AeroCoil: Pneumatically Controlled Dual-Tunable RF Coil for Proton (¹H) and Deuterium (²H)

Area of Science:

• Magnetic Resonance Imaging (MRI)
• RF Coil Engineering
• Biomedical Engineering

Background:

• Multinuclear MRI and spectroscopy require RF coils operating at multiple frequencies.
• Traditional multituned and frequency-switchable RF coils face challenges like electromagnetic coupling, RF interference, and image quality degradation.
• Existing switchable coils often rely on PIN diodes, necessitating complex bias circuitry and introducing RF noise.

Purpose of the Study:

• To introduce and evaluate a novel pneumatically actuated, frequency-switchable RF coil (AeroCoil).
• To demonstrate resonance switching between proton (¹H) and deuterium (²H) frequencies at 9.4 Tesla (T) without electrical biasing.
• To compare the performance of the AeroCoil against single-tuned coils and a PIN diode-based switchable coil.

Main Methods:

• Development of the AeroCoil, utilizing pneumatic actuation to mechanically adjust capacitance for frequency switching.
• Bench measurements of return loss and quality factor (Q factor) for different configurations.
• MRI experiments to assess signal-to-noise ratio (SNR) and image artifacts at ¹H and ²H frequencies.

Main Results:

• The AeroCoil achieved 88.2%-91.9% of the SNR of a single-tuned ¹H coil, significantly higher than the 68.3%-75% from a PIN diode coil.
• At the ²H frequency, the AeroCoil retained 71.7%-74.6% SNR, while the PIN diode coil performance dropped to 27.1%-28.8%.
• The pneumatic mechanism eliminated the need for local electrical components, reducing RF noise and EM interference.

Conclusions:

• The pneumatically actuated AeroCoil offers a viable solution for frequency-switchable RF coils in MRI.
• AeroCoil technology significantly improves SNR and reduces artifacts compared to PIN diode-based designs.
• This approach simplifies coil architecture and enhances multinuclear imaging capabilities in MRI.