Sparse Shear Modulus Ultrasound Imaging via Strain Diffusion
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Solution Overview
Problem
Current ultrasound imaging techniques for determining tissue viscoelastic properties, such as elasticity and stiffness, face challenges in accurately measuring internal stress and strain due to limitations in pressure sensor accuracy and acoustic radiation force propagation errors, leading to relative and qualitative strain measurements that are difficult to quantify.
Innovation Solution
The method involves estimating shear modulus values at sparse locations within a field of view using ultrasound and calculating these values for a denser sampling of the grid based on strain information, allowing for the display of quantitative tissue property information across the entire field of view with reduced patient exposure to acoustic energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If strain measurements are taken at all locations in the field of view, then measurement precision is improved, but loss of time increases due to additional transmissions
Solution Approach 1:
The field of view is divided into two groups of locations: a first group where strain measurements are directly obtained from ultrasound transmissions, and a second group where strain values are calculated using diffusion equations based on measurements from the first group. This segmentation allows sparse direct measurements combined with computational estimation to achieve full-field strain imaging without requiring dense direct measurements at all locations.
2Measurement precision
If acoustic radiation force is increased to improve stress measurement accuracy, then measurement precision is improved, but object-affected harmful factors increase due to tissue heating
Solution Approach 1:
Acoustic radiation force is applied only at a subset of locations (first group) rather than all locations in the field of view. The stress and strain information from these sparse locations is then used to calculate values at all other locations through diffusion equations. This partial action reduces the total acoustic energy delivered to the tissue, minimizing heating while still enabling full-field quantitative strain imaging.
3Measurement precision
If pressure sensors are used to measure applied stress, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The mechanical pressure sensor system is replaced with an acoustic-based stress measurement system. Acoustic radiation force is applied to tissue, and the resulting tissue displacement and strain are measured using ultrasound. The applied stress is calculated from the known acoustic force parameters and measured strain, eliminating the need for external pressure sensors while achieving quantitative stress measurement.
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 enables the rapid acquisition of quantitative shear modulus values across the entire field of view, reducing patient exposure to acoustic energy and minimizing heating of the transducer, while providing accurate viscoelastic tissue property imaging.
Implementation Method 1
Acoustic radiation force may be transmitted at a known amplitude
Implementation Method 2
One tissue property or component of viscoelasticity is elasticity. Ultrasound imaging may operate in an elasticity imaging mode
Data Source
AI summary
The shear modulus information is measured for sparse locations in a scanning field of view. For other locations, the shear modulus information is calculated as a function of the sparsely measured values and strain information. For example, shear modulus values are provided for every grid point in a field of view based on strain values for every grid point and on sparsely measured shear modulus values.