Shear Wave Boundary Detection in Thermal Ablation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current ultrasound imaging modalities, particularly shear wave imaging (SWI) elastography, fail to provide sufficient information on thermal lesions created by radiofrequency ablation (RFA) due to substantial stiffness changes and artifacts caused by the ablation electrode, leading to inadequate detection of tissue boundaries.

Innovation Solution

A system that generates a displacement field with a spatial and temporal component, using directional filters to isolate and accumulate shear wave reflections from stiff ablation lesions, enabling a boundary estimator to accurately detect tissue boundaries over time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If shear wave imaging elastography is used to monitor thermal lesions, then real-time monitoring capability is provided, but detection accuracy deteriorates due to substantial stiffness changes and artifacts from the ablation electrode

Engineering Contradiction:

Improvereal-time monitoring capabilityVSAvoiddetection accuracy of tissue boundaries

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent segments the displacement field into different directional components using directional filters. By separating the displacement field into radial and tangential components, the system can selectively analyze reflected shear waves while filtering out artifacts from the ablation electrode, thereby maintaining detection accuracy during real-time monitoring

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces directional filters as an intermediary processing step between shear wave generation and boundary detection. These filters act as a mediator that selectively passes reflected shear wave signals while attenuating artifacts from the ablation electrode, enabling accurate boundary detection despite the presence of substantial stiffness changes

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If conventional ultrasound imaging is used, then imaging capability is provided, but sufficient information on thermal lesions is not obtained due to inadequate detection of tissue boundaries

Engineering Contradiction:

Improveimaging capabilityVSAvoidinformation on thermal lesions

Core Design Contradiction:

Ease of operationVSLoss of information

Solution Approach 1:

The patent transitions from conventional B-mode ultrasound imaging to shear wave elastography, adding the dimension of mechanical wave propagation analysis. By incorporating temporal dynamics of shear wave displacement fields and applying directional filtering in the frequency-wavenumber domain, the system recovers information about thermal lesion boundaries that is invisible to conventional imaging

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent changes the physical parameters being measured from conventional acoustic impedance to shear wave velocity and displacement. By monitoring the temporal evolution of shear wave reflections and analyzing directional displacement components, the system provides comprehensive information on thermal lesion characteristics including boundary location, growth, and stiffness changes

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If shear wave imaging is applied to stiff ablation lesions, then boundary detection is attempted, but performance deteriorates due to substantial stiffness change within the region of interest

Engineering Contradiction:

Improveboundary detection capabilityVSAvoidperformance of SWI elastography

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent inverts the conventional approach by not trying to measure shear wave velocity through the stiff lesion, but instead detecting reflected shear waves from the lesion boundary. By analyzing the reflection patterns and directional displacement fields, the system reliably detects boundaries despite the substantial stiffness mismatch that would normally degrade SWI performance

Inventive Principle:

Principle #13The other way round (Inversion)

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 detection sensitivity for thermal ablation zones, providing real-time monitoring and improving the accuracy of ablation area visualization, thus ensuring adequate treatment coverage during RFA procedures.

Implementation Method 1

An ultrasound mode generates shear wave displacements using a push pulse through a medium to generate a displacement field

Methodology Applied

Scientific EffectShear wave generation: Ultrasonic Vibration

Implementation Method 2

The significant shear wave reflection from a highly stiff ablation boundary is preferentially detected using directional filters configured to filter shear wave displacements

Methodology Applied

Scientific EffectShear wave reflection: Reflection

Data Source

PatentUS11337673B2Using reflected shear waves for monitoring lesion growth in thermal ablations

Publication Date: 2022.05.24 KONINKLIJKE PHILIPS NV

AI summary

A system for boundary identification includes a memory (42) to store shear wave displacements through a medium as a displacement field including a spatial component and a temporal component. A directional filter (206, 208) filters the displacement field to provide a directional displacement field. A signal processing device (26) is coupled to the memory to execute a boundary estimator (214) to estimate a tissue boundary in a displayed image based upon a history of the directional displacement field accumulated over time.