Analysis of Magnetic Resonance Imaging Acoustic Noise Generated by a 4.7 T Experimental System

High intensity acoustic noise is an undesirable side-effect in magnetic resonance imaging (MRI) that can cause discomfort and hearing loss in patients and may be an impediment in functional MRI (fMRI) studies of the auditory system. Experimental MRI systems with high magnetic field strengths may gen...

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Bibliographic Details
Published in:Acta oto-laryngologica 2000, Vol.120 (6), p.739-743
Main Authors: COUNTER, S. Allen, OLOFSSON, Ake, BORG, Erik, BJELKE, Börje, HÄGGSTRÖM, Alexander, GRAHN, Hans F
Format: Article
Language:English
Subjects:
Acoustics
Biological and medical sciences
Ear, auditive nerve, cochleovestibular tract, facial nerve: diseases, semeiology
Humans
Investigative techniques, diagnostic techniques (general aspects)
Magnetic Resonance Imaging - instrumentation
Medical sciences
Medicin och hälsovetenskap
Noise
Non tumoral diseases
Otorhinolaryngology. Stomatology
Otorhinolaryngology. Stomatology. Orbit
Physical Phenomena
Physics
Radiodiagnosis. Nmr imagery. Nmr spectrometry
Signal Processing, Computer-Assisted
Sound Spectrography
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Summary:High intensity acoustic noise is an undesirable side-effect in magnetic resonance imaging (MRI) that can cause discomfort and hearing loss in patients and may be an impediment in functional MRI (fMRI) studies of the auditory system. Experimental MRI systems with high magnetic field strengths may generate acoustic noise of higher sound pressure levels (SPLs) than conventional 1.0 and 1.5 T clinical systems. We measured the SPL and spectral content of the acoustic noise generated by the Bruker Biospect 47/40 4.7 T experimental MRI system during scanning sequences commonly used in animal testing. Each sequence generated acoustic noise of high SPL, rapid pulse rates, amplitude-modulated pulse envelopes and multi-peaked spectra. The rapid acquisition with enhancement sequence with a 0.25 mm slice thickness generated SPLs of up to 129 dB peak SPL and 130 dB (A). Fourier analysis of the spectral content of the acoustic noise generated by each MRI sequence showed a wide band of acoustic energy with spectral peaks from 0.2-5 kHz. The intense MRI acoustic impulse noise generated by the 4.7 T system may cause masking of stimuli used in fMRI of the auditory cortex, reduce the hearing acuity of experimental animals and present a risk for unprotected human ears.
ISSN:0001-6489
1651-2251
DOI:10.1080/000164800750000270