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The optical properties of human stomach wall mucosa were measured in the wavelength range 400-2000 nm. The measurements were carried out using the commercially available spectrophotometer CARY-2415 with an integrating sphere. The combined method based on inverse adding-doubling and inverse Monte Carlo techniques was used to determine the absorption and scattering coefficients and anisotropy factor from the measurements.

The kinetics of collimated transmittance of the gastric mucosa under the action of an aqueous 40%-glucose solution was experimentally investigated. Based on the analysis of the transmittance kinetics, the value of the effective diffusion coefficient of glucose in the gastric mucosa was estimated and amounted to (1.59±0.96)×10-6 cm 2 /s. The permeability coefficient of the mucosa for glucose, calculated using the first Fick diffusion law, was estimated as (2.81±0.90)×10-5 cm/s. It was shown that the introduction of the glucose solution into the mucosa reduced the light scattering coefficient by approximately 5-10%. The increase in the depth of light penetration was from 5% to 15%, depending on the selected spectral range. The results can be used to develop new methods of diagnosis and treatment of stomach diseases.

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The paper presents the results of ex vivo studies of the possibility to control the absorption and scattering properties of the human gastric wall mucosa. For the first time we obtained the increase of the tissue absorption coefficient in the range 350-1250 nm by 2-4.5 times under the injection of haemoglobin solution with the concentration of 70 g/L into the mucosa. The observed increase of the absorbed energy fraction by nearly 65-90% was accompanied by almost 50-60% decrease of the penetration depth at the wavelengths of the sources widely used for laser ablation and coagulation of gastric mucosa paraplasms. Under the injection of 40% glucose solution into the mucosa, we observed the reduction of the absorption coefficient in the spectral region of water absorption bands approximately by 20% and the reduction of the transport scattering coefficient by nearly 24-27% in the spectral range 350-2500 nm. Increasing of the depth of laser radiation penetration in this case amounted to 15-17% in the range 800-1100 nm. The performed studies show the possibility in principle to control the optical parameters of the gastric wall tissues from the point of view of both varying the laser radiation penetration depth and regulating the tissue absorbance and, hence, the power of laser radiation, which, in turn, will allow more safety and less invasion in the course of laser therapeutic procedures.