Ultrasound Shear Wave Amplitude Reconstruction for Tissue Elasticity
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Solution Overview
Problem
Current ultrasound systems for determining tissue elasticity, particularly in the context of radiofrequency ablation, face challenges in accurately delineating the boundaries of stiff tissue regions due to low signal-to-noise ratios caused by high stiffness of thermal lesions and the presence of a rigid ablation electrode, leading to inaccurate and unreliable tissue elasticity maps.
Innovation Solution
The system generates qualitative tissue elasticity maps by determining the displacement amplitude of shear waves and combining them with quantitative maps to refine the boundaries of stiff regions, using a processor to compare displacement amplitudes with reference values and overlay contour plots onto quantitative maps to improve the precision of tissue elasticity determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If shear wave velocity measurement is used to determine tissue elasticity, then the ability to estimate tissue stiffness is improved, but the signal-to-noise ratio deteriorates due to high stiffness of thermal lesions and rigid ablation electrode
Solution Approach 1:
The patent introduces displacement amplitude as an intermediary parameter to bridge the gap between shear wave velocity measurement and tissue elasticity assessment. Instead of relying solely on shear wave velocity (which suffers from low SNR in stiff tissues), the system uses displacement amplitude attenuation and decorrelation as intermediate metrics that can be reliably measured even in regions with high stiffness, thereby resolving the contradiction between measurement precision and signal reliability
Solution Approach 2:
The patent changes the measurement parameter from shear wave velocity to displacement amplitude. By measuring the amplitude of shear wave displacement and its attenuation characteristics, the system can accurately characterize tissue elasticity in stiff regions where velocity-based methods fail. This parameter transformation enables reliable elasticity mapping in ablation zones with high stiffness and low SNR
2Measurement precision
If quantitative elasticity maps are generated using shear wave velocity, then tissue stiffness quantification is improved, but boundary delineation accuracy deteriorates due to noise and low signal quality in ablation zones
Solution Approach 1:
The patent merges quantitative elasticity maps (based on shear wave velocity) with qualitative elasticity maps (based on displacement amplitude attenuation and decorrelation). By combining these two complementary approaches, the system leverages the quantitative precision of velocity-based methods while incorporating the noise-resistant boundary detection capabilities of amplitude-based methods, thereby improving overall boundary delineation accuracy in ablation zones
Solution Approach 2:
The patent segments the elasticity assessment into two independent components: quantitative elasticity mapping (using shear wave velocity for tissue stiffness quantification) and qualitative elasticity mapping (using displacement amplitude for boundary detection). This segmentation allows each component to optimize for its specific strength, with quantitative maps providing stiffness values and qualitative maps providing reliable boundary information, which are then integrated to produce final results
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 accuracy and precision of tissue elasticity mapping, enabling clearer delineation of stiff tissue boundaries and improving the overall precision of ablation therapies by reducing noise and improving computational efficiency.
Implementation Method 1
transmitting a push pulse into the target tissue to generate a shear wave in the target tissue
Implementation Method 2
a shear wave that propagates laterally therethrough. Tracking pulses emitted by the transducer can then be used to measure the velocity of the shear wave as it propagates
Data Source
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AI summary
The present disclosure describes ultrasound systems and methods configured to determine the elasticity of a target tissue. Systems can include an ultrasound transducer configured to acquire echoes responsive to ultrasound pulses transmitted toward the tissue, which may include a region of increased stiffness. Systems can also include a beamformer configured to control the transducer to transmit a push pulse into the tissue, thereby generating a shear wave in the region of increased stiffness. The beamformer can be configured to control the transducer to emit tracking pulses adjacent to the push pulse. Systems can further include a processor configured to determine a displacement amplitude of the shear wave and based on the amplitude, generate a qualitative tissue elasticity map of the tissue. The processor can combine the qualitative map with a quantitative map of the same tissue, and based on the combination, determine a boundary of the region of increased stiffness.