MRI acoustic noise: sound pressure and frequency analysis
| Autor: | S. A. Counter, A Olofsson, H F Grahn, E Borg |
|---|---|
| Rok vydání: | 1997 |
| Předmět: |
Materials science
Acoustics Low frequency Risk Assessment law.invention law otorhinolaryngologic diseases Pressure Humans Radiology Nuclear Medicine and imaging Sound pressure Child Frequency analysis Fourier Analysis Pulse (signal processing) Phantoms Imaging Attenuation Infant Pulse sequence Models Theoretical Magnetic Resonance Imaging Noise Hearing Loss Noise-Induced Calibration Spin echo sense organs Environmental Monitoring |
| Zdroj: | Journal of magnetic resonance imaging : JMRI. 7(3) |
| ISSN: | 1053-1807 |
| Popis: | The large gradient coils 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 T1/2 mm (117 dB SPL linear), was found to have the high SPLs, rapid pulse rates, amplitude-modulated pulse envelopes, and multipeaked spectra. Since thickness and SPL were inversely related, the T1-weighted images generated more intense acoustic noise than the proton-dense T2-weighted measures. The unfiltered 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 1 kHz, with a steep high frequency cutoff for each pulse sequence. Ear protectors of known attenuation ratings are recommended for all patients during MRI testing. |
| Databáze: | OpenAIRE |
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