscoelasticity of Boundary Sensitive Organs

Sara Aristizabal¹, Matthew Urban², Luiz Vasconcelos³, Benjamin Wood³, Miguel Bernal⁴, Javier Brum⁵ and Ivan Nenadic³

¹ Well Living Lab, Rochester, MN, USA

² Department of Radiology, Mayo Clinic, Rochester, MN, USA

³ Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, USA

⁴ Universidad Pontificia Bolivariana, Medellín, Colombia

⁵ Laboratorio deAcustica Ultrasonora, Instituto de Fisica, Facultad de Ciencias, Universidad de la Republica, Montevideo, Uruguay

27.1 Introduction

The field of shear wave elastography has offered numerous techniques to quantify the viscoelastic properties of various biological tissues such as kidneys, myocardium, breast, liver, prostate, and others [1–3]. The majority of these methods assume the presence of a “pure” shear wave and relate the observed shear wave velocity (c) to the shear modulus of elasticity (μ) via μ = c ² ρ, where ρ is tissue density (around 1000 kg/m³). The pure shear wave assumption is appropriate for tissues such as the liver, kidneys, and breast tissue (often referred to as bulky organs) when the shear waves propagate in the middle of the organ and do not reflect from the organ boundaries. In bulky organs, the focused radiation force excites shear waves and compressional waves that attenuate before they reach the edges of the medium, and therefore do not form an interference ...