Electrical conductivity and permittivity maps of brain tissues derived from water content based on T<sub>1</sub>‐weighted acquisition

Michel, Eric; Hernández, Daniel; Lee, Soo Yeol

doi:10.1002/mrm.26193

Cited by 59 publications

(103 citation statements)

References 76 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For the clinical purpose of tumor malignancy diagnosis, conductivity tends to provide more valuable information than permittivity in the frequency above 100 MHz because permittivity is dominated by water content, whereas conductivity is related to both water content and ion concentration (1,46,47). In the current study, a lower relative difference of permittivity than that of conductivity has been observed in the imaging experiment and confirmed by dielectric measurement with a probe.…”

Section: Discussionsupporting

confidence: 70%

In vivo imaging of electrical properties of an animal tumor model with an 8‐channel transceiver array at 7 T using electrical properties tomography

Liu

Shao

Wang

et al. 2017

Magnetic Resonance in Med

View full text Add to dashboard Cite

Purpose To develop and evaluate a technique for imaging electrical properties (EP, conductivity and permittivity) of an animal tumor model in vivo using MRI. Methods EP were reconstructed from the calculated EP gradient, which was derived using two sets of measured transmit B1 magnitude and relative phase maps with the sample and RF coil oriented in the positive and negative z-directions, respectively. An eight-channel transceiver microstrip array RF coil fitting the size of the animal was developed for generating and mapping B1 fields to reconstruct EP. The technique was evaluated at 7T using a physical phantom and in vivo on two Copenhagen rats with subcutaneously implanted AT-1 rat prostate cancer on a hind limb. Results The reconstructed EP in the phantom experiment was in good agreement with the target EP map determined by a dielectric probe. Reconstructed conductivity map of the animals revealed the boundary between tumor and healthy tissue consistent with the boundary indicated by T1-weighted MRI. Conclusion A technique for imaging EP of an animal tumor model using MRI has been developed with high sensitivity, accuracy and resolution as demonstrated in the phantom experiment. Further animal experiments are needed to demonstrate its translational value for tumor diagnosis.

show abstract

Section: Discussionsupporting

confidence: 70%

In vivo imaging of electrical properties of an animal tumor model with an 8‐channel transceiver array at 7 T using electrical properties tomography

Liu

Shao

Wang

et al. 2017

Magnetic Resonance in Med

View full text Add to dashboard Cite

show abstract

“…This overestimated derived brain conductivity suggests that the agarose gel might not be an accurate model for brain conductivity. To build an appropriate brain conductivity surrogate, in addition to ion concentrations (Na + , K + , CL − ), factors such as ion binding effects, 42 the mobility of conductive ions, 43,44 and tissue water fraction 17,40 should be considered in future studies. Recently, van Lier et al 18 demonstrated a positive correlation between brain conductivity and sodium concentration at 7T, and the regression slope and offset was found to be in accordance with saline solutions.…”

Section: Discussionmentioning

confidence: 99%

“…In addition, as cellular membranes presented extremely low resistance to the electromagnetic (EM) wave propagation at RF and microwave frequencies, tissue conductivity becomes highly correlated with the tissue water fraction. Based on this correlation model, conductivity maps were computed from the water content maps of the brain …”

Section: Introductionmentioning

confidence: 99%

“…Based on this correlation model, conductivity maps were computed from the water content maps of the brain. 17 However, apart from the effects of tissue water content and the movement of water molecules, ionic salts in tissue, such as sodium (Na + ), potassium (K + ), and chlorine (Cl − ), also influence tissue conductivity. Thus far, studies on the relationship between tissue ion content and conductivity are not sufficiently elaborated.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Correlation of quantitative conductivity mapping and total tissue sodium concentration at 3T/4T

