Using Magnetic Resonance Imaging to visualize ultrasound wave propagation through a medium

Motivation: Lack of a feedback mechanism renders focused ultrasound neuromodulation results inconsistent and difficult to reproduce. Goal(s): This study hypothesis that electromagnets coupled with MRI can quantify low pressure acoustic fields in a gel sample. Approach: We constructed a custom resonant electromagnet coil to encode propagating acoustic waves into the complex phase of MR images. Results: Acoustic propagation appeared in the phase patterns of MR images, they differed from hydrophone measurements. The speed of sound was correct, but the measured pressure amplitude was different. Impact: This is the first acquisition of acoustic waves using MRI with a human compatible coil.