High-Density MRI RF Arrays Using Mixed Dipole Antennas and Microstrip Transmission Line Resonators.

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Electromagnetics
• Coil Array Design

Background:

• High-density multi-coil arrays are crucial for enhancing signal-to-noise ratio (SNR) and enabling accelerated parallel imaging in MRI.
• Conventional designs using dipole antennas or microstrip transmission line (MTL) resonators face significant coupling challenges in dense configurations.

Purpose of the Study:

• To investigate the inherent electromagnetic coupling between dipole antennas and MTL resonators.
• To propose and validate a novel interleaved array configuration to mitigate coupling issues in high-density MRI coils.

Main Methods:

• Bench testing to measure electromagnetic (EM) coupling between single dipole and MTL elements at varying separations.
• Electromagnetic simulations to validate and analyze coupling characteristics.
• Construction and evaluation of a 16-channel mixed dipole and MTL array using bench tests and MRI experiments.

Main Results:

• Demonstrated naturally low coupling between dipoles and MTLs, with worst-case coupling of -15.8 dB at 4.7 cm separation, significantly better than same-element pairs.
• Achieved inter-element isolation greater than -14 dB in a dense 16-channel mixed array without decoupling treatments.

Conclusions:

• Dipole antennas and MTL resonators exhibit intrinsically low coupling, contrary to common assumptions.
• An interleaved array configuration effectively leverages this low coupling to create high-density MRI arrays with improved isolation.