Comparison of the threshold for peripheral nerve stimulation during gradient switching in whole body MR systems
✍ Scribed by Jacques A. Den Boer; Joe D. Bourland; John A. Nyenhuis; Cornelis L.G. Ham; Johan M.L. Engels; Franz X. Hebrank; Georg Frese; Daniel J. Schaefer
- Publisher
- John Wiley and Sons
- Year
- 2002
- Tongue
- English
- Weight
- 433 KB
- Volume
- 15
- Category
- Article
- ISSN
- 1053-1807
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
Purpose:
To compare thresholds for peripheral nerve stimulation from gradient switching in whole body magnetic resonance (MR) equipment of different design.
Materials and Methods:
Threshold data obtained in three experiments were reformatted into a single joint data set describing thresholds for anterio‐posterior (AP) gradient orientation and Echo Planar Imaging (EPI) waveforms with bipolar ramp times between 0.07 and 1.2 ms. Reformatting included the use of: a) the rate of change of the maximum field in the patient space as a measure of gradient output, b) lowest observable thresholds, c) lognormal distribution of thresholds, and d) equal standard deviation (SD) of all samples.
Results:
The joint data fit a hyperbolic threshold function. The residues were not significantly different between experiments.
Conclusion:
When expressed in appropriate format, the thresholds for peripheral nerve stimulation in volunteers for whole body MR equipment can be described with a hyperbolic threshold curve with rheobase 18.8 ± 0.6 Tesla/second and chronaxie 0.36 ± 0.02 milliseconds. J. Magn. Reson. Imaging 2002;15:520–525. © 2002 Wiley‐Liss, Inc.