Cognitive effects of head-movements in stray fields generated by a 7 Tesla whole-body MRI magnet

Authors

  • F. de Vocht,

    Corresponding author
    1. Environmental and Occupational Health Division, Institute for Risk Assessment Sciences, Utrecht University, Utrecht, The Netherlands
    • Environmental and Occupational Health Division, Institute for Risk Assessment Sciences, Utrecht University, PO Box 80.176, 3508 TD, Utrecht, The Netherlands.
    Search for more papers by this author
  • T. Stevens,

    1. Environmental and Occupational Health Division, Institute for Risk Assessment Sciences, Utrecht University, Utrecht, The Netherlands
    Search for more papers by this author
  • P. Glover,

    1. Sir Peter Mansfield Magnetic Resonance Centre, School of Physics and Astronomy, The University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
    Search for more papers by this author
  • A. Sunderland,

    1. School of Psychology, The University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
    Search for more papers by this author
  • P. Gowland,

    1. Sir Peter Mansfield Magnetic Resonance Centre, School of Physics and Astronomy, The University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
    Search for more papers by this author
  • H. Kromhout

    1. Environmental and Occupational Health Division, Institute for Risk Assessment Sciences, Utrecht University, Utrecht, The Netherlands
    Search for more papers by this author

Abstract

The study investigates the impact of exposure to the stray magnetic field of a whole-body 7 T MRI scanner on neurobehavioral performance and cognition. Twenty seven volunteers completed four sessions, which exposed them to ∼1600 mT (twice), 800 mT and negligible static field exposure. The order of exposure was assigned at random and was masked by placing volunteers in a tent to hide their position relative to the magnet bore. Volunteers completed a test battery assessing auditory working memory, eye–hand co-ordination, and visual perception. During three sessions the volunteers were instructed to complete a series of standardized head movements to generate additional time-varying fields (∼300 and ∼150 mT·s−1 r.m.s.). In one session, volunteers were instructed to keep their heads as stable as possible. Performance on a visual tracking task was negatively influenced (P<.01) by 1.3% per 100 mT exposure. Furthermore, there was a trend for performance on two cognitive-motor tests to be decreased (P<.10). No effects were observed on working memory. Taken together with results of earlier studies, these results suggest that there are effects on visual perception and hand–eye co-ordination, but these are weak and variable between studies. The magnitude of these effects may depend on the magnitude of time-varying fields and not so much on the static field. While this study did not include exposure above 1.6 T, it suggests that use of strong magnetic fields is not a significant confounder in fMRI studies of cognitive function. Future work should further assess whether ultra-high field may impair performance of employees working in the vicinity of these magnets. Bioelectromagnetics 28:247–255, 2007. © 2007 Wiley-Liss, Inc.

Ancillary