A transmit-receive array for brain imaging with a high-performance gradient insert.

Area of Science:

• Magnetic Resonance Imaging (MRI)
• RF Coil Engineering
• Medical Physics

Background:

• Parallel imaging techniques accelerate MRI acquisition but are limited by gradient system constraints.
• Developing specialized RF coils is crucial for optimizing performance within confined gradient inserts.

Purpose of the Study:

• To design and evaluate an 8-channel transmit-receive RF array coil for parallel imaging in a 33-cm inner diameter gradient insert.
• To address challenges of space, encoding ambiguity, and eddy current immunity.

Main Methods:

• Investigated eddy current behavior through heating and field deviation measurements.
• Assessed RF performance using S-parameters, noise statistics, B1 maps, and g-factor maps.
• Acquired in vivo human head and knee images with fast (TE < 0.45 ms) Cartesian imaging.

Main Results:

• The RF coil demonstrated low eddy current-induced field distortions, superior to a commercial coil.
• Achieved low element coupling (< -15 dB) and noise correlation (< 0.31) with head loading.
• Showcased power efficiency (0.52 ± 0.02 μT/√W) and minimal flip angle variation (< 10%).
• Enabled up to fourfold acceleration with < 30% noise amplification, functional during full gradient performance.

Conclusions:

• The developed RF coil successfully provides parallel imaging capability within a high-performance gradient insert.
• The coil design is suitable for accelerated MRI of the human head and knee.