MRI Phantom With Variable Volume Reservoirs

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Solution Overview

Problem

MRI geometric distortion phantoms face accuracy issues due to pressure changes caused by thermal expansion mismatches between materials, leading to potential structural integrity problems and image distortion, especially in image-guided applications where precision is critical.

Innovation Solution

A fluid-filled quality assurance device with a rigid housing containing sealed reservoirs, featuring a fixed volume portion and a variable volume portion to accommodate temperature and pressure fluctuations, using susceptibility-matched materials to minimize distortion and prevent rupture.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a sealed MRI phantom is constructed with rigid materials and fluid filling, then it provides structural stability and contains the signal-producing material, but thermal expansion mismatch causes internal pressure increase and geometric distortion

Engineering Contradiction:

Improvestructural stabilityVSAvoidgeometric accuracy

Core Design Contradiction:

Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The sealed reservoir is divided into two distinct portions: a first portion with fixed volume providing structural stability, and a second portion with variable volume that accommodates thermal expansion. This segmentation allows each portion to fulfill its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the volume parameter of the second reservoir portion from fixed to variable, allowing it to expand and contract in response to thermal conditions. This parameter change enables the reservoir to maintain geometric accuracy while accommodating thermal expansion of the fluid.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If temperature and pressure fluctuations occur during shipping and use, then the MRI phantom must maintain geometric accuracy, but pressure changes cause structural integrity problems and potential fluid rupture

Engineering Contradiction:

Improvegeometric accuracyVSAvoidstructural integrity

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The variable volume second portion acts as a pre-designed cushioning space that absorbs pressure changes before they can cause harmful effects. This beforehand cushioning prevents fluid rupture and maintains structural integrity during temperature and pressure fluctuations.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The second variable volume portion serves as an intermediary element between the fluid and the external environment, mediating the effects of pressure and temperature changes. It absorbs the stress of expansion and contraction, protecting the overall phantom structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of manufacture

If the MRI phantom uses commonly available materials like mineral oil and acrylic, then manufacturing is simplified and cost-effective, but the volume thermal coefficient mismatch causes significant pressure increase of about 60 kPa/°C

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidinternal pressure

Core Design Contradiction:

Ease of manufactureVSStress or pressure

Solution Approach 1:

By segmenting the reservoir into fixed and variable volume portions, the patent allows the use of simple, commonly available materials while managing the pressure issue. The variable portion accommodates the thermal expansion that would otherwise create excessive pressure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent converts the harmful effect of thermal expansion (which causes pressure buildup) into a beneficial feature by providing a variable volume space that allows controlled expansion. The material mismatch that creates the problem also defines the expansion capacity of the second portion.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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

Maintains geometric accuracy and structural integrity of the MRI phantom across varying temperatures and pressures, ensuring precise imaging modality performance and preventing fluid leakage during shipping and use.

Implementation Method 1

the change in pressure per degree Celsius (ΔP/°C) is about 60 kPa/°C. This is a significant increase in the internal pressure of a sealed vessel

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

The second variable volume portion varies in response to changes in volume of the fluid material contained in each of the one or more sealed reservoirs

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP3403113B1Fluid-filled quality assurance device for an imaging modality such as MRI

Publication Date: 2022.06.15 MODUS MEDICAL DEVICES INC

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AI summary

A MRI quality assurance device, according to the present invention, has a housing made of a rigid MRI invisible material containing one or more sealed reservoirs containing a fluid MRI signal producing material. Each sealed reservoir has a first volume portion and a second variable volume portion in fluid communication therewith.