Depth dependence of vascular fluorescence imaging

Area of Science:

• Neuroimaging
• Biophotonics
• Medical Physics

Background:

• In vivo surface imaging of fluorescently labeled vasculature is crucial for functional brain imaging.
• Current techniques like phosphorescence quenching and indocyanine green fluorescence rely on surface vascular measurements.
• The depth dependence of these fluorescence signals is not well-modeled.

Purpose of the Study:

• To investigate the depth dependence of fluorescence signals in in vivo vascular imaging.
• To develop a more accurate model for predicting fluorescence signal penetration depth.
• To evaluate illumination and detection strategies for enhancing surface vasculature sensitivity.

Main Methods:

• Utilized a three-dimensional Monte Carlo model.
• Integrated high-resolution vascular anatomy data.
• Simulated various illumination and detection configurations.

Main Results:

• A bulk-vascularization assumption is insufficient for modeling depth dependence.
• Microvasculature distribution, absorption differences, and wavelength-dependent absorption significantly impact signal penetration.
• Targeted illumination and small area detection improve surface vessel sensitivity.
• Increasing detector or illumination area enhances depth sensitivity.

Conclusions:

• Accurate modeling of fluorescence signal depth dependence necessitates considering microvasculature, optical properties, and illumination/detection strategies.
• Targeted illumination and optimized detection parameters are key for sensitive surface vasculature imaging.
• This work provides a more refined understanding for improving functional brain imaging techniques.