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Published on: February 8, 2019
Dual hearing protection effectively preserves outer hair cell function during 7 T MRI
L Wennberg1, S Waechter2, K J Brännström2
1Department of Medical Imaging and Physiology, Skåne University Hospital, Lund, Sweden; Department of Clinical Sciences Lund/ Diagnostic Radiology, Faculty of Medicine, Lund University, Lund, Sweden.
Introduction:
Exposure to high acoustic noise levels generated during 7 Tesla (T) magnetic resonance imaging (MRI) may affect auditory function. To better understand these effects, this study examines how such noise exposure influences outer hair cell function in healthy adults, with a focus on the efficiency of a dual hearing protection method.
Methods:
In this within-subjects longitudinal study, outer hair cell function was assessed in 39 participants (aged 18-41 years) using distortion product otoacoustic emissions (DPOAEs). Participants completed two 7 T MRI sessions on the same day while wearing dual hearing protection (foam earplugs in combination with sound-absorbing impression paste). DPOAEs were measured before the first MRI session and immediately after both MRI sessions, with follow-up assessments on a separate day to detect any enduring alterations in auditory function.
Results:
Among the 39 participants, DPOAEs demonstrated no significant variations in outer hair cell function across the assessed time points, suggesting that cochlear function remained stable.
Conclusion:
This study suggests that, with adequate dual hearing protection, repeated exposure to high acoustic noise during 7 T MRI does not adversely affect outer hair cell function in healthy adults.
Implications For Practice:
Our findings highlight the importance of rigorous hearing protection in MRI, particularly in ultra-high-field settings. Dual hearing protection, combining foam earplugs with sound-absorbing impression paste, is shown to effectively prevent measurable cochlear deterioration during repeated 7 T MRI sessions. These results support adopting multiple protective barriers as a practical standard and contribute to auditory safety in diagnostic imaging.
