Estimation of biological chromophores using diffuse optical spectroscopy: benefit of extending the UV-VIS wavelength range to include 1000 to 1600 nm

With an optical fiber probe, we acquired spectra from swine tissue between 500 and 1600 nm by combining a silicon and an InGaAs spectrometer. The concentrations of the biological chromophores were estimated by fitting a mathematical model derived from diffusion theory. The advantage of our technique relative to those presented in previous studies is that we extended the commonly-used wavelength ranges of 500 and 1000 nm to include the range of 1000 to 1600 nm, where additional water and lipid absorption features exist. Hence, a more accurate estimation of these two chromophores is expected when spectra are fitted between 500 and 1600 nm than between 500 and 1000 nm. When extending the UV-VIS wavelength range, the estimated total amount of chromophores approached 100% of the total as present in the probed volume. The confidence levels of the water and lipid related parameters increases by a factor of four.