Design of a Folded, Double-Tuned Loop Coil for ¹H/X-Nuclei MRI Applications

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Coil Design
• Biomarker Discovery

Background:

• X-nuclei and proton MRI offer complementary metabolic and anatomical data.
• X-nuclei signals are weak, necessitating combined coil designs for improved shimming and scout imaging.
• Existing double-tuned coil geometries can lead to shifted transmit efficiency patterns.

Purpose of the Study:

• To design and evaluate a novel folded double-tuned MRI coil for simultaneous X-nuclei and proton imaging.
• To compensate for the shifted transmit efficiency pattern observed in straight double-tuned coils.
• To assess the coil's performance in terms of tuning, losses, and application in receive-only arrays.

Main Methods:

• A 2x1 ladder network was designed and tuned for both proton and X-nuclei frequencies.
• Coil geometry was modified by folding a portion of the ladder network to correct transmit efficiency patterns.
• Simulations and MR measurements were used to evaluate the folded coil's performance.
• The coil was further assessed with overlapped decoupling in a receive-only array.

Main Results:

• The designed ladder network was successfully tuned at both proton and X-nuclei frequencies.
• The folded double-tuned coil effectively moderated the shifted transmit efficiency pattern.
• The proposed coil demonstrated minimum losses at both imaging frequencies.
• The coil design was successfully extended to a receive-only array configuration.

Conclusions:

• The folded double-tuned loop coil offers improved performance for simultaneous X-nuclei and proton MRI.
• This coil design mitigates issues with transmit efficiency patterns and signal loss.
• The developed coil is suitable for advanced MRI applications, including metabolic and anatomical imaging.