Measurement of visual evoked potential during and after periods of pulsed magnetic field exposure

✍ Scribed by Paul M. Glover; Sally Eldeghaidy; Tejal R. Mistry; Penny A. Gowland

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 281 KB
• Volume: 26
• Category: Article
• ISSN: 1053-1807
• DOI: 10.1002/jmri.21155

✦ Synopsis

Abstract

Purpose

To study the effect of switched magnetic fields used in MR scanners on the visual evoked potential (VEP) in human subjects.

Materials and Methods

We have used an MRI gradient coil, remote from an MRI magnet to produce a time‐varying magnetic field (0.5 kHz, peak field ∼8.7 T/second) in the human brain without the confounding effects of static field exposure or accompanying acoustic noise. The VEP response to a 2‐Hz reversal, 8 × 8 checkerboard, occupying 20 degrees of the visual field was recorded from occipital locations O1 and O2. VEP recordings were made every five minutes before, during, and after a 10‐minute magnetic field exposure period for seven subjects.

Results

In contradiction to studies previously reported in the literature for fields of 50 Hz and 60 mT, no significant effects on the peak amplitude or latency of the VEP P100 O1 and O2 responses were found.

Conclusion

Switched magnetic fields of a level and frequency comparable to those used in MRI do not have a significant effect on primary retinal or visual processing. J. Magn. Reson. Imaging 2007;26:1353–1356. © 2007 Wiley‐Liss, Inc.