Frequency domain broadband short-wave infrared spectroscopy for measurement of tissue optical properties from 685 to 1300 nm.

SIGNIFICANCE

Extending frequency domain diffuse optical spectroscopy (FD-DOS) into the short-wave infrared (SWIR) region has the potential to improve measurements of key biological tissue chromophores such as water and lipids, given their higher absorption in SWIR compared with near-infrared wavelengths. Few studies have explored FD-DOS in the SWIR range.

AIM

We present the first demonstration of a frequency domain broadband SWIR spectroscopy (FD-Bb-SWIRS) system to measure optical properties from 685 to 1300 nm.

APPROACH

A custom hybrid system was developed, combining discrete frequency domain measurements from 685 to 980 nm with broadband continuous wave measurements from 900 to 1300 nm. This setup provided absolute absorption ( ) spectra from 685 to 1300 nm. Validation was performed using mineral oil-based solid phantoms, deuterium oxide ( ) liquid phantoms, and desiccating porcine tissue.

RESULTS

The FD-Bb-SWIRS system was sensitive to changes in from varying concentrations of absorbers in solid and liquid phantoms. measurements of spectra indicated differences in tissue water content across different porcine tissue samples during baseline and desiccation.

CONCLUSIONS

FD-Bb-SWIRS is highly sensitive to in the 685 to 1300 nm range and enables precise quantification of water in biological tissues. It represents a significant step forward in advancing SWIR-based optical spectroscopy for clinical applications.