Irving N. Weinberg1, Pavel Stepanov, Steven
C. Glidden2, Howard D. Sanders, Daniel Warnow, Alan B. McMillan3,
Rao P. Gullapalli, Piotr M. Starewicz4, Kai-Ming Lo, Amnon Fisher5,
J. Patrick Reilly6, Michael S. Niziol7, Stanley T.
Fricke8
1Weinberg Medical Physics
LLC, Bethesda, MD, United States; 2Applied Pulsed Power Inc.,
Freeville, NY, United States; 3Radiology, University of Maryland,
Baltimore, MD; 4Resonance Research, Inc,, Billerica, MA; 5Physics,
Technion-Israel Institute of Technology, Haifa, Israel; 6Applied
Physics Laboratory, Johns Hopkins University, Laurel, MD; 7Family
Practice Associates, Dryden, NY; 8Radiology, Children's National
Medical Center, Washington, DC
Prior clinical trials have examined peripheral nerve stimulation (PNS) for magnetic gradients with ramp times of 50 s and higher. We conducted a prospective IRB-approved controlled clinical trial in which 26 volunteers were exposed to magnetic gradient pulses with ramp times as short as 3.5 microseconds. The data suggests that at 3.5 s, the threshold of gradient dB/dt (unipolar pulses) for 50% PNS in the general population would be 128,000 T/s (with substantially lower thresholds for younger subjects), representing dB/dt and slew rate thresholds more than 1,000 times higher than in typical MRI scanners.
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