Acousto-electrical speckle pattern in Lorentz force electrical impedance tomography

TL;DR

This paper demonstrates the existence of an acousto-electrical speckle pattern in Lorentz force electrical impedance tomography, showing similarities to ultrasound speckle and linking acoustic parameters with electrical impedance variations.

Contribution

It introduces the concept of acousto-electrical speckle in Lorentz force electrical impedance tomography and compares its characteristics with ultrasound speckle.

Findings

Similar speckle patterns observed in both methods

Speckle driven by acoustic parameters but related to electrical impedance

Experimental validation with bovine muscle sample

Abstract

Ultrasound speckle is a granular texture pattern appearing in ultrasound imaging. It can be used to distinguish tissues and identify pathologies. Lorentz force electrical impedance tomography is an ultrasound-based medical imaging technique of the tissue electrical conductivity. It is based on the application of an ultrasound wave in a medium placed in a magnetic field and on the measurement of the induced electric current due to Lorentz force. Similarly to ultrasound imaging, we hypothesized that a speckle could be observed with Lorentz force electrical impedance tomography imaging. In this study, we first assessed the theoretical similarity between the measured signals in Lorentz force electrical impedance tomography and in ultrasound imaging modalities. We then compared experimentally the signal measured in both methods using an acoustic and electrical impedance interface. Finally, a bovine muscle sample was imaged using the two methods. Similar speckle patterns were observed. This indicates the existence of an "acousto-electrical speckle" in the Lorentz force electrical impedance tomography with spatial characteristics driven by the acoustic parameters but due to electrical impedance inhomogeneities instead of acoustic ones as is the case of ultrasound imaging.