Shear Speed Imaging Using Constructive Interference
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Solution Overview
Problem
Shear wave speed imaging faces challenges in penetration depth due to acoustic push pulse attenuation and signal-to-noise ratio limitations, leading to unreliable velocity estimates, especially in stiffer tissues like fibrotic liver.
Innovation Solution
The method employs constructive interference from multiple shear waves generated by acoustic radiation force impulses (ARFI) at different locations, using the time difference and displacement patterns to estimate shear wave speed, enhancing signal-to-noise ratio and improving measurement reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If acoustic radiation force impulses are transmitted to generate shear waves for speed imaging, then shear wave speed can be estimated, but the acoustic push pulse attenuates at deeper depths resulting in weaker signals and lower signal-to-noise ratio
Solution Approach 1:
The patent combines multiple shear waves generated by sequential acoustic radiation force impulses to create constructive interference patterns. By merging the displacement signals from multiple shear wave events, the system amplifies the useful signal while maintaining consistent noise levels, thereby improving the signal-to-noise ratio for deeper tissue imaging and more reliable shear wave speed estimation.
Solution Approach 2:
The system employs periodic transmission of acoustic radiation force impulses to generate repeated shear waves. By transmitting impulses at regular intervals and accumulating the resulting displacement signals, the method enhances signal detection through temporal averaging and constructive interference, overcoming the attenuation problem at deeper depths.
2Length of moving object
If acoustic radiation force impulses are transmitted to generate shear waves, then shear wave propagation can be monitored, but the push pulse strength decreases at deeper depths due to attenuation and safety limits
Solution Approach 1:
The patent merges displacement signals from multiple shear wave events to compensate for the decrease in push pulse strength at deeper depths. By combining the constructive interference patterns from several impulses, the system maintains adequate signal amplitude even when individual push pulses are weakened by attenuation and safety constraints.
Solution Approach 2:
The system performs preliminary transmission of acoustic radiation force impulses to generate shear waves that propagate through the tissue. By preparing and accumulating these shear wave events before final analysis, the method ensures sufficient signal accumulation at deeper depths where individual push pulses are inherently weaker.
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 increases the signal-to-noise ratio, allowing for more accurate and reliable shear wave speed measurements, especially at deeper depths and in stiffer tissues, by detecting constructive interference patterns and calculating shear wave speed based on displacement and time differences.
Implementation Method 1
transmitting an acoustic radiation force impulse (ARFI), a shear wave is generated at the ARFI focus
Implementation Method 2
constructive interference from multiple shear waves is used. By transmitting ARFI focused at different locations, the resulting shear waves may constructively interfere within a region of interest
Data Source
AI summary
To increase the signal-to-noise ratio for displacements used to estimate the shear speed in patient tissue, constructive interference from multiple shear waves is used. By transmitting acoustic radiation force impulses focused at different locations, the resulting shear waves may constructively interfere within a region of interest. This constructive interference causes a greater amplitude of displacement. The location of this more easily detected greater interference and the difference in time of the transmitted acoustic radiation force impulses are used to estimate the shear wave speed for the tissue.