Phase Gradient Calculation for Ultrasound Shear Wave Elastography
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Solution Overview
Problem
Existing ultrasound elastography techniques face limitations in spatial resolution and computational resources due to the need for wide autocorrelation windows and non-uniform reverberant shear wave fields, especially near strong vibration sources.
Innovation Solution
The phase gradient calculation method uniquely calculates wavenumber and phase velocity, allowing for accurate localization of tumors and improved spatial resolution without the need for autocorrelation, even in non-homogeneous reverberant fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If autocorrelation with a wide autocorrelation window is used to estimate shear wave speed and tissue stiffness, then measurement precision is improved, but spatial resolution deteriorates
Solution Approach 1:
The patent extracts and utilizes only the phase information from the ultrasound signals, separating it from the full signal processing approach. By focusing specifically on phase gradient calculation rather than full autocorrelation, the method achieves accurate shear wave speed estimation without requiring wide autocorrelation windows, thereby maintaining spatial resolution.
Solution Approach 2:
The patent replaces the traditional autocorrelation-based mechanical signal processing system with a phase gradient calculation approach. This substitution uses phase information directly from the ultrasound signals to determine shear wave speed, eliminating the need for wide autocorrelation windows and their associated spatial resolution losses.
2Measurement precision
If autocorrelation method is used for shear wave speed estimation, then measurement precision is improved, but computational resources increase
Solution Approach 1:
The patent extracts only the necessary phase information from the ultrasound signals, discarding the computationally intensive full autocorrelation processing. By focusing on phase gradient calculation alone, the method maintains measurement precision while significantly reducing computational resource requirements.
Solution Approach 2:
The patent employs a computationally lighter phase gradient calculation method that requires fewer processing resources compared to full autocorrelation. This approach uses simpler, more efficient calculations that consume less computational power while still achieving accurate shear wave speed estimation.
3Measurement precision
If reverberant shear wave field is used near strong vibration sources, then the field is not uniformly reverberant, but the phase gradient method still enables accurate tumor localization
Solution Approach 1:
The patent applies local quality by calculating phase gradients at each spatial location independently, allowing the method to adapt to local variations in the reverberant field. This localized approach enables accurate tumor localization even when the overall field uniformity is compromised by proximity to strong vibration sources.
Solution Approach 2:
The patent changes the measurement parameter from full signal autocorrelation to phase gradient calculation. This parameter change makes the measurement process more robust to field non-uniformities, enabling accurate tumor localization in challenging environments near strong vibration sources where traditional methods fail.
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 method enhances spatial resolution and reduces computational requirements, enabling accurate tumor localization and stiffness measurement in challenging conditions, such as near strong vibration sources.
Implementation Method 1
shear-inducing transducers acting as vibration sources introduce acoustic energy into the organ of interest, generating shear waves within the organ
Implementation Method 2
when two characteristics of a reverberant field—namely, the wavenumber and the phase velocity (shear wave speed)—are calculated in a new and unique way using the herein-disclosed phase gradient ('PG') calculation method
Implementation Method 3
This diversity of differently-directed shear waves is also enhanced by all the reflections that naturally occur from the boundaries of the organ and from the inhomogeneities within it
Data Source
AI summary
The wave number and phase velocity (shear wave speed) of ultrasound energy within an organ of interest are calculated using a herein-disclosed phase gradient calculation method. This calculation method is less sensitive to imperfections in the reverberant field distribution and requires a smaller support window, relative to earlier calculation methods based on autocorrelation. Applications are shown in simulations, phantoms, and in vivo liver.