Micro-vibrations underlying temporal enhanced ultrasound: The effect of scatterer size and elasticity

Abstract

Temporal-enhanced ultrasound (TeUS) imaging is a recently developed method based on the analysis of US time series. In this report, we show experimentally that the TeUS amplitude is sensitive to scatterer size and their density, as well as to the microvibration amplitude. Since the microvibration amplitude depends on the local elasticity of the medium, TeUS is able to differentiate tissues based on their elasticity, in addition to scatterer density and cross section. It is argued that interference effects, i.e., US speckle, are enhancing the TeUS effect. In this study, ultrasound phantoms were designed to mimic tissues with three different viscoelasticities and three different scatterer sizes. Into each of the nine phantoms, a flexible tubing was embedded and used to generate local microvibrations at 1 Hz and with an amplitude below 20 μm. Time series of raw ultrasound images were analyzed to extract the B-mode intensity, the scatterer displacement, and the shear modulus at a variety of different microvibration amplitudes.