The predictive properties of methods aimed for estimating the water content in skin from the spectral diffuse reflection characteristics near the water absorption line in the near-IR spectral range are analysed. Numerical simulation data, experimental data on diffuse reflection from human skin phantoms, and data from the reference data set of human skin reflectance spectra are used to consider the possibility of gaining additional information about the water distribution in skin. The influence of variations in the scattering coefficient and oxyhaemoglobin concentration on the water content estimates is investigated.

The impaired balance of water distribution in the human organism accompanies numerous pathological states, and measuring water content in tissues is required for biomedical diagnostics. For instance, during heart failure,¹ physical examination using the “pitting scale” and weighing the patient remains the most useful approaches for assessing edematous syndrome; however, these methods are subjective and insufficient.² Assessment of water and lipids content in breast cancer tissues can provide important information about the characteristics of a tumor,³ as the high water content in a tumor indicates edema and increased cellularity.^4,5 Likewise, the measurement of hydration in different skin layers is interesting for dermatology and cosmetology:⁶ for instance, water content in the dermis is a marker of changes in the elastic properties of the skin,⁷ and hydration of the stratum corneum is indicative of its barrier function.⁸ Hence, the necessity of water content assessment stimulates the development of appropriate techniques, including those based on optical spectroscopy.⁹

Edema, i.e., fluid accumulation in the interstitial space, accompanies numerous pathological states of the human organism, including heart failure (HF), inflammatory response, and lymphedema. Nevertheless, techniques for quantitative assessment of the edema’s severity and dynamics are absent in clinical practice, and the analysis is mainly limited to physical examination. This fact stimulates the development of novel methods for fast and reliable diagnostics of fluid retention in tissues. In this work, we focused on the possibilities of two microscopic techniques, nailfold video capillaroscopy (NVC) and confocal laser scanning microscopy (CLSM), in the assessment of the short-term and long-term cutaneous edema. We showed that for the patients with HF, morphological parameters obtained by NVC—namely, the apical diameter of capillaries and the size of the perivascular zone—indicate long-term edema. On the other hand, for healthy volunteers, the application of two models of short-term edema, venous occlusion, and histamine treatment of the skin, did not reveal notable changes in the capillary parameters. However, a significant reduction of the NVC image sharpness was observed in this case, which was suggested to be due to water accumulation in the epidermis. To verify these findings, we made use of CLSM, which provides the skin structure with cellular resolution. It was observed that for the histamine-treated skin, the areas of the dermal papillae become hyporefractive, leading to the loss of contrast and the lower visibility of capillaries. Similar effect was observed for patients undergoing infusion therapy. Collectively, our results reveal the parameters can be used for pericapillary edema assessment using the NVC and CLSM, and paves the way for their application in a clinical set-up.

Objective. To develop the algorithm for selecting donor material from various facial zones and surgical approach for external nasal defect repair considering the theory of nasal subunits. Material and methods. The study included 15 healthy people without nasal defects. In these ones, we chose 4 points on the face corresponding to the main areas for donor material harvesting in nasal defect closure and 4 points on the nose corresponding to the main nasal subunits. We analyzed skin thickness and color and compared these parameters in different areas of the face and nose using diffuse reflectance spectroscopy. Thus, we determined the most optimal donor zone for each subunit. Twenty patients were operated on according to the developed algorithm. Results. We determined the most optimal donor zones for each subunit considering thickness and color of facial zones. We developed the algorithm for selecting donor material from various facial zones and surgical approach for external nasal defect repair considering the theory of nasal subunits.

Optical spectroscopy and microscopy techniques are widely used for basic studies of living systems. However, their application in clinical practice has two