Occup Environ Med doi:10.1136/oemed-2011-100468
  • Practice
  • Original article

Effects of magnetic stray fields from a 7 Tesla MRI scanner on neurocognition: a double-blind randomised crossover study

Press Release
  1. Hans Kromhout1
  1. 1Division of Environmental Epidemiology, Institute for Risk Assessment Sciences, Utrecht University, Utrecht, The Netherlands
  2. 2Helmholz Institute, Utrecht University, Utrecht, The Netherlands
  3. 3Centre for Occupational and Environmental Health, School of Community Based Medicine, University of Manchester, Manchester, UK
  1. Correspondence to Professor Dr Hans Kromhout, Institute for Risk Assessment Sciences, Utrecht University, PO Box 80178, Utrecht 3508 TD, The Netherlands; h.kromhout{at}
  1. Contributors HK and FV conceived the study. LEvN designed the original protocol supervised by PS, MJEvanZ and HK. All authors were involved in amending the protocol. LEvN coordinated the data collection. Data entry and analysis was carried out by LEvN under the supervision of PS and HK. LEvN wrote the first draft of the manuscript and all authors contributed to subsequent and final drafts.

  • Accepted 3 May 2012
  • Published Online First 27 August 2012


Objective This study characterises neurocognitive domains that are affected by movement-induced time-varying magnetic fields (TVMF) within a static magnetic stray field (SMF) of a 7 Tesla (T) MRI scanner.

Methods Using a double-blind randomised crossover design, 31 healthy volunteers were tested in a sham (0 T), low (0.5 T) and high (1.0 T) SMF exposure condition. Standardised head movements were made before every neurocognitive task to induce TVMF.

Results Of the six tested neurocognitive domains, we demonstrated that attention and concentration were negatively affected when exposed to TVMF within an SMF (varying from 5.0% to 21.1% per Tesla exposure, p<0.05), particular in situations were high working memory performance was required. In addition, visuospatial orientation was affected after exposure (46.7% per Tesla exposure, p=0.05).

Conclusion Neurocognitive functioning is modulated when exposed to movement-induced TVMF within an SMF of a 7 T MRI scanner. Domains that were affected include attention/concentration and visuospatial orientation. Further studies are needed to better understand the mechanisms and possible practical safety and health implications of these acute neurocognitive effects.


  • Funding This work was supported by The Netherlands Organisation for Health Research (ZonMW) within the program Electromagnetic Fields and Health Research under grant numbers 85100001 and 85800001.

  • Competing interests None.

  • Ethics approval The study was approved by the local medical ethics committee (study number: 09-310) of University Medical Center Utrecht (UMCU), the Netherlands. Medical ethics committee of University Medical Center Utrecht (UMCU), the Netherlands (study number: 09-310).

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement All authors had full access to all data and can take responsibility for the integrity of the data and the accuracy of the data analysis.

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