1. Articles from Lidia B. Timofeeva

    1-6 of 6
    1. Optical coefficients as tools for increasing the optical coherence tomography contrast for normal brain visualization and glioblastoma detection

      Optical coefficients as tools for increasing the optical coherence tomography contrast for normal brain visualization and glioblastoma detection

      The methods used for digital processing of optical coherence tomography (OCT) and crosspolarization (CP) OCT images are focused on improving the contrast ratio of native structural OCT images. Such advances are particularly important for the intraoperative detection of glioma margins where the visual assessment of OCT images can be difficult and lead to errors. The aim of the study was to investigate the application of optical coefficients obtained from CP OCT data for the differentiation of glial tumorous tissue from a normal brain. Pseudocolor en-face OCT maps based on two optical coefficients (the commonly used rate of attenuation in the ...

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    2. Time-related ex vivo changes in the optical properties of normal brain tissues

      Time-related ex vivo changes in the optical properties of normal brain tissues

      The aim of the study was to observe time-related changes in the optical properties of normal brain tissues as measured using cross-polarization optical coherence tomography (CP OCT). 32 ex vivo tissue samples from 16 animals (rats) were monitored under different external conditions, over a period of 1 hour after excision, to measure time-related optical changes. It was found that the optical properties of white matter were quite stable over the time scales of the experiments, while the optical properties of the gray matter could change significantly. However, these changes could be minimized by using fresh sections from samples that had ...

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    3. Quantitative nontumorous and tumorous human brain tissue assessment using microstructural co- and cross-polarized optical coherence tomography

      Quantitative nontumorous and tumorous human brain tissue assessment using microstructural co- and cross-polarized optical coherence tomography

      Optical coherence tomography (OCT) is a promising method for detecting cancer margins during tumor resection. This study focused on differentiating tumorous from nontumorous tissues in human brain tissues using cross-polarization OCT (CP OCT). The study was performed on fresh ex vivo human brain tissues from 30 patients with high- and low-grade gliomas. Different tissue types that neurosurgeons should clearly distinguish during surgery, such as the cortex, white matter, necrosis and tumorous tissue, were separately analyzed. Based on volumetric CP OCT data, tumorous and normal brain tissue were differentiated using two optical coefficients — attenuation and forward cross-scattering. Compared with white matter ...

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    4. Quantitative evaluation of atherosclerotic plaques using cross-polarization optical coherence tomography, nonlinear, and atomic force microscopy

      Quantitative evaluation of atherosclerotic plaques using cross-polarization optical coherence tomography, nonlinear, and atomic force microscopy

      A combination of approaches to the image analysis in cross-polarization optical coherence tomography (CP OCT) and high-resolution imaging by nonlinear microscopy and atomic force microscopy (AFM) at the different stages of atherosclerotic plaque development is studied. This combination allowed us to qualitatively and quantitatively assess the disorganization of collagen in the atherosclerotic arterial tissue (reduction and increase of CP backscatter), at the fiber (change of the geometric distribution of fibers in the second-harmonic generation microscopy images) and fibrillar (violation of packing and different nature of a basket-weave network of fibrils in the AFM images) organization levels. The calculated CP channel-related ...

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    5. Characterization of atherosclerotic plaques by cross-polarization optical coherence tomography

      Characterization of atherosclerotic plaques by cross-polarization optical coherence tomography

      We combined cross-polarization optical coherence tomography (CP OCT) and non-linear microscopy based on second harmonic generation (SHG) and two-photon-excited fluorescence (2PEF) to assess collagen and elastin fibers in the development of the atherosclerotic plaque (AP). The study shows potential of CP OCT for the assessment of collagen and elastin fibers condition in atherosclerotic arteries. Specifically, the additional information afforded by CP OCT, related to birefringence and cross-scattering properties of arterial tissues, may improve the robustness and accuracy of assessment about the microstructure and composition of the plaque for different stages of atherosclerosis.

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    6. Multi-modal optical imaging characterization of atherosclerotic plaques

      Multi-modal optical imaging characterization of atherosclerotic plaques

      We combined cross-polarization optical coherence tomography (CP OCT) and non-linear microscopy based on second harmonic generation (SHG) and two-photon-excited fluorescence (2PEF) to assess collagen and elastin fibers and other vascular structures in the development of atherosclerosis, including identification of vulnerable plaques, which remains an important clinical problem and imaging application. CP OCT's ability to visualize tissue birefringence and cross-scattering adds new information about the microstructure and composition of the plaque. However its interpretation can be ambiguous, because backscattering contrast may have a similar appearance to the birefringence related fringes. Our results represent a step towards minimally invasive characterization and ...

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    1-6 of 6
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    1. (6 articles) Grigory V. Gelikonov
    2. (6 articles) Natalia D. Gladkova
    3. (6 articles) Elena B. Kiseleva
    4. (5 articles) Institute of Applied Physics
    5. (3 articles) Nizhny Novgorod State Medical Academy
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    Multi-modal optical imaging characterization of atherosclerotic plaques Characterization of atherosclerotic plaques by cross-polarization optical coherence tomography Quantitative evaluation of atherosclerotic plaques using cross-polarization optical coherence tomography, nonlinear, and atomic force microscopy Quantitative nontumorous and tumorous human brain tissue assessment using microstructural co- and cross-polarized optical coherence tomography Time-related ex vivo changes in the optical properties of normal brain tissues Optical coefficients as tools for increasing the optical coherence tomography contrast for normal brain visualization and glioblastoma detection Optical Coherence Tomography Angiography in Myopic Patients Quantification of retinal microvasculature and neurodegeneration changes in branch retinal vein occlusion after resolution of cystoid macular edema on optical coherence tomography angiography Machining head for a laser machining device Quantitative Comparison Of Microvascular Metrics On Three Optical Coherence Tomography Angiography Devices In Chorioretinal Disease Detection of and validation of shadows in intravascular images Automated intravascular plaque classification