Directional Filter for Bounded Tissue Stiffness
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Solution Overview
Problem
Existing ultrasound systems struggle to accurately determine the stiffness of thin, bounded tissues using shear wave elastography due to wave mode conversion and dispersion caused by tissue boundaries, leading to underestimation of tissue stiffness.
Innovation Solution
The system employs a directional filter to remove unwanted noise from shear wave echo data based on tissue thickness and angular orientation relative to the ultrasound transducer, allowing for the estimation of shear wave velocities at different frequencies and independent determination of tissue stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional shear wave elastography is used to measure stiffness in bounded tissues, then the measurement process is simple and follows standard protocols, but the tissue stiffness is underestimated due to wave mode conversion and dispersion at tissue boundaries
Solution Approach 1:
The patent segments the shear wave propagation analysis into distinct components: primary shear waves and reflected/reverberating waves. By applying directional filters to separate these wave components based on their propagation directions, the system can independently analyze the primary wave velocity while excluding boundary-induced wave interference, thereby resolving the measurement accuracy issue in bounded tissues
Solution Approach 2:
The patent introduces angular orientation as an additional dimension for analyzing shear wave propagation. By determining the angular orientation of the bounded tissue relative to the transducer and applying directional filtering in this angular dimension, the system can distinguish between waves propagating along the tissue (primary waves) and waves reflecting off boundaries (reverberating waves), thus improving stiffness measurement accuracy
2Measurement precision
If directional filtering is applied to remove reverberating waves, then tissue stiffness measurement accuracy improves, but processing time and computational complexity increase
Solution Approach 1:
The patent performs preliminary determination of tissue angular orientation and thickness before applying directional filters to the shear wave data. By pre-establishing the expected propagation direction range based on anatomical knowledge and initial imaging, the system can apply targeted directional filtering that removes reverberating waves while preserving primary waves, reducing unnecessary computational processing
Solution Approach 2:
The patent dynamically adjusts filtering parameters (such as angular range and filter strength) based on the determined tissue orientation and thickness. By optimizing these parameters for each specific tissue configuration, the system achieves effective separation of primary and reverberating waves with minimal processing overhead, balancing accuracy improvement with processing efficiency
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 accurate characterization of tissue stiffness in bounded tissues, such as vascular and cardiac tissues, by filtering out wave reverberations and accounting for tissue dimensions and orientation, providing more reliable clinical assessments.
Implementation Method 1
transmitting a push pulse into the bounded target tissue to generate shear waves in the bounded target tissue
Implementation Method 2
tracking pulses emitted by the transducer can then be used to measure the velocity of the shear wave as it propagates
Implementation Method 3
wave mode conversion generated by wave reflections off restrictive tissue boundaries
Implementation Method 4
wave reflections off restrictive tissue boundaries
Data Source
Figure 1A~1B
Figure 1C
Figure 2
AI summary
The present disclosure describes systems and methods configured to determine shear wave velocity and tissue stiffness levels of thin tissue of finite size, also referred to as bounded tissue, via shear wave elastography. Systems can include an ultrasound transducer configured to acquire echoes responsive to pulses transmitted toward a tissue. Systems can also transmit a push pulse into the tissue for generating shear waves, and tracking pulses intersecting the shear waves. The system can also apply a directional filter to received echo data and generate directionally filtered shear wave data based on a dimension and angular orientation of the bounded target relative to the ultrasound transducer. The system can estimate velocities of the shear waves at different shear wave frequencies based on the filtered shear wave data and angular orientation relative to the transducer, and determine a tissue stiffness value independent of the shape or form of the tissue.