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Abstract:
Introduction: Deep Brain Stimulation (DBS) is a validated technique to treat many neurological diseases. Post-surgical imaging is currently done with magnetic resonance imaging (MRI), which, due to susceptibility artifacts around electrodes, can result in their imperfect localization. Most DBS electrodes are made of a Pt-Ir (90%/10%) alloy, which exhibits good conductivity, biocompatibility and resistance to corrosion, but causes large artifacts due to susceptibility differences to tissue. Developing new electrodes to better match tissue susceptibility using carbon monofilament electrodes is difficult due to their electrical and mechanical properties. By combining materials that alone do not have the mechanical, electrical or biocompatible properties, we aim to design electrodes with improved MRI characteristics. Methods: Copper is a flexible, non-biocompatible metal with great conductivity and susceptibility properties. Combined with a Polyurethane insulation, tin coating at the tip and an additional fiber for stabilization it could work as low-susceptibility (multi-channel) electrode. The coating was done using a galvanization method. To test the susceptibility properties, gradient echo images of different electrode materials were acquired in a 14 T MR scanner. Results: It is clearly visible that the copper wires H1, H6 and V5 show the lowest susceptibility artifact, independent of whether the copper wire is insulated and/or coated. The silver plated copper alloy shows a slightly higher susceptibility artifact than the pure copper wires. Pt/Ir, NeuroNexus and carbon fiber perform worst. Discussion: The use of insulated copper wire in combination with biocompatible coating can be considered as alternative to conventional electrodes with bigger susceptibility artifacts. This gets even more important, since there is clearly a trend to use higher field strengths. In addition to DBS, those electrodes can also be used for animal experiments where the combination of electrophysiology and fMRI experiments can offer valuable insights into brain function.
