MRI Gradient Load Calculation via Frequency Band Impedance

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Solution Overview

Problem

Conventional MRI systems face challenges in accurately estimating the electric load on gradient magnetic field generation systems, leading to suboptimal imaging conditions due to excessive safety margins, which limits the number of slices that can be imaged and inefficiencies in power usage.

Innovation Solution

The implementation of a method to calculate the electric load on gradient magnetic field generation systems by separating gradient magnetic field waveforms into frequency bands based on impedance characteristics, allowing for precise determination of the total electric load and optimizing imaging conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional MRI systems use maximum temperature allowable for gradient magnetic field coil to calculate initial rise characteristics, then safety is improved, but imaging conditions become suboptimal and productivity decreases

Engineering Contradiction:

ImprovesafetyVSAvoidimaging efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent changes the temperature parameter from maximum allowable temperature to actual operating temperature for calculating initial rise characteristics. This allows the system to operate closer to actual conditions rather than worst-case scenarios, improving imaging efficiency while maintaining safety through accurate load estimation.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the conservative mechanical safety margin approach with an electrical calculation-based approach. By calculating electric load based on actual operating temperature and impedance characteristics, the system substitutes overly conservative safety controls with precise electrical parameter-based control.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If conventional MRI systems apply large safety margins to gradient magnetic field generation, then reliability is improved, but the number of imaged slices is limited and productivity decreases

Engineering Contradiction:

Improvesystem reliabilityVSAvoidnumber of slices imaged

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent implements feedback by calculating actual electric load based on measured or estimated impedance characteristics and operating conditions. This feedback mechanism allows the system to adjust imaging parameters dynamically, increasing the number of slices that can be imaged while maintaining safety through accurate load monitoring.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent transitions from static safety margins to dynamic load estimation. By calculating electric load based on actual operating temperature and impedance characteristics that change with conditions, the system adapts safety controls to real-time conditions, enabling higher productivity without compromising reliability.

Inventive Principle:

Principle #15Dynamics

3Device complexity

If conventional MRI systems underestimate electric load on gradient magnetic field generation system, then device complexity is reduced, but measurement precision of electric load decreases

Engineering Contradiction:

Improvesystem complexityVSAvoidelectric load estimation accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent performs preliminary calculation of electric load based on impedance characteristics and operating conditions before actual imaging. This preliminary action provides accurate load estimation without requiring complex real-time measurement systems, maintaining low device complexity while improving measurement precision.

Inventive Principle:

Principle #10Preliminary 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 enables more accurate estimation of electric loads, allowing for safer operation and optimization of imaging conditions within the power limits of the gradient magnetic field generation system, potentially increasing the number of slices that can be imaged and improving overall efficiency.

Implementation Method 1

A gradient magnetic field generation system in an MRI apparatus includes a gradient magnetic field coil which adds spatial positional information to MR signals by applying a gradient magnetic field in an imaging space where an object is set

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

This gradient magnetic field coil produces heat by being provided with pulse electric current during imaging

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS8717019B2Magnetic resonance imaging apparatus and load calculation method of a gradient magnetic field generation system

Publication Date: 2014.05.06 TOSHIBA MEDICAL SYST CORP

AI summary

According to one embodiment, an MRI apparatus performs magnetic resonance imaging under a gradient magnetic field by providing a gradient magnetic field generation system with electric current so as to apply the gradient magnetic field on an imaging region. This MRI apparatus includes a condition setting unit and a load acquisition unit. The condition setting unit sets imaging conditions of the magnetic resonance imaging. The load acquisition unit acquires information on a waveform of the gradient magnetic field, and calculates respective electric loads for a plurality of frequency bands imposed on the gradient magnetic field generation system in a case of performance of the magnetic resonance imaging, based on the information on a waveform.