In this work time-resolved reflectance spectroscopy (TRS) measurements were performed in vivo on biological tissues (arm and forehead) over a broad spectral range (610- 1000 nm) and at different interfiber distances (2-4 cm), by a fully automated system based on mode-locked, continuously tunable laser sources and on time-correlated single photon counting for detection. Preliminary estimates of average tissue optical properties are obtained by interpreting the TRS curves at each wavelength with a homogeneous model for photon migration. The scattering coefficient decreases progressively upon increasing wavelength, while the absorption line shapes show the typical spectral features of the principal tissue components (hemoglobin, water, and lipids), with different weight depending on the tissue type and structure. The best fit of the absorption spectra with the spectra of the pure constituents and of the reduced scattering spectra to Mie theory provided information on the average percentage composition of the different tissues and on the average equivalent tissue structure, respectively. Moreover, TRS measurements at different interfiber distances allowed us to probe different tissue depths, showing the presence of a inhomogeneous structure with different average optical properties.
In vivo multi-distance multi-wavelength time-resolved reflectance spectroscopy of layered tissues
CUBEDDU, RINALDO;D'ANDREA, COSIMO;PIFFERI, ANTONIO GIOVANNI;TARONI, PAOLA;TORRICELLI, ALESSANDRO
2001-01-01
Abstract
In this work time-resolved reflectance spectroscopy (TRS) measurements were performed in vivo on biological tissues (arm and forehead) over a broad spectral range (610- 1000 nm) and at different interfiber distances (2-4 cm), by a fully automated system based on mode-locked, continuously tunable laser sources and on time-correlated single photon counting for detection. Preliminary estimates of average tissue optical properties are obtained by interpreting the TRS curves at each wavelength with a homogeneous model for photon migration. The scattering coefficient decreases progressively upon increasing wavelength, while the absorption line shapes show the typical spectral features of the principal tissue components (hemoglobin, water, and lipids), with different weight depending on the tissue type and structure. The best fit of the absorption spectra with the spectra of the pure constituents and of the reduced scattering spectra to Mie theory provided information on the average percentage composition of the different tissues and on the average equivalent tissue structure, respectively. Moreover, TRS measurements at different interfiber distances allowed us to probe different tissue depths, showing the presence of a inhomogeneous structure with different average optical properties.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
