Investigation of electrical conductivity changes during brain functional activity in 3T MRI

Area of Science:

• Neuroimaging
• Biophysics
• Electrical Engineering

Background:

• Blood oxygenation level-dependent functional magnetic resonance imaging (fMRI) visualizes brain activity via hemodynamic responses.
• Investigating in-vivo electrical property changes during brain function using MRI remains underexplored.
• Existing MRI methods primarily focus on metabolic demand rather than direct electrical property monitoring.

Purpose of the Study:

• To explore the relationship between fMRI signals and changes in electrical conductivity during brain function.
• To investigate the feasibility of using phase-based electrical property tomography for in-vivo measurements.
• To correlate electrical conductivity changes with known brain activation patterns.

Main Methods:

• Phase-based electrical property tomography was employed to measure electrical conductivity changes at the Larmor frequency.
• In-vivo experiments were conducted on motor and visual cortex activations.
• Electromagnetic radio-frequency simulations were performed to model activation states and validate in-vivo findings.

Main Results:

• Consistent negative correlations were observed between electrical conductivity changes and functional activity, with conductivity decreasing in active regions.
• B1 phase mapping showed positive correlations around activation areas, complementing conductivity measurements.
• Simulations corroborated in-vivo findings, demonstrating similar trends for B1 phase and conductivity under simulated activation states.

Conclusions:

• In-vivo electrical conductivity changes are measurable during brain activity, providing a new dimension to functional neuroimaging.
• The study highlights the potential of electrical property tomography as a complementary technique to fMRI.
• Further research is required to elucidate the underlying biophysical mechanisms and refine measurement techniques, addressing potential false-positive signals.