The aims of this study were to investigate the subjective discomfort and sensory side effects during ultrahigh field (UHF) magnetic resonance imaging (MRI) examinations in a large-scale study and to evaluate differences between magnetic resonance (MR) sites.
Four MR sites with a 7-T MR system and 2 MR sites with a 9.4-T MR system participated in this multicenter study with a total number of 3457 completed questionnaires on causes of discomfort and sensations during the examination. For a pooled retrospective analysis of the results from the partially different questionnaires, all data were adapted to an answer option with a 4-point scale (0 = no discomfort/side effect, 3 = very unpleasant/very strong sensation). To differentiate effects evoked by the low-frequency time-varying magnetic fields due to movement through the static magnetic field, most questionnaires separated the manifestation of sensory side effects during movement on the patient table from manifestation while lying still in the isocenter.
In general, a high acceptance of UHF examinations was found, where in 82% of the completed questionnaires, the subjects stated the examination to be at least tolerable. Although in 7.6% of the questionnaires, subjects felt discomfort during the examination, only 0.9% of the image acquisitions had to be terminated prematurely. No adverse events occurred in any of the examinations. Only 1% of the subjects were unwilling to undergo further UHF MRI examinations. Examination duration was the most complained cause of discomfort, followed by acoustic noise and lying still. All magnetic-field–related sensations were more pronounced when moving the patient table versus the isocenter position (19%/2% of the subjects felt unpleasant vertigo during the moving/stationary state). In general, vertigo was the most often stated sensory side effect and was more pronounced at 9.4 T compared with 7 T. However, the results varied substantially among the different sites.
The high levels of subjective acceptance found in this study lead to the conclusion that UHF MRI would be tolerated as a diagnostic tool in clinical practice. For more consistent data ascertainment, we propose a standardized questionnaire for subjective perception monitoring.
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From the *Department of Medical Physics in Radiology, German Cancer Research Center, Heidelberg; †Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen; ‡Department of Diagnostic and Interventional Radiology and Neuroradiology, University Duisburg-Essen, University Hospital, Essen; §Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig; ∥Department of High-Field Magnetic Resonance, Max Planck Institute for Biological Cybernetics, Tübingen; ¶Department of Biomedical Magnetic Resonance, University of Tüingen; #Special Lab Non-Invasive Brain Imaging, Leibniz Institute for Neurobiology, Magdeburg; **Research Center Jülich, Institute of Neuroscience and Medicine, Jülich; and ††Department of Neurology, RWTH Aachen University, Aachen, Germany.
Received for publication July 17, 2013; and accepted for publication, after revision, December 13, 2013.
Conflicts of interest and source of funding: Jülich has received funding through a BMBF grant, (number 13N9121). All other authors declared no conflicts of interest or funding sources.
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Reprints: Armin M. Nagel, PhD, German Cancer Research Center (DKFZ), Department of Medical Physics in Radiology (E020), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany. E-mail: email@example.com.