Acoustic Noise Reduction of Echo Planar Imaging in Diffusion MRI

Abstract

Acoustic noise during MR scans, generated by the gradient coil vibration, has been compromising for patient comfort and even poses risk for sensitive populations such as fetuses and infants. Although recommended noise level for neonatal MRI with hearing protection such as earplugs is 65 dBA, noise level of an MRI scan could be as high as 125-130 dB(A) at 3T. Further, hearing protection compliance for neonates using earplug could be unreliable. Single-shot echo planar imaging (EPI) has a rapid switching readout gradient waveform that is very efficient for data acquisition but also very loud. Given that EPI is widely used diffusion MRI techniques, modifications in the EPI sequence design could offer a solution that is ubiquitous across scanner platforms. In this work, we investigated the acoustic noise reduction effects of gradient waveform adjustments, echo spacing adjustments, in combination with parallel imaging. Through gradient waveform and echo spacing (ESP) adjustment, the acoustic noise was reduced by 7.5 dBA while keeping high image SNR. Besides, we validated the image consistency and ADC value accuracy quantitatively between traditional EPI-DWI sequence and the modified versions of EPI-DWI sequences in both phantom and human studies.