5. Conclusions

Acoustic noise measurement in the vicinity of the investigated open-air MRI device yielded the maximum sound pressure level of about 82 dB(C) at the distance of 45 cm from the central point of the MRI scanning area for the GE scan sequence with short TE and TR times and the sagittal orientation of scan slices. For examination of other parts of the human body (leg, arm, etc.), the head is not inserted directly between the upper and the lower gradient coils, so the noise level is much lower as documented for different distances in Figure 10. Finally, the scanning times for the mostly used 3D or Hi-Res sequences are in general less than 15 minutes (typically about 3–5 minutes depending on the chosen number and thickness of the slices)—exposition of the examined person and his/her hearing system to the noise and vibration is not significant.

If there is need for more detailed MR images with higher quality factor Q<sup>F</sup> (e.g., in scanning of particular parts of the human brain, the eye, the middle and inner ear, etc.), the time duration TDUR can be much longer (more than half an hour). In such a case, the long exposition to the vibration and acoustic noise may impose great physiological and psychological stress on the patient. Therefore, these scan parameters should be chosen only in the urgent cases.

The results of the performed measurements are useful for precise description of the process of the mechanical vibration excitation and the acoustic noise radiation in the scanning area and in the vicinity of the MRI device. The measurement results and comparisons with a similar low-field MRI tomograph can be used in optimization of the acoustic noise suppression in the speech recorded parallel with application of MRI scanning for 3D modeling of the human vocal tract [19].

Author details

\*, Anna Přibilová<sup>2</sup> and Ivan Frollo<sup>1</sup>

Information Technology, SUT, Bratislava, Slovak Republic

\*Address all correspondence to: umerprib@savba.sk

provided the original work is properly cited.

1 Institute of Measurement Science, SAS, Bratislava, Slovak Republic

2 Institute of Electronics and Photonics, Faculty of Electrical Engineering and

Analysis of Energy Relations between Noise and Vibration Produced by a Low-Field MRI Device

DOI: http://dx.doi.org/10.5772/intechopen.85275

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

Jiří Přibil1

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#### Acknowledgements

This work was funded by the Slovak Scientific Grant Agency project VEGA 2/ 0001/17 and the Ministry of Education, Science, Research, and Sports of the Slovak Republic VEGA 1/0905/17, and the Slovak Research and Development Agency, project no. APVV-15-0029.

### Conflict of interest

The authors declare no conflict of interest.

Analysis of Energy Relations between Noise and Vibration Produced by a Low-Field MRI Device DOI: http://dx.doi.org/10.5772/intechopen.85275
