Metamaterials Implants for Magnetic Resonance Imaging

Clinical electrical stimulation systems are increasingly common therapeutic options
to treat a broad range of medical conditions, such as cardioverter-defibrillators,
pacemakers, spinal cord stimulators, and deep brain stimulators. Despite their
remarkable success, a significant limitation of these medical devices is their limited
compatibility with magnetic resonance imaging (MRI), a standard and widely used
diagnostic tool in medicine. A primary concern when performing MRI examinations in
patients with electrically conductive implants is the antenna effect, which can potentially
cause a large amount of energy to be absorbed in the tissue, leading to heat-related
severe injury. In this application, we propose designing, developing, and testing a novel
metamaterials technology to produce MRI conditional leads that could be used in
implanted electrical recording and stimulation devices. The innovative nanoscale thin-
film metamaterial is truly the only MRI cloaking technology that does not occupy any
"brain" space compared to additional RF-choking components. We will develop a
general framework for any arbitrary electrical stimulation lead implanted in the body to
prevent a build-up of induced currents and reduce imaging artifacts during a 3 Tesla MRI.
Furthermore, we propose novel electrocorticography (ECoG) electrodes based on
biocompatible materials that will be stretchable, and conformable for optimal
biocompatibility, safety, and performance. These novel electrodes will be thin and
flexible and can be created in a wide range of configurations (i.e., strips, grids, and
various combinations) for different applications. Notably, the electrodes will be MRI-safe
and CT artifact-free, allowing for perfect registration of the electrode location to the brain
anatomy. The electrodes also permit the combination of intracranial (depth and cortical)
recordings with fMRI imaging, leading to a greater understanding of the neural
organization in both individual patients and for neuroscientific knowledge.
A complete test plan is in place that includes electromagnetic numerical simulation to
support the design of both depth and ECoG Neuropace electrodes and bench-top and
large animal testing for efficacy validation and biocompatibility on rodents. This project's
long-term goal is to develop electrical stimulation system leads compatible with 3 Tesla
MRI and other external radiofrequency sources, providing significant benefits to patients
who may require implanted stimulators to treat pathological conditions such as heart
arrhythmias and Parkinson's disease, epilepsy, and stroke.

Grant Number: 5R01NS128962-04
NIH Institute/Center: NIH
Principal Investigator: GIORGIO BONMASSAR