Measurement of acoustic noise during MR imaging: evaluation of six "worst-case" pulse sequences.
OBJECTIVE
To assess acoustic noise levels for ambient noise and magnetic resonance (MR) imaging at 1.5 T during use of six "worst-case" pulse sequences.


METHODS
Acoustic noise measurements were obtained at the entrance, center, and exit of the magnet bore of the MR system by means of a specially modified device that is unaffected by electromagnetic radiation.


RESULTS
The highest ambient noise level was 73 dB at both the entrance and exit of the magnet bore (A-weighted scale). The highest noise levels during MR imaging occurred during use of a gradient-echo (GRE) pulse sequence and was 102 dB at the entrance and exit of the magnet bore and 103 dB at the center (A-weighted scale).


CONCLUSIONS
MR imaging performed with the worst-case pulse sequences did not produce noise levels that exceeded federal guidelines. Noise levels were, however, high enough to impair oral communication and annoy patients. Thus, techniques to attenuate acoustic noise and allow improved operator-patient communication should be used during MR imaging, especially during use of GRE pulse sequences.
Shellock
F G
FG
Tower Imaging, Los Angeles, CA 90048.
Morisoli
S M
SM
Ziarati
M
M
D000162:Acoustics; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*