Vestibular effects of a 7 Tesla MRI examination compared to 1.5 T and 0 T in healthy volunteers

• Published in: PloS one 2014-03, Vol.9 (3), p.e92104-e92104
• Main Authors: Theysohn, Jens M, Kraff, Oliver, Eilers, Kristina, Andrade, Dorian, Gerwig, Marcus, Timmann, Dagmar, Schmitt, Franz, Ladd, Mark E, Ladd, Susanne C, Bitz, Andreas K
• Format: Article
• Language: English
• Subjects: Adult; Biology and Life Sciences; Comparative analysis; Exposure; Female; Hair; Health care; Health physics; Healthy Volunteers; Hospitals; Humans; Magnetic fields; Magnetic resonance imaging; Magnetic Resonance Imaging - adverse effects; Male; Medical imaging equipment; Medical research; Medicine and Health Sciences; NMR; Normalizing; Nuclear magnetic resonance; Otology; Physiology; Postural Balance; Posture; Radio frequency; Rotating bodies; Scanners; Sensation Disorders - etiology; Stability; Stability analysis; Ultrasound; Vertigo; Vestibular Diseases - physiopathology; Vestibular system; Vestibule, Labyrinth - physiopathology
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0092104

Ultra-high-field MRI (7 Tesla (T) and above) elicits more temporary side-effects compared to 1.5 T and 3 T, e.g. dizziness or "postural instability" even after exiting the scanner. The current study aims to assess quantitatively vestibular performance before and after exposure to different MRI scenarios at 7 T, 1.5 T and 0 T. Sway path and body axis rotation (Unterberger's stepping test) were quantitatively recorded in a total of 46 volunteers before, 2 minutes after, and 15 minutes after different exposure scenarios: 7 T head MRI (n = 27), 7 T no RF (n = 22), 7 T only B0 (n = 20), 7 T in & out B0 (n = 20), 1.5 T no RF (n = 20), 0 T (n = 15). All exposure scenarios lasted 30 minutes except for brief one minute exposure in 7 T in & out B0. Both measures were documented utilizing a 3D ultrasound system. During sway path evaluation, the experiment was repeated with eyes both open and closed. Sway paths for all long-lasting 7 T scenarios (normal, no RF, only B0) with eyes closed were significantly prolonged 2 minutes after exiting the scanner, normalizing after 15 minutes. Brief exposure to 7 T B0 or 30 minutes exposure to 1.5 T or 0 T did not show significant changes. End positions after Unterberger's stepping test were significantly changed counter-clockwise after all 7 T scenarios, including the brief in & out B0 exposure. Shorter exposure resulted in a smaller alteration angle. In contrast to sway path, reversal of changes in body axis rotation was incomplete after 15 minutes. 1.5 T caused no rotational changes. The results show that exposure to the 7 Tesla static magnetic field causes only a temporary dysfunction or "over-compensation" of the vestibular system not measurable at 1.5 or 0 Tesla. Radiofrequency fields, gradient switching, and orthostatic dysregulation do not seem to play a role.