scholarly journals Analysis of the Influence of Different Settings of Scan Sequence Parameters on Vibration and Noise Generated in the Open-Air MRI Scanning Area

Sensors ◽  
2019 ◽  
Vol 19 (19) ◽  
pp. 4198 ◽  
Author(s):  
Jiří Přibil ◽  
Anna Přibilová ◽  
Ivan Frollo
Keyword(s):  
Acoustic Noise ◽  
Subjective Evaluation ◽  
Test Method ◽  
Time Duration ◽  
Slice Orientation ◽  
Scanning Area ◽  
Repetition Time ◽  
Negative Impacts ◽  
Magnetic Resonance Imaging Mri ◽  
Sequence Parameters

A system of gradient coils of the magnetic resonance imaging (MRI) device produces significant vibration and noise. Energetic relations of these phenomena are analyzed depending on MRI scan parameters (sequence type, repetition time (TR), echo time (TE), slice orientation, body weight). This issue should be investigated because of negative physiological and psychological effects on a person exposed to vibration and acoustic noise. We also measured the sound pressure level in the MRI scanning area and its vicinity in order to minimize these negative impacts, depending on intensity and time duration of exposition. From the recorded vibration and noise signals, the energy parameters were determined and statistically analyzed, and the obtained results were visually and numerically compared. Finally, subjective evaluation by a listening test method was used to analyze the influence of the generated MRI noise on the human psyche.

scholarly journals Analysis of Energy Relations between Noise and Vibration Signals in the Scanning Area of an Open-Air MRI Device

Proceedings ◽  
2018 ◽  
Vol 4 (1) ◽  
pp. 29 ◽  
Author(s):  
Jiří Přibil ◽  
Anna Přibilová ◽  
Ivan Frollo
Keyword(s):  
Signal Analysis ◽  
Sound Pressure ◽  
Acoustic Noise ◽  
Vibration Signals ◽  
Noise And Vibration ◽  
Signal Energy ◽  
Scanning Area ◽  
Repetition Time ◽  
Energy Relations ◽  
Sequence Parameters

The paper analyzes the influence of different magnetic resonance (MR) scan sequence parameters (echo time, repetition time, orientation of scan slices, sequence type, mass of a tested object) on the energy of the produced noise and vibration. The measured sound pressure levels, together with the recorded noise and vibration signals, were stored in a database and then processed using similar methods to speech signal analysis because the main frequencies of the acoustic noise and vibration lie in the standard audio frequency range. In the signal processing phase, four types of parameters describing the signal energy were determined and statistically analyzed, and the obtained results were visually and numerically compared.

scholarly journals Model forB1Imaging in MRI Using the Rotating RF Field

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Adnan Trakic ◽  
Jin Jin ◽  
Ewald Weber ◽  
Stuart Crozier
Keyword(s):  
Degrees Of Freedom ◽  
Acoustic Noise ◽  
Bloch Equation ◽  
Gradient Coil ◽  
Imaging Method ◽  
Nonuniform Field ◽  
Rf Coil ◽  
Image Encoding ◽  
Magnetic Resonance Imaging Mri ◽  
Space Requirements

Conventionally, magnetic resonance imaging (MRI) is performed by pulsing gradient coils, which invariably leads to strong acoustic noise, patient safety concerns due to induced currents, and costly power/space requirements. This modeling study investigates a new silent, gradient coil-free MR imaging method, in which a radiofrequency (RF) coil and its nonuniform field (B1+) are mechanically rotated about the patient. The advantage of the rotatingB1+field is that, for the first time, it provides a large number of degrees of freedom to aid a successfulB1+image encoding process. The mathematical modeling was performed using flip angle modulation as part of a finite-difference-based Bloch equation solver. Preliminary results suggest that representative MR images with intensity deviations of <5% from the original image can be obtained using rotating RF field approach. This method may open up new avenues towards anatomical and functional imaging in medicine.

scholarly journals Canadian Association of Radiologists Recommendations for the Safe Use of MRI During Pregnancy

2021 ◽  
pp. 084653712110156
Author(s):  
Pejman Jabehdar Maralani ◽  
Anish Kapadia ◽  
Grace Liu ◽  
Felipe Moretti ◽  
Hournaz Ghandehari ◽  
...  
Keyword(s):  
Working Group ◽  
Energy Deposition ◽  
Expert Panel ◽  
Acoustic Noise ◽  
Evidence Based ◽  
Resonance Imaging ◽  
Canadian Association ◽  
Fetal Safety ◽  
Magnetic Resonance Imaging Mri ◽  
In Pregnancy

