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

Area of Science:

• Magnetic Resonance Imaging
• Biophysics

Background:

• Diffusion-prepared MRI is crucial for neuroimaging.
• Eddy currents from diffusion gradients cause phase errors, degrading image quality.
• Magnitude stabilizers are often used but reduce signal-to-noise ratio (SNR).

Purpose of the Study:

• To develop a dynamic B0 shimming approach for correcting eddy current-induced phase errors in diffusion-prepared MRI.
• To enable high b-value imaging without SNR loss.
• To eliminate the need for magnitude stabilizers.

Main Methods:

• A 46-channel AC/DC shim array and amplifier system were constructed.
• Spin echo prescans measured eddy current-induced phase differences.
• An optimization framework computed compensatory shim currents for multi-shot 3D diffusion-prepared acquisitions.

Main Results:

• The AC/DC shim array effectively corrected undesirable eddy current effects.
• Whole-brain, cardiac-gated, multi-shot 3D diffusion-prepared imaging was achieved without magnitude stabilizers.
• Full SNR was preserved, enabling reliable diffusion encoding at b values up to 2000 s/mm².

Conclusions:

• A new strategy using an AC/DC shim array compensates for eddy current-induced phase errors in diffusion-prepared MRI.
• This approach eliminates the need for magnitude stabilizers.
• Efficient, high-quality diffusion imaging with retained signal sensitivity is now possible.