Ultrasound Viscoelastic Estimation via Shear Wave Speed Distribution
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Solution Overview
Problem
Current ultrasound imaging methods for estimating viscoelastic properties of tissue using acoustic radiation force impulse (ARFI) are prone to noise due to low signal levels in frequency bands, making them impractical for in vivo applications.
Innovation Solution
Measuring shear wave speed without frequency band division and correlating the distribution of speeds with modeled viscoelastic properties, using group velocity to improve signal-to-noise ratio and enhance sensitivity and specificity of viscoelastic parameter estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequency band division is used to estimate phase velocities, then viscoelastic property estimation is performed, but signal levels are low and estimates are prone to noise
Solution Approach 1:
The patent divides the tissue response signal into multiple frequency bands and estimates phase velocity independently in each band. This segmentation allows for frequency-specific viscoelastic characterization while maintaining sufficient signal levels through proper band selection and processing.
Solution Approach 2:
The patent transforms the measurement approach by using phase velocity estimation in the Fourier domain and then combining results across frequency bands. This parameter transformation from time domain to frequency domain enables more robust viscoelastic property estimation with improved signal-to-noise ratio.
2Reliability
If shear wave speed is measured without frequency band division, then signal-to-noise ratio is improved, but frequency-dependent viscoelastic characterization is lost
Solution Approach 1:
The patent segments the frequency spectrum into multiple bands and performs phase velocity estimation in each segment. This allows preservation of frequency-dependent information while maintaining adequate signal levels in each band for reliable measurement.
Solution Approach 2:
The patent adds the frequency dimension to the measurement by performing independent phase velocity estimates across multiple frequency bands. This dimensional expansion enables frequency-dependent viscoelastic characterization without sacrificing signal-to-noise ratio, as each band can be processed independently with sufficient signal energy.
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 allows for more accurate and robust estimation of viscoelastic properties, enabling non-invasive evaluation of fibrosis, steatosis, and differentiation of benign and malignant breast cancers, and compensating for increased shear wave speed estimates caused by tissue compression.
Implementation Method 1
tissue displacement is caused by a wave generated from a stress, such as an acoustic force radiation impulse (ARFI)
Implementation Method 2
The primary characteristic of shear wave propagation in viscoelastic media is that the media has a complex wave number corresponding to a frequency-dependent shear wave speed and shear wave attenuation
Data Source
AI summary
For viscoelastic estimation with ultrasound, shear wave speed is measured for different locations in a region of interest. For each location, the shear wave speed is estimated without frequency band division. A distribution of shear wave speeds in the region of interest is matched a modeled distribution corresponding to a particular value of the viscoelastic property.