ELECTRICAL-IMPEDANCE TOMOGRAPHY USING INDUCED CURRENTS

Date

1994-06-01

Author

Gençer, Nevzat Güneri
Kuzuoğlu, Mustafa

Metadata

Show full item record

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Item Usage Stats

153
views

0
downloads

The mathematical basis of a new imaging modality, Induced Current Electrical Impedance Tomography (EIT), is investigated. The ultimate aim of this technique is the reconstruction of conductivity distribution of the human body, from voltage measurements made between electrodes placed on the surface, when currents are induced inside the body by applied time varying magnetic fields. In this study the two-dimensional problem is analyzed. A specific 9-coil system for generating nine different exciting magnetic fields (50 kHz) and 16 measurement electrodes around the object are assumed. The partial differential equation for the scalar potential function in the conductive medium is derived and Finite Element Method (FEM) is used for its solution. Sensitivity matrix, which relates the perturbation in measurements to the conductivity perturbations, is calculated. Singular Value Decomposition of the sensitivity matrix shows that there are 135 independent measurements. It is found that measurements are less sensitive to changes in conductivity of the object's interior. While in this respect induced current EIT is slightly inferior to the technique of injected current EIT (using Sheffield protocol), its sensitivity matrix is better conditioned. The images obtained are found to be comparable to injected current EIT images in resolution. Design of a coil system for which parameters such as sensitivity to inner regions and condition number of the sensitivity matrix are optimum, remains to be made.

Subject Keywords

Computed-tomography

URI

https://hdl.handle.net/11511/46505

Journal

IEEE TRANSACTIONS ON MEDICAL IMAGING

DOI

https://doi.org/10.1109/42.293927

Collections

Department of Electrical and Electronics Engineering, Article

Suggestions

OpenMETU
Core

Induced current magnetic resonance electrical impedance tomography (ICMREIT) with low frequency switching of gradient fields Eroğlu, Hasan Hüseyin; Eyüboğlu, Behçet Murat; Department of Electrical and Electronics Engineering (2017) In this thesis, it is aimed to investigate induced current magnetic resonance electrical impedance tomography (ICMREIT) starting from modeling and analysis to experimental validation. Forward and inverse problems of ICMREIT are formulated. A magnetic resonance imaging (MRI) pulse sequence is proposed for the realization of ICMREIT using the slice selection (z) gradient coil of MRI scanners. Considering the proposed MRI pulse sequence, relationship between the low frequency (LF) MR phase and the secondary ma...
ELECTRICAL-IMPEDANCE TOMOGRAPHY OF TRANSLATIONALLY UNIFORM CYLINDRICAL OBJECTS WITH GENERAL CROSS-SECTIONAL BOUNDARIES IDER, YZ; Gençer, Nevzat Güneri; ATALAR, E; TOSUN, H (1990-03-01) An algorithm is developed for electrical impedance tomography (EIT) of finite cylinders with general cross-sectional boundaries and translationally uniform conductivity distributions. The electrodes for data collection are assumed to be placed around a crosssectional plane; therefore the axial variation of the boundary conditions and also the potential field are expanded in Fourier series. For each Fourier component a two-dimensional (2-D) partial differential equation is derived. Thus the 3-D forward probl...
Tissue resistivity estimation in the presence of positional and geometrical uncertainties Baysal, U; Eyüboğlu, Behçet Murat (2000-08-01) Geometrical uncertainties (organ boundary variation and electrode position uncertainties) are the biggest sources of error in estimating electrical resistivity of tissues from body surface measurements. In this study, in order to decrease estimation errors, the statistically constrained minimum mean squared error estimation algorithm (MiMSEE) is constrained with a priori knowledge of the geometrical uncertainties in addition to the constraints based on geometry, resistivity range, linearization and instrume...
Equipotential projection based magnetic resonance electrical impedance tomography (mr-eit) for high resolution conductivity imaging Özdemir, Mahir Sinan; Eyüboğlu, Behçet Murat; Department of Electrical and Electronics Engineering (2003) In this study, a direct reconstruction algorithm for Magnetic Resonance Electrical Impedance Tomography (MR-EIT) is proposed and experimentally implemented for high resolution true conductivity imaging. In MR-EIT, elec trical impedance tomography (EIT) and magnetic resonance imaging (MRI) are combined together. Current density measurements are obtained making use of Magnetic Resonance Current Density Imaging (MR-CDI) techniques and peripheral potential measurements are determined using conventional EIT tech...
Electrical Impedance Tomography Induced Current Gençer, Nevzat Güneri (2006-01-01) The ultimate goal of induced‐current electrical impedance tomography (ICEIT) is to image the electrical impedance distribution within the human body. In ICEIT, time‐varying magnetic fields are applied to induce currents in the body and surface voltage measurements are used to reconstruct impedance distribution. Time‐varying fields are usually generated by sinusoidal current‐carrying wires encircling the conducting body. Given the conductivity distribution, calculating the surface voltages due a given coil c...

Citation Formats

N. G. Gençer and M. Kuzuoğlu, “ELECTRICAL-IMPEDANCE TOMOGRAPHY USING INDUCED CURRENTS,” IEEE TRANSACTIONS ON MEDICAL IMAGING, pp. 338–350, 1994, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/46505.