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Induced Current Magnetic Resonance Electrical Conductivity Imaging With Oscillating Gradients
Date
2018-07-01
Author
Eroglu, Hasan H.
Sadighi, Mehdi
Eyüboğlu, Behçet Murat
Metadata
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In this paper, induced current magnetic resonance electrical impedance tomography (ICMREIT) by means of current induction due to time-varying gradient fields of magnetic resonance imaging (MRI) systems is proposed. Eddy current and secondary magnetic flux density distributions are calculated for a numerical model composed of a z-gradient coil and a cylindrical conductor. An MRI pulse sequence is developed for the experimental evaluation of ICMREIT on a 3T MRI scanner. A relationship between the secondary magnetic flux density and the low-frequency (LF) MR phase is formulated. Characteristics of the LF phase, the eddy current, and the reconstructed conductivity distributions based on the simulated and the physical measurements are in agreement. Geometric shifts, which may contaminate the LF phase measurements, are not observed in the MR magnitude images. Low sensitivity of the LF phase measurements is a major limitation of ICMREIT towards clinical applications. The reconstructed conductivity images are rough estimates of true conductivity distribution of the experimental phantoms. Although the experimental results show that ICMREIT is safe and potentially applicable, its measurement sensitivity and reconstruction accuracy need to be optimized in order to improve the technique towards clinical applications.
Subject Keywords
Electrical impedance tomography
,
Eddy current
,
Gradient coil
,
Induced current
,
Image reconstruction
,
Low frequency phase
,
Magnetic resonance imaging
URI
https://hdl.handle.net/11511/37780
Journal
IEEE TRANSACTIONS ON MEDICAL IMAGING
DOI
https://doi.org/10.1109/tmi.2018.2795718
Collections
Department of Electrical and Electronics Engineering, Article
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Eroğlu, Hasan Hüseyin; Sadighi, Mehdi; Eyüboğlu, Behçet Murat (2018-06-27)
In gradient coil based induced current magnetic resonance electrical impedance tomography (ICMREIT), gradient coils of a conventional magnetic resonance imaging (MRI) scanner are excited with time varying waveforms embedded in an MRI pulse sequence [1], [2], [3]. As a result of the excitation, low frequency (LF) eddy current is induced in the volume conductor media being imaged which accumulates phase to MR signal. By measuring and post-processing the LF phase of the eddy current, LF conductivity images are...
Induced Current Magnetic Resonance Electrical Impedance Tomography with z-Gradient Coil
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Magnetic Resonance Electrical Impedance Tomography (MREIT) is a medical imaging method that provides images of electrical conductivity at low frequencies (0-1 kHz). In MREIT, electrical current is applied to the body via surface electrodes and corresponding magnetic flux density is measured by means of Magnetic Resonance (MR) phase imaging techniques. By utilizing the magnetic flux density measurements and surface potential measurements images of true conductivity distribution can be reconstructed. In order...
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Induced Current Magnetic Resonance Electrical Impedance Tomography (ICMREIT) is an emerging imaging methodology that utilizes Magnetic Resonance Imaging (MRI) techniques to visualize the electrical conductivity as a new contrast. In ICMREIT, by fast switching of gradient fields of Magnetic Resonance (MR) system eddy currents are induced in the imaging volume. The secondary magnetic field generated by the induced eddy currents can be extracted from the MR phase images. Image reconstruction algorithms then us...
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BibTeX
H. H. Eroglu, M. Sadighi, and B. M. Eyüboğlu, “Induced Current Magnetic Resonance Electrical Conductivity Imaging With Oscillating Gradients,”
IEEE TRANSACTIONS ON MEDICAL IMAGING
, pp. 1606–1617, 2018, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/37780.