A 32-channel multi-coil setup optimized for human brain shimming at 9.4T

Area of Science:

• Magnetic Resonance Imaging
• Biophysics

Background:

• B0 inhomogeneity is a significant challenge in human brain imaging, particularly at ultrahigh magnetic fields.
• Effective shimming is crucial for obtaining high-resolution and artifact-free MRI data.

Purpose of the Study:

• To design and optimize a multi-coil shim setup for improved human brain shimming.
• To enhance shim performance without increasing the number of local coils, especially for ultrahigh field applications.

Main Methods:

• Optimization of coil size and position for 32 independent coils.
• Utilized B0 maps from 8 healthy volunteers at 9.4T as training data.
• Compared optimized design against symmetric arrangements and standard shim setups via simulations and measurements.

Main Results:

• Achieved 14.7% improvement in standard deviation (SD) for global shimming compared to symmetric coil positioning.
• Demonstrated comparable global shimming performance to a 65-channel multi-coil and full fifth-order spherical harmonic coils.
• Attained average in vivo SD of 48.4 Hz after global shimming and 31.9 Hz after dynamic slice-wise shimming.

Conclusions:

• An optimized multi-coil shim setup was successfully designed and constructed for whole-brain shimming.
• Optimal coil arrangement allows achieving high performance with fewer channels, making it suitable for ultrahigh field MRI.