1. Articles from Alexander L. Matveyev

    1-5 of 5
    1. Analysis of low-scattering regions in optical coherence tomography: applications to neurography and lymphangiography

      Analysis of low-scattering regions in optical coherence tomography: applications to neurography and lymphangiography

      Analysis of semi-transparent low scattering biological structures in optical coherence tomography (OCT) has been actively pursued in the context of lymphatic imaging, with most approaches relying on the relative absence of signal as a means of detection. Here we present an alternate methodology based on spatial speckle statistics, utilizing the similarity of a distribution of given voxel intensities to the power distribution function of pure noise, to visualize the low-scattering biological structures of interest. In a human tumor xenograft murine model, we show that these correspond to lymphatic vessels and nerves; extensive histopathologic validation studies are reported to unequivocally establish ...

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    2. Analysis of low-scattering regions in optical coherence tomography

      Analysis of low-scattering regions in optical coherence tomography

      Analysis of semi-transparent low scattering biological structures in optical coherence tomography (OCT) has been actively pursued in the context of lymphatic imaging, with most approaches relying on the relative absence of signal as a means of detection. Here we present an alternate methodology based on spatial speckle statistics, utilizing the similarity of a distribution of given voxel intensities to the power distribution function of pure noise, to visualize the low-scattering biological structures of interest. In a human tumor xenograft murine model, we show that these correspond to lymphatic vessels and nerves; extensive histopathologic validation studies are reported to unequivocally establish ...

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    3. Optical coherence elastography for strain dynamics measurements in laser correction of cornea shape

      Optical coherence elastography for strain dynamics measurements in laser correction of cornea shape

      We describe the use of elastographic processing in phase-sensitive optical coherence tomography (OCT) for visualizing dynamics of strain and tissue-shape changes during laser-induced photothermal corneal reshaping, for applications in the emerging field of non-destructive and non-ablative (non-LASIK) laser vision correction. The proposed phase-processing approach based on fairly sparse data acquisition enabled rapid data processing and near-real-time visualization of dynamic strains. The approach avoids conventional phase unwrapping, yet allows for mapping strains even for significantly supra-wavelength inter-frame displacements of scatterers accompanied by multiple phase-wrapping. These developments bode well for real-time feedback systems for controlling the dynamics of corneal deformation with 10 ...

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    4. Optical coherence tomography for visualizing transient strains and measuring large deformations in laser-induced tissue reshaping

      Optical coherence tomography for visualizing transient strains and measuring large deformations in laser-induced tissue reshaping

      In the context of the development of emerging laser-assisted thermo-mechanical technologies for non-destructive reshaping of avascular collagenous tissues (cartilages and cornea), we report the first application of phase-sensitive optical coherence tomography (OCT) for visualizing transient strains involving supra-wavelength inter-frame displacements of scatterers. Usually phase-sensitive OCT assumes the visualization of sub-pixel and even sub-wavelength displacements of scatterers and fairly small strains (say, <10 −3 ), which conventionally implies the necessity of averaging for enhancing the effective signal-to-noise ratio and, correspondingly, the application of small-amplitude actuators producing periodic deformations. The original approach used here allows for direct estimation of elevated strains ~10 −2 ...

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    5. Robust strain mapping in optical coherence elastography by combining local phase-resolved measurements and cumulative displacement tracking

      Robust strain mapping in optical coherence elastography by combining local phase-resolved measurements and cumulative displacement tracking

      We report a novel hybrid method of robust strain mapping in compressional optical coherence elastography using combined phase measurements on sub-wavelength-scale and cumulative pixel-scale displacement tracking. This hybrid nature significantly extends the range of measurable displacements and strains in comparison with conventional direct phase-resolved measurements. As a result, the proposed strain-mapping method exhibits significantly increased robustness with respect to both additive noise and decorrelation noise produced by displacements and strains. The main advantages of the proposed approach are illustrated by numerical simulations. Experimental examples of obtained strain maps for phantoms and real biological tissues are also presented

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    1-5 of 5
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  2. Topics in the News

    1. (4 articles) University of Toronto
    2. (4 articles) I. Alex Vitkin
    3. (3 articles) Institute of Applied Physics
    4. (3 articles) Grigory V. Gelikonov
    5. (2 articles) Nizhny Novgorod State Medical Academy
    6. (2 articles) National Research Council Canada
    7. (2 articles) Costel Flueraru
    8. (1 articles) Natalia D. Gladkova
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