![]() However, the radiology community should not become complacent on this matter. Overall, it seems that MRI scanner noise does not pose a significant risk for permanent hearing loss as long as patients are appropriately fitted with hearing protection during the procedure. However, patients scanned without wearing earplugs would be at substantially increased risk for developing hearing loss if they were to undergo frequent MRI evaluations or are more susceptible to developing noise-induced hearing loss. Taken together, these two studies indicate that patients who wear earplugs during an MRI scan could experience very slight, temporary hearing loss following exposure to scanner noise but are unlikely to experience any permanent damage. OAEs obtained immediately after MRI scanning decreased by 1.84 dB, compared with a 0.43 dB decrease for controls. All participants wore protective earplugs during the measurements, but the noise attenuation rating was not indicated. The researchers assessed cochlear function using otoacoustic emissions (OAEs) before and after a 20- to 40-minute MRI scan with a time-averaged equivalent intensity ranging from 100 to 110 dBA, equivalent to a PEL of 91.3 dBA. However, thresholds returned to pre-scan levels four weeks later, suggesting no permanent damage.Īnother study completed by Radomskij, et al., produced similar results with a 1.5T scanner ( Lancet. The investigators found a slight 5 dB threshold increase immediately after the scan. Thus, the noise reaching the ear was below the PEL for one hour (105 dBA) and would conceivably be considered safe. The average equivalent noise intensity during the nearly one-hour scan was 103.5-111.3 dBA, which equates to 82.5 to 90.3 dB after factoring in the attenuating properties of the protective earplug. ![]() Participants wore protective earplugs rated for 21 dBA attenuation during the procedure. The researchers obtained the thresholds of 26 normal hearing participants and compared these to thresholds obtained after the subjects underwent 3T MRI scanning. Jin, et al., recently tested if the noise produced by a 3T MRI scanner could cause temporary or permanent noise-induced hearing loss by using an auditory brainstem response (ABR) threshold screening device ( Radiology. To determine if MRI scanner noise poses a significant risk for acquired hearing loss despite the use of hearing protection, several studies have evaluated hearing ability before and after scanning ( Radiology. Despite this theoretical presumption, a number of case reports have found evidence of hearing loss following MRI scans, leaving the matter somewhat unsettled ( Case Rep Radiol. Fortunately, it is common practice for patients to wear protective earplugs during the scanning procedure, allowing for a passive sound attenuation of as much as 30 dB, which is sufficient to prevent permanent damage. Thus, modern 3T MRI scanners are capable of exceeding the PEL and could conceivably result in hearing loss. If a typical MRI scan lasts one hour, the PEL would increase to 105 dBA. The PEL increases by 5 dB with every halving of exposure duration (i.e., 95 dB for 4 h, 100 dB for 2 h, etc.). The maximum permissible exposure limit (PEL) is 90 dBA for an exposure duration of eight hours. Occupational Safety and Health Administration (OSHA) regulations, which consider the intensity, spectral content, and duration of noise exposures. The risk of hearing loss from MRI scanner noise can be put into context by referencing the U.S. MRI scan, hearing loss INTENSITIES OF MRI SCANNER NOISE Nevertheless, it seems reasonable that exposure to such high-intensity noise could result in noise-induced hearing loss ( Radiology. The noise produced is also predominantly of a low frequency (below 1 kHz), which is typically less damaging to the ear than noise in the higher 4 kHz range ( J Magn Reson Imaging. The intensity of noise produced by MRI scanners generally has a positive correlation with the magnetic field strength (i.e., 3T scanners are louder than 1.5T scanners). This high-intensity noise could easily cause hearing loss or induce tinnitus or hyperacusis ( Nagoya J Med Sci. However, a frequent concern has revolved around the high-intensity noise produced by modern 3-Tesla (3T) MRI scanners that can reach peak sound pressure levels of 125.7 to 130.7 dB and have an average equivalent intensity of 110 to 115 dB. MRI images allow physicians to diagnose medical conditions such as multiple sclerosis, acoustic neuromas, strokes, traumatic brain injury, and more. The development of magnetic resonance imaging (MRI) scanners has profoundly enhanced our ability to non-invasively visualize the brain, spinal cord, and other parts of the body.
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