Making MRI Quieter

Edelstein, William A.; Hedeen, Robert A.; Mallozzi, R.; El-Hamamsy, Sayed Amr; Ackermann, Robert F.; Havens, Timothy

doi:10.1016/s0730-725x(02)00475-7

Cited by 106 publications

(111 citation statements)

References 4 publications

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“…These vibrations are coupled into the magnet structure and are manifested as acoustic noise [45,46]. Since the forces are proportional to the strength of the magnetic field, one would expect higher noise levels for higher magnetic fields, as indeed has been noted for example in the 0.2-3.0 T range [47].…”

Section: Acoustic Noisementioning

confidence: 75%

Safety of Ultra-High Field MRI: What are the Specific Risks?

Osch

Webb

2014

Curr Radiol Rep

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There are currently more than 50 ultra-high field (7 T and above) MRI systems installed around the world. The vast majority of these perform studies on humans, whether healthy volunteers, volunteers for clinical research, or actual patients. The increased magnetic field strength potentially raises new safety concerns in the areas of the effects of the static magnetic field itself, increased power deposition due to the higher operating frequency, and acoustic noise. There are currently very different operational modes in different institutions, with policies effectively set by local ethics committees. This article summarizes the current legal and practical status regarding safety of ultra-high field MRI.

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Section: Acoustic Noisementioning

confidence: 75%

Safety of Ultra-High Field MRI: What are the Specific Risks?

Osch

Webb

2014

Curr Radiol Rep

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“…Firstly, machine noise, which has been previously documented as an annoyance during MRI [32,41,42], was noted by three patients. Acoustic noise reduction may be achieved with hardware-based techniques aimed at minimizing the mechanical gradient coil vibration to the rest of the system, and/or sequence-based techniques aimed at optimizing the gradient activity and avoiding acoustic resonance frequencies [43][44][45]. Future developments in silent MRI and quieter sequences specifically for MRA may help to minimize acoustic noise.…”

Section: Discussionmentioning

confidence: 99%

Patient Perception of Lower Limb Non-Contrast Magnetic Resonance Angiography and Digital Subtraction Angiography in Diabetic Patients with Peripheral Arterial Disease

Lukies

Richmond

Hornsey

et al. 2017

Cardiovasc Imaging Asia

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Peripheral arterial disease (PAD) is common in diabetic patients, with an estimated prevalence of 20-29% in those over 50 years of age, and causes significant morbidity, with amputation or limb loss occurring in around 4% of patients [1]. The imaging diagnosis of PAD in diabetic patients is challenging because renal impairment is common and vessels tend to be cc This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Objective: Non-contrast magnetic resonance angiography (NC-MRA) is an attractive technique for imaging peripheral arterial disease (PAD) in diabetic patients where arterial calcification and renal impairment are common. Our purpose was to evaluate patient perception of lower limb NC-MRA and compare this perception to that of digital subtraction angiography (DSA). Materials and Methods:Thirty-one diabetic patients (18 male, 13 female, mean age=69 years) with symptomatic PAD (critical ischemia, n=10) referred for DSA were prospectively recruited, and 1.5T quiescent-interval single-shot NC-MRA was performed before DSA (intervention performed during DSA, n=23). Patients rated anxiety, pain, discomfort, willingness to repeat (Likert scale: 1 most favorable to 7 least favorable), and difficulty compared to expectations (-3 better to +3 worse).Results: Twenty-nine patients' results were analyzed (DSA under general anesthesia, n=1; incomplete NC-MRA due to morbid obesity, n=1). NC-MRA and DSA median scores were 1 vs. 3, 1 vs. 2, 2 vs. 2, and 1 vs. 1 for anxiety, pain, discomfort, and willingness to repeat, respectively. The median score for difficulty compared to expectations was 0 (as expected) for both examinations. The anxiety and pain scores for NC-MRA were significantly lower than those for DSA (p=0.006 and p=0.001, respectively). Reasons for the less favorable NC-MRA experience included machine noise (n=3), pain from coil pressure (n=3), and claustrophobia (n=1).Conclusion: NC-MRA was well tolerated overall, and better than DSA for anxiety and pain. Although DSA is commonly required for intervention in PAD, NC-MRA may inform disease management and potentially obviate DSA where conservative management, or open surgery, are indicated. Reduced acoustic noise, lighter receiver coils, and wider scan bores may improve procedural tolerance.

