Induced current effects on functional magnetic resonance imaging interpretability during monopolar deep brain...

Area of Science:

• Neuroscience
• Medical Imaging
• Biomedical Engineering

Background:

• Deep brain stimulation (DBS) is a therapeutic intervention.
• Functional magnetic resonance imaging (fMRI) is used to assess brain activity.
• Concurrent MRI and DBS raise concerns about device stability and data integrity.

Purpose of the Study:

• To evaluate the stability of DBS current during MRI scans.
• To determine if MRI-induced current variability affects fMRI interpretability.
• To compare current stability between monopolar and bipolar DBS configurations.

Main Methods:

• Two current-controlled DBS systems were tested in a phantom during 3-T MRI.
• Stimulation was applied in monopolar and bipolar modes, both on and off.
• Induced currents were measured using an MRI-conditional setup across various sequences, including fMRI protocols.

Main Results:

• Monopolar DBS exhibited significant current fluctuations (-3.2 to +3.9 mA) and polarity inversions during MRI, particularly during fMRI sequences.
• Bipolar DBS demonstrated stable output with minimal deviation from programmed parameters.
• Variability in monopolar output was consistent across systems and not due to impedance changes.

Conclusions:

• MRI-induced currents substantially alter monopolar DBS output, compromising concurrent fMRI data.
• The observed blood oxygen level-dependent (BOLD) response during monopolar DBS may reflect distorted stimulation.
• Bipolar DBS configurations are recommended to avoid confounding effects and ensure accurate fMRI interpretation during stimulation.