Acoustic noise analysis in echo planar imaging: multicenter trial and comparison with other pulse sequences

Miyati, Tosiaki; Banno, Tomohiro; Fujita, Hiroshi; Mase, Mitsuhito; Narita, Hiroki; Imazawa, Masayoshi; Ohba, Satoru

doi:10.1109/42.796286

Cited by 17 publications

(17 citation statements)

References 8 publications

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“…The small but insignificant flattening of 0.5 dB(L) may tentatively be explained by restriction of extreme movements of the gradient coils, probably caused by the elastic properties of the gradient coil encasings. The frequency distribution of the pulse sequences tested was similar to that of previous reports [8,9,11,12,18]. Alterations of the frequency distribution were not expected a priori because of unchanged gradient current pulses and acoustic transfer function [15], which …”

Section: Discussionsupporting

confidence: 56%

“…This is relevant for measurements of acoustic noise, as it has been demonstrated previously that the type of imager dominates the overall acoustic noise levels [9,18], that is, the influence of the magnetic field strength on SPL might not adequately be elucidated by comparing various MR systems. The results of our experiments were in good agreement with what theory predicts, i.e.…”

Section: Discussionmentioning

confidence: 94%

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Relationship between magnetic field strength and magnetic-resonance-related acoustic noise levels

Moelker

Wielopolski

Pattynama

2003

MAGMA Magnetic Resonance Materials in Physics, Biology and Medi

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The need for better signal-to-noise ratios and resolution has pushed magnetic resonance imaging (MRI) towards high-field MR-scanners for which only little data on MR-related acoustic noise production have been published. The purpose of this study was to validate the theoretical relationship of sound pressure level (SPL) and static magnetic field strength. This is relevant for allowing adequate comparisons of acoustic data of MR systems at various magnetic field strengths. Acoustic data were acquired during various pulse sequences at field strengths of 0.5, 1.0, 1.5 and 2.0 Tesla using the same MRI unit by means of a Helicon rampable magnet. Continuous-equivalent, i.e. time-averaged, linear SPLs and 1/3-octave band frequencies were recorded. Ramping from 0.5 to 1.0 Tesla and from 1.0 to 2.0 Tesla resulted in an SPL increase of 5.7 and 5.2 dB(L), respectively, when averaged over the various pulse sequences. Most of the acoustic energy was in the 1-kHz frequency band, irrespective of magnetic field strength. The relation between field strength and SPL was slightly non-linear, i.e. a slightly less increase at higher field strengths, presumably caused by the elastic properties of the gradient coil encasings.

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Section: Discussionsupporting

confidence: 56%

Section: Discussionmentioning

confidence: 94%

Relationship between magnetic field strength and magnetic-resonance-related acoustic noise levels

Moelker

Wielopolski

Pattynama

2003

MAGMA Magnetic Resonance Materials in Physics, Biology and Medi

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“…From the rate of increase in the noise level in the axial direction, it is estimated that the noise level at the position of the mice was between 90 and 100 dB. The measured acoustic noise level is near the OSHA standard for long-term exposure (90 -105 dB) (27).…”

Section: Acoustic Noisementioning

confidence: 68%

“…Sham MRI animals were placed in identical chambers outside the magnet at the 5 G line and remained there for the duration of the exposure. The acoustic sound level was measured (A scale weighting, peak response) at the position of the sham animals and at the bore opening of the magnet using a digital sound meter (model 01617-00, Cole-Parmer Instrument Company, Vernon Hills, IL) (27).…”

Section: Magnetic Field Exposure Systemmentioning

confidence: 99%

Biological Effects of Long-Duration, High-Field (4 T) MRI on Growth and Development in the Mouse

Magin

Lee

Klintsova

et al. 2000

J. Magn. Reson. Imaging

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The effects of long-duration, high-field magnetic resonance imaging (MRI) on fetal growth and postnatal development in mice were studied. Seven experimental groups of pregnant ICR mice were exposed for 9 hours on day 9 and/or day 12 post coitus (pc) to magnetic fields (4 T static, 5 T/sec switched gradient, and 0.2 W/kg radiofrequency at 170 MHz) associated with MRI conditions. Two experimental groups (sham and exposure groups) were exposed to a combination of ultrasound (day 9 pc, 3.25 MHz, focused) and MRI-associated fields (day 12 pc). No statistically significant changes in fetal growth were observed in the animals exposed to only MRI or ultrasound fields. However, in the combined ultrasound and MRI-exposed group, the fetal weight and crown-rump length were reduced compared with the sham and cage controls. These results suggest that MRI and ultrasound exposure well in excess of current clinical conditions can exert biological effects if applied at sensitive stages of fetal development.

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“…First, the background noise caused by compressors and air conditioning is often clearly audible, and potentially produces activation in both stimulated and nominally unstimulated epochs. More importantly, acquisition induces a loud burst of sound that exceeds 110 dB SPL in 1.5 Tesla ͑T͒ scanners and can be as high as 130 dB SPL in 3 T scanners ͑Shellock et Ravicz et al, 2000;Miyati et al, 1999;Foster et al, 2000͒. This scanner noise is potentially damaging to the listener's hearing ͑Foster et al, 2000͒, can be unpleasant, and leads to fatigue.…”

Section: Introductionmentioning

confidence: 96%

Active control of the volume acquisition noise in functional magnetic resonance imaging: Method and psychoacoustical evaluation

Chambers

Akeroyd

Summerfield

et al. 2001

The Journal of the Acoustical Society of America

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Functional magnetic resonance imaging (fMRI) provides a noninvasive tool for observing correlates of neural activity in the brain while a subject listens to sound. However, intense acoustic noise is generated in the process of capturing MR images. This noise stimulates the auditory nervous system, limiting the dynamic range available for displaying stimulus-driven activity. The noise is potentially damaging to hearing and is distracting for the subject. In an active noise control (ANC) system, a reference sample of a noise is processed to form a sound which adds destructively with the noise at the listener's ear. We describe an implementation of ANC in the electromagnetically hostile and physically compact MRI scanning environment. First, a prototype system was evaluated psychoacoustically in the laboratory, using the electrical drive to a noise-generating loudspeaker as the reference. This system produced 10-20 dB of subjective noise-reduction between 250 Hz and 1 kHz, and smaller amounts at higher frequencies. The system was modified to operate in a real MR scanner where the reference was obtained by recording the acoustic scanner noise. Objective reduction by 30-40 dB of the most intense component in scanner noises was realized between 500 Hz and 3500 Hz, and subjective reduction of 12 dB and 5 dB in tests at frequencies of 600 Hz and at 1.9 kHz, respectively. Although the benefit of ANC is limited by transmission paths to the cochlea other than air-conduction routes from the auditory meatus, ANC achieves worthwhile attenuation even in the frequency range of maximum bone conduction (1.5-2 kHz). ANC should, therefore, be generally useful during auditory fMRI.

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Acoustic noise analysis in echo planar imaging: multicenter trial and comparison with other pulse sequences

Cited by 17 publications

References 8 publications

Relationship between magnetic field strength and magnetic-resonance-related acoustic noise levels

Relationship between magnetic field strength and magnetic-resonance-related acoustic noise levels

Biological Effects of Long-Duration, High-Field (4 T) MRI on Growth and Development in the Mouse

Active control of the volume acquisition noise in functional magnetic resonance imaging: Method and psychoacoustical evaluation

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