Temperature Controlled Magnet Shim Pieces for MRI Field Uniformity

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Solution Overview

Problem

Existing magnetic resonance apparatuses face challenges in maintaining the uniformity and intensity of the main magnetic field due to temperature variations of magnetic metal pieces, which affect the magnetic susceptibility and field distribution.

Innovation Solution

A magnetic resonance apparatus that includes an acquisition unit for temperature information and a temperature adjustment unit to preheat magnetic metal pieces to a target temperature, ensuring stable temperature control and maintaining the magnetic metal pieces at a temperature higher than normal, thereby reducing temperature-induced variations in magnetic susceptibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If passive shimming is used to correct main magnetic field uniformity, then magnetic field uniformity can be improved, but temperature variations of magnetic metal pieces cause magnetic susceptibility changes that degrade field uniformity and intensity

Engineering Contradiction:

Improvemain magnetic field uniformityVSAvoidmagnetic susceptibility stability

Core Design Contradiction:

Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The patent applies parameter changes by actively controlling the temperature of magnetic metal pieces (shims) to maintain them at a stable target temperature. This prevents temperature-induced variations in magnetic susceptibility, thereby maintaining both field uniformity and intensity. The system monitors temperature and adjusts heating/cooling to keep shims within a controlled temperature range.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements feedback control by detecting the temperature of magnetic metal pieces and using this information to adjust the temperature control system. Temperature sensors monitor the shims, and the control unit adjusts heating or cooling accordingly to maintain the target temperature, ensuring stable magnetic susceptibility and consistent main magnetic field characteristics.

Inventive Principle:

Principle #23Feedback

2Reliability

If temperature control is implemented for magnetic metal pieces, then magnetic field stability is improved, but device complexity increases due to additional temperature monitoring and adjustment mechanisms

Engineering Contradiction:

Improvemain magnetic field stabilityVSAvoidtemperature control system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies universality by integrating the temperature control function into the existing shim accommodation structure. The same accommodation section that holds the magnetic metal pieces also contains temperature sensors and heating/cooling elements, allowing temperature control without adding separate complex systems. This multi-functional approach reduces overall device complexity while maintaining field stability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Manufacturing precision

If magnetic metal pieces are heated to target temperature, then temperature-induced magnetic susceptibility variations are reduced, but energy consumption increases

Engineering Contradiction:

Improvemagnetic field uniformityVSAvoidenergy consumption for temperature control

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The patent applies periodic action by using intermittent heating or cooling cycles rather than continuous operation. The temperature control system activates heating or cooling elements only when temperature deviations are detected, and adjusts the duration and intensity based on real-time temperature feedback. This periodic control maintains magnetic field uniformity while minimizing energy consumption compared to continuous temperature maintenance.

Inventive Principle:

Principle #19Periodic 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 effectively maintains the uniformity and intensity of the main magnetic field, ensuring high-quality imaging by stabilizing the magnetic field and reducing spatial unevenness in image quality.

Implementation Method 1

a temperature adjustment unit which adjusts the temperature of the magnetic metal pieces to a target temperature by preheating the magnetic metal pieces

Methodology Applied

Scientific EffectThermal energy transfer: Conduction (thermal)

Implementation Method 2

heat generation caused in a magnetic metal by an eddy current induced by generation a gradient magnetic field

Methodology Applied

Scientific EffectEddy current heating: Eddy Currents

Data Source

PatentUS7741847B2Magnetic resonance apparatus with temperature controlled magnet shim pieces

Publication Date: 2010.06.22 TOSHIBA MEDICAL SYST CORP

AI summary

A magnetic resonance apparatus in which magnetic metal pieces are accommodated in an accommodation section so as to correct uniformity in a main magnetic field, includes an acquisition unit which acquires temperature information related to at least one of a temperature of the magnetic metal pieces accommodated in the accommodation section, a temperature of the accommodation section, and a temperature of a position in the vicinity of the accommodation section, and a temperature adjustment unit which adjusts the temperature of the magnetic metal pieces to a target temperature by preheating the magnetic metal pieces on the basis of the temperature information acquired by the acquisition unit.