MRI Shimming Using Genetic Algorithm Optimization

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Solution Overview

Problem

Current methods for shimming magnetic fields in MRI systems are complex, time-consuming, and require specialized skills, often relying on fixed grids for positioning correction elements, which limits flexibility and precision, and are user-dependent, making it difficult to achieve repeatable results.

Innovation Solution

A method that uses a three-dimensional closed surface to define the shimming field of view, measures the magnetic field on a grid, and calculates continuous position and magnitude parameters for correction elements to minimize homogeneity variations, allowing for iterative adjustments to achieve optimal magnetic field homogeneity using nonlinear programming algorithms and genetic algorithms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If current analytical methods are used for shimming, then magnetic field correction can be achieved, but the process becomes complex and time-consuming

Engineering Contradiction:

Improvemagnetic field homogeneityVSAvoidshimming process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex analytical calculations with a numerical optimization approach using genetic algorithms. Instead of manually solving intricate equations involving magnetic field distributions, the system automatically iterates through possible correction element configurations to minimize field inhomogeneities, substituting mechanical/mathematical complexity with computational automation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The shimming process becomes autonomous through the genetic algorithm optimization. The system self-adjusts by iteratively evaluating different correction element positions and strengths, automatically converging on the optimal configuration without requiring specialized manual intervention or complex analytical expertise from service personnel.

Inventive Principle:

Principle #25Self-service

2Ease of manufacture

If fixed grids are used for positioning correction elements, then the shimming process can be standardized, but flexibility and precision are limited

Engineering Contradiction:

Improveshimming process standardizationVSAvoidcorrection element positioning flexibility

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent transitions from static fixed grids to dynamic continuous positioning. Correction elements can be placed at any continuous coordinate on the pole surfaces rather than being constrained to predetermined grid points. The optimization algorithm automatically determines the optimal continuous positions, providing flexibility while maintaining standardization through the automated decision-making process.

Inventive Principle:

Principle #15Dynamics

3Manufacturing precision

If multiple repetitions are performed to converge to optimal solution, then magnetic field homogeneity improves, but time consumption increases

Engineering Contradiction:

Improvemagnetic field homogeneityVSAvoidshimming process time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The genetic algorithm performs continuous iterative optimization without requiring discrete repetition steps. The algorithm continuously evolves the population of potential solutions, smoothly converging on the optimal configuration. This continuous action eliminates the need for multiple separate repetition cycles, reducing time while maintaining convergence to the optimal solution.

Inventive Principle:

Principle #20Continuity of useful action

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 simplifies the shimming process, reduces time, and achieves precise magnetic field homogeneity, allowing for flexible positioning of correction elements, thereby improving the efficiency and consistency of magnetic field correction in MRI systems.

Implementation Method 1

a magnetic structure generating a magnetic field permeating a volume of space

Methodology Applied

Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

the said correction elements being magnetic dipoles

Methodology Applied

Scientific EffectMagnetic dipole: Magnetism

Data Source

PatentUS20230085309A1Method for correcting inhomogeneity of the static magnetic field particularly of the static magnetic field generated by the magnetic structure of a machine for acquiring nuclear magnetic resonance images and MRI system for carrying out such method

Publication Date: 2023.03.16 ESAOTE

AI summary

Method for shimming a magnetic field which is generated by a magnetic structure, and which permeates a volume of space uses the following steps: measuring the magnetic field in a region of a volume of space permeated by the said magnetic field; determining a parameter which is a measure of the homogeneity of the magnetic field; defining a distribution of correction elements including a predetermined number of magnetic dipoles each having a predetermined magnetic charge and a predetermined position relatively to the magnetic structure generating the magnetic field; calculating the charges of each of the dipoles and the position of each of the dipoles of a distribution which minimizes the parameter being a measure of the homogeneity of the magnetic field; using the distribution of dipoles as the shimming distribution of dipoles to be positioned on the magnetic structure.