Experimental setup for transfer function measurement to assess RF heating of medical leads in MRI: Validation in the case of a single wire

Abstract

Purpose: The measurement of the transfer function is a good tool to evaluate the radiofrequency heating of complex conductive wires, such as pacemaker leads. The aim is to describe precisely the design of a transfer function bench and compare the measurements to simulations.

Methods: The transfer function was measured by mean of an excitation probe and a receiving probe, both connected to a two-port vector network analyzer. The experimental results were compared with the simulated results, reproducing the excitation scheme. This procedure was applied to two different cables with different geometrical and insulation properties to test the robustness of the setup.

Results: It is possible to touch the cable electrode with the excitation probe without inducing an error in the measured transfer function, which solves the direct coupling problem. There is a good agreement between the measured and simulated transfer function for both tested cables.

Conclusions: A valid transfer function measurement bench is described. Magn Reson Med 79:1766-1772, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Keywords: cables, MRI safety; heating; pacemaker leads; radiofrequency; transfer function.