Blood viscosity could explain shear wave dispersion in the liver

Abstract

We recently showed that the observed shear wave dispersion in a soft, porous, water-saturated tissue can be explained by Biot’s theory of poroelasticity. The theory explains the shear wave velocity increase with frequency due to a relative movement between the solid and the viscous fluid. We propose that fluid-solid interaction explains the observed shear wave dispersion in the liver, a naturally saturated organ. The liver is drawn through by a network of blood vessels and exposes a total porosity of about 14% [1]. Blood viscosity changes from patient to patient and depends on different factors such as hydration and fitness. We included the blood viscosity for a 14% porosity liver into the elasticity estimation from shear wave speed measurements for a given shear wave elastography dataset [2]. For 11 out of 50 patients, the fibrosis classification would change if blood viscosity is included. [1] C. Debbaut et al., “Perfusion characteristics of the human hepatic microcirculation based on three-dimensional reconstructions and computational fluid dynamic analysis,” J. Biomech. Eng. 134(1), 011003 (2012). [2] Jang et al., “Hemorheological alteration in patients clinically diagnosed with chronic liver diseases,” J. Korean Med. Sci. 31(12), 1943–1948 (2016).