1. Articles from Fernando Zvietcovich

    1-6 of 6
    1. Dynamic optical coherence elastography (Thesis)

      Dynamic optical coherence elastography (Thesis)

      Dynamic optical coherence elastography (OCE) is a functional imaging modality which leverages the propagation of mechanical waves in order to estimate the mechanical properties of tissues. It is very useful since it does not require (i) a priori knowledge of force/stress, (ii) mandatory direct contact between the mechanical loading source and the tissue under study, and (iii) large deformation of tissues. Therefore, dynamic OCE shows promise for non-contact, in situ, and in vivo mechanical characterization of tissues with applications in laboratory and clinical studies. To date, the impact of using transient/continuous temporal excitation produced by one/multiple loading ...

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    2. Reverberant 3D optical coherence elastography maps the elasticity of individual corneal layers

      Reverberant 3D optical coherence elastography maps the elasticity of individual corneal layers

      The elasticity mapping of individual layers in the cornea using non-destructive elastography techniques advances diagnosis and monitoring of ocular diseases and treatments in ophthalmology. However, transient Lamb waves, currently used in most dynamic optical coherence and ultrasound elastography techniques, diminish the translation of wave speed into shear/Young’s modulus. Here, we present reverberant 3D optical coherence elastography (Rev3D-OCE), a novel approach leveraging the physical properties of diffuse fields in detecting elasticity gradients not only in the lateral direction, but also along the depth axis of the cornea. A Monte Carlo analysis, finite element simulations, and experiments in layered phantoms ...

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    3. Viscoelastic characterization of dispersive media by inversion of a general wave propagation model in optical coherence elastography

      Viscoelastic characterization of dispersive media by inversion of a general wave propagation model in optical coherence elastography

      Determining the mechanical properties of tissue such as elasticity and viscosity is fundamental for better understanding and assessment of pathological and physiological processes. Dynamic optical coherence elastography uses shear/surface wave propagation to estimate frequency-dependent wave speed and Young’s modulus. However, for dispersive tissues, the displacement pulse is highly damped and distorted during propagation, diminishing the effectiveness of peak tracking approaches. The majority of methods used to determine mechanical properties assume a rheological model of tissue for the calculation of viscoelastic parameters. Further, plane wave propagation is sometimes assumed which contributes to estimation errors. To overcome these limitations, we ...

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    4. Comparative study of shear wave-based elastography techniques in optical coherence tomography

      Comparative study of shear wave-based elastography techniques in optical coherence tomography

      We compare five optical coherence elastography techniques able to estimate the shear speed of waves generated by one and two sources of excitation. The first two techniques make use of one piezoelectric actuator in order to produce a continuous shear wave propagation or a tone-burst propagation (TBP) of 400 Hz over a gelatin tissue-mimicking phantom. The remaining techniques utilize a second actuator located on the opposite side of the region of interest in order to create three types of interference patterns: crawling waves, swept crawling waves, and standing waves, depending on the selection of the frequency difference between the two ...

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    5. Experimental classification of surface waves in optical coherence elastography

      Experimental classification of surface waves in optical coherence elastography

      Various types of waves are produced when a harmonic force is applied to a semi-infinite half space elastic medium. In particular, surface waves are perturbations with transverse and longitudinal components of displacement that propagate in the boundary region at the surface of the elastic solid. Shear wave speed estimation is the standard for characterizing elastic properties of tissue in elastography; however, the penetration depth of Optical Coherence Tomography (OCT) is typically measured in millimeters constraining the measurement region of interest to be near the surface. Plane harmonic Rayleigh waves propagate in solid-vacuum interfaces while Scholte waves exist in solid-fluid interfaces ...

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    6. Crawling wave optical coherence elastography

      Crawling wave optical coherence elastography

      Elastography is a technique that measures and maps the local elastic property of biological tissues. Aiming for detection of micron-scale inclusions, various optical elastography, especially optical coherence elastography (OCE), techniques have been investigated over the past decade. The challenges of current optical elastography methods include the decrease in elastographic resolution as compared with its parent imaging resolution, the detection sensitivity and accuracy, and the cost of the overall system. Here we report for the first time, we believe, on an elastography technique—crawling wave optical coherence elastography (CRW-OCE)—which significantly lowers the requirements on the imaging speed and opens the ...

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    1-6 of 6
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  2. Topics in the News

    1. (6 articles) University of Rochester
    2. (5 articles) Jannick P. Rolland
    3. (3 articles) Panomsak Meemon
    4. (2 articles) Sun Yat-Sen University
    5. (2 articles) National Institutes of Health
    6. (1 articles) Dalhousie University
    7. (1 articles) National University of Singapore
    8. (1 articles) Singapore Eye Research Institute
    9. (1 articles) Duke University
    10. (1 articles) Sharon F. Freedman
    11. (1 articles) Jodhbir S. Mehta
    12. (1 articles) Cynthia A. Toth
    13. (1 articles) Joseph A. Izatt
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    Crawling wave optical coherence elastography Experimental classification of surface waves in optical coherence elastography Comparative study of shear wave-based elastography techniques in optical coherence tomography Viscoelastic characterization of dispersive media by inversion of a general wave propagation model in optical coherence elastography Reverberant 3D optical coherence elastography maps the elasticity of individual corneal layers Dynamic optical coherence elastography (Thesis) Spectrometer calibration with reduced dispersion for optical coherence tomography High‐Aspect‐Ratio Plasmonic Heterostructures for In Vivo Enhanced Optical Coherence Tomography Imaging in the Second Near‐Infrared Biological Window Influence of sleep quality on macula and retinal nerve fiber layer in caucasian healthy adolescents: A cross-sectional assessment with optical coherence tomography Comparison of measurements of anterior chamber angle via anterior segment optical coherence tomography and ultrasound biomicroscopy Optical coherence tomography angiography (OCTA) findings of microvascular and neural changes in primary pulmonary hypertension Optical coherence tomography vs fundus photography in detecting macular edema in subjects with type 2 diabetes (Thesis)