NEURAL PROBE BEHAVIOUR IN MAGNETIC RESONANCE
Relevant for Research Area
Dr. Matthias Wapler (Contact PI)
Magnetic resonance imaging is a highly useful and versatile diagnostic procedure, but it poses a harsh electromagnetic environment: The constant homogeneous magnetic field, a strong dynamic gradient magnetic field and a radio frequency field. All of these can interact with different structures of neural implants, resulting in heating, forces, induced electric signals and, in converse, field distortion. Hence, the diagnostic imaging value may suffer, the implant may get damaged or the patient safety can be jeopardized which is why such implants are initially contraindicated to MRI. Hence, our goal is to enable the development of MR compatible neural implants. We first develop the testing instrumentation: A modular MR probehead with different measurement channels and an integrated camera and methods to determine the magnetic susceptibility of arbitrary samples and MR artifacts of implant structures. We then develop design rules for MR-safe implants, supported by systematic measurements.
We have developed a highly precise method to measure the magnetic susceptibility of materials using MRI with a large data base of measured material data and obtained systematic data on the MR artifacts of different structures. With the probehead completed and the integration of the camera in progress, we are next moving towards device testing and the systematic measurements of heating, forces and induced voltages to support the development of the theoretical framework of the design rules.
JB Erhardt, E Fuhrer, OG Gruschke, J Leupold, MC Wapler, J Hennig, T Stieglitz and JG Korvink. „Should patients with brain implants undergo MRI?”, Journal of neural engineering, 15(4), (2018): p.041002.
E Fuhrer, A Bäcker, S Kraft, FJ Gruhl, M Kirsch, N MacKinnon JG Korvink and S Sharma, “3D Carbon Scaffolds for Neural Stem Cell Culture and Magnetic Res-onance Imaging”, Advanced Healthcare Materials, (7), 2018
BP Bruno, AR Fahmy, M Stürmer, U Wallrabe, MC Wapler, “Properties of pi-ezoceramic materials in high electric field actuator applications”, accepted at Smart Materials and Structures, arXiv preprint arXiv:1804.00192
MC Wapler, F Lemke, G Alia, U Wallrabe, “Aspherical high-speed varifocal mirror for miniature catadioptric objectives”, Optics express 26 (5), 6090-6102 (2018)
MC Wapler, J Leupold, I Dragonu, D von Elverfeld, M Zaitsev, U Wallrabe, “Magnetic properties of materials for MR engineering, micro-MR and beyond”, Journal of Magnetic Resonance
D Ashouri Vajari, M Vomero, JB Erhardt, A Sadr, J Ordonez, V Coenen and T Stieglitz, “Integrity Assessment of a Hybrid DBS Probe that Enables Neurotransmit-ter Detection Simultaneously to Electrical Stimulation and Recording” Micromachines, 9(10), (2018) p.510.
Hennig J., Göbel-Guéniot K., Hesse L., Leupold J. Efficient Pulse Sequences for NMR Microscopy. In: Anders J., Korvink J.G.: Micro and Nano Scale NMR: Tech-nology and Systems, Wiley 2018, DOI:10.1002/9783527697281
Bär S., Weigel M., Elverfeldt D., Hennig J., Leupold J. Intrinsic diffusion sen-sitivity of the balanced steady-state free precession (bSSFP) imaging sequence. NMR Biomed 2015;28: 1383-1392
Bär S., Oerther T., Weigel M., Müller A., Hucker P., Korvink J.G., Ko C., Wapler M., Leupold J. On the Application of Balanced Steady-State Free Precession to MR Microscopy. Submitted to MAGMA, current decision (oct 2018): major revision
Leupold J. Balanced Steady-State free Precession Signals of Arbitrary Dephasing Order and their Sensitivity to T2*. Concepts in Magnetic Resonance Part A, 2018, doi.org/10.1002/cmr.a.21435