A Dynamic Shim Approach for Correcting Eddy Current Effects in Diffusion-Prepared MRI Acquisition Using a Multi-Coil...

We developed a dynamic B₀ shimming approach using a 46-channel AC/DC shim array to correct phase errors caused by eddy currents from diffusion-encoding gradients in diffusion-prepared MRI, enabling high b value imaging without the SNR loss from the use of a magnitude stabilizer.

A 46-channel AC/DC shim array and corresponding amplifier system were built. Spin echo prescans with and without diffusion preparation were then used to rapidly measure eddy current-induced phase differences. These phase maps were used as targets in an optimization framework to compute compensatory shim currents for multi-shot 3D diffusion-prepared acquisitions.

The proposed method allows flexible use of the AC/DC shim array to correct undesirable eddy current effects in diffusion-prepared MRI. Phantom and in vivo experiments demonstrate whole-brain, cardiac-gated, multi-shot 3D diffusion-prepared imaging without the use of magnitude stabilizers. The approach enables preservation of full SNR while achieving reliable diffusion encoding at b values up to 2000 s/mm².

This work demonstrates a new strategy for applying an AC/DC shim array to compensate for eddy current-induced phase errors in diffusion-prepared MRI. By eliminating the need for a magnitude stabilizer, it enables efficient high-quality diffusion imaging with full signal sensitivity retained.