Acoustic Radiation Force Interface for Elastography Displacement

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Solution Overview

Problem

Current transient elastography methods face limitations in generating sufficient displacement amplitudes for accurate imaging of viscoelastic media without causing harm, particularly in biological tissues, due to constraints in power and synchronization of mechanical excitation.

Innovation Solution

A method involving the generation of acoustic radiation force by focusing acoustic waves at an interface between zones of distinct acoustic properties within the viscoelastic medium, allowing for higher displacement amplitudes and improved imaging quality through the propagation of shear waves.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If external mechanical stimulation is used to generate displacement in transient elastography, then displacement amplitude can reach 100 μm, but the device becomes bulky and synchronization with imaging becomes difficult

Engineering Contradiction:
Improvedisplacement amplitudeVSAvoiddevice bulk
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the external mechanical stimulation system with an ultrasonic acoustic radiation force system. Instead of using a bulky external mechanical device to generate displacement, the invention uses focused ultrasonic waves to create acoustic radiation force within the tissue, which generates the necessary mechanical displacement for elastography. This substitution eliminates the need for external mechanical contact and reduces device complexity while maintaining measurement precision.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If ultrasonic beam is focused within the medium to generate acoustic radiation force, then ease of handling and synchronization are improved, but displacement amplitude is limited by maximum acoustic power

Engineering Contradiction:
ImprovesynchronizationVSAvoiddisplacement amplitude
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent introduces an interface layer (such as a membrane or coupling medium) as an intermediary between the ultrasonic transducer and the tissue medium. This interface serves as a mediator that concentrates and transfers the acoustic radiation force more efficiently to the tissue, thereby amplifying the displacement amplitude without requiring excessive acoustic power. The interface acts as a force concentrator that overcomes the power limitation while maintaining the ease of operation and synchronization benefits of ultrasonic stimulation.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Measurement precision

If acoustic power is increased to generate higher displacement amplitude, then measurement precision improves, but thermal and mechanical damage to tissue occurs

Engineering Contradiction:
Improvedisplacement amplitudeVSAvoidtissue damage
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The interface layer acts as a mechanical amplifier that concentrates the acoustic radiation force, allowing higher displacement amplitudes to be generated with lower acoustic power. By using this intermediary to focus and amplify the force transmission, the system achieves the necessary measurement precision without increasing the acoustic power to levels that would cause thermal or mechanical damage to the tissue.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Measurement precision

If mechanical excitation is localized to specific areas, then imaging quality in regions of interest improves, but the complexity of optimizing wave amplitude increases

Engineering Contradiction:
Improveimaging qualityVSAvoidoptimization complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies local quality by focusing the ultrasonic beam and the interface structure specifically at the region of interest within the tissue. The interface (membrane or coupling medium) is positioned and configured to concentrate the acoustic radiation force precisely where needed, creating localized mechanical excitation. This approach improves imaging quality in the target area while the focused nature of the ultrasonic beam inherently simplifies the optimization process compared to distributed excitation methods.

Inventive Principle:
Principle #3Local quality

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 enhances the quality of elastographic imaging by increasing displacement amplitudes to 100 μm, enabling better characterization of interfacial zones and monitoring of tissue elasticity during therapeutic treatments, while minimizing harm to the medium.

Implementation Method 1

generating an acoustic radiation force within the viscoelastic medium by applying acoustic waves focused on an interface delimiting two zones having distinct acoustic properties

Methodology Applied
Scientific EffectAcoustic radiation force: Acoustic Radiation Pressure

Data Source

PatentEP2084702B1Method for generating mechanical waves by creating an interfacial acoustic radiation force
Publication Date: 2020.03.18 SUPERSONIC IMAGINE SA
  • EP2084702B1 patent drawingFigure 1~3
  • EP2084702B1 patent drawingFigure 4a~5
  • EP2084702B1 patent drawing

AI summary

The present invention relates to a method for generating mechanical waves in a viscous-elastic medium (11), that comprises the step of generating an acoustic radiation force (15) in the viscous-elastic medium (11) by the application of acoustic waves focused on an interface (13) separating two areas (11, 14) having different acoustic properties.