Silent high resolution echo-planar imaging for auditory fMRI

Introduction Acoustic scanner noise during image acquisition is a well-known problem in functional MRI (fMRI). The noise is created by gradient coil switching and causes an unwanted BOLD signal in the auditory cortex [1]. Most of the time, echo-planar imaging (EPI) is used for fMRI. However, this sequence produces high acoustic noise due to fast switching of trapezoidal gradients. The sound pressure level (SPL) of such EPI sequences on a 3T-scanner can reach up to 130 dB [2]. This effects fMRI at high resolution seriously. High resolution in EPI can be achieved by a parallel acquisition technique (PAT). The aim of this work is to extend an existing silent sinusoidal EPI (sEPI) sequence by means of PAT. This technique allows for doubling the current resolution (64 x 64 matrix) of the sEPI at approximately the same acquisition time. The developed sequence is evaluated in an auditory fMRI experiment. The combination of the sEPI sequence with PAT results in a high resolution sequence that reduces the SPL compared to the conventional EPI sequence with PAT.