Time-Resolved ICG Angiography for Perforator Localization
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Solution Overview
Problem
The localization and evaluation of perforator vessels for plastic and reconstructive surgery are time-consuming and subjective, with existing imaging methods like ICG fluorescence angiography facing challenges in distinguishing between candidate perforators due to rapid fluorescence accumulation and dissipation, and the need for objective standards to determine ICG-bound blood volume, duration, and movement.
Innovation Solution
A method using time-resolved image processing to analyze ICG fluorescence angiography images, computing metrics such as time-integrated fluorescence, rate of increase/wash-out, and elapsed time to peak fluorescence, enabling objective visualization and comparison of perforator locations through numerical arrays and color-coded images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If ICG fluorescence angiography is used to locate perforators, then localization capability is improved, but the process becomes time-consuming and subjective
Solution Approach 1:
The system performs preliminary image capture and processing to generate perfusion maps before surgical incision. By pre-processing the fluorescence images and calculating perfusion metrics in advance, the system reduces the time required during the actual surgical procedure, allowing surgeons to make informed decisions about perforator selection without time-consuming manual evaluation.
2Difficulty of detecting and measuring
If visual observation of ICG fluorescence is used, then localization is achieved, but objective discrimination among candidate perforators is difficult
Solution Approach 1:
The system introduces an intermediary processing layer that captures fluorescence images and automatically calculates perfusion metrics (such as time to peak, peak intensity, and area under the curve). This intermediary computational process transforms subjective visual observations into objective, quantifiable data, enabling precise discrimination among candidate perforators based on measured perfusion characteristics rather than subjective visual assessment.
3Adaptability or versatility
If multiple ICG injections are performed to evaluate different perforators, then comparison capability is improved, but background brightness accumulates and reduces discrimination
Solution Approach 1:
The system incorporates feedback mechanisms that monitor the fluorescence signal over time and adjust evaluation parameters accordingly. By analyzing the temporal dynamics of fluorescence accumulation and dissipation, the system can distinguish between genuine perforator perfusion differences and background accumulation effects. The feedback loop allows the system to compensate for residual ICG from previous injections by comparing relative changes in perfusion metrics rather than absolute intensity values.
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
Facilitates rapid and objective discrimination among candidate perforators, improving preoperative planning and reducing subjectivity in surgical decision-making by providing detailed, quantifiable data on tissue perfusion and perfusion dynamics.
Implementation Method 1
Fluorescence in ICG with an emission peak around 830 nm occurs as a result of excitation by radiation in the near-infrared spectral range. Excitation light with a wavelength around 800 nm can be produced, for example, by a diode laser, light emitting diodes (LED), or other conventional illumination sources
Implementation Method 2
ICG strongly binds to blood proteins and has previously been used for cardiac output measurement, hepatic function evaluation, and ophthalmic angiography
Data Source
AI summary
A method and an apparatus for preoperative identification of a perforator vessel for plastic and/or reconstructive surgery using ICG fluorescence angiography imaging are disclosed. Time-resolved image processing is used to highlight perforator locations and to enable visual discrimination among candidate perforators by various computed metrics. Based on these metrics, the surgeon is able to interactively locate and select perforator vessels suitable for plastic and reconstructive surgery.