Active cancellation system of acoustic noise in MR imaging

Chen, C.K.; Chiueh, Tzi‐Dar; Chen, Jyh-Horng

doi:10.1109/10.740881

Cited by 61 publications

(43 citation statements)

References 15 publications

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“…Several studies of acoustic noise reduction and control for MR imaging [16][17][18][19] could reduce sound pressure approximately 20 to 40 dB using a subtraction algorithm with a cross-correlation or leastmean-square algorithm with several adaptiveˆl-ters. Most applied the methods to sound data recorded using a multiple microphone system.…”

Section: Discussionmentioning

confidence: 99%

“…Several studies have proposed techniques to reduce such acoustic noise for acquisition of general, 17 dynamic, 16,18 and functional 19 MR imaging data. In this study, we applied a segmental subtraction approach explained below to reduce the acoustic noise in the recorded speech sound to detect the onset time of utterance of the speech material, /aki/.…”

Section: Acoustical Processing To Reduce Scanner Noise (Nr)mentioning

confidence: 99%

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A Technique to Reduce Motion Artifact for Externally Triggered Cine-MRI(EC-MRI) Based on Detecting the Onset of the Articulated Word with Spectral Analysis

et al. 2012

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One issue in externally triggered cine-magnetic resonance imaging (EC-MRI) for the dynamic observation of speech organs is motion artifact in the phase-encoding direction caused by unstable repetitions of speech during data acquisition. We propose a technique to reduce such artifact by rearranging the k-space data used to reconstruct MR images based on the analysis of recorded speech sounds.We recorded the subject's speech sounds during EC-MRI and used post hoc acoustical processing to reduce scanning noise and detect the onset of each utterance based on analysis of the recorded sounds. We selected each line of k-space from several data acquisition sessions and rearranged them to reconstruct a new series of dynamic MR images according to the analyzed time of utterance onset. Comparative evaluation showed signiˆcant reduction in motion artifact signal in the dynamic MR images reconstructed by the proposed method. The quality of the reconstructed images was su‹cient to observe the dynamic aspects of speech production mechanisms.

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Section: Discussionmentioning

confidence: 99%

Section: Acoustical Processing To Reduce Scanner Noise (Nr)mentioning

confidence: 99%

A Technique to Reduce Motion Artifact for Externally Triggered Cine-MRI(EC-MRI) Based on Detecting the Onset of the Articulated Word with Spectral Analysis

et al. 2012

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“…This method has already been applied to numerous problems where acoustic noise was severe and traditional passive approaches were not suitable or efficient. However, only a few studies using active control for MRI noise reduction have been reported in the literature [14][15][16][17][18][19][20]. To apply the ANC technique on MRI acoustic noise suppression, two things need to be addressed.…”

Section: Introductionmentioning

confidence: 99%

“…However, similar to Pal's study, only fundamental harmonic signals were treated. Chen et al [18] proposed a feedback controller system with a cascaded neural-network architecture to achieve the reduction of MRI acoustic noise. This system was tested using a loudspeaker that presented pre-recorded scanner noises.…”

Section: Introductionmentioning

confidence: 99%

Simulation study on active noise control for a 4-T MRI scanner

Lim

Lee

2008

Magnetic Resonance Imaging

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The purpose of this work is to study computationally the possibility of the application of a hybrid active noise control technique for MRI acoustic noise reduction.A hybrid control system combined with both feedforward and feedback loops embedded is proposed for potential application on active MRI noise reduction. A set of computational simulation studies were performed. Sets of MRI acoustic noise emissions measured at the patient's left ear location were recorded and used in the simulation study.By comparing three different control systems, namely the feedback, the feedforward and the hybrid control, our results revealed that the hybrid control system is the most effective. The hybrid control system achieved approximately a 20 dB reduction at the principal frequency component.We concluded that the proposed hybrid active control scheme could have a potential application for MRI scanner noise reduction.

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“…Sensitive feedback systems should be designed to adjust the secondary noise signal. This method can create a quiet region in space and is mainly used in headphones [76][77][78][79][80]. In addition, actuators can be mounted on the gradient assembly.…”

Section: Acoustic Noise In Mri -Sources and Reduction Techniquesmentioning

confidence: 99%

Gradient coil design and acoustic noise control in magnetic resonance imaging systems

Wang¹

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In magnetic resonance imaging (MRI), three-dimensional linearly varied magnetic field gradients are required in the imaging volume, for the encoding of the spatial information of the imaged object.The gradient magnetic field is generated by gradient coils, whose performance directly affects the final MR image quality. Modern MRI applications demand gradient coils to be designed with higher performance such as a faster slew rate for rapid imaging, and fewer system interactions to ensure distortion-free images.During MR imaging, the gradient coil current switches quickly and the alternating current under a strong magnetic field generates a large Lorentz force, thus increasing the vibrations and noise in the gradient assembly, and the vibrations can also transmit to other components in the system. Moreover, the gradient magnetic field induces eddy currents on the surrounding conductive materials, resulting in further mechanical vibration. The sound pressure level (SPL) of an MRI scanner very commonly exceeds 100 dB, which may be discomforting to patients. Therefore, an effective acoustic noise control is necessary for the MRI operation.This thesis attempts to design a novel gradient coil system in an MRI scanner with a particular focus on the investigation of an acoustic noise control scheme. A brief summary of the thesis work is as follows.(1) Gradient coil design A conventional cylindrical MRI scanner has a long patient bore, which may make some patients uneasy due to claustrophobia. In order to alleviate this, an asymmetric gradient coil was proposed to accommodate an asymmetric MRI magnet. The coil was designed with a number of features, for example, to enable the installation of the shim tray, the coil was configured with one end connected and the other end separated. The electromagnetic and acoustic performances were also improved compared with a conventional non-connected coil system.The stream function approach is commonly used in gradient coil design, but an issue with this design is a connection problem between coil loops. To eliminate the field errors due to the coil connections, this thesis proposed a novel spiral coil design scheme, including both transverse coils and a longitudinal coil. The proposed coil design method was not only able to improve the magnetic II performance of the coil, but also could integrate the cooling system into the coil design using hollow wires in the discrete wire space.Wire spacing is a major engineering problem in gradient coil design. Conventional gradient coils are designed with three primary layers and three shielding layers, and in general, primary transverse coils are located in two layers separated by a very dense wire structure. In this thesis, a novel gradient coil design strategy using a layer-sharing scheme was proposed. This design scheme mutually combined the x and y gradient coil layers, effectively utilizing the unoccupied or sparse coil-layer space. The new method was modelled in the case of an asymmetric head coil design, and enhanced coil performan...

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Active cancellation system of acoustic noise in MR imaging

Cited by 61 publications

References 15 publications

A Technique to Reduce Motion Artifact for Externally Triggered Cine-MRI(EC-MRI) Based on Detecting the Onset of the Articulated Word with Spectral Analysis

A Technique to Reduce Motion Artifact for Externally Triggered Cine-MRI(EC-MRI) Based on Detecting the Onset of the Articulated Word with Spectral Analysis

Simulation study on active noise control for a 4-T MRI scanner

Gradient coil design and acoustic noise control in magnetic resonance imaging systems

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