Fluorescence lifetime measurements in heterogeneous scattering medium

Area of Science:

• Biomedical Optics
• Fluorescence Spectroscopy
• Photonics

Background:

• Accurate fluorescence lifetime measurements are crucial for various applications, including biological imaging and diagnostics.
• Heterogeneous scattering media and complex geometries pose significant challenges for conventional analysis methods.
• Existing techniques often rely on solving diffusion or radiative transfer equations, which can be computationally intensive and limited in scope.

Purpose of the Study:

• To develop and validate a novel algorithm for determining fluorescence lifetime in heterogeneous multiple light scattering systems.
• To provide a method that bypasses the need to solve complex optical equations.
• To demonstrate the algorithm's applicability to diverse sample geometries and optical properties.

Main Methods:

• An algorithm was developed assuming constant optical properties across excitation and emission wavelengths.
• The method utilizes measurements of the temporal point-spread function of excitation light and fluorescence at two fluorophore concentrations.
• The approach is independent of medium heterogeneity and excitation-detection geometry.

Main Results:

• The algorithm successfully determines fluorescence lifetime in heterogeneous multiple light scattering systems.
• Validation was performed using indocyanine green fluorescence in phantom measurements.
• The method was further demonstrated through in vivo measurements, showcasing its practical utility.

Conclusions:

• The developed algorithm offers a robust and versatile method for fluorescence lifetime analysis in challenging optical environments.
• This approach simplifies fluorescence lifetime determination, making it more accessible for various research and clinical applications.
• The technique's independence from complex equation solving and geometric constraints broadens its potential impact in biomedical optics.