SLT MRI Array Coil with Birdcage Transmit Row
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Solution Overview
Problem
Magnetic Resonance Imaging (MRI) systems face challenges in creating a uniform B1+ field during transmission mode in high channel count coils with multiple rows, leading to inefficiencies and increased Specific Absorption Rate (SAR) due to the use of whole body coils, which apply RF energy to unnecessary body parts.
Innovation Solution
A cylindrical-like single-layer technology (SLT) MRI RF coil array with multiple rows, where each row has a plurality of channels, uses diodes to connect coil elements into a birdcage configuration in transmit mode, allowing for inductive coupling to create a uniform B1+ field and reducing SAR by only applying energy to the scanned region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a whole body coil is used to transmit RF energy, then the B1 field can be generated, but RF energy is applied to unnecessary body parts increasing SAR
Solution Approach 1:
The coil array is divided into multiple independent row units that can be selectively activated. Each row unit contains multiple coil elements that can be independently controlled, allowing the system to segment the RF energy transmission to only the anatomical region being scanned, thereby reducing SAR to unnecessary body parts while maintaining the ability to cover the entire body when needed.
Solution Approach 2:
Different row units in the coil array are designed with different activation characteristics. The system can locally activate only the necessary row units for the scanned region, creating a localized B1 field in the area of interest while leaving other body parts unaffected by RF energy, thus reducing overall SAR.
2Area of stationary object
If multiple rows of coil elements are used, then the scanned region can be covered, but creating a uniform B1+ field becomes difficult
Solution Approach 1:
The coil array employs dynamic control of RF phase and amplitude across different row units. By adjusting the excitation parameters dynamically for each row unit based on its position and the desired B1 field distribution, the system achieves uniform B1+ field coverage across the scanned region while maintaining flexibility in coil design and operation.
Solution Approach 2:
The system varies RF transmission parameters (phase, amplitude, frequency) across different row units to compensate for geometric and electromagnetic differences. This parameter adjustment enables uniform B1 field generation across multiple rows while maintaining ease of manufacture and operation.
3Manufacturing precision
If diodes are used to connect coil elements into birdcage configuration, then inductive coupling can be created for uniform B1+ field, but device complexity increases
Solution Approach 1:
The diode-connected birdcage configuration is implemented in specific row units that can serve multiple functions: they can operate as traditional receive coils, as transmit coils with inductive coupling, or as part of the SLT array. This multi-functionality reduces the need for separate dedicated transmit and receive coil systems, thereby managing device complexity while achieving uniform B1 field generation.
Solution Approach 2:
Diodes serve as intermediary components that enable bidirectional control of coil element connections. By using diodes, the system can switch between different operational modes (receive, transmit, birdcage configuration) without requiring complex switching networks, thus achieving flexible B1 field generation with manageable device complexity.
4Power
If traditional RF coil design is used, then the coil can operate in receive mode, but it cannot efficiently transmit RF energy with uniform B1 field
Solution Approach 1:
The coil array is designed with dynamic reconfigurability, allowing each row unit to switch between receive and transmit modes based on the imaging task. In receive mode, the coil elements operate as traditional receivers. In transmit mode, the same elements can be configured as birdcage coils with inductive coupling or as SLT array elements, providing versatile RF energy transmission capability with uniform B1 field generation.
Solution Approach 2:
The coil array elements are designed as universal components that can function as both transmit and receive elements. Each row unit can be configured for receive mode, transmit mode with inductive coupling, or transmit mode with SLT configuration, eliminating the need for separate dedicated transmit and receive coils and improving overall system versatility.
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 enables efficient and uniform RF energy distribution across the scanned area, reducing SAR and scan time, while maintaining flexibility in coil design and operation in both transmit and receive modes.
Implementation Method 1
uses diodes to connect coil elements into a birdcage configuration in transmit mode, allowing for inductive coupling to create a uniform B1+ field
Implementation Method 2
uses diodes to connect coil elements into a birdcage configuration
Implementation Method 3
An imaging coil should be able to resonate at a selected Larmor frequency
Data Source
AI summary
Embodiments relate to cylindrical MRI coils with at least one row as a birdcage row in a transmit mode. One example embodiment is a MRI Radio Frequency (RF) coil array comprising two or more rows of four or more RF coil elements each. Each of the RF coil elements can be configured to resonate at a working frequency of the coil array in a receive mode. At least one of the rows can be configured as a birdcage coil in the transmit mode, and the two or more rows can inductively couple together such that all the two or more rows can resonate together in the transmit mode at the working frequency.