Dense Speed-of-Sound Imaging for Real-Time Ablation Thermometry
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Solution Overview
Problem
Current ultrasound-based thermal strain imaging methods for monitoring temperature changes during high-intensity focused ultrasound (HIFU) therapy are computationally burdensome and lack spatial coherence, limiting their effectiveness in providing real-time, accurate temperature monitoring.
Innovation Solution
The Dense Speed-of-Sound Shift Imaging (DSI) algorithm calculates the change in internal sound speed of biological tissue by determining pixel shift between successive ultrasound images, solving an inverse problem to achieve faster and more accurate temperature assessment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thermal strain imaging methods are used for temperature monitoring, then temperature measurement capability is provided, but computational burden increases and processing speed decreases
Solution Approach 1:
The patent changes the fundamental parameter being measured from thermal strain (displacement) to speed of sound directly. By measuring the speed of sound through acoustic radiation force imaging and analyzing the phase shift of acoustic waves, the system obtains temperature information without the computationally intensive processing required for thermal strain methods, thus resolving the contradiction between measurement capability and processing speed.
Solution Approach 2:
The patent replaces the mechanical/displacement-based thermal strain imaging approach with an acoustic wave-based speed of sound measurement approach. By using acoustic radiation force to generate and measure sound wave phase shifts, the system substitutes the complex mechanical deformation analysis with simpler acoustic phase measurement, significantly reducing computational burden while maintaining temperature monitoring capability.
2Measurement precision
If thermal strain imaging is used for temperature monitoring, then temperature change detection is achieved, but spatial coherence is insufficient
Solution Approach 1:
The patent changes from measuring thermal strain (which suffers from lack of spatial coherence) to measuring speed of sound directly through acoustic phase shift analysis. This parameter change inherently provides better spatial coherence because acoustic wave phase measurements are more directly tied to the local speed of sound properties, which vary smoothly with temperature, rather than relying on displacement field coherence.
3Measurement precision
If MRI is used for temperature monitoring, then accurate real-time temperature measurement is achieved, but system cost and complexity increase
Solution Approach 1:
The patent substitutes the complex MRI system with a simpler ultrasound-based system. By using acoustic radiation force imaging to measure speed of sound changes, the system achieves real-time temperature monitoring without requiring expensive MRI hardware, magnetic fields, or specialized radiofrequency coils, thus dramatically reducing system complexity and cost while maintaining measurement accuracy.
Solution Approach 2:
The patent employs standard ultrasound transducers and conventional imaging equipment instead of expensive MRI systems. By using readily available ultrasound technology and acoustic radiation force methods, the system provides a cost-effective alternative to MRI that achieves similar real-time temperature monitoring capabilities without the high equipment costs and operational complexity of magnetic resonance systems.
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
DSI provides real-time, accurate temperature monitoring with a 20-fold increase in processing speed compared to thermal strain imaging, reducing the risk of unwanted tissue damage by allowing precise control of thermal ablation and cryo-ablation procedures.
Implementation Method 1
Ultrasound is a safe, cheap, and portable imaging modality with excellent temporal characteristics
Implementation Method 2
HIFU inflicted necrosis inherently changes the speed of sound in tissue, causing a measurable latency in the echo over successive ultrasound frames captured by an imaging transducer
Implementation Method 3
This approach, later named thermal strain imaging (TSI), serves as the basis for many of the more recent developments in the field of ultrasonic thermometry. Thermal strain is impartial to the underlying ultrasound acquisition method or heating procedure.
Implementation Method 4
the Proton Resonance Frequency (PRF) shift method, which utilizes the hydrogen bonds in water molecules to measure temperature change
Implementation Method 5
HIFU therapy is considered effective for various uses ranging originally from lesion destruction in the central nervous system to treatment of a wide array of tumors and cancers. Tumor necrosis is induced by the HIFU beam as the surrounding tissue is heated to temperatures at which the local damage is irreversible.
Data Source
AI summary
Disclosed are methods and systems, comprising real-time dense algorithms calculating the speed-of-sound shift between acoustic acquisitions, that allows enhanced noninvasive temperature evaluation during treatment such as thermal ablation.