Bioelectromagnetics 32:610^619 (2011) A Large-Scale Study on Subjective Perception of Discomfort During 7 and 1.5 T MRI Examinations Christina Heilmaier, 1,2,3 * Jens M.Theysohn, 2,3 Stefan Maderwald, 2,3 Oliver Kraff, 2,3 Mark E. Ladd, 2,3 and Susanne C. Ladd 2,3 1 Department of Diagnostic and Interventional Radiology, HELIOS Klinikum, Krefeld, Germany 2 Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen, Germany 3 Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital, Essen, Germany A study on subjective perception has been carried out in order to gain further insight into subjec- tive discomfort and sensations experienced during 7 T magnetic resonance imaging (MRI). This study provides information about subjective acceptance, which is essential if 7 T MRI is to become a clinical diagnostic tool. Of 573 subjects who underwent 7 T MRI, 166 were also examined at 1.5 T, providing a means of discriminating field-dependent discomfort. All subjects judged sources of discomfort and physiological sensations on an 11-point scale (0 ¼ no side effects, 10 ¼ intolerable side effects) and scores were analyzed separately for exam phases, with and without table movement at each field strength. Results revealed that 7 T MRI was, in general, judged more uncomfortable than 1.5 T; however, most subjects rated the effects as being non- critical (mean scores between 0.5 and 3.5). Significant differences were detected regarding vertigo and sweating between subjects positioned ‘‘head-first’’ and ‘‘feet-first’’ at 7 T (worse in ‘‘head- first’’) and between 7 and 1.5 T (worse at 7 T), with the effects being more pronounced in the moving compared to the stationary table position. The most unpleasant factor at 7 T was the extensive examination duration, while potentially field-dependent sensations were rated less bothersome. In summary, our study indicates that although certain sensations increase at 7 T compared to 1.5 T, they are unlikely to hinder the use of 7 T MRI as a clinical diagnostic tool. Bioelectromagnetics 32:610–619, 2011. ß 2011 Wiley Periodicals, Inc. Key words: high-field MR imaging; side effects; sensations; subjective acceptance; vertigo INTRODUCTION During the last three decades, magnetic reson- ance imaging (MRI) has experienced vast technical developments and improvements and has established itself as an important diagnostic tool with a broad spectrum of applications [Schild, 2005]. MRI offers various advantages over alternative imaging tech- niques, including its great flexibility in achievable tissue contrasts, its provision of both morphologic and functional parameters, its non-invasiveness, as well as its freedom from ionizing radiation. So far, hundreds of millions of patient examinations have been safely performed using MRI [United States Food and Drug Administration, 2003; Shellock and Crues, 2004; Health Protection Agency, 2008] with the exception of a few cases of burns [Chaljub et al., 2001] and injuries by projectiles [Chaljub et al., 2001; Colletti, 2004]; all of these cases, however, can be attributed to disregarding contraindications and precautions for performing MRI. To date, there is no evidence of potential long-term health effects of static magnetic fields [Formica and Silvestri, 2004; Chakeres and de Vocht, 2005; Feychting, 2005; Advisory Group on Non-Ionising Radiation (AGNIR), 2008]. Nowadays, primarily 1.5 T and, to a lesser degree 3 T scanners are routinely used in a clinical setting [Kim et al., 2009]. MR systems with higher field strengths (mainly 7 T) are currently used for research purposes only. Increasing the field strength *Correspondence to: Christina Heilmaier, Arendals Wiese 199, 45141 Essen, Germany. E-mail: christina.heilmaier@uni-due.de Received for review 12 April 2010; Accepted 23 April 2011 DOI 10.1002/bem.20680 Published online 19 May 2011 in Wiley Online Library (wileyonlinelibrary.com). ß 2011Wiley Periodicals,Inc.