Nonlinear Scatterer Imaging with Dual-Frequency Elastic Wave Pulses
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Solution Overview
Problem
Current ultrasound image reconstruction techniques face challenges in suppressing acoustic noise and accurately estimating nonlinear scattering parameters due to acoustic noise produced by multiple scattering and wave front aberrations, which degrades image quality and complicates the extraction of nonlinearly scattered signals in heterogeneous materials.
Innovation Solution
The method involves transmitting at least two elastic wave pulse complexes, one in a high frequency (HF) band and one in a low frequency (LF) band, with the LF pulse varying in phase, amplitude, or frequency to nonlinearly manipulate material elasticity and scattering properties observed by the HF pulse, and using signal processing techniques to filter out harmonic components and combine signals from multiple pulse complexes to enhance nonlinear measurement signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current ultrasound image reconstruction techniques are used, then image reconstruction is simple, but acoustic noise from multiple scattering and wave front aberrations degrades image quality and complicates extraction of nonlinearly scattered signals
Solution Approach 1:
The patent segments the scattered signal into linear and nonlinear components by transmitting multiple pulse complexes with different characteristics (frequency, phase, amplitude) and processing the received signals to separate these components. This allows precise extraction of nonlinearly scattered signals while suppressing linear scattering and acoustic noise through systematic signal decomposition
Solution Approach 2:
The patent changes multiple parameters of the transmitted pulse complexes including frequency (HF and LF bands), phase relationships, and amplitude ratios. By varying these parameters across multiple transmissions and analyzing the changes in received signals, the system can isolate and extract nonlinear scattering parameters from the complex acoustic field
2Reliability
If multiple pulse complexes are transmitted to suppress acoustic noise, then image quality improves, but the measurement and imaging process becomes more complex
Solution Approach 1:
The patent employs periodic transmission of multiple pulse complexes with systematically varied characteristics (different phase relationships between HF and LF pulses, different amplitude ratios). This periodic action with controlled variations enables the system to accumulate sufficient data for noise suppression while maintaining a structured, manageable transmission sequence
Solution Approach 2:
The patent introduces low frequency (LF) pulses as intermediary elements that modulate the material properties and scattering characteristics during the measurement process. These LF pulses act as mediators that enable the extraction of nonlinear scattering information from the high frequency (HF) signals without requiring direct complex HF manipulations
3Measurement precision
If LF pulses are used to nonlinearly manipulate material elasticity, then nonlinear scattering measurement accuracy improves, but the transmission and reception system becomes more complex
Solution Approach 1:
The patent designs the pulse complex transmission system to serve multiple functions simultaneously: the LF pulses manipulate material elasticity for nonlinear scattering measurement, the HF pulses provide high-resolution imaging, and the combined system enables both linear and nonlinear scattering characterization. This multi-functionality reduces the need for separate specialized systems
Solution Approach 2:
The patent replaces complex mechanical manipulation of material properties with acoustic field manipulation using LF pulses. Instead of physically deforming the material, the system uses acoustic radiation pressure and nonlinear elastic effects induced by LF pulses to achieve the same measurement objectives, simplifying the overall system architecture
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 effectively suppresses linear scattering and pulse reverberation noise, improving the estimation of nonlinear scattering parameters and enhancing image quality by isolating nonlinear scatterers with memory of scattering parameters, such as micro-bubbles and micro-calcifications, while maintaining adequate suppression of image components from other scatterers.
Implementation Method 1
Nonlinear elasticity means that the material elastic stiffness changes with elastic deformation of the material. For example does the material volume compression stiffness increase with volume compression of the material with a subsequent increase in the volume compression wave propagation velocity.
Implementation Method 2
compression/expansion/deformation of a spatially heterogeneous material will change the spatial variation of the elasticity and hence produce a scattering that depends on the material strain.
Data Source
AI summary
Measurement or imaging of elastic wave nonlinear scatterers with a memory of scattering parameters comprises selecting LF pulses having characteristics to change the scattering parameters of nonlinear scatterers. A transmit time relation is selected so that the incident HF pulse propagates sufficiently close to the LF pulse that the effect of the incident LF pulse on its scatterer parameters is observed by the HF pulse. At least two elastic wave pulse complexes comprising a high frequency (HF) pulse and a selected low frequency (LF) pulse are transmitted towards the region. Received HF signals are combined to form nonlinear HF signals representing the scatterers with memory, with suppression of received HF signals from other scatterers. At least one of the received HF signals may be corrected by time delay correction and/or speckle correction with a speckle correction filter, determined by movement of the scattering object. Systems are also disclosed.