Aims and objectives
Strong Lorentz forces acting on the gradient coils are the source of acoustic noise in MRI.
Fast current switch in the gradient coil lead to vibration in their mountings and to emission of sound waves .
Acoustic noise during an MR examination is an issue in clinical MRI examinations due to impairment of communication with the operator and patient annoyance [2–5]. Various acoustic noise control techniques are available to reduce acoustic noise and improve patient comfort in MRI.
They can be...
Methods and materials
Acoustic noise levels were recorded in the isocenter of a 1.5T Philips Ingenia MRI Scanner (Best,
The acoustic noise levels for eight widely used brain MR sequences were measured during their whole acquisition time,
with and without acoustic noise reduction.
The MR protocol included survey scan,
prescans (Coil survey scan,
reference scan for parallel imaging),
T1 weighted spinecho (T1w SE),
T2 weighted turbospinecho (T2w TSE),
Fluid attenuated inversion recovery (FLAIR),...
Acoustic noise control resulted in an average reduction of 12.5 dB (A) which equals a reduction of the average acoustic noise level of 74% (range: 56% - 90%) for the A-weighted scale (Figure 5).
As averaged over the complete brain protocols,
an A-weighted RMS SPL of 90.5 dB (range: 61.4 dB – 100.5 dB) without acoustic noise reduction and an A-weighted RMS SPL of 78 dB (range: 69.5 dB – 85.7 dB) with acoustic noise reduction were measured. Peak acoustic noise levels without noise reduction...
Acoustic noise may be a major factor for patient discomfort during the MR examination.
MR noise is strongly varying in time,
and may have complex patterns.
Our measurement method provides a more comprehensive description of the characteristics of the acoustic noise in MR than a single average number output from handheld analyzers.
This offers the possibility to extend the characterization of the noise pattern of MR sequences beyond average sound pressure,
such as roughness,
Michael Wyss,Institute for Radiology and Nuclearmedicine,
Switzerland Kantonsspital Winterthur
Institut für Radiologie und Nuklearmedizin
Telefon: +41(0)52 266 21 21
Mobile: +41 (0)79 584 01 66 E-Mail: firstname.lastname@example.org
De Wilde JP,
Investigation of acoustic noise on 15 MRI scanners from 0.2 T to 3 T.
J Magn Reson Imaging.
Acoustic analysis of gradient-coil noise in MR imaging.
The use of active noise control (ANC)...