MRI Antenna Control Module Using Singular Value Decomposition
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Solution Overview
Problem
High-frequency phased array antennas used in MRI devices at high magnetic fields (>7 Tesla) face challenges with inhomogeneous magnetic field distribution and high production costs due to the need for multiple power amplifiers and control electronics, which are not optimally adapted for human head imaging.
Innovation Solution
A method using Singular Value Decomposition (SVD) to create a piloting module that optimizes the transmission signal for regions of interest by determining the singular vectors of a matrix representing the magnetic field distribution, allowing fewer piloting elements to control multiple radiating elements, thereby reducing costs and improving field homogeneity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple power amplifiers and control electronics are used for each channel of the antenna, then the magnetic field distribution becomes more controllable, but the production cost increases significantly
Solution Approach 1:
The patent merges multiple control functions into a single control module that manages multiple radiating elements. Instead of having separate power amplifiers and control electronics for each antenna channel, a unified control module with singular value decomposition capability coordinates all radiating elements, reducing the overall number of control components while maintaining field distribution control
Solution Approach 2:
The control module serves multiple functions simultaneously: it performs singular value decomposition of the magnetic field distribution matrix, determines optimal excitation signals for all radiating elements, and coordinates the phased array operation. This multi-functional approach eliminates the need for dedicated control electronics for each channel
2Manufacturing precision
If conventional birdcage antennas are used at low magnetic fields, then satisfactory magnetic field homogeneity is achieved, but they become critical and produce significant artifacts at high magnetic fields (≥7 Tesla)
Solution Approach 1:
The patent implements dynamic control of the phased array antenna at high magnetic fields through real-time singular value decomposition of the magnetic field distribution. Unlike static conventional antennas, the system dynamically adjusts the excitation signals of individual radiating elements based on the calculated singular vectors, enabling adaptive compensation for high-field artifacts and maintaining reliability at ≥7 Tesla
Solution Approach 2:
The system changes the operational parameters by using phased array technology with independent control of each radiating element's amplitude and phase. This parameter control, guided by singular value decomposition results, allows optimization of the magnetic field distribution at high fields where conventional fixed-geometry antennas fail
3Manufacturing precision
If phased array antennas with multiple radiating elements are used at high frequency, then the magnetic field can be optimized for regions of interest, but the number of required piloting elements increases the system complexity
Solution Approach 1:
The patent extracts the essential control information from the full magnetic field distribution matrix through singular value decomposition. By identifying and utilizing only the dominant singular vectors that contribute most to the magnetic field in the region of interest, the system reduces the effective number of control parameters needed, managing complexity while maintaining optimization capability
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 approach enables more efficient power transmission to radiating elements, improves magnetic field homogeneity, and reduces the number of piloting elements needed, making high-frequency antennas more economical and effective for high-field MRI applications.
Implementation Method 1
determining the singular vectors of a matrix B̃ by decomposition into singular values
Implementation Method 2
They receive an electrical excitation enabling them to produce the radio frequency (RF) magnetic field B1 orthogonal to B0, at the precession resonance frequency (also called the Larmor frequency)
Implementation Method 3
the magnetic spin moments will then resonate and gradually deviate from this longitudinal axis z to go and be placed perpendicular to their starting axis by describing a movement, called a precession movement
Implementation Method 4
the magnetic field therefore makes it possible to 'tilt' the magnetic spin moments to place them in a plane perpendicular to the direction of the field B0, according to a tilt angle FA
Implementation Method 5
When the excitation is interrupted, the magnetic spin moments which have deviated from their initial axis return to their equilibrium position, that is to say the z axis, without ceasing to rotate. This return to balance is called relaxation
Data Source
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AI summary
The present invention relates to a method for creating a module (10) for controlling a magnetic resonance imaging apparatus antenna (300), said method comprising: a step of determining magnetic field distribution mapping B1 + ; a step of constructing a matrix ~B from the selection of a plurality of x x m points B+ 1(i, j) such that ~B(i, j) = B+ 1(i, j) ; a step of determining the singular vectors of said matrix ~B by singular value decomposition; and a step of arranging a coupling means and/or phase-shifting means, forming said control module (10), such that a signal Soj outputted from said control module is a function of the equation (I), with Sik being the input signal.