Article

# Magnetic Resonance Electrical Impedance Tomography (MREIT)

(Impact Factor: 2.91). 02/2011; 53(1):40-68. DOI: 10.1137/080742932
Source: DBLP

ABSTRACT

Magnetic resonance electrical impedance tomography (MREIT) is a recently developed medical imaging modality visualizing conductivity images of an electrically conducting object. MREIT was motivated by the well-known ill-posedness of the image reconstruction problem of electrical impedance tomography (EIT). Numerous experiences have shown that practically measurable data sets in an EIT system are insufficient for a robust reconstruction of a high-resolution static conductivity image due to its ill-posed nature and the influences of errors in forward modeling. To overcome the inherent ill-posed characteristics of EIT, the MREIT system was proposed in the early 1990s to use the internal data of magnetic flux density ${\bf B}=(B_x,B_y,B_z)$, which is induced by an externally injected current. MREIT uses an MRI scanner as a tool to measure the $z$-component $B_z$ of the magnetic flux density, where $z$ is the axial magnetization direction of the MRI scanner. In 2001, a constructive $B_z$-based MREIT algorithm called the harmonic $B_z$ algorithm was developed and its numerical simulations showed that high-resolution conductivity image reconstructions are possible. This novel algorithm is based on the key observation that the Laplacian $\Delta B_z$ probes changes in the log of the conductivity distribution along any equipotential curve having its tangent to the vector field ${\bf J}\times (0,0,1)$, where ${\bf J}=(J_x,J_y,J_z)$ is the induced current density vector. Since then, imaging techniques in MREIT have advanced rapidly and have now reached the stage of in vivo animal and human experiments. This paper reviews MREIT from its mathematical framework to the most recent human experiment outcomes.

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Available from: Eung Je Woo, Dec 18, 2013
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• "Such methods are also known under the name of " hybrid inverse problems " . Notable examples are the coupling of Magnetic Resonance with Electrical Impedance Tomography [45], Ultrasound and Electrical Impedance Tomography [11], Magnetic Resonance and Elastography [26]. To fix ideas, let us focus on Ultrasound Modulated Electrical Impedance Tomography. "
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• "EIT has however a limited spatial resolution, since the surface measurements are less sensitive to conductivity changes in inner regions of the patient [5]. Recently, several hybrid tomography techniques have been developed, which are based on electric and magnetic fields [6], [7], MR signals [8] Corresponding author: N. De Geeter (E-mail: Nele.DeGeeter@UGent.be). or acoustic modalities [9], [10]. "
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• "In 2001 [5], an imaging technique of MREIT without mechanical rotation, called harmonic í µí°µ í µí± § algorithm, was developed to provide both conductivity image and current density image. After invention of the harmonic í µí°µ í µí± § algorithm, MREIT has advanced rapidly [6] [7]. However, it still remains a technical problem to reduce the injection current down to a level for routine clinical use while maintaining the spatial resolution of the resulting conductivity images. "
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