Time-Resolved Reflectance Spectroscopy for Deep Tissue Oxygenation
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Solution Overview
Problem
Monitoring the vascularization of a buried subcutaneous flap post-reconstructive surgery is challenging due to its inaccessibility, which can lead to serious complications like necrosis from failed vascularization, especially during thrombosis, as existing methods are non-invasive and struggle to accurately assess oxygenation deep within the tissue layers.
Innovation Solution
A non-invasive method using Time-Resolved Reflectance Spectroscopy (TRS) that illuminates the tissue with pulsed light at different wavelengths, detecting backscattered photons to calculate temporal distributions and determine hemoglobin concentrations, allowing for the detection of venous or arterial occlusions by analyzing the correlation between superficial and deep tissue layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical measurement methods are used to monitor flap oxygenation, then the measurement can be performed non-invasively, but the measurement precision for deep tissue layers is insufficient
Solution Approach 1:
The patent segments the detected photons by their time of flight, creating temporal distributions that separate photons based on how long they took to traverse the tissue. This temporal segmentation allows differentiation between superficial and deep tissue contributions, improving measurement precision for deep layers without requiring physically complex depth-resolved sensors
Solution Approach 2:
The patent adds the time dimension to the optical measurement by using pulsed light sources and time-resolved detection. This transforms a spatial measurement problem into a temporal one, where depth information is encoded in photon arrival times, enabling deep tissue monitoring without increasing spatial device complexity
2Ease of operation
If the flap is buried under skin for reconstructive surgery, then the surgical reconstruction can be achieved, but the accessibility for monitoring vascularization is lost
Solution Approach 1:
The patent uses the overlying skin and superficial tissues as an intermediary medium rather than treating them as obstacles. By utilizing time-resolved spectroscopy, the system penetrates through these superficial layers to reach the buried flap, maintaining monitoring accessibility while ensuring reliable oxygenation assessment of the deep tissue
3Measurement precision
If time-resolved spectroscopy is used to differentiate deep and superficial layers, then the measurement precision for deep tissue can be improved, but the use of energy and measurement time increase
Solution Approach 1:
The patent employs continuous pulsed illumination where each pulse generates a temporal distribution of photons. By continuously acquiring temporal distributions over multiple pulses and integrating the signals, the system maintains deep tissue measurement precision while managing energy consumption through efficient signal accumulation rather than requiring excessive energy per pulse
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 accurate, non-invasive monitoring of vascularization, effectively detecting occlusions and estimating hemoglobin concentrations in deep tissue layers, thereby facilitating early intervention to prevent complications like necrosis.
Implementation Method 1
each wavelength extending in a spectral absorption band of oxyhemoglobin and/or deoxyhemoglobin
Implementation Method 2
detection of photons backscattered by the biological tissue, after propagating through the biological tissue
Implementation Method 3
detection of photons backscattered by the biological tissue... by a photodetector
Data Source
Figure 1A~1C
Figure 1D~2B
Figure 3
AI summary
The invention is a method for detecting arterial or venous occlusion from backscattered photon measurements, the measurements being time-resolved. The measurements yield a temporal distribution, corresponding to the number of backscattered photons measured as a function of time. Different temporal intensities are determined from this temporal distribution, each temporal intensity corresponding to a depth within the sample. From these temporal intensities, the method enables the determination of arterial or venous occlusion. Figure 7B.