Reduction of Radiofrequency Induced Heating around Passive Implants via Flexible Metasurface Shielding at 7T

Motivation: Metallic implant compatibility at ultra-high field strengths (≥7T) continues to be often contraindicated as RF induced heating can result in surrounding tissue damage. Metasurface technology has been shown in the past to locally null the B1+ field, thereby providing a potential solution for shielding implants. Goal(s): To demonstrate a metasurface based method for shielding metallic implants to reduce RF heating. Approach: Eight implants were tested in a polyacrylic acid (PAA) phantom using a high-SAR sequence with and without a prototype metasurface. Results: On average the metasurface design reduced RF induced implant heating in the phantom by 41.6%. Impact: Patient undergoing invasive brain or trauma surgeries typically have passive metallic devices placed, making them unable to receive MRI scans at ultra-high field strengths due to RF induced heating. This work benefits this patient population by reducing RF heating.