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MRI-related static magnetic stray fields and postural body sway: A double-blind randomized crossover study

Authors

  • Lotte E. van Nierop,

    Corresponding author
    1. Division of Environmental Epidemiology, Institute for Risk Assessment Sciences, Utrecht University, The Netherlands
    • Institute for Risk Assessment Sciences, Utrecht University, PO Box 80178, 3508 TD Utrecht, The Netherlands
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  • Pauline Slottje,

    1. Division of Environmental Epidemiology, Institute for Risk Assessment Sciences, Utrecht University, The Netherlands
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  • Herman Kingma,

    1. Division of Balance Disorders, University Hospital Maastricht, The Netherlands
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    • H. Kingma and H. Kromhout contributed equally.

  • Hans Kromhout

    1. Division of Environmental Epidemiology, Institute for Risk Assessment Sciences, Utrecht University, The Netherlands
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    • H. Kingma and H. Kromhout contributed equally.


Abstract

We assessed postural body sway performance after exposure to movement induced time-varying magnetic fields in the static magnetic stray field in front of a 7 Tesla (T) magnetic resonance imaging scanner. Using a double blind randomized crossover design, 30 healthy volunteers performed two balance tasks (i.e., standing with eyes closed and feet in parallel and then in tandem position) after standardized head movements in a sham, low exposure (on average 0.24 T static magnetic stray field and 0.49 T·s−1 time-varying magnetic field) and high exposure condition (0.37 T and 0.70 T·s−1). Personal exposure to static magnetic stray fields and time-varying magnetic fields was measured with a personal dosimeter. Postural body sway was expressed in sway path, area, and velocity. Mixed-effects model regression analysis showed that postural body sway in the parallel task was negatively affected (P < 0.05) by exposure on all three measures. The tandem task revealed the same trend, but did not reach statistical significance. Further studies are needed to investigate the possibility of independent or synergetic effects of static magnetic stray field and time-varying magnetic field exposure. In addition, practical safety implications of these findings, e.g., for surgeons and others working near magnetic resonance imaging scanners need to be investigated. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.

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