The use of magnetic resonance imaging (MRI) during pregnancy is associated with concerns among patients and health professionals with regards to fetal safety. In this work, the Canadian Association of Radiologists (CAR) Working Group on MRI in Pregnancy presents recommendations for the use of MRI in pregnancy, derived from literature review as well as expert panel opinions and discussions. The working group, which consists of academic subspecialty radiologists and obstetrician-gynaecologists, aimed to provide updated, evidence-based recommendations addressing safety domains related to energy deposition, acoustic noise, and gadolinium-based contrast agent use based on magnetic field strength (1.5T and 3T) and trimester scanned, in addition to the effects of sedative use and occupational exposure.

scholarly journals Characteristics of Movement of the Lips, Tongue and Velum during a Bilabial Plosive

2007 ◽  
Vol 77 (4) ◽  
pp. 612-618 ◽  
Author(s):  
Maristela Sayuri Inoue ◽  
Takashi Ono ◽  
Ei-ichi Honda ◽  
Tohru Kurabayashi
Keyword(s):  
Anterior Part ◽  
Posterior Part ◽  
Mean Values ◽  
Place Of Articulation ◽  
Temporal Relationships ◽  
Articulatory Movements ◽  
Custom Made ◽  
Repetition Time ◽  
Magnetic Resonance Imaging Mri ◽  
The Individual

Abstract Objective: To obtain dynamic images of articulators using a magnetic resonance imaging (MRI) movie and to clarify the relationships among the articulators. Materials and Methods: The subjects consisted of 10 volunteers. Custom-made circuitry was connected to an MRI apparatus to enable an external trigger pulse to control the timing of the scanning sequence and to provide an auditory cue for synchronization of the subject's utterance. The subject repeated a bilabial plosive, and the run was measured using a gradient echo sequence with a repetition time of 30 ms. Several variables were defined to delineate the individual movements of articulators and to determine the temporal relationships among them. Results: It was found that (1) the change in these variables showed distinctive waveforms; (2) mean values of the standard deviations for these variables were relatively small; and (3) the movement of the velum was significantly correlated with those of the lips and the anterior part of the tongue, but not with the posterior part of the tongue. Conclusions: These results suggest that (1) articulatory movements were clearly recorded using an MRI movie, and (2) there seems to be a central mechanism for controlling articulators, and the level of coupling may be associated with the place of articulation.

scholarly journals Improvements in MR imaging of solids through gradient waveform optimization

2011 ◽  
Vol 89 (7) ◽  
pp. 729-736
Author(s):  
Marco L.H. Gruwel ◽  
Peter Latta ◽  
Boguslaw Tomanek
Keyword(s):  
Mr Imaging ◽  
Acoustic Noise ◽  
Signal To Noise Ratio ◽  
Single Point ◽  
Waveform Optimization ◽  
Imaging Sequence ◽  
Wide Range ◽  
Gradient Waveform ◽  
Condensed Materials ◽  
Magnetic Resonance Imaging Mri

Magnetic resonance imaging (MRI) is known to provide a useful approach for the exploration of the chemistry and dynamics of a wide range of soft condensed materials. However, its application to solids has been limited to those materials with relatively narrow resonances. The time needed to obtain an image of a solid with a given resolution and signal-to-noise ratio (SNR) is directly proportional to the line width of the resonance. For MRI to become practical for the imaging of solids it will have to rely on the development and use of MR sequences that avoid the issues raised by line broadening of the resonance. In this paper we review the latest contributions towards MR imaging of solids from our laboratory, in particular, applications using optimized gradient waveforms. Acoustic noise reduction and SNR improvement obtained with modifications of the standard single-point imaging sequence are presented and discussed using examples.

scholarly journals Magnetic Resonance Imaging of Hepatic Neoplasms in the Rat

1989 ◽  
Vol 26 (4) ◽  
pp. 303-308 ◽  
Author(s):  
G. A. Johnson ◽  
M. B. Thompson ◽  
G. P. Cofer ◽  
D. Campen ◽  
R. R. Maronpot
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Relaxation Times ◽  
Three Dimensional ◽  
Resonance Imaging ◽  
Focal Lesions ◽  
Hepatic Neoplasms ◽  
Histologic Evaluation ◽  
Repetition Time ◽  
Magnetic Resonance Imaging Mri

