Induced Current Magnetic Resonance Electrical Conductivity Imaging With Oscillating Gradients

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 n...

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Bibliographic Details
Published in:IEEE transactions on medical imaging 2018-07, Vol.37 (7), p.1606-1617
Main Authors: Eroglu, Hasan H., Sadighi, Mehdi, Eyuboglu, B. Murat
Format: Article
Language:English
Subjects:
Algorithms
Computer simulation
Conductivity
Conductors
Current measurement
eddy current
Eddy currents
Electric Conductivity
Electrical conductivity
Electrical impedance
Electrical impedance tomography
Electrical resistivity
Flux density
gradient coil
Image Processing, Computer-Assisted - methods
Image reconstruction
induced current
low frequency phase
Magnetic flux
Magnetic resonance imaging
Magnetic Resonance Imaging - methods
Magnetism
Mathematical models
Medical imaging
NMR
Nuclear magnetic resonance
Phantoms
Phantoms, Imaging
Radio frequency
Resonance
Sensitivity
Signal-To-Noise Ratio
Therapeutic applications
Tomography - methods
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Summary: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.
ISSN:0278-0062
1558-254X
DOI:10.1109/TMI.2018.2795718