Dipole Array MRI Coil with Conducting Rings for B1+ Shimming

The volume coil is segmented into multiple independent dipole antenna elements arranged in a specific geometry. Each dipole can be independently controlled through separate T/R channels, allowing the B1+ field to be synthesized by combining fields from multiple segments. This segmentation enables B1+ shimming to compensate for dielectric effects and improve field uniformity while maintaining a manageable structural complexity.

The patent introduces multiple spatial dimensions by arranging dipoles in a three-dimensional configuration rather than using a single conventional coil structure. The dipoles are positioned at different locations and orientations in space, creating a multi-dimensional field synthesis capability that enables effective B1+ uniformity control across the imaging volume despite the increased dielectric effects at ultra-high fields.

The patent merges the advantages of surface coils (ability to provide localized B1+ field control) with the coverage capability of volume coils. By arranging multiple dipoles in a volumetric configuration rather than as separate surface coils, the system achieves B1+ uniformity improvement without the excessive complexity of multiple independent surface coil assemblies. The dipoles are electrically isolated but structurally integrated into a unified volume coil framework.

The dipole array structure serves multiple functions simultaneously: it provides B1+ field transmission, enables B1+ shimming through independent channel control, and maintains a relatively simple structural framework. Each dipole element can be independently tuned and controlled, providing universal applicability for different imaging scenarios at ultra-high fields without requiring completely different coil designs.

The patent implements dynamic control of the dipole array by providing independent T/R channels for each or groups of dipoles. This dynamic capability allows the system to adaptively adjust the amplitude and phase of each dipole element to optimize both receive sensitivity and transmit B1+ uniformity. The number of effectively utilized T/R channels can be dynamically adjusted based on the imaging requirements, enabling flexible B1+ shimming strategies.

The patent exploits parameter changes in the RF excitation signals applied to each dipole element to achieve B1+ shimming. By independently varying the frequency, phase, and amplitude parameters of the signals fed to different dipoles, the system can constructively interfere to create uniform B1+ fields across the imaging volume. This parameter control capability transforms the fixed dipole array into a flexible B1+ uniformity optimization system.