Z-Segmented RF Antenna for MRI Homogeneity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current multiple-channel RF antenna devices for MRI systems are expensive, complex, and difficult to produce due to residual coupling and patient-dependent reflections, which complicates the placement of power amplifiers and differs from commercially available designs, limiting their availability and effectiveness in improving homogeneity, especially for applications like leg imaging.
Innovation Solution
A segmented RF antenna device with a tubular body, featuring capacitive antenna rings and rungs that form high-pass or band-pass filters, allowing independent control of each segment with two activation ports, enabling geometric decoupling and simplified power feeding without circulators, and capable of operating as both a transmit and receive antenna.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple-channel research systems are used to improve homogeneity and enable special applications like leg imaging, then the channel number increases, but the device complexity and cost increase significantly due to residual coupling and patient-dependent reflections requiring circulators
Solution Approach 1:
The RF antenna device is divided into multiple segments along the longitudinal direction, with each segment having independent activation ports. This segmentation allows each segment to be controlled independently, enabling multiple channels without requiring complex circulators for isolation. The segments are geometrically decoupled through their spatial arrangement, simplifying the overall system design while maintaining multi-channel capability.
Solution Approach 2:
The patent transitions from traditional planar coil designs to a three-dimensional segmented structure extending along the longitudinal direction. By utilizing the longitudinal dimension and arranging segments with geometric decoupling, the system achieves multiple channels without the residual coupling problems that plague planar multi-channel designs, thereby reducing the need for circulators and simplifying the system.
2Reliability
If circulators are added to isolate power amplifiers for different channels, then residual coupling and patient-dependent reflections are managed, but the placement of power amplifiers near the coil becomes difficult due to very defined magnetic field requirements
Solution Approach 1:
By segmenting the antenna device and achieving geometric decoupling between segments, the patent eliminates the need for circulators to isolate power amplifiers. Each segment can be fed independently through its own activation ports, and the geometric arrangement provides sufficient isolation without requiring circulators, thereby enabling flexible placement of power amplifiers near the coil.
3Device complexity
If conventional fixed 90° excitation with same amplitude is used, then the coil structure is simple, but the homogeneity of the magnetic field is insufficient for certain applications
Solution Approach 1:
The patent enables dynamic control of the magnetic field by providing independent activation ports for each segment. This allows the excitation amplitude and phase to be adjusted independently for each segment, transforming the static fixed 90° excitation into a dynamic system that can adapt to achieve homogeneous field distribution across different applications and subject positions.
Solution Approach 2:
By allowing independent control of each segment through separate activation ports, the patent enables local optimization of the magnetic field. Different segments can be adjusted to provide the appropriate field strength and phase locally, achieving overall homogeneity while maintaining a relatively simple coil structure without requiring complex additional components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution allows for increased channel numbers, improved homogeneity, and efficient RF shimming, reducing costs and complexity by enabling easy upgrades from conventional coils and allowing operation in various geometries and magnetic fields, while maintaining a compact design.
Implementation Method 1
capacitors in the antenna rings providing a high-pass filter design, or, together with additional capacitors in the rungs, providing a band-pass filter design
Implementation Method 2
radio frequency (RF) antenna device for applying an RF field to an examination space of a magnetic resonance (MR) imaging system
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention provides a radio frequency (RF) antenna device (140) for applying an RF field to an examination space (116) of a magnetic resonance (MR) imaging system (110), whereby the RF antenna device (140) is provided having a tubular body, the RF antenna device (140) is segmented in its longitudinal direction (154), and each segment (162, 164) is provided with at least one activation port. The result is that each mode, corresponding to an activation port, may be controlled individually. Accordingly, the inhomogeneity of the subject of interest in this direction, i.e. in the longitudinal direction of the RF antenna device, can directly be addressed. There are different ways to build up a z- segmented RF antenna device.