Noninvasive Imaging of Bioimpedance Distribution by Means of Current Reconstruction Magnetic Resonance Electrical Impedance Tomography

Abstract

We have developed a novel magnetic resonance electrical impedance tomography (MREIT) algorithm-current reconstruction MREIT algorithm-for noninvasive imaging of electrical impedance distribution of a biological system using only one component of magnetic flux density. The newly proposed algorithm uses the inverse of Biot-Savart Law to reconstruct the current density distribution, and then, uses a modified J-substitution algorithm to reconstruct the conductivity image. A series of computer simulations has been conducted to evaluate the performance of the proposed current reconstruction MREIT algorithm with simulation settings for breast cancer imaging applications, with consideration of measurement noise, current injection strength, size of simulated tumors, spatial resolution, and position dependency. The present simulation results are highly promising, demonstrating the high spatial resolution, high accuracy in conductivity reconstruction, and robustness against noise of the proposed algorithm for imaging electrical impedance of a biological system. The present MREIT method may have potential applications to breast cancer imaging and imaging of other organs.

A feasibility study of magnetic resonance electrical impedance tomography for prostate cancer detection

“…The entity model, forward FE model and cross-section view of the inverse FE model for the external MREIT study are shown in figure 1. In the present study, two bipolar rectangular currents (Gao et al 2006, 2008) were injected from E1 to E3 and from E2 to E4, respectively. A number of research results reported that a current density of 2 A/m 2 is safe for the human body below 3 kHz (Giland et al 2007, Dalziel 1972).…”

2D-Stromverteilungen und ihre Magnetfelder: ein Beispiel-Problem / 2D Current Distributions and Their Magnetic Fields: A Showcase Problem

“…Ansätze zur Rekonstruktion der Stromdichte J aus dem gemessenen (diskretisierten) Magnetfeld lassen sich grob, in diskrete und kontinuierliche Verfahren, unterteilen [6]. Im diskreten Ansatz wird J als Ströme durch diskrete Leitungsstücke mit diskreten Flächen modelliert, die in einem Gitter angeordnet sind [1]. Kontinuierliche Verfahren betrachten das Gesetz von Biot-Savart hingegen als Faltungsintegral, mit der vom Messabstand h x abhängigen Green- Funktion G(x -x , y -y ), das über die Fourier-Transformation im Frequenzbereich gelöst werden kann [3; 8].…”

Magnetic-Resonance-Based Electrical Properties Tomography: A Review

“…However, similar to EIT, the surface measurements and ill-posedness of the inverse problem result in low spatial resolution. 3) Magnetic Resonance Electrical Impedance Tomography (MREIT), which originates from Magnetic Resonance Current Density Imaging (MRCDI) [30], [31], measures the local magnetic field induced by surface current injection, and reconstructs static cross-sectional conductivity images [32]–[35]. While MREIT provides high spatial resolution, what remains to be demonstrated includes the safety issues due to the usage of high level of current injection in order to achieve sufficient SNR, and the shielding effect due to the use of surface electrodes for current injection.…”