Movable Shim Coil for MRI Field Homogeneity

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Solution Overview

Problem

Magnetic resonance apparatuses face challenges in effectively compensating for inhomogeneities in the magnetic field, particularly localized inhomogeneities near the object under investigation, which can lead to suboptimal imaging quality.

Innovation Solution

A method and system that utilize a local shim coil, which is automatically positioned and oriented relative to the object and the magnetic resonance apparatus, allowing for precise compensation of magnetic field inhomogeneities by determining the optimal placement and alignment of the shim coil based on pre-defined combinations of positions and orientations, and adjusting the shim currents accordingly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a local shim coil is positioned close to the object under investigation, then localized inhomogeneities of the B0 field may be compensated for effectively, but the position and orientation of the shim coil require precise manual adjustment which is time-consuming and complex

Engineering Contradiction:

Improvecompensation precision of magnetic field inhomogeneitiesVSAvoidcomplexity of shim coil positioning and orientation adjustment

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The shim coil is made movable relative to the object under investigation, allowing dynamic adjustment of position and orientation. The coil can be moved together with local coils (receiver or transmitter/receiver coils) to automatically maintain optimal positioning without manual intervention for each adjustment.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system automatically determines the position and orientation of the shim coil in relation to the magnetic resonance apparatus and object, eliminating the need for manual measurement and adjustment. The shim coil communicates its own position and orientation data to the control system, enabling self-service positioning.

Inventive Principle:

Principle #25Self-service

2Productivity

If the shim coil is moved relative to the object under investigation to achieve optimal positioning, then compensation efficiency is maximized, but determining the optimal position and orientation becomes more complex

Engineering Contradiction:

Improveefficiency of magnetic field compensationVSAvoiddifficulty of determining optimal shim coil position and orientation

Core Design Contradiction:

ProductivityVSDifficulty of detecting and measuring

Solution Approach 1:

The system uses feedback from the determined position and orientation of the shim coil to automatically calculate and adjust the shim currents. The control system receives position data from the shim coil, processes this information to determine optimal compensation parameters, and adjusts the currents accordingly, creating a closed-loop feedback system.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system pre-determines the position and orientation of the shim coil before compensation operation begins. By automatically establishing the optimal position and orientation in advance, the system eliminates the need for complex real-time adjustments during the compensation process.

Inventive Principle:

Principle #10Preliminary action

3Device complexity

If manual positioning of the shim coil is used, then device complexity is reduced, but the time required for setup and adjustment increases

Engineering Contradiction:

Improvesimplicity of shim coil systemVSAvoidtime for shim coil positioning and orientation adjustment

Core Design Contradiction:

Device complexityVSLoss of time

Solution Approach 1:

The patent replaces manual mechanical positioning with an automated system that uses electronic communication and computer-controlled movement. The shim coil's position and orientation are determined automatically through electronic data exchange between the coil and the magnetic resonance apparatus, substituting mechanical manual adjustment with automated electronic control.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 compensation of magnetic field inhomogeneities, improving the homogeneity of the magnetic field and thereby enhancing the quality of magnetic resonance imaging by optimizing the placement and operation of the shim coil.

Implementation Method 1

compensates for inhomogeneities in a magnetic field generated by a magnetic resonance apparatus via a shim coil

Methodology Applied

Scientific EffectMagnetic field generation: Magnetic Field

Data Source

PatentUS10488478B2Method, system and magnetic resonance apparatus for compensating for inhomogeneities in the magnetic field

Publication Date: 2019.11.26 SIEMENS HEALTHINEERS AG

AI summary

A method and a magnetic resonance apparatus compensate for inhomogeneities in a magnetic field generated by the magnetic resonance apparatus with a shim coil of the magnetic resonance apparatus. The shim coil is arranged at an object under investigation. A position and an orientation of the shim coil are automatically determined. The inhomogeneities of the magnetic field are determined. The inhomogeneities are compensated for via the shim coil depending on the position and the orientation of the shim coil.