Acoustic noise analysis in echo planar imaging: multicenter trial and comparison with other pulse sequences

The purpose of this study was to evaluate acoustic noise in echo planar imaging (EPI) at various magnetic resonance imaging (MRI) centers and to compare EPI acoustic noise with that in other fast pulse sequences. We measured A-weighted root-mean-square sound pressure levels and peak impulse sound pressure levels for EPI, under the same conditions, in eleven clinical super-conducting MRI systems. We also compared sound pressure levels for the EPI and six different pulse sequences and analyzed the acoustic noise spectra. Sound pressure levels during the use of the EPI differed greatly among institutions. Moreover, sound pressure levels of the EPI were not significantly different from those of other fast pulse sequences and were within permissible noise exposure levels. In comparison to other fast sequences, the EPI had significantly greater acoustic noise in the high-octave band frequency.