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A Potential Pitfall in the Interpretation of Microscope-Integrated Fluorescence Angiography: The Center-Periphery
Dieder Stolk1, Paul Bloemen2, Richard Martin van den Elzen2
1Department of Vascular Surgery, Noordwest Ziekenhuisgroep Alkmaar, 1815 JD Alkmaar, The Netherlands.
Medical Sciences (Basel, Switzerland)
|May 23, 2025
Summary
Microscope-integrated indocyanine green fluorescence angiography (ICG-FA) shows peripheral signal loss. Optimizing settings like working distance and magnification improves image homogeneity for better tissue perfusion assessment in free-flap surgery.
Area of Science:
- Surgical imaging technology
- Medical device evaluation
- Fluorescence angiography
Background:
- Indocyanine green fluorescence angiography (ICG-FA) visualizes tissue perfusion in real-time.
- Objective research on microscope-integrated ICG-FA is lacking.
- Understanding light distribution is crucial for accurate perfusion assessment.
Purpose of the Study:
- Evaluate fluorescence light distribution in microscope-integrated ICG-FA.
- Compare performance across different working distances and magnification factors.
- Provide recommendations for optimal microscope settings in clinical practice.
Main Methods:
- Utilized an ICG and Intralipid phantom for spatial fluorescence sensitivity evaluation.
- Tested two surgical microscopes at various working distances (WDs) and magnification factors (MFs).
- Quantified signal using custom Python software to analyze image homogeneity.
Main Results:
- A center-periphery effect with signal loss was observed, particularly at lower magnifications.
- Increasing magnification improved image homogeneity, with significant changes between the first and second MF.
- Optimal homogeneity for free-flap surgery was achieved at 30 cm WD and 3.5× MF.
- Manually widening the light beam diameter reduced the center-periphery effect.
Conclusions:
- Peripheral signal loss in microscope-integrated ICG-FA requires consideration during clinical interpretation.
- Recommended settings for reconstructive free-flap surgery include 30 cm WD, 3.5 MF, and an opened light beam diameter.
- These parameters ensure the most homogeneous images for reliable tissue perfusion assessment.