Magnetic resonance imaging (MRI) at microscopic resolution was done on a live rat that had chemically induced hepatic neoplasms. Beginning at the anterior aspect of the liver, 16 contiguous transaxial slices (each 1.25 mm thick) were produced using three-dimensional Fourier transform sequences. The rat had been treated with diethylnitrosamine (200 mg/kg) at 70 days of age, and, subsequently, received periodic implants of 17a-ethynylestradiol for 60 weeks. Carr-Purcell-Meiboom-Gill (CPMG) sequences (repetition time = 2,000 and echo time = 20, 40, 60, 80 ms) were done to give quantitative measures of spin-spin relaxation times (T2). Pixel-by-pixel curve fitting from these multiple images yielded calculated T2 images. Histologic evaluation of three abnormal areas in the liver revealed solid and cystic hepatocellular adenomas. Although lesions were evident in early-echo images of the CPMG sequence, they were more apparent in the late-echo images. This was consistent with longer T2 relaxation times for the lesions. The voxels of dimensions (230 × 230 × 1,250 /μm) permitted resolution of volume elements <0.07 mm3. This in turn permitted clear delineation of focal lesions <3 mm in diameter. The potential for MRI at microscopic resolution in toxicologic research is clearly demonstrated.

scholarly journals Influence of the Human Body Mass in the Open-air MRI on Acoustic Noise Spectrum

ACTA IMEKO ◽  
2016 ◽  
Vol 5 (3) ◽  
pp. 81 ◽  
Author(s):  
Jiri Pribil ◽  
Anna Pribilová ◽  
Ivan Frollo
Keyword(s):  
Spectral Analysis ◽  
Spectral Properties ◽  
Vocal Tract ◽  
Acoustic Noise ◽  
Noise Spectrum ◽  
3D Modelling ◽  
Pressure Level ◽  
Gradient Coils ◽  
Scanning Area ◽  
Mechanical Mass

The paper analyses changes in spectral properties of the acoustic noise when the examined person lies in the scanning area of the open-air magnetic resonance imager (MRI) and consequently the holder of the lower gradient coils is loaded with the mechanical mass represented by the person’s weight. The acoustic noise pressure level is mapped in the MRI neighborhood, too. Obtained results of spectral analysis will be used for design of a correction filter to suppress the noise in the simultaneously recorded speech signal for 3D modelling of the human vocal tract.

scholarly journals Analysis of Influence of Coil Gradient System on Vibration Properties and Acoustic Noise Level Generated by the Low Field MRI Device

2018 ◽  
Vol 18 (5) ◽  
pp. 193-200 ◽  
Author(s):  
Jiří Přibil ◽  
Anna Přibilová ◽  
Ivan Frollo
Keyword(s):  
Permanent Magnets ◽  
Noise Suppression ◽  
Vocal Tract ◽  
Acoustic Noise ◽  
Spectral Characteristics ◽  
Gradient Coil ◽  
Gradient System ◽  
Vibration Signals ◽  
Parallel Acquisition ◽  
Scanning Area

Abstract The paper focuses on investigation of influence of the volume inserted in the scanning area of the magnetic resonance imaging (MRI) device working with a low magnetic field generated by a pair of permanent magnets on vibration and acoustic noise. In addition, its aim is to evaluate the influence of different types of used scan sequences, different settings of slice orientation and scan parameters on the energy and spectral properties of vibration and noise generated by the gradient coil system of the MRI device. Two basic measurements were performed within this work: mapping of sound pressure levels in the MRI device vicinity and parallel acquisition of vibration signals by sensors mounted on the lower and upper parts of the MRI gradient system. The paper next analyzes changes in properties of the vibration signals for the examined person lying in the scanning area compared with the situation of using only the testing phantom. Spectral characteristics of the recorded vibration signals are then analyzed statistically, and compared visually and numerically. The obtained results of the detailed analysis will be used for improvement of noise suppression algorithms applied to a speech signal recorded simultaneously with scanning of the human vocal tract for its 3D modeling.

An Improved Method for AMR-WB Speech Codec

2013 ◽  
Vol 756-759 ◽  
pp. 1259-1263
Author(s):  
Chun Ling Zhang ◽  
Sheng Hui Zhao ◽  
Hong Yuan Xiao ◽  
Jing Wang ◽  
Jing Ming Kuang
Keyword(s):  
Linear Prediction ◽  
Subjective Evaluation ◽  
Objective Evaluation ◽  
Original Method ◽  
Test Method ◽  
Improved Method ◽  
Perceptual Evaluation ◽  
Look Ahead ◽  
The Look

an improved method is proposed to skip the look-ahead period in this paper. The improved method uses the autocorrelation algorithm to calculate the Linear Prediction (LP) coefficients and then the LP coefficients are employed to extrapolate new samples for replacing the look-ahead samples. To evaluate the quality of this method, perceptual evaluation of speech quality (PESQ) and the A/B listening test method are designed for the objective evaluation and subjective evaluation. The reconstructed quality of the modified method is near to the original AMR codec, at the same time, the delay of the improved method is lower 5ms than the original method.

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