Bryan K Ward, MD Topic：High Strength MRI: From Vertigo to Inner Ear Imaging.

Strong magnetic resonance imaging (MRI) scanners cause dizziness in humans due to magnetic vestibular stimulation. We have demonstrated that all healthy humans tested develop nystagmus in magnetic fields of 3T and higher, and the effect increases with magnetic field strength. The nystagmus suggests that strong magnetic fields directly interact with inner ear hair cell transduction currents, causing a Lorentz force that moves endolymph and stimulates the hair cells. MRI also has the promise to reveal pathophysiology in vivo, allowing real-time correlation with symptoms, a window to intervene on the natural history of the disease, and in ideal conditions, histology-like images of the inner ear. Without confirmatory histopathology or imaging, however, clinicians have proposed myriad peripheral vestibular disorders that have not been identifiable in vivo, but are expected to have signal changes on high resolution MRI or with other imaging techniques (e.g. vestibular atelectasis, light cupula, head-jolting nystagmus, and congenital absence of otoconia are recent examples). This talk will review the effects of strong static magnetic fields on the vestibular system, how MRI can improve our understanding of vestibular pathophysiology, and how there is an urgent need to better see inside the human inner ear to diagnose and treat vestibular disorders.