# First-Order Induced Current Density Imaging and Electrical Properties Tomography in MRI

Patrick S. Fuchs, Stefano Mandija, Peter R.S. Stijnman, Wyger M. Brink, Cornelis A.T. van den Berg, Rob F. Remis

Research output: Contribution to journalArticleScientificpeer-review

## Abstract

In this paper, we present an efficient dedicated electrical properties tomography (EPT) algorithm (called first-order current density EPT ) that exploits the particular radio frequency field structure, which is present in the midplane of a birdcage coil, to reconstruct conductivity and permittivity maps in this plane from B ^ + 1 data. The algorithm consists of a current density and an electrical properties step. In the current density reconstruction step, the induced currents in the midplane are determined by acting with a specific first-order differentiation operator on the B ^ + 1 data. In the electrical properties step, we first determine the electric field strength by solving a particular integral equation, and subsequently determine conductivity and permittivity maps from the constitutive relations. The performance of the algorithm is illustrated by presenting reconstructions of a human brain model based on simulated (noise corrupted) data and of a known phantom model based on experimental data. The method manages to reconstruct conductivity profiles without model related boundary artifacts and is also more robust to noise because only first-order differencing of the data is required as opposed to second-order data differencing in Helmholtz-based approaches. Moreover, reconstructions can be performed in less than a second, allowing for essentially real-time electrical properties mapping.
Original language English 624-631 8 IEEE Transactions on Computational Imaging 4 4 https://doi.org/10.1109/TCI.2018.2873407 Published - 2018

### Bibliographical note

Accepted author manuscript

## Keywords

• Magnetic resonance imaging
• electrical properties tomography
• dielectric tissue properties
• $\hat{B}_1^+$field

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• ### Electromagnetic Fields in MRI: Analytical Methods and Applications

Fuchs, P. S., 2020, 133 p.

Research output: ThesisDissertation (TU Delft)

Open Access
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