Optoacoustic Temperature Mapping via Intermediary Calibration
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Solution Overview
Problem
Current optoacoustic imaging technologies face challenges in accurately mapping temperature in vivo due to sample-to-sample and spatial variations of the Gruneisen parameter, limiting their effectiveness in providing reliable temperature measurements and co-registered anatomical images, which is crucial for thermal therapy and cryotherapy.
Innovation Solution
An imaging system that combines optoacoustic and ultrasound imaging modules with an image processing and calibration module, using pulsed optical illumination and automatic self-focusing algorithms to generate accurate temperature maps independently of optical fluence and tissue properties, and a method for calibrating temperature-structure imaging by normalizing optoacoustic image intensity ratios to achieve absolute temperature measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optoacoustic imaging is used for temperature mapping, then temperature information can be obtained, but measurement precision is reduced due to sample-to-sample and spatial variations of Gruneisen parameter
Solution Approach 1:
The patent introduces an intermediary substance (contrast agent or exogenous absorber) that is administered to the patient before imaging. This intermediary has known and stable optical absorption properties that are independent of tissue Gruneisen parameter variations. By imaging the intermediary rather than the native tissue, the system achieves temperature measurement precision that is not degraded by sample-to-sample or spatial variations in tissue properties.
Solution Approach 2:
The patent changes the measurement parameter from relying on intrinsic tissue properties (Gruneisen parameter) to relying on the optical absorption properties of an administered intermediary substance. This parameter change allows temperature to be determined through the temperature-dependent optical absorption of the intermediary, which can be calibrated independently of tissue variability.
2Loss of information
If optoacoustic imaging provides only temperature information, then temperature mapping is achieved, but anatomical context is lost
Solution Approach 1:
The patent merges two imaging modalities: optoacoustic imaging for temperature measurement and ultrasound imaging for anatomical visualization. The system simultaneously acquires both types of images and co-registers them spatially, allowing temperature information to be overlaid on anatomical structures. This combination preserves both the temperature data and the anatomical context, eliminating the loss of information that would occur if only temperature mapping were provided.
3Measurement precision
If calibration is performed for each particular tissue, then measurement accuracy is maintained for that tissue, but device complexity increases due to multiple calibration methods
Solution Approach 1:
The patent creates a universal calibration approach where a single calibration curve, derived from the known optical absorption properties of the administered intermediary substance, can be applied across different tissue types. The intermediary substance provides a consistent reference that works universally regardless of the underlying tissue characteristics, eliminating the need for tissue-specific calibration methods and reducing system 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
Enables precise, non-invasive temperature mapping and co-registration with anatomical structures, enhancing the accuracy and safety of thermal therapy by providing real-time temperature distribution maps, thereby improving the efficiency and effectiveness of thermal treatments.
Implementation Method 1
the imaging system utilizes an optical source to provide laser energy to a tissue and an ultrasonic transducer to detect acoustic waves generated by the irradiated tissue as raw data
Implementation Method 2
The magnitude of optoacoustic response is sensitive to the local temperature. The phenomenon is attributed to temperature dependent behavior of thermodynamic and mechanical properties, which comprise thermoacoustic efficiency of the tissue, also known as Gruneisen parameter
Data Source
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Figure 3C~3D
AI summary
Provided herein are system and methods for monitoring and guiding thermal therapy procedures within a human or animal tissue. The system comprises a therapeutic module configured to apply thermal treatment to a subject; an ultrasound imaging module; an optoacoustic imaging module; a processing module connected to both ultrasound and optoacoustic based imaging module; and an operating controlling module connected with said processing module and configured to manipulate at least one of said therapeutic module, ultrasound imaging module or optoacoustic imaging module. The calibration method is able to eliminate the inconsistency of optoacoustic based temperature measurements caused by sample-to-sample and spatial variations of Gruneisen parameter for different tissues. The method for temperature-structure imaging is able to generate both two dimensional and three dimensional co-registered structure and temperature images for the tissues inside a region of interest of a subject.