A PIN diode controlled dual-tuned MRI RF coil and phased array for multi nuclear imaging

Area of Science:

• Medical Imaging
• Biophysics
• Electrical Engineering

Background:

• Magnetic Resonance Imaging (MRI) enables non-invasive study of metabolism using nuclei beyond hydrogen.
• Lower signal-to-noise ratio (SNR) in non-proton MRI necessitates specialized radio frequency (RF) coils.
• Conventional dual-tuned RF coils often use trap circuits, leading to increased losses and tuning challenges.

Purpose of the Study:

• To develop and evaluate a new method for dual-tuned RF coils using PIN diodes for switching between resonance frequencies.
• To compare the performance of PIN diode switched coils against conventional trap circuit designs.
• To investigate the impact of conductor segmentation on coil performance at dual frequencies.

Main Methods:

• Designed and constructed surface coils with identical geometry, one using conventional trap circuits and the other using PIN diode switches.
• Investigated coil performance with and without conductor segmentation at dual operating frequencies.
• Developed a dual-tuned, receive-only phased array with PIN diode switching and a conventional dual-tuned birdcage coil for transmission.

Main Results:

• PIN diode switching eliminated trap circuit losses and associated issues with tuning and matching.
• Coil performance was significantly improved at both operating frequencies using PIN diode switched dual-frequency operation compared to trap circuit designs.
• Conductor segmentation was explored for its benefits in reducing losses for both coil types.

Conclusions:

• PIN diode switching offers a superior alternative to trap circuits for dual-tuned MRI coils.
• The new design enhances SNR and overall performance for multi-nuclei metabolic imaging.
• This advancement facilitates more efficient and effective in-vivo metabolic investigations.