Method for rapid multidiameter single-fiber reflectance and fluorescence spectroscopy through a fiber bundle

Area of Science:

• Biomedical Optics
• Spectroscopy
• Tissue Optics

Background:

• Accurate quantification of intrinsic fluorescence in biological tissues is crucial for various diagnostic applications.
• Previous methods for measuring tissue optical properties, such as multidiameter single-fiber reflectance (MDSFR) spectroscopy, faced limitations with pinholes and free-space optics.
• Correcting single-fiber fluorescence (SFF) spectra for optical properties is essential for reliable intrinsic fluorescence measurements.

Purpose of the Study:

• To develop and validate a clinical MDSFR/SFF spectroscopy system that overcomes previous limitations.
• To enable simultaneous measurement of tissue optical properties and intrinsic fluorescence.
• To provide a robust platform for quantitative fluorescence spectroscopy in biological tissues.

Main Methods:

• Construction and validation of a novel clinical MDSFR/SFF spectroscopy system.
• Acquisition of reflectance spectra at effective diameters of 200, 600, and 1000 μm during a single measurement.
• Acquisition of fluorescence spectra at an effective diameter of 1000 μm.
• Measurement of absolute absorption coefficient (μ(a)), reduced scattering coefficient (μ'(s')), phase function parameter (γ), and intrinsic fluorescence (Qμ(a,x)(f)).
• Validation using Intralipid and polystyrene sphere phantoms with and without Evans Blue.

Main Results:

• The developed system successfully acquires reflectance and fluorescence spectra at multiple effective diameters.
• The system accurately measures key optical properties: μ(a), μ'(s'), and γ.
• Validation studies confirmed the system's reliability with scattering and absorbing phantoms.
• Demonstrated combined MDSFR/SFF measurements for accurate quantification of intrinsic fluorescence (Qμ(a,x)(f)) in phantoms.

Conclusions:

• The new clinical MDSFR/SFF system provides a reliable method for quantifying biological tissue optical properties and intrinsic fluorescence.
• This system overcomes limitations of previous free-space optics and pinhole-based approaches.
• The ability to correct SFF spectra using MDSFR measurements enables accurate intrinsic fluorescence quantification, advancing biomedical optics applications.