Traditional electrodes used for neural recording and stimulation generate large regions of signal void (no functional MRI signal) when used in ultrahigh field (UHF) MRI scanners. This is a significant disadvantage when simultaneous neural recording/stimulation and fMRI signal acquisition is desired, for example in understanding the functional mechanisms of deep brain stimulation (DBS). In this work, a novel gold-aluminum microwire neural electrode is presented which overcomes this disadvantage. The gold-aluminum design greatly reduces the magnetic susceptibility difference between the electrode and brain tissue leading to significantly reduced regions of signal void. Gold-aluminum microwire samples are imaged at ultrahigh field 16.4 Tesla and compared with gold-only and aluminum-only microwire samples. First, B0 field mapping was used to quantify field distortions at 16.4T and compared with analytical computations in an agarose phantom. The gold-aluminum microwire samples generated substantially less field distortion and signal loss in comparison with gold-only and aluminum-only samples at 16.4T using gradient echo imaging and echo planar imaging sequences. Next, the proposed gold-aluminum electrode was used to successfully record local field potential signals from a rat cortex. The newly proposed gold-aluminum microwire electrode exhibits reduced field distortions and signal loss at 16.4T, a finding which translates to MRI scanners of lower magnetic field strengths as well. The design can be easily reproduced for widespread study of DBS using MRI in animal models. Additionally, the use of non-reactive gold and aluminum materials presents an avenue for translation to human implant applications in the future.
Bibliographical noteFunding Information:
This work was supported in part by NIH grant R01 MH111413, P41 EB027061, P30 NS076408, S10 RR025031, and by the University of Minnesota?s MnDRIVE (Minnesota?s Discovery, Research and Innovation Economy) initiative. A portion of the work reported in this paper has been protected through a patent filing. The pending patent will belong to the University of Minnesota which has a standard royalty sharing agreement with university employees, in case any royalties are earned from the licensing of said patent.
This work was supported in part by NIH grant R01 MH111413, P41 EB027061, P30 NS076408, S10 RR025031, and by the University of Minnesota’s MnDRIVE (Minnesota’s Discovery, Research and Innovation Economy) initiative.
© 2021, Biomedical Engineering Society.
- Gold-aluminum electrodes
- Image artifacts
- MRI scanners
- Matched magnetic susceptibility
- Neural electrodes