Development and testing of implanted carbon electrodes for electromagnetic field mapping during neuromodulation

Area of Science:

• Biomedical Engineering
• Neuroscience
• Medical Imaging

Background:

• Deep brain stimulation (DBS) is a crucial neuromodulation technique.
• Standard DBS electrodes can cause significant artifacts in Magnetic Resonance Imaging (MRI).
• Simultaneous MREIT current administration and imaging with DBS electrodes is challenging due to artifacts and heating.

Purpose of the Study:

• To evaluate custom carbon-fiber electrodes for MREIT current administration and imaging.
• To compare the artifact and heating properties of carbon-fiber DBS electrodes with standard DBS electrodes.

Main Methods:

• Carbon-fiber electrodes were fabricated and matched to standard DBS electrode dimensions.
• Artifacts and thermal effects were assessed in phantom and tissue samples under 7T MRI conditions.
• Magnetic flux and current density distributions were analyzed for both electrode types.

Main Results:

• Carbon electrodes produced significantly smaller magnitude artifacts (FWHM) than standard DBS electrodes.
• Standard DBS electrodes exhibited substantial size exaggeration (269%) in gradient echo images, unlike carbon electrodes.
• Carbon electrodes generated less heat during RF excitation compared to standard DBS electrodes.
• Current and magnetic flux density distributions were comparable between carbon and standard DBS electrodes.

Conclusions:

• Carbon-fiber electrodes present a safer, MR-compatible alternative for neuromodulation current delivery.
• These electrodes facilitate imaging near the stimulation site, potentially improving targeting and functional assessments.
• Carbon electrodes may enhance the utility of MREIT in conjunction with DBS.