Pilot study investigating the effect of the static magnetic field from a 9.4-T MRI on the vestibular system

Objective: To objectively evaluate workers' sensory symptoms and vestibular function after exposure to a strong, new generation 9.4-T Magnetic Resonance Imaging (MRI) scanner. Method: Six MRI employees underwent standardized electronystagmographic evaluation, Postural testing, and caloric function at baseline evaluation, 30 minutes postexposure to 9.4 T static field and at a 3-month follow-up. Results: All participants noted sensory symptoms after exposure. No overall deterioration in vestibular function was noted following 30-minute exposure or at a 3-month follow-up. A higher occurrence of tonic vestibular asymmetry, hyperreactive caloric responses, and spontaneous nystagmus was noted compared with that of the normal population. Conclusion: Workers exposed to the new, stronger MRIs experience sensory symptoms but it is unclear as yet whether long-term vestibular damage occurs. The higher rates of vestibular changes noted could argue for improved worker surveillance and exposure control.