Electrical impedance tomography using the magnetic field generated by injected currents

Birgül, Özlem; Ider, Y.Z.

doi:10.1109/iembs.1996.651975

Cited by 19 publications

(27 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Finally, the MR-EIT method [27]- [29] is closest in spirit to the method proposed in this paper. Like in our method, the excitation is by currents injected by boundary electrodes, and the currents in the cross section are sensed by sensing the magnetic field perpendicular to the cross section.…”

Section: Introductionmentioning

confidence: 91%

“…(The MRI acquisition of the magnetic field distribution reported in [30] took about 8 s.) In contrast, the EMIT method proposed in this paper uses inexpensive, small pickup inductor coils. Second, the versions of MR-EIT proposed in [27], [28] only used sensing of the magnetic field, whereas EMIT utilizes the information available from measurements of both electrode potentials and coil-induced voltage. Finally, while [29] incorporated the use of electrode potentials, its proposed reconstruction procedure, which uses knowledge of the magnetic field (and, therefore, of the current density) throughout the object, is fundamentally different from the one we propose for EMIT, which only measures the magnetic field at a finite number of locations outside the object.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Electromagnetic impedance tomography (EMIT): a new method for impedance imaging

Levy

Adam

Bresler

2002

IEEE Trans. Med. Imaging

View full text Add to dashboard Cite

We propose a new impedance imaging method, electromagnetic impedance tomography (EMIT), in which the boundary electric potential measurements in electrical impedance tomography (EIT) are augmented by measurements of the exterior magnetic field induced by the currents excited in the object by the standard EIT procedures. These magnetic measurements can be obtained reliably and inexpensively by simple pickup coils located around the imaged cross section. We derive expressions for the forward problem and for the Jacobian of the measurements, and propose an iterative reconstruction algorithm using a squared error cost function. The performance of EMIT and EIT is compared in numerical simulations using a finite-element model for the conductivity distribution of several phantoms. Evaluation of the rank and condition of the Jacobian demonstrates that the additional magnetic measurements provided by a few pickup coils in EMIT turn an underdetermined EIT problem into a well-posed one with reasonable condition, or significantly improve the conditioning of the EIT problem when it is already fully determined. Reconstructions of various phantoms reveal that EMIT provides particularly significant visual and quantitative improvement (threefold to tenfold reduction in the root-mean-squared error) in the sensitivity at the center of the object, which is the area most difficult to image using EIT.

show abstract

Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Electromagnetic impedance tomography (EMIT): a new method for impedance imaging

Levy

Adam

Bresler

2002

IEEE Trans. Med. Imaging

View full text Add to dashboard Cite

show abstract

“…It utilizes an MRI scanner to measure magnetic flux density data inside the object induced by externally injected currents at frequencies less than several kHz [1][2][3][4][5][6][7]. Recent MREIT studies of postmortem and in vivo animals and human subjects demonstrated that significant conductivity contrasts exist among different tissues and organs at such a low frequency [8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

In vivo magnetic resonance electrical impedance tomography of canine brain: Disease model study of ischemia and abscess

et al. 2011

View full text Add to dashboard Cite

Purpose In this study, we performed in vivo disease model animal experiments to validate the MREIT technique in terms of its capability to produce a conductivity contrast corresponding to brain ischemia and abscess. Methods Injecting 5 mA imaging currents into the head of an anesthetized dog, we collected induced magnetic flux density data using a 3T MRI scanner. Applying the harmonic B z algorithm to the data, we reconstructed scaled conductivity images providing conductivity contrast information. To investigate any change of electrical conductivity due to brain diseases of ischemia and abscess, we scanned an animal with such a regional brain disease along with a separate prior scan of the same animal having no disease model. Results In the brain ischemic region, conductivity images show a significantly decreased contrast. The conductivity images of brain abscess show a significantly increased contrast, which is not apparent in the normal brain. ConclusionsThe results indicate that MREIT conductivity images provide meaningful diagnostic information that is not available from other imaging modalities. We suggest further animal imaging experiments with numerous disease models to support clinical significance of the MREIT conductivity imaging method.

show abstract

“…A Magnetic Resonance Imaging (MRI) scanner is used to measure the induced magnetic flux density inside the subject and the current density distribution can be calculated according to the Ampere's law. The conductivity distribution images can be reconstructed based on the relationship between the conductivity and the measured magnetic flux density combined with the current density [3].…”

Section: Introductionmentioning

confidence: 99%

Reconstruction of conductivity distribution of brain tissue from two components magnetic flux density

Xu¹,

Yan²

2010

JBiSE

View full text Add to dashboard Cite

In this paper the recent Magnetic resonance electrical impedance imaging (MREIT) technique is used to image non-invasively the three-dimensional continuous conductivity distribution of the head tissues. With the feasibility of the human head being rotated twice in the magnetic resonance imaging (MRI) system, a continuous conductivity reconstruction MREIT algorithm based on two components of the measured magnetic flux density is introduced. The reconstructed conductivity image could be obtained through solving iter- atively a non-linear matrix equation. According to the present algorithm of using two magnetic flux den- sity components, numerical simulations were per- formed on a concentric three-sphere and realistic human head model (consisting of the scalp, skull and brain) with the uniform and non-uniform isotropic target conductivity distributions. Based on the algorithm, the reconstruction of scalp and brain conductivity ratios could be figured out even under the condition that only one current is injected into the brain. The present results show that the three-dimensional continuous conductivity reconstruction method with two magnetic flux density components for the realistic head could get better results than the method with only one magnetic flux density component. Given the skull conductivity ratio, the relative errors of scalp and brain conductivity values were reduced to less than 1% with the uniform conductivity distribution and less than 6.5% with the non-uniform distribution for different noise levels. Furthermore, the algorithm also shows fast convergence and improved robustness against noise

show abstract

Electrical impedance tomography using the magnetic field generated by injected currents

Cited by 19 publications

References 3 publications

Electromagnetic impedance tomography (EMIT): a new method for impedance imaging

Electromagnetic impedance tomography (EMIT): a new method for impedance imaging

In vivo magnetic resonance electrical impedance tomography of canine brain: Disease model study of ischemia and abscess

Reconstruction of conductivity distribution of brain tissue from two components magnetic flux density

Contact Info

Product

Resources

About