Reconfigurable dipole receive array for dynamic parallel imaging at ultra-high magnetic field

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Radiofrequency (RF) Engineering
• Parallel Imaging Techniques

Background:

• 3D dynamic parallel imaging is crucial for accelerated MRI acquisition.
• Existing radiofrequency (RF) coil designs have limitations in optimizing sensitivity profiles for advanced imaging techniques.
• Electronically reconfigurable antennas offer potential for dynamic adjustments in MRI.

Purpose of the Study:

• To develop and evaluate an electronically reconfigurable dipole array for 3D dynamic parallel imaging.
• To demonstrate the capability of altering receive sensitivity along the dipole length.
• To improve parallel imaging performance through dynamic sensitivity modulation.

Main Methods:

• Developed an 8-element reconfigurable elevated-end dipole antenna array.
• Utilized positive-intrinsic-negative-diode (PIN) diodes for electronic adjustment of dipole arm lengths, altering sensitivity profiles.
• Tested the prototype at 9.4T on phantoms and volunteers, employing a modified 3D SENSE reconstruction and calculating geometry factor (g-factor).

Main Results:

• Electromagnetic simulations and phantom/volunteer measurements showed successful dynamic alteration of receive sensitivity profiles.
• The reconfigurable dipole array demonstrated significant improvements in g-factor compared to static dipoles.
• Achieved up to 220% improvement in maximum g-factor and 54% in mean g-factor for 3x2 acceleration.

Conclusions:

• An 8-element electronically reconfigurable dipole receive array prototype was successfully developed.
• Dynamic sensitivity modulation enables emulation of virtual receive element rows, enhancing 3D parallel imaging.
• This technology offers improved parallel imaging performance for 3D MRI acquisitions.