Hybrid Microstrip MRI Coil Arraying via Segmented Transmission Line
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Solution Overview
Problem
Microstrip magnetic resonance coils are too long to be arrayed in the superior/inferior direction, limiting parallel imaging with accelerations in this direction due to their design and wavelength constraints, making them unsuitable for high-field MRI applications.
Innovation Solution
A hybrid microstrip coil design that combines microstrip assemblies with coaxial sections to form a continuous transmission line, allowing the coils to be arrayed in the superior/inferior direction while maintaining desired wavelength characteristics, using shorter physical lengths and incorporating lumped elements for tuning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If microstrip coils are designed as half-wave or quarter-wave resonators aligned along the B0 axis, then they maintain desired wavelength characteristics, but they become too long (46 cm or 92 cm) to be arrayed in the superior/inferior direction
Solution Approach 1:
The microstrip resonator is divided into multiple discrete elements arranged in a matrix array. Each element is shorter than the full wavelength, but collectively they achieve the desired electrical length through phased coupling. This segmentation allows the coil to be arrayed in the superior/inferior direction while maintaining wavelength characteristics.
Solution Approach 2:
The patent transitions from a one-dimensional linear resonator to a two-dimensional matrix array. By distributing multiple shorter elements across the superior/inferior and left/right dimensions, the system achieves the electrical length equivalent to a long resonator while maintaining compact physical dimensions suitable for arraying.
2Area of stationary object
If multiple microstrips are arrayed in the anterior/posterior and right/left directions, then coverage is improved, but parallel imaging with accelerations in the superior/inferior direction becomes impossible
Solution Approach 1:
The coil system is segmented into multiple independently controllable elements arranged in a matrix. This segmentation enables selective excitation and encoding of signals from different spatial locations, providing the geometric encoding necessary for parallel imaging in all three anatomical directions including superior/inferior.
Solution Approach 2:
The matrix array design provides universal functionality for parallel imaging in multiple directions. By configuring elements in both superior/inferior and left/right orientations, the system can perform accelerated imaging regardless of the encoding direction, making the system adaptable to various imaging protocols.
3Length of moving object
If tuning with lumped elements is used for microstrips, then the coils can be shortened to 30 cm or greater, but this remains too long for arraying in the superior/inferior direction
Solution Approach 1:
Rather than using lumped elements to shorten a single resonator, the patent segments the resonator into multiple distributed elements. Each element is naturally short, and the collective array achieves the required electrical length through constructive interference and phased coupling, enabling superior/inferior arraying.
Solution Approach 2:
The patent replaces the mechanical approach of lumped element tuning with an electromagnetic field-based solution. By using distributed capacitive and inductive coupling between array elements, the system achieves resonance at the desired frequency without requiring additional lumped tuning elements, resulting in a more compact and versatile design.
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
Enables parallel imaging with accelerations in the superior/inferior direction and faster imaging at high field strengths by reducing coil length and maintaining desired electrical properties, enhancing the utility of microstrip coils in MRI systems.
Implementation Method 1
Each microstrip assembly has one or more conductive strips disposed upon a first side of a substrate and corresponding shield planes disposed on a second side of the substrate, wherein the shield planes are aligned opposing the conductive strips. There are one or more coaxial sections disposed on the first or second side of the substrate, wherein the coaxial sections form a continuous transmission line with the microstrip assembly
Data Source
AI summary
A hybrid microstrip coil for magnetic resonance imaging including a microstrip assembly aligned in the superior/inferior (S/I) direction. In one example, the microstrip assembly has conductive strips disposed on one side of a substrate corresponding shield planes disposed on the other side of the substrate. The microstrip assemblies are coupled together by coaxial sections forming a continuous transmission line and having a specific overall electrical length.