The current study is aimed at investigating the influence of radiotherapy on the optical properties of white matter in patients with brain gliomas using cross-polarization OCT. It was performed on ex vivo samples of peritumoral white matter collected from patients with primary surgery and patients who underwent a course of radiotherapy before surgery. The enhancement of scattering properties in case of use of radiotherapy was detected and the optical coefficients that most accurately reflect the relationship between the optical and morphological properties of white matter in both groups of patients were determined.
KEYWORDS: Optical coherence tomography, States of matter, Optical fibers, Data analysis, Brain, Tumors, Statistical analysis, Data processing, Tissue optics, Signal attenuation
Log-and-linear fit and depth-resolved approaches for OCT data processing were applied for white matter state evaluation. Both approaches are suitable for this purpose, however, the choice of necessary method depends on features of used OCT device.
Successful gastrointestinal surgery is based on the precise knowledge of the morphological, functional and metabolic state of the bowel wall at a specific time point. Current trends include the development of real-time, minimally invasive, label-free and rapid techniques for tissue assessment in combination with algorithms of data processing. The aim of the study was to evaluate the performance of trans-serous multimodal optical coherence tomography (MM OCT) and FLIM macro-imaging in detecting changes in microstructure, blood circulation and metabolism of intestinal wall caused by acute arterial ischemia in experiment. The study was supported by the Russian Science Foundation, project No. 19-75-10096.
Cross-polarization (CP) OCT is a so-called functional extension of OCT that seems to have benefits in visualization of myelin. During surgery it may be quite useful receiving information concerning myelination rate in white matter surrounding tumor mass. It this study it was shown that the quantification of peritumoral white matter using pseudocolor en-face OCT maps based on three optical coefficients (the rate of attenuation in the co- and cross-channel, and the interchannel attenuation difference) correlated well with histological data. Therefore, accurate quantitative CP OCT assessment of peritumoral white matter condition supports the developing the intraoperative implementation of this method.
The objective of the research was a multifaceted study of strangulated small intestine to reveal the optical, morphofunctional and biochemical signs of small bowel ischemia. The study was carried out in vivo using an artificially induced strangulation model of the small intestine (together with its mesentery and blood vessels) in 12 Wistar rats. Over a period of 120 minutes following the bowel ligation, changes in the density of the intramural vasculature and intestinal wall microstructure were detected using multimodal optical coherence tomography (MM OCT). Fluorescence lifetime changes of endogenous fluorophores were also measured using macro-FLIM of the strangulated loop and the adjacent segments of the intestine. At the end of the experiment, a morphometric study of the thickness of the layers and the prevalence of necrosis in the intestinal wall was carried out. A comprehensive analysis of the results of the OCT, FLIM and morphometry of the ischemic wall of the small intestine made it possible to determine the correlating morphofunctional and biochemical manifestations that are specific to this model of mesenteric blood flow disturbance.
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