Construction and modeling of a reconfigurable MRI coil for lowering SAR in patients with deep brain stimulation implants

Abstract

Post-operative MRI of patients with deep brain simulation (DBS) implants is useful to assess complications and diagnose comorbidities, however more than one third of medical centers do not perform MRIs on this patient population due to stringent safety restrictions and liability risks. A new system of reconfigurable magnetic resonance imaging head coil composed of a rotatable linearly-polarized birdcage transmitter and a close-fitting 32-channel receive array is presented for low-SAR imaging of patients with DBS implants. The novel system works by generating a region with low electric field magnitude and steering it to coincide with the DBS lead trajectory. We demonstrate that the new coil system substantially reduces the SAR amplification around DBS electrodes compared to commercially available circularly polarized coils in a cohort of 9 patient-derived realistic DBS lead trajectories. We also show that the optimal coil configuration can be reliably identified from the image artifact on B1+ field maps. Our preliminary results suggest that such a system may provide a viable solution for high-resolution imaging of DBS patients in the future. More data is needed to quantify safety limits and recommend imaging protocols before the novel coil system can be used on patients with DBS implants.

Measurements and simulation of RF heating of implanted stereo‐electroencephalography electrodes during MR scans

“…All temperature measurements were performed on a Siemens 3T whole‐body Prisma scanner (Siemens, Erlangen, Germany) with a head‐only, single‐channel, 16‐rung RF Tx/Rx coil. All studies used an ASTM (American Society for Testing and Materials) whole‐body phantom filled with polyacrylic acid gelled saline (ASTM F2182‐02a, West Conshohocken, PA) having thermal and electrical properties similar to that of human tissue . The gel was prepared by rigorously mixing 24 g of NaCl and 175.4 g of polyacrylic acid (Sigma‐Aldrich Corp, St. Louis, MO) into 30 L of deionized water.…”

Transmission efficiency analysis and optimization of magnetically coupled resonant wireless power transfer system with misalignments

“…1 MCR-WPT technology can be extended to military, aerospace, coal mining, medical implantation, household appliances, wireless sensor networks, electric vehicles, safety monitoring of buildings and other fields, owing to the advantages of higher transmission efficiency, bigger transmission power, smaller electromagnetic radiation and longer transmission distance. [2][3][4][5][6][7][8] Therefore, it is considered to be one of the most potential techniques for mid-range WPT applications at present.…”

Ultrahigh-Magnitude Brain Magnetic Resonance Imaging Scan on Rhesus Monkeys With Implanted Deep Brain Stimulation Hardware

“…He found that the temperature alteration near the DBS leads was within 1°, which is acceptable . Dr. Golestanirad and his team tested the influences of different wire arrangements and different MRI scanners on the heating of DBS leads and found that some specific setups are conducive for decreasing temperature alterations. Considering these findings, a higher magnitude may not necessarily be accompanied by increased risks of heating injury.…”