Combined imaging and shimming with the dynamic multi-coil technique

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Biophysics
• Medical Physics

Background:

• Traditional MRI spatial encoding and shimming rely on dedicated coils producing specific magnetic fields.
• Recent advancements show multi-coil hardware can generate MRI-relevant fields using localized, non-orthogonal coils.

Purpose of the Study:

• To demonstrate the feasibility of a purely multi-coil-based MRI field generation system.
• To establish the capability of multi-coil hardware for conventional Cartesian k-space encoding and echo-planar imaging (EPI).
• To investigate concurrent encoding and shimming using multi-coil systems.

Main Methods:

• Utilized the Dynamic Multi-Coil Technique (DYNAMITE) with a 48-channel system for combined Cartesian encoding, shimming, and EPI.
• Implemented Cartesian Fourier-encoded MRI and EPI using linear combinations of multi-coil fields.
• Performed experiments on phantom objects and biological specimens at 9.4T, including concurrent DYNAMITE shimming and imaging.

Main Results:

• DYNAMITE-based MR and EPI images were comparable to those from conventional linear gradients.
• Concurrent DYNAMITE shimming effectively corrected extreme shim challenges, recovering over 92% of signal in severe cases.
• Demonstrated successful implementation of combined DYNAMITE imaging and shimming.

Conclusions:

• Successfully implemented combined DYNAMITE imaging and shimming, proving its feasibility for EPI.
• Multi-coil hardware shows potential as a comprehensive MRI imaging and shimming system.
• Potential benefits include reduced echo time and lower risk of peripheral nerve stimulation during EPI.