Peripheral Nerve Stimulation (PNS) Analysis of MRI Head Gradient Coils with Human Body Models

Abstract

AbstractThe main objective of this chapter is to provide a comprehensive and intuitive introduction to MRI gradient coil related PNS modeling with human body models. We will present the fundamental concepts and analytical processes behind gradient coil-induced peripheral nerve stimulation (PNS) modeling and also show some new results of our work. We first describe the process of performing electromagnetic simulation of a gradient coil, the neurodynamic simulation of nerves, and the gradient coil design. Then, we present improvements of two existing human body models by adding more nerve trajectories in the head and upper body to reduce the discrepancies between the simulated and measured results for PNS thresholds in head gradient coils. Further, we apply the modified human body models to analyze three folded and non-folded gradient coils and reveal the relationship between the eddy current flow in the human body and the gradient coil wire pattern and its impact on the PNS. We also show the connection between concomitant fields and PNS and assess the accuracy of PNS calculations in human body models with simplified tissue properties. Finally, we give our thoughts on the future direction of this work.