The effect of magnetic resonance imaging noise on cochlear function in dogs

- Exposure to noise during MRI in dogs results in a significant reduction in cochlear function, although it is not known whether this is reversible or permanent.
- The frequency region affected is probably influenced by the frequency of the noise spectra of the MRI.
- The finding that MRI noise results in hearing loss, albeit only assessed in the immediate post-MRI period, would suggest that all dogs undergoing MRI studies should have ear protection as a standard precaution.
- What is not evident from the present study is the longer-term effect of excessive MRI noise on hearing, and further studies are also required to assess the efficacy of ear protection to protect against the effects of MRI noise in dogs.

Noise produced by magnetic resonance imaging (MRI) scanners (which can peak at a sound pressure level of 131 dB) has been shown to cause noise-induced cochlear dysfunction in people. The aim of this study was to investigate whether noise produced during MRI had a deleterious effect on cochlear function in dogs, using distortion product otoacoustic emission (DPOAE) testing, which allows frequency specific, non-invasive assessment of cochlear function. DPOAE testing was performed before and after MRI in one or both ears under general anaesthesia at 14 frequency pairs (f2 frequency ranging from 0.84 kHz to 8.0 kHz). A control group comprised dogs undergoing anaesthesia of a similar duration for quiet procedures. Thirty-six dogs (66 ears) and 17 dogs (28 ears) were included in the MRI and control groups respectively.There was a reduction in DPOAE at all frequencies tested in the MRI group; a similar effect was not evident in the control group. This reduction in the MRI group was statistically significant in five of the 14 frequencies assessed (P < 0.05). These results demonstrate that exposure to MRI noise results in a significant reduction in frequency-specific cochlear function in dogs, although it is not known whether this is reversible or permanent. This suggests that all dogs undergoing MRI studies should be provided with ear protection as a routine precautionary measure.