An improved trap design for decoupling multinuclear RF coils.

Area of Science:

• Magnetic Resonance Imaging
• Spectroscopy
• Radiofrequency Engineering

Background:

• Multinuclear magnetic resonance (MR) requires probes transmitting/receiving at proton and non-proton frequencies.
• Inductor-capacitor (LC) traps are used to minimize probe element coupling at different frequencies.
• LC traps block current at the proton (1H) frequency in non-proton elements.

Purpose of the Study:

• Compare standard LC traps with modified LCC traps for MR applications.
• Evaluate the LCC trap's ability to control reactance at low frequencies while maintaining proton frequency blocking.
• Assess the impact of both trap types on radiofrequency coil performance.

Main Methods:

• Circuit models analyzed losses introduced by LC and LCC traps.
• Radiofrequency coils with series LC and LCC traps were constructed and bench-tested.
• LCC trap performance was validated using 1H and 13C measurements in a 7T human scanner.

Main Results:

• Both LC and LCC traps effectively prevent proton and non-proton coil interaction at the proton frequency.
• LCC traps caused a 5±2% sensitivity reduction, less than half that of LC traps.
• The LCC trap design demonstrates superior performance in minimizing sensitivity loss.

Conclusions:

• Sensitivity in non-proton coils is crucial for effective MR imaging and spectroscopy.
• The LCC trap, with an added capacitor, significantly reduces losses in non-proton coils.
• This improved trap design enhances the performance of multinuclear MR probes.