Radiofrequency ablation lesion detection using MR-based electrical conductivity imaging: A feasibility study of<i>ex vivo</i>liver experiments

Chauhan, Munish; Jeong, Woo Chul; Kim, Hyung Joong; Kwon, Oh In; Woo, Eung Je

doi:10.3109/02656736.2013.842265

Cited by 10 publications

(15 citation statements)

References 34 publications

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“…27 Considering that tissue conditions such as anisotropy and isotropy originate from microscopic structural features, in vivo imaging of current density has potential clinical applications as a monitoring tool for understanding the therapeutic effects of electrical stimulation such as deep brain stimulation, transcranial direct current stimulation, and radiofrequency ablation. [27][28][29][30] In conclusion, we experimentally imaged the cross-sectional current density distribution of living brain tissue using a recently developed MREIT technique. To implement in vivo current density mapping, we obtained magnetic flux density of canine brains.…”

Section: Discussionmentioning

confidence: 99%

In vivo mapping of current density distribution in brain tissues during deep brain stimulation (DBS)

Sajib

Kim

et al. 2017

AIP Advances

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New methods for in vivo mapping of brain responses during deep brain stimulation (DBS) are indispensable to secure clinical applications. Assessment of current density distribution, induced by internally injected currents, may provide an alternative method for understanding the therapeutic effects of electrical stimulation. The current flow and pathway are affected by internal conductivity, and can be imaged using magnetic resonance-based conductivity imaging methods. Magnetic resonance electrical impedance tomography (MREIT) is an imaging method that can enable highly resolved mapping of electromagnetic tissue properties such as current density and conductivity of living tissues. In the current study, we experimentally imaged current density distribution of in vivo canine brains by applying MREIT to electrical stimulation. The current density maps of three canine brains were calculated from the measured magnetic flux density data. The absolute current density values of brain tissues, including gray matter, white matter, and cerebrospinal fluid were compared to assess the active regions during DBS. The resulting current density in different tissue types may provide useful information about current pathways and volume activation for adjusting surgical planning and understanding the therapeutic effects of DBS.

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Section: Discussionmentioning

confidence: 99%

In vivo mapping of current density distribution in brain tissues during deep brain stimulation (DBS)

Sajib

Kim

et al. 2017

AIP Advances

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“…4 The injected currents through the attached electrode on the surface of imaging objects induce unique electromagnetic fields depending on the tissues type and current pathways. 3,4,10 These are closely related to the internal conductivity distribution, the boundary geometry of the imaging object, and partially to the electrode configuration. 12,13 Therefore, the image quality is highly dependent on the measured voltage, current density, and magnetic flux density when reconstructing the electrical conductivity.…”

Section: Introductionmentioning

confidence: 99%

“…[10][11][12] Although they provide distinct effects and reliable outcomes, the exact response to the objective tissues is still unclear because of the difficulties in in vivo measurement of electromagnetic fields. Since the electromagnetic field is affected by the injected currents and electrical conductivities of biological tissue, [13][14][15][16] the map of voltage (u), current density (J), and magnetic flux density (B z ) can provide meaningful information for determining the tissue type and current pathways inside biological tissues.…”

Section: Introductionmentioning

confidence: 99%

“…[3][4][5] Numerous studies have reported significant conductivity changes observed not only in the tissue itself, such as tumors, abscesses, or ischemia, but also in the physical environment, such as electrical stimulation, temperature, therapeutic ablation, and measuring frequencies. [6][7][8][9][10] Therefore, in vivo measurement of electrical conductivity has potential as a clinically useful tool for representing the physiological and pathological conditions of tissues.…”

Section: Introductionmentioning

confidence: 99%

“…The cell membrane is regarded as an electrical insulator, showing a high capacitance and a low but complicated pattern of conductivity. 4,10 The extra-and intracellular fluids are regarded as highly conductive materials. 4 The injected currents through the attached electrode on the surface of imaging objects induce unique electromagnetic fields depending on the tissues type and current pathways.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of three-dimensional anisotropic head model for mapping realistic electromagnetic fields of brain tissues

Jeong

Sajib

et al. 2015

AIP Advances

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Electromagnetic fields provide fundamental data for the imaging of electrical tissue properties, such as conductivity and permittivity, in recent magnetic resonance (MR)-based tissue property mapping. The induced voltage, current density, and magnetic flux density caused by externally injected current are critical factors for determining the image quality of electrical tissue conductivity. As a useful tool to identify bio-electromagnetic phenomena, precise approaches are required to understand the exact responses inside the human body subject to an injected currents. In this study, we provide the numerical simulation results of electromagnetic field mapping of brain tissues using a MR-based conductivity imaging method. First, we implemented a realistic three-dimensional human anisotropic head model using high-resolution anatomical and diffusion tensor MR images. The voltage, current density, and magnetic flux density of brain tissues were imaged by injecting 1 mA of current through pairs of electrodes on the surface of our head model. The current density map of anisotropic brain tissues was calculated from the measured magnetic flux density based on the linear relationship between the water diffusion tensor and the electrical conductivity tensor. Comparing the current density to the previous isotropic model, the anisotropic model clearly showed the differences between the brain tissues. This originates from the enhanced signals by the inherent conductivity contrast as well as the actual tissue condition resulting from the injected currents.

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Experimental validations of in vivo human musculoskeletal tissue conductivity images using MR‐based electrical impedance tomography

Jeong

Meng

Kim

et al. 2014

Bioelectromagnetics

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Magnetic resonance (MR)-based electrical impedance tomography (MREIT) is a widely used imaging technique that provides high-resolution conductivity images at DC or below the 1 kHz frequency range. Using an MR scanner, this technique injects imaging currents into the human body and measures induced internal magnetic flux density data. By applying the recent progress of MREIT techniques, such as chemical shift artifact correction, multi-echo pulse sequence, and improved reconstruction algorithm, we can successfully reconstruct conductivity images of the human body. Meanwhile, numerous studies reported that the electrical conductivity of human tissues could be inferred from in vitro or ex vivo measurements of different species. However, in vivo tissues may differ from in vitro and/or ex vivo state due to the complicated tissue responses in living organs. In this study, we performed in vivo MREIT imaging of a human lower extremity and compared the resulting conductivity images with ex vivo biological tissue phantom images. The human conductivity images showed unique contrast between two different types of bones, muscles, subcutaneous adipose tissues, and conductive body fluids. Except for muscles and adipose tissues, the human conductivity images showed a similar pattern when compared with phantom results due to the anisotropic characteristic of muscle and the high conductive fluids in the adipose tissue.

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Radiofrequency ablation lesion detection using MR-based electrical conductivity imaging: A feasibility study ofex vivoliver experiments

Abstract: This ex vivo feasibility study demonstrates that current MREIT conductivity imaging can detect liver RF ablation lesions without using any contrast media or additional MR scan.

Cited by 10 publications

References 34 publications

In vivo mapping of current density distribution in brain tissues during deep brain stimulation (DBS)

In vivo mapping of current density distribution in brain tissues during deep brain stimulation (DBS)

Evaluation of three-dimensional anisotropic head model for mapping realistic electromagnetic fields of brain tissues

Experimental validations of in vivo human musculoskeletal tissue conductivity images using MR‐based electrical impedance tomography

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