Magnetic Resonance Imaging (MRI) is a powerful imaging tool used in clinical diagnosis and biomedical research. One of the undesirable characteristics of the process is the loud noise generated during a scan. A major source of this noise is the result of switching electrical current in gradient coils within the static magnetic field. As the technology has evolved, the quality of images has improved by, among other things, increasing static magnetic fields and gradient switching rates. These improvements have also increased the imaging speed, allowing for observation of dynamic events. For example, functional MRI (fMRI) allows changes in brain function over short time intervals to be observed. However, the downside is a corresponding increase in the level of noise generated. The sound pressure levels (SPLs) the patient is subjected to not only produce discomfort, but are potentially harmful as well. Reducing exposure to these high SPLs would not only result in improved patient comfort, but also allow for more robust imaging procedures, since the magnitude of noise exposure can be a limiting factor in certain types of MRI procedures. In this paper recent patents related to reducing noise exposure with the potential for application to MRI will be examined.
Keywords: Active noise control, active noise reduction/attenuation, MRI noise control, active noise suppression, acoustics, unwanted sound, acoustic noise tuning
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