Liquid phantoms for near-infrared and diffuse correlation spectroscopies with tunable optical and dynamic properties.

Lorenzo Cortese,Alberto Dalla Mora,Davide Contini,An Nguyen-Dihn,Antonio Pifferi,Marco Pagliazzi,Giuseppe Lo Presti,Lorenzo Spinelli,Turgut Durduran,Paola Taroni,Sanathana Konugolu Venkata Sekar,Marta Zanoletti,Udo M Weigel,Bogdan Rosinski,Sixte De Fraguier

doi:10.1364/boe.9.002068

Abstract

We present the recipe and characterization for preparing liquid phantoms that are suitable for both near-infrared spectroscopy and diffuse correlation spectroscopy. The phantoms have well-defined and tunable optical and dynamic properties, and consist of a solution of water and glycerol with fat emulsion as the scattering element. The recipe takes into account the effect of bulk refractive index changes due to the addition of glycerol, which is commonly used to alter the sample viscosity.

Highlights

The combination of diffuse correlation spectroscopy (DCS) with near-infrared diffuse optical spectroscopy (NIRS) provides important and complementary information about the composition, structure and hemodynamics of the tissue under investigation [1]
By combining the information retrieved by NIRS and DCS, it is possible to enhance the sensitivity to the hemodynamic biomarkers in order to discriminate between healthy and different pathological conditions such as brain injury, malignancy and others
In literature we find several examples of liquid phantoms made of suspension of small fat droplets in water

Summary

Introduction

The combination of diffuse correlation spectroscopy (DCS) with near-infrared diffuse optical spectroscopy (NIRS) provides important and complementary information about the composition, structure and hemodynamics of the tissue under investigation [1]. Recently this combination has gained popularity as an emerging non-invasive biomedical modality. NIRS methods like time-resolved spectroscopy (TRS), frequency-domain or continuous wave optical spectroscopy allow the quantification of the wavelength dependent optical absorption and scattering coefficients of the probed tissue which, in turn, permit the estimation of the concentration of chromophores like oxy- and deoxy-haemoglobin, water, lipids, collagen, and give information on cell structure [2, 3]. The combination of NIRS and DCS increases the precision in retrieving the blood flow index by fixing parameters such as the reduced scattering coefficient and the absorption coefficient in DCS fitting procedure [1, 6]

Methods

Results

Conclusion