MRI Field Probe Winding Segmentation for Homogeneity

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Solution Overview

Problem

Existing magnetic field probes in MRI systems face challenges in accurately measuring static and dynamic magnetic fields due to signal-to-noise ratio limitations and susceptibility issues from materials used in the probes, which can affect the homogeneity of the measured fields.

Innovation Solution

A field probe design with a solenoid coil divided into three winding sections, where the outer sections are short-circuited using blocking capacitors to minimize interference and allow for precise localization of the active measurement area, reducing the impact of susceptibility and improving field homogeneity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a field probe is used to measure magnetic fields in MRI systems, then field measurement capability is provided, but signal-to-noise ratio limitations and susceptibility issues reduce measurement precision

Engineering Contradiction:

Improvemagnetic field measurement precisionVSAvoidsusceptibility interference and noise

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent extracts and removes the harmful susceptibility effects by using non-magnetic materials for the probe body and mounting structure. The field probe is designed to minimize its own magnetic susceptibility, thereby eliminating the interference that would otherwise degrade measurement precision in the strong magnetic field environment of MRI systems.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies local quality by creating a highly homogeneous magnetic field region specifically at the measurement location within the probe. Through careful geometric design of the coil windings and positioning, the field homogeneity is optimized locally at the measurement point while the rest of the probe structure maintains non-magnetic properties to minimize susceptibility interference.

Inventive Principle:

Principle #3Local quality

2Measurement precision

If additional windings are added to the field probe coil, then field homogeneity is improved and measuring volume is localized, but device complexity increases

Engineering Contradiction:

Improvefield homogeneityVSAvoidcoil winding structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the coil winding into multiple distinct sections with different functions. The first winding section provides the main measurement signal, while the second winding section is specifically designed to cancel magnetic field inhomogeneities. This segmentation allows each section to be optimized for its specific purpose, achieving field homogeneity through the coordinated action of simplified individual sections rather than a single complex winding.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs asymmetric coil winding configurations where the second winding section is positioned and wound in a specific asymmetric manner relative to the first section. This asymmetric arrangement is deliberately designed to create compensating magnetic field effects that correct inhomogeneities, achieving field homogeneity through geometric asymmetry rather than symmetric complexity.

Inventive Principle:

Principle #4Asymmetry

3Adaptability or versatility

If the field probe measures both static and dynamic magnetic fields, then measurement versatility is improved, but distinguishing signal sources becomes more difficult

Engineering Contradiction:

Improvemeasurement versatilityVSAvoidsignal source differentiation

Core Design Contradiction:

Adaptability or versatilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent implements feedback mechanisms through the dual-winding configuration where the second winding section provides information about field inhomogeneities that can be used to distinguish between static and dynamic field components. By analyzing the signals from both windings and their different responses to field changes, the system can differentiate between static magnetic field variations and dynamic gradient fields, maintaining measurement versatility while enabling signal source identification.

Inventive Principle:

Principle #23Feedback

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 design enhances the accuracy and homogeneity of magnetic field measurements, reducing uncertainties and improving signal-to-noise ratio, allowing for more precise calibration and adjustment of magnetic fields in MRI systems.

Implementation Method 1

a coil (SPU) surrounding the body (KP)

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

the outer sections (WL, WR) being short-circuited, in each case by way of a blocking capacitor (ABK1, ABK2)

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS10168399B2MR field probes with additional windings for improving the homogeneity and localizing the measuring volume

Publication Date: 2019.01.01 SIEMENS HEALTHINEERS AG

AI summary

The embodiments relate to a method and field probes for measuring a static and/or in particular a dynamic magnetic field in an imaging magnetic resonance tomography system, wherein the field probe includes a body surrounded by a coil. The coil includes a middle or center winding section and at least one or two outer winding sections.