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Abstract #0175

Simulation of the dB/dt-over-electric field cardiac magnetostimulation safety ratio in 75 body models and 18 gradient systems

Valerie Klein1,2, Jonathan Edmonson3, Mathias Davids1, Natalie G. Ferris1,4, Johan S. van den Brink5, Michael Steckner6, Lawrence L. Wald1,2,4, and Bastien Guerin1,2
1A. A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, United States, 2Harvard Medical School, Boston, MA, United States, 3Medtronic Cardiac Rhythm Management, Minneapolis, MN, United States, 4Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA, United States, 5Philips Healthcare, Best, Netherlands, 6MKS Consulting, Beachwood, OH, United States

Synopsis

Keywords: Safety, Safety

Motivation: IEC 60601-2-33 uses simple electromagnetic calculations in a homogeneous ellipsoid to derive the ratio between cardiac stimulation E-field and dB/dt for setting actionable scanner limits.

Goal(s): Re-compute the dB/dt-over-E-field ratio using simulations in multiple realistic body models and body gradient coils (GC).

Approach: We performed two independent electromagnetic simulation studies of 13 GCs in 56 body models (study #1) and 5 GCs in 19 body models (study #2).

Results: The dB/dt-over-E99 ratio (E99 is 99th percentile of E-fields in myocardium) is between 12 (worst-case) and 16 (T/s)*(V/m)-1 (1st percentile), suggesting that some increase beyond the current value of 10 (T/s)*(V/m)-1 may be justified.

Impact: Our simulations of the IEC 60601-2-33 cardiac magnetostimulation dB/dt-over-E-field ratio indicate values between 12 and 16 (T/s)*(V/m)-1, which is greater than the current value of 10 (T/s)*(V/m)-1. Increasing this ratio would allow for more liberal use of modern gradient performance.

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Keywords