Magnetohydrodynamic flow imaging of ionic solutions using electrical current injection and MR phase measurements

Area of Science:

• Medical Imaging
• Fluid Dynamics
• Biophysics

Background:

• Magnetohydrodynamic (MHD) flow, driven by electrical currents in conductive media, is relevant in biological systems.
• Imaging such flows during Magnetic Resonance Imaging (MRI) presents unique challenges.
• Understanding MHD flow is crucial for applications involving electrical stimulation in MRI environments.

Purpose of the Study:

• To develop and validate a method for imaging MHD flow of ionic solutions during MRI scans.
• To establish the relationship between MHD flow, injected electrical current, and MRI signal parameters.
• To assess the potential clinical applicability of the proposed imaging technique.

Main Methods:

• A multi-physics (MP) model integrating electrical current, laminar flow, and MR equations was developed.
• Conventional spoiled gradient echo MRI sequences with bipolar flow encoding gradients were employed.
• Numerical simulations and physical experiments were conducted for validation.

Main Results:

• The proposed method successfully images MHD flow, demonstrating a clear dependence of the MR phase on injected current and flow encoding parameters.
• Simulation and experimental results showed good agreement.
• A significant MR phase shift (1.5 radians) was observed for specific current and gradient parameters, indicating sensitivity.

Conclusions:

• The developed method enables the evaluation of MHD flow in conductive liquids during MRI with simultaneous electrical current injection.
• The technique shows promise for clinical applications, such as studying cerebrospinal fluid (CSF) dynamics during electrical neuromodulation in MRI.
• Further consideration of physiological flow dynamics, like CSF velocity, is necessary for clinical translation.