A transmit/receive volume strip array and its mode mixing theory in MRI

Area of Science:

• Medical Physics
• Biomedical Engineering
• Magnetic Resonance Imaging

Background:

• Higher magnetic fields in MRI necessitate advanced radiofrequency (RF) coil arrays to address high-frequency limitations.
• Existing RF coil designs face challenges with penetration depth and dielectric resonance at higher frequencies.

Purpose of the Study:

• To describe an arbitrary n-element transmit/receive volume strip array (VSA) and its associated mixing mode theory.
• To understand the behavior of multiple-port, cyclic symmetrical VSAs in both physical port and complementary mode spaces.
• To formulate explicit relations between physical port and complementary mode spaces for VSA analysis.

Main Methods:

• Development of a mixing mode theory for analyzing n-element VSAs.
• Formulation of relations between physical port space and complementary mode space.
• Diagonalization of the VSA impedance matrix using mode-space analysis for analytical solutions.
• Application of analytical solutions to Kirchhoff's laws for large n-element arrays.

Main Results:

• Mode-space analysis simplifies the impedance matrix of VSAs, making analytical solutions for large arrays manageable.
• External power source manipulation allows generation of desired mixed-mode excitation profiles without physical tuning.
• Identification of sensitivity profiles for complementary mode distributions during reception.
• Extensive verification of predictions through network analyzer measurements and MR imaging experiments.

Conclusions:

• The developed theory and analysis provide a powerful framework for designing and controlling multi-port RF coil arrays for high-field MRI.
• This approach facilitates precise control over transmission excitation profiles and enhances understanding of reception sensitivity.
• The findings pave the way for improved performance and novel applications in advanced MRI techniques.