A 32-Channel Head Coil Array with Circularly Symmetric Geometry for Accelerated Human Brain Imaging

Area of Science:

• Medical Imaging
• Magnetic Resonance Imaging (MRI)
• Coil Design

Background:

• Accelerated MRI techniques are crucial for reducing scan times in human brain imaging.
• Optimizing radiofrequency (RF) coil arrays is essential for improving signal-to-noise ratio (SNR) and image quality, especially at higher field strengths like 3 Tesla (3T).
• Traditional head coil geometries may present limitations in achieving optimal performance for accelerated imaging protocols.

Purpose of the Study:

• To optimize a 32-channel head coil array for accelerated 3T human brain proton MRI.
• To compare the performance of a novel circular symmetry (CS) coil geometry against a conventional soccer-ball (SB) geometry in terms of SNR and noise amplification.
• To evaluate the impact of coil geometry on image reconstruction quality using Cartesian and radial k-space trajectories under accelerated conditions.

Main Methods:

• Design and optimization of a 32-channel head coil array with curved trapezoidal elements in a circular symmetry (CS) geometry.
• Minimization of mutual inductance through optimal coil overlapping and use of low-noise pre-amplifiers for improved decoupling.
• Quantitative comparison of SNR, noise amplification (g-factor), and image reconstruction error between the CS and SB coil arrays under various acceleration factors (1D 4-fold, 2- to 5-fold radial).

Main Results:

• The CS array demonstrated significantly higher maximal SNR (120% at periphery, 62% at center) compared to the SB array.
• The CS array achieved higher averaged SNR across the entire field of view (FOV) during 4-fold accelerated imaging.
• The CS array exhibited a smaller g-factor at the head periphery and reduced image reconstruction error with radial trajectories for accelerations up to 5-fold.

Conclusions:

• The optimized 32-channel CS head coil array provides superior SNR and reduced artifacts for accelerated 3T brain MRI compared to the SB array.
• The CS geometry is highly effective in enhancing image quality and reducing reconstruction errors, particularly with radial k-space trajectories in accelerated acquisitions.
• This novel coil design holds significant potential for improving the efficiency and diagnostic performance of advanced MRI techniques for neurological studies.