# A mathematical and numerical framework for ultrasonically-induced lorentz force electrical impedance tomography

Habib Ammari, Pol Grasland-Mongrain, Pierre Millien, Laurent Seppecher, Jin Keun Seo

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)

## Abstract

We provide a mathematical analysis and a numerical framework for Lorentz force electrical conductivity imaging. Ultrasonic vibration of a tissue in the presence of a static magnetic field induces an electrical current by the Lorentz force. This current can be detected by electrodes placed around the tissue; it is proportional to the velocity of the ultrasonic pulse, but depends nonlinearly on the conductivity distribution. The imaging problem is to reconstruct the conductivity distribution from measurements of the induced current. To solve this nonlinear inverse problem, we first make use of a virtual potential to relate explicitly the current measurements to the conductivity distribution and the velocity of the ultrasonic pulse. Then, by applying a Wiener filter to the measured data, we reduce the problem to imaging the conductivity from an internal electric current density. We first introduce an optimal control method for solving such a problem. A new direct reconstruction scheme involving a partial differential equation is then proposed based on viscosity-type regularization to a transport equation satisfied by the current density field. We prove that solving such an equation yields the true conductivity distribution as the regularization parameter approaches zero. We also test both schemes numerically in the presence of measurement noise, quantify their stability and resolution, and compare their performance.

Original language English 1390-1409 20 Journal des Mathematiques Pures et Appliquees 103 6 https://doi.org/10.1016/j.matpur.2014.11.003 Published - 2015 Jun 1

## All Science Journal Classification (ASJC) codes

• Mathematics(all)
• Applied Mathematics

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