MRI acoustic noise: Sound pressure and frequency analysis
- 1 May 1997
- journal article
- research article
- Published by Wiley in Journal of Magnetic Resonance Imaging
- Vol. 7 (3) , 606-611
- https://doi.org/10.1002/jmri.1880070327
Abstract
The large gradient colls used in MRI generate, simultaneously with the pulsed radiofrequency (RF) wave, acoustic noise of high intensity that has raised concern regarding hearing safety. The sound pressure levels (SPLs) and power spectra of MRI acoustic noise were measured at the position of the human head in the isocenter of five MRI systems and with 10 different pulse sequences used in clinical MR scanning. Each protocol, including magnetization‐prepared rapid gradient echo (MP‐RAGE; 113 dB SPL linear), fast gradient echo turbo (114 dB SPL linear), and spin echo Tl/2 mm (117 dB SPL linear), was found to have the high SPLs, rapid pulse rates, amplitude‐modulated pulse envelopes, and multi‐peaked spectra. Slice thickness and SPL were inversely related, and Tl‐weighted images generated more intense acoustic noise than the proton‐dense T2‐weighted measures. The unflltered linear peak values provided more accurate measurements of the SPL and spectral content of the MRI acoustic noise than the commonly used dB A‐weighted scale, which filters out the predominant low frequency components. Fourier analysis revealed predominantly low frequency energy peaks ranging from .05 to approximately.Keywords
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