Ultrasound Tomography for Quantitative Bone Imaging
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Solution Overview
Problem
Current medical ultrasound systems struggle to provide non-contact, quantitative imaging of bone and soft tissues, especially due to challenges in handling large impedance contrasts and achieving repeatable, high-resolution images without distorting the tissue.
Innovation Solution
The development of ultrasound tomography (UST) and laser ultrasound (LUS) systems that use full waveform inversion (FWI) and level set techniques to generate simulated time series data, minimizing differences with experimental data, and employing non-contact methods to collect reflective and transmissive data, allowing for quantitative imaging of bone and soft tissues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional ultrasound systems are used to image bone and soft tissue, then the imaging capability is limited due to large impedance contrasts, but the systems cannot provide non-contact imaging or quantitative results
Solution Approach 1:
The imaging process is segmented into multiple computational stages: forward wave propagation simulation, adjoint wave simulation, gradient computation, and iterative model updating. This segmentation allows complex quantitative imaging to be broken down into manageable steps that can be implemented systematically
Solution Approach 2:
The system performs preliminary actions by generating simulated wave propagation data based on an initial model before actual imaging. This simulated data serves as a reference for comparison with experimental measurements, enabling iterative refinement of the tissue model before final image reconstruction
2Reliability
If contact-based ultrasound imaging is used, then the system can obtain images, but the tissue may be distorted and the imaging is not repeatable
Solution Approach 1:
The patent replaces the mechanical contact-based ultrasound imaging system with a non-contact optical measurement system. Laser beams substitute for mechanical transducers to generate and detect acoustic waves, eliminating physical contact with the tissue and thereby preventing distortion while improving repeatability
Solution Approach 2:
The system introduces water or gel as an intermediary medium between the ultrasound transducer and the tissue. This intermediary allows acoustic coupling without direct mechanical contact, reducing tissue distortion while maintaining imaging capability
3Measurement precision
If full waveform inversion is implemented to improve image quality, then quantitative imaging is achieved, but the computational complexity and processing time increase
Solution Approach 1:
The full waveform inversion process is implemented through periodic iterative updates. The algorithm cycles through forward simulation, adjoint simulation, gradient computation, and model updating in repeated iterations, progressively refining the tissue model until convergence is achieved
Solution Approach 2:
The system performs preliminary wave propagation simulations and adjoint simulations before final image reconstruction. These preliminary computational actions prepare the data structures and intermediate results that accelerate the subsequent inversion process, reducing overall computational time
4Manufacturing precision
If level set techniques are used to handle tissue boundaries, then imaging accuracy at interfaces is improved, but the algorithm complexity increases
Solution Approach 1:
The level set method changes the parameter representation of tissue boundaries from fixed geometric descriptions to evolving level set functions. This parameter transformation allows boundaries to adapt dynamically during inversion, improving accuracy at tissue interfaces while the mathematical framework manages the associated complexity
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
These systems enable non-contact, quantitative imaging of bone and soft tissues, providing improved resolution and accuracy, reducing sidelobe interference, and overcoming the limitations of traditional ultrasound systems in imaging bone and soft tissue properties.
Implementation Method 1
an ultrasound transducer that emits an ultrasound beam of known beam geometry for reflection and transmission at the biological body segment
Implementation Method 2
an ultrasound transducer that emits an ultrasound beam of known beam geometry for reflection and transmission at the biological body segment
Implementation Method 3
A laser is configured to generate an acoustic wave at a surface of a biological body segment
Data Source
AI summary
Systems and methods are provided for imaging of soft and hard tissues with ultrasound. Such systems and methods can provide for non-contact and quantitative ultrasound images of bone and soft tissue. A method for imaging a biological body segment of soft and hard tissues includes setting geometry and material properties according to a model of the biological body segment to thereby generate a simulated time series data set. The method further includes collecting reflective and transmissive time series data of the biological body segment to thereby form an experimental time series data set and minimizing a difference between the simulated time series data set and the experimental time series data set, thereby imaging the biological body segment. Regularizing travel-time and/or using full waveform tomographic techniques with level set methods enable recovery of cortical bone geometry.