A Review of MRI Acoustic Noise Outputs and Hearing Protection Device Performance

Area of Science:

• Medical Imaging Physics
• Audiology
• Occupational Health

Background:

• Magnetic Resonance (MR) equipment generates significant acoustic noise, necessitating hearing protection devices (HPDs) for patients.
• Existing HPD performance metrics (e.g., NRR, SNR, SLC80) vary globally due to different lab methodologies, leading to inconsistent real-world performance assessments.
• MR manufacturers use standards like NEMA MS-4 for worst-case noise output measurement, but assessing patient exposure is complex due to confined spaces and imaging variability.

Purpose of the Study:

• To review the challenges in determining and providing adequate hearing protection for patients undergoing MR imaging.
• To assess the efficacy of current HPDs against the loudest MR equipment noise levels.
• To highlight the critical role of proper HPD deployment and verification in ensuring patient safety.

Main Methods:

• Review of existing standardized methodologies for HPD performance evaluation.
• Analysis of MR equipment acoustic output measurements and HPD performance ratings.
• Assessment of theoretical worst-case patient exposure levels considering HPD application uncertainty and population variability.
• Evaluation of government agency derating recommendations for practical HPD application.

Main Results:

• The loudest MR equipment requires the highest-performing passive HPDs to meet patient protection guidelines, contingent on correct deployment.
• Inconsistent derating recommendations from government agencies cast doubt on whether best-in-class HPDs consistently provide sufficient protection in practical use.
• Variability in HPD performance metrics and application effectiveness complicates the assurance of adequate patient hearing protection.

Conclusions:

• Ensuring adequate patient hearing protection during MR scans is challenging due to varying HPD metrics and noise output complexities.
• Proper deployment and verification of hearing protection devices are paramount for patient safety.
• Further research and standardization may be needed to consistently guarantee sufficient hearing protection in clinical MR environments.