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. 2022 Jul:10:907619.
doi: 10.3389/fphy.2022.907619. Epub 2022 Jul 8.

Overview of Methods for Noise and Heat Reduction in MRI Gradient Coils

Elizaveta Motovilova  1   2 , Simone Angela Winkler  1
Affiliations

Overview of Methods for Noise and Heat Reduction in MRI Gradient Coils

Elizaveta Motovilova et al. Front Phys. 2022 Jul.

Abstract

Magnetic resonance imaging (MRI) gradient coils produce acoustic noise due to coil conductor vibrations caused by large Lorentz forces. Accurate sound pressure levels and modeling of heating are essential for the assessment of gradient coil safety. This work reviews the state-of-the-art numerical methods used in accurate gradient coil modeling and prediction of sound pressure levels (SPLs) and temperature rise. We review several approaches proposed for noise level reduction of high-performance gradient coils, with a maximum noise reduction of 20 decibels (dB) demonstrated. An efficient gradient cooling technique is also presented.

Keywords: MR safety; MRI; acoustic noise; gradient coil; heating; sound pressure level; vibroacoustics.

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Conflict of interest statement

Conflict of Interest: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

FIGURE 1 |
FIGURE 1 |
Timeline of analytical/numerical studies and noise reduction techniques for MRI gradient coils.
FIGURE 2 |
FIGURE 2 |
Simulation model. (A) X-, (B) Y-, and (C) Z-axis gradient coils. (D,E) Applied boundary conditions.
FIGURE 3 |
FIGURE 3 |
Lorentz forces on the gradient coil.
FIGURE 4 |
FIGURE 4 |
Comparison of head and body gradient coil spectra. (A) Standalone and (B) complete analysis.
FIGURE 5 |
FIGURE 5 |
SPL spectra (A) without and (B) with Lorentz damping at different field strengths.
FIGURE 6 |
FIGURE 6 |
Noise reduction with an absorbing foam. (A) 3D model of the gradient coil and the absorber. (B) Simulated SPL results with and without the absorber.
FIGURE 7 |
FIGURE 7 |
Noise reduction with an absorbing ceramic. 3D models of the gradient coil with (A) a single inner layer absorber and (B) inner and outer layer absorbers. (C) Simulated SPL spectra at various absorbing layer thicknesses. (D) Simulated average SPL and acceleration at various absorbing layer thicknesses.
FIGURE 8 |
FIGURE 8 |
Noise reduction with ceramic layer of various shapes. 2D sketch of the head gradient coils setup with (A) a stepped ceramic insert, (B) a ceramic endcap. (C) Simulated average SPLs for the studied configurations.
FIGURE 9 |
FIGURE 9 |
Noise reduction using a horn and endcaps. (A) 3D representation of a gradient coil with an additional horn structure for noise guidance and suppression. (B) 2D representation of the gradient coil with a horn and an end cap. (C) Simulated SPL spectrum. (D) Measured SPL spectra.
FIGURE 10 |
FIGURE 10 |
Efficient gradient cooling. (A) Temperature as a function of time. (B) Temperature distribution on the inner bore.
See this image and copyright information in PMC

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