Liao

Lechea

Magill

et al. 2019

Magnetic Resonance in Med

View full text Add to dashboard Cite

Purpose To investigate the correlation between electrical conductivity and sodium concentration, both measured in vivo, in the human brain. Methods Conductivity measurements were performed on samples with different sodium (Na+) and agarose concentrations using a dielectric probe, and the correlation between conductivity and Na+ content was evaluated. Subsequently, brain conductivity and total Na+ content maps were measured in 8 healthy subjects using phase‐based MREPT and sodium MRI, respectively. After co‐registration and spatial normalization to the 1 mm 152 MNI brain atlas, the relationship between conductivity and tissue sodium concentration (TSC) was examined within different brain regions. Results The conductivities of agarose gels increased linearly with NaCl concentration, while remaining almost independent of agarose content. When measured in healthy subjects, conductivities showed positive correlation with total tissue sodium concentration (R = 0.39, P < 0.005). The same trend was found in gray matter (R = 0.36, P < 0.005) and in white matter (R = 0.28, P < 0.05). Conclusion Tissue conductivity shows a positive correlation with total sodium concentration. Conductivity might serve as a novel technique to visualize the total tissue electrolyte concentration, although refinements in the consideration of e.g., tissue water content, would be necessary to improve the quantitative value.

show abstract

“…From a biological point of view, the human brain is a multilayered heterogeneous structure with different relative permittivities ε r . Michel, Hernandez, and Lee () provide specific values for brain mediums and demonstrate that water concentration levels result in different permittivities. Indeed, the electrical characteristics of the water molecule and, consequently, the relative permittivity of the medium are function of the wave frequency.…”

Section: Existing Tracking Systemsmentioning

confidence: 99%

Tracking systems for intracranial medical devices: A review

François

Duplat²,

Haliyo

et al. 2019

Med Devices & Sens

View full text Add to dashboard Cite

In minimally invasive surgery, especially in neurosurgery, the ability to reach deep and functional structures without damage remains a major challenge. Recent breakthroughs in microtechnologies have enabled the downsizing of an increasing number of devices. In such a context, the possibility to navigate a micromedical device inside the human brain is a reachable ambition. One of the most expected applications is the identification and the treatment of early‐stage cancers which could strongly improve therapies efficiency. Despite these remarkable attainments, micromachines, to actually become revolutionary, require a tracking system at least as accurate as its size and working in an heterogeneous environment. The aim of the present paper was to provide an overview of the state of the art in medical device tracking systems for the brain. Firstly, the latest advances are categorized by technological family: magnetic field, electromagnetic waves, magnetic resonance, ultrasound waves and hybrid solutions. Secondly, in a comparative purpose, performance criteria are evaluated and displayed in radar diagrams and graphs to highlight the three dimensions challenge the systems should take up: performance, invasiveness and user experience. Finally, the present and future of each localization family are provided.

show abstract

Electrical conductivity and permittivity maps of brain tissues derived from water content based on T₁‐weighted acquisition

Cited by 59 publications

References 76 publications

In vivo imaging of electrical properties of an animal tumor model with an 8‐channel transceiver array at 7 T using electrical properties tomography

In vivo imaging of electrical properties of an animal tumor model with an 8‐channel transceiver array at 7 T using electrical properties tomography

Correlation of quantitative conductivity mapping and total tissue sodium concentration at 3T/4T

Tracking systems for intracranial medical devices: A review

Contact Info

Product

Resources

About

Electrical conductivity and permittivity maps of brain tissues derived from water content based on T1‐weighted acquisition

Cited by 59 publications

References 76 publications

In vivo imaging of electrical properties of an animal tumor model with an 8‐channel transceiver array at 7 T using electrical properties tomography

In vivo imaging of electrical properties of an animal tumor model with an 8‐channel transceiver array at 7 T using electrical properties tomography

Correlation of quantitative conductivity mapping and total tissue sodium concentration at 3T/4T

Tracking systems for intracranial medical devices: A review

Contact Info

Product

Resources

About

Electrical conductivity and permittivity maps of brain tissues derived from water content based on T₁‐weighted acquisition