Abstract #0410

Exploiting Nerve Membrane Dynamics to Reduce Peripheral Nerve Stimulation using Asymmetric Readout Gradient Waveforms

Natalie G Ferris^1,2, Mathias Davids^3,4,5, Valerie Klein^3,5, Bastien Guérin^3,4, and Lawrence L Wald^3,4

¹Harvard Graduate Program in Biophysics, Harvard University, Cambridge, MA, United States, ²Harvard-MIT Division of Health Sciences and Technology, MIT, Cambridge, MA, United States, ³A. A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, United States, ⁴Harvard Medical School, Boston, MA, United States, ⁵Computer Assisted Clinical Medicine, Heidelberg University, Heidelberg, Germany

Peripheral Nerve Stimulation (PNS) limits the use of high-performance gradient systems. We exploit nerve membrane hyperpolarization and depolarization in readout gradient waveform design to achieve a higher gradient moment (area) in a given time without initiating PNS. In a typical symmetric trapezoidal readout waveform, the slew ramps have identical rise times but opposite dB/dt (E-field sign). Asymmetrizing the waveform enables achieving the same gradient moment while emphasizing membrane hyperpolarization over depolarization. The disparate effects of hyperpolarizing and depolarizing pulses are sufficient to impact the nerve’s PNS threshold, potentially increasing the spatial resolution.

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