Study of the Changes of Gastric Wall Mucosa Optical Properties under the Impact of Aqueous Solutions of Haemoglobin and Glucose for Improving Conditions of the Laser Coagulation

The paper presents the results of ex vivostudies 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.