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“…MR scanning noise is generated by Lorentz forces during the rapid switching of current directions within the gradient coils under a strong static magneticˆeld. [11][12][13][14][15][16][17][18][19] Various patterns of acoustic noise are generated when the forces cause vibration of the gradient coil unit as they impact against the mounting frame. The frequency characteristics of this noise are altered by the gradient waveform deˆned by the pulse sequence design and imaging parameters such as slice thickness, direction of the imaging plane axis,ˆeld of view (FOV), repetition time (TR), and echo time (TE).…”

Section: Discussionmentioning

confidence: 99%

“…An interesting initial approach was a`rotating direct current (DC) gradient', 25 which employed a mechanically rotating gradient coil system encoding steps to achieve 20.7 dB (A) noise reduction. Several approaches have been developed to improve the physical characteristics of the gradient coil system: 1) passive acoustic attenuating liners, 17 epoxy-potting, 16 or a screen consisting ofˆberglass, 18 2) sealing the gradient coil in a vacuum chamber to block airborne vibration propagation, 25 3) cancellation of gradient coil vibration using opposing forces applied to coilforming segments by opposite currents in the gradient and return arcs of the coil, 19 and 4) active noise cancelation using an out-of-phase secondary acoustic wave form. 13,23 An early attempt at a silent pulse technique was a sinusoidal waveform for gradient driving.…”

Section: Discussionmentioning

confidence: 99%

A Survey Analysis of Acoustic Trauma Related to MR Scans

et al. 2012

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Purpose: The maximum limit of MR scanner noise and necessity of ear protection is dened in the IEC standard (IEC60601-2-33) of MR safety. With improvements in MR scanner performance, pulse sequences generating higher scanning noise have been used clinically. In this study, we investigated the factors signiˆcantly related to potential acoustic trauma cases (PATC) after MR examinations. To consider the future direction for MR safety and prevention of acoustic trauma, issues related to noise generation by MR scanners and acoustic trauma were systematically reviewed.Methods: A statistical analysis was performed using the data set from a survey (n＝974) conducted in 2010 by the JSMRM safety committee. Hierarchical clustering analysis was used to extract the characteristics of the responders. With this classiˆcation as a reference, tests of independence and a residual analysis were employed to evaluate the factors related to PATC.Results: No signiˆcant relationship was observed between the ear protection policy and the incidence or the reported outcome of PATC. While the two main clusters out of the six clusters extracted were associated with who reported the PATC and the conˆrmation process of the acoustic noise level of MR scanners, no cluster was associated with the frequency of PATC. An absence of PATC was signiˆcantly less reported (p＝0.03) and more PATC was reported (p＝0.04) by facilities with 3T MR systems.Discussion: Although the total frequency was 4 cases, it should be noted that persistent hearing disturbances are a possible consequence of MR examinations. Neither the condition of the subjects nor the ear protection method was signiˆcantly related to the probability of PATC, suggesting the di‹culty of predicting the potential risk of acoustic trauma. It is recommended to more systematically follow up PATC cases and clarify the risk factors.

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Making MRI Quieter

Cited by 106 publications

References 4 publications

Safety of Ultra-High Field MRI: What are the Specific Risks?

Safety of Ultra-High Field MRI: What are the Specific Risks?

Patient Perception of Lower Limb Non-Contrast Magnetic Resonance Angiography and Digital Subtraction Angiography in Diabetic Patients with Peripheral Arterial Disease

A Survey Analysis of Acoustic Trauma Related to MR Scans

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