We developed a compact, hand-held hyperspectral imaging system for 2D neural network-based visualization of skin chromophores and blood oxygenation. State-of-the-art microoptic multichannel matrix sensor combined with the tunable Fabry-Perot micro interferometer enables a portable diagnostic device sensitive to the changes of the oxygen saturation as well as the variations of blood volume fraction of human skin. Generalized object-oriented Monte Carlo model is used extensively for the training of an artificial neural network utilized for the hyperspectral image processing. In addition, the results are verified and validated via actual experiments with tissue phantoms and human skin in vivo. The proposed approach enables a tool combining both the speed of an artificial neural network processing and the accuracy and flexibility of advanced Monte Carlo modeling. Finally, the results of the feasibility studies and the experimental tests on biotissue phantoms and healthy volunteers are presented.

The goal of this study is a comparative analysis of the efficiency of the PDT protocols for CT26 tumor model treatment in Balb/c mice employing red and blue light with both topical and intravenous administration of chlorin-based photosensitizers (PSs). The considered protocols include the doses of 250 J/cm2 delivered at 660 nm, 200 J/cm2 delivered at 405 nm, and 250 J/cm2 delivered at both wavelengths with equal energy density contribution. Dual-wavelength fluorescence imaging was employed to estimate both photobleaching efficiency, typical photobleaching rates and the procedure impact depth, while optical coherence tomography with angiography modality (OCT-A) was employed to monitor the tumor vasculature response for up to 7 days after the procedure with subsequent histology inspection. Red light or dual-wavelength PDT regimes with intravenous PS injection were demonstrated to provide the most pronounced tumor response among all the considered cases. On the contrary, blue light regimes were demonstrated to be most efficient among topical application and irradiation only regimes. Tumor size dynamics for different groups is in good agreement with the tumor response predictions based on OCT-A taken in 24h after exposure and the results of histology analysis performed in 7 days after the exposure.

Modern trends in optical bioimaging require novel nanoproducts combining high image contrast with efficient treatment capabilities. Silicon nanoparticles are a wide class of nanoobjects with tunable optical properties, which has potential as contrasting agents for fluorescence imaging and optical coherence tomography. In this paper we report on developing a novel technique for fabricating silicon nanoparticles by means of picosecond laser ablation of porous silicon films and silicon nanowire arrays in water and ethanol. Structural and optical properties of these particles were studied using scanning electron and atomic force microscopy, Raman scattering, spectrophotometry, fluorescence, and optical coherence tomography measurements. The essential features of the fabricated silicon nanoparticles are sizes smaller than 100 nm and crystalline phase presence. Effective fluorescence and light scattering of the laser-ablated silicon nanoparticles in the visible and near infrared ranges opens new prospects of their employment as contrasting agents in biophotonics, which was confirmed by pilot experiments on optical imaging.

Analytical expression for the fluorescence response of a photosensitiser uniformly distributed in the superficial layer of biotissue is obtained in the diffusion approximation of radiative transfer theory, and the approach for estimating the fluorescent layer thickness based on dual-wavelength excitation of fluorescence is proposed. It is shown that the error in estimation of the fluorescent layer thickness employing the ratio of the fluorescence signals obtained at different excitation wavelengths does not exceed 30 % for the thickness range of 0.1 – 2 mm in the case of 30 %-variation of biotissue optical properties.

We report on the comparison of two approaches to the reconstruction of oxygen saturation (StO 2 ) within blood vessels from multispectral optoacoustic (OA) measurements. The spatially-resolving approach is based on determination of the optical absorption coefficient µ a from OA signal amplitudes, while the calibration-free approach is based on evaluation of the effective optical attenuation coefficient µ eff derived from the in-depth OA signal decay. Both approaches were verified in phantom experiments as well as in in vitro and in vivo measurements. The results demonstrate good agreement of µ a spectra derived from OA signal amplitudes with the published data indicating this approach to be preferable for the in vivo determination of StO 2 . Reconstruction of µ a spectra from the in vivo measured OA signal amplitudes in a rat yields StO 2 values of 0.57 ± 0.08 and 0.50 ± 0.07 for two veins of the thoracic spine. We demonstrate that for cost-effective measurements a dual-probing wavelength scheme can be employed instead of multiple wavelength probing. We found that the probing wavelength of 700 nm combined with a wavelength from the range of 850-1069 nm provides reconstructed StO 2 values close to the reference ones derived from multiple wavelength measurements in the entire range of 658-1069 nm.