Angled RF Coil Elements for MRI Transmit Receive Efficiency
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Solution Overview
Problem
High-field magnetic resonance imaging (MRI) faces challenges with the design of radio frequency (RF) coils due to complex interactions at higher frequencies, leading to inhomogeneous excitation and reduced efficiency, especially in achieving uniform excitation across larger volumes.
Innovation Solution
A RF coil arrangement with elements angled relative to each other to optimize transmit and receive efficiency, featuring a substrate with surface coil receivers and loops that can be shifted to compensate for twisted B1+ and B1− fields, allowing for dynamic phase control and minimization of inductive coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a transmit-receive surface coil is used for high field imaging, then the design complexity is reduced, but the transmit and receive efficiency decreases due to twisted B1+ and B1- profiles
Solution Approach 1:
The coil is divided into separate transmit and receive elements that can be independently optimized and positioned. This segmentation allows each element to be tuned for its specific function, overcoming the limitations of a single transmit-receive element where B1+ and B1- profiles twist in opposite directions.
Solution Approach 2:
The patent introduces spatial separation between transmit and receive elements along with phase cycling in the time dimension. By distributing multiple transmit elements and receive elements in space and using phase cycling sequences, the system achieves constructive interference in the target region while canceling out the twisted field profiles.
2Measurement precision
If receive arrays are optimized for specific regions of interest, then signal-to-noise ratio improves, but the complexity of achieving uniform excitation increases
Solution Approach 1:
The receive array elements are specifically positioned and configured to optimize sensitivity for the carotid region of interest. Each receive element is placed to maximize signal detection from the target anatomy while the transmit elements are arranged to provide uniform excitation across the imaging volume.
Solution Approach 2:
The patent uses phase cycling parameters to control the interference patterns of multiple transmit elements. By varying the phase relationships between transmit elements in a systematic manner, uniform excitation is achieved across the imaging volume while the receive array maintains optimized sensitivity for the specific region of interest.
3Adaptability or versatility
If dedicated transmit capability is added to 7 Tesla coils, then imaging capability improves, but the design complexity and inductive coupling increase
Solution Approach 1:
The patent introduces phase cycling as an intermediary control mechanism that mediates the interaction between multiple transmit and receive elements. By systematically varying the phase relationships, the system achieves desirable imaging capabilities while managing the inductive coupling between elements through constructive and destructive interference patterns.
Solution Approach 2:
Phase cycling employs periodic switching of transmit element phases in a systematic sequence. This periodic action allows each transmit element to be activated in turn with different phase relationships, achieving uniform excitation and managing inductive coupling through time-multiplexed operation rather than simultaneous activation.
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
This configuration enhances signal-to-noise ratio (SNR) by up to 40% at 7 Tesla, improving imaging quality and extending coverage, while maintaining efficiency and reducing peak local heating.
Implementation Method 1
radio frequency (RF) coil arrangement for a high field magnetic resonance imaging
Implementation Method 2
compensate for twisted B1+ and B1- fields
Data Source
AI summary
For example, the present disclosure provides exemplary embodiments of a coil arrangement that can include, e.g., a plurality of elements which can be provided at an angle from one another. The angle can be selected to effectuate an imaging of a target region of interest at least one of a predetermined depth or range of depths, for example. In certain exemplary embodiments according to the present disclosure, the angle can be selected to effectuate an exemplary predetermined transmit efficiency for at least one of the elements. Additionally, the exemplary angle can be selected to effectuate a predetermined receive sensitivity for at least one of the elements. Further, according to certain exemplary embodiments of a coil arrangement in according to the present disclosure, the angle can be adjusted manually and/or automatically.