Keywords:
Education and training, Imaging sequences, MR, MR physics
Authors:
M. Wyss1, I. Dobrev1, J. H. Sim1, T. D. J. Sartoretti2, A. Najafi2, M. Koepfli3, A. M. Huber1, C. A. Binkert2; 1Zürich/CH, 2Winterthur/CH, 3Lucerne/CH
DOI:
10.1594/ecr2018/C-2186
Conclusion
Acoustic noise may be a major factor for patient discomfort during the MR examination.
MR noise is strongly varying in time,
and may have complex patterns.
Our measurement method provides a more comprehensive description of the characteristics of the acoustic noise in MR than a single average number output from handheld analyzers.
This offers the possibility to extend the characterization of the noise pattern of MR sequences beyond average sound pressure,
such as roughness,
modulation or fluctuation of the signal.
A set of come comprehensive metrics potentially offers more accurate description for the expected impact on the patient’s hearing,
annoyance,
comfort and consequently the resulting negative impact on image quality due to patient motion.
It may enable future work on the evaluation of properties of acoustic noise which are important or key factors in the annoyance of patients during an MRI exam.
The choice of the noise reduction method (Softone or Comfortone) or reduction factor (Softone) is governed by a balance between minimization of acoustic noise while keeping side effects to imaging quality minimal.
Interestingly,
more negative effects such as higher receiver bandwidth or longer TE (less signal to noise ratio),
are often compensated by a longer TR (more T1 relaxation).
This may be the main reason that the image quality did not differ substantially when using acoustic noise reduction.
To conclude: acoustic noise reduction based on MR pulse sequence optimization offers a substantial reduction in acoustic noise,
enhances patient communication and improves patient comfort.
These techniques tend to increase the acquisition time.
Although imaging parameters are affected,
image quality and contrast are virtually the same.