Neural Implant Materials: Safety Evaluation in Implanted Neural Probes Under MRI

Tissue temperature rise caused by MRI-induced currents can pose a serious risk to the safety of patients with implanted neural probes in their brain while undergoing MRI scans. In this paper, we present the initial results of finite element method simulations which predict the temperature rise induced by MRI gradient coils in an implanted disk using a brain tissue phantom. In order to verify the results of our simulations we used a model consisting of a disk which is implanted into a cylindrical tissue phantom inside an animal bore found in the literature. Multiple electromagnetic and transient thermal simulations were performed on the disks made of various materials which are used commonly for the fabrication of neural probes including titanium, iridium, platinum, titanium nitride, and cubic silicon carbide (3C-SiC). Hereby, we primarily focus on the effects of MRI gradient coils that generate a time-varying electromagnetic field with a switching frequency of 500 Hz at the rate of 25 T/s. These simulations revealed that the 3C-SiC disk has the lowest temperature rise and specific absorption rate (SAR), in comparison with the other common materials, under MRI scans.