1. Articles from Stanislav Emelianov

    1-10 of 10
    1. Hybrid intravascular imaging: recent advances, technical considerations, and current applications in the study of plaque pathophysiology

      Hybrid intravascular imaging: recent advances, technical considerations, and current applications in the study of plaque pathophysiology

      Cumulative evidence from histology-based studies demonstrate that the currently available intravascular imaging techniques have fundamental limitations that do not allow complete and detailed evaluation of plaque morphology and pathobiology, limiting the ability to accurately identify high-risk plaques. To overcome these drawbacks, new efforts are developing for data fusion methodologies and the design of hybrid, dual-probe catheters to enable accurate assessment of plaque characteristics, and reliable identification of high-risk lesions. Today several dual-probe catheters have been introduced including combined near infrared spectroscopy-intravascular ultrasound (NIRS-IVUS), that is already commercially available, IVUS-optical coherence tomography (OCT), the OCT-NIRS, the OCT-near infrared fluorescence (NIRF) molecular ...

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    2. Feature Of The Week 03/22/15: Assessing Age-Related Changes in the Biomechanical Properties of Rabbit Lens using a Co-Focused Ultrasound and Optical Coherence Elastography System

      Feature Of The Week 03/22/15: Assessing Age-Related Changes in the Biomechanical Properties of Rabbit Lens using a Co-Focused Ultrasound and Optical Coherence Elastography System

      Presbyopia, the progressive, age-related loss of accommodation power of the eye, is closely related to the viscoelastic properties of the crystalline lens and their alterations by aging. The increase in lens stiffness is generally believed to be responsible for the progressive loss of the ability of the lens to change shape, leading to presbyopia. Noninvasive measurements of mechanical properties of the lens in vivo will promote the comprehensive understandings of the mechanism of accommodation and presbyopia, as well as help in developing new approaches for presbyopia treatment. In this work, we have studied the age-related changes in the biomechanical properties ...

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    3. Assessing Age-Related Changes in the Biomechanical Properties of Rabbit Lens Using a Coaligned Ultrasound and Optical Coherence Elastography System

      Assessing Age-Related Changes in the Biomechanical Properties of Rabbit Lens Using a Coaligned Ultrasound and Optical Coherence Elastography System

      Purpose. To evaluate the capability of a novel, coaligned focused ultrasound and phase-sensitive optical coherence elastography (US-OCE) system to assess age-related changes in biomechanical properties of the crystalline lens in situ. Methods. Low-amplitude elastic deformations in young and mature rabbit lenses were measured by an US-OCE system consisting of a spectral-domain optical coherence tomography (OCT) system coaligned with a focused ultrasound system used to produce a transient force on the lens surface. Uniaxial compressional tests were used to validate the OCE data. Results. The OCE measurements showed that the maximum displacements of the young rabbit lenses were significantly larger than ...

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    4. Assessing age-related changes in the biomechanical properties of rabbit lens using a co-aligned ultrasound and optical coherence elastography system

      Assessing age-related changes in the biomechanical properties of rabbit lens using a co-aligned ultrasound and optical coherence elastography system

      Purpose: To evaluate the capability of a novel co-aligned focused ultrasound and phase-sensitive optical coherence elastography (US-OCE) system to assess age-related changes in biomechanical properties of the crystalline lens in situ. Methods: Low-amplitude elastic deformations in young and mature rabbit lenses were measured by the US-OCE system consisting of a spectral-domain optical coherence tomography (OCT) system co-aligned with focused ultrasound used to produce a transient force on the lens surface. Uniaxial compressional tests were used to confirm the OCE data. Results: The OCE measurements showed that the maximum displacements of the young rabbit lenses were significantly larger than those of ...

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    5. Spatial characterization of corneal biomechanical properties with optical coherence elastography after UV cross-linking

      Spatial characterization of corneal biomechanical properties with optical coherence elastography after UV cross-linking

      Corneal collagen cross-linking (CXL) is a clinical treatment for keratoconus that structurally reinforces degenerating ocular tissue, thereby limiting disease progression. Clinical outcomes would benefit from noninvasive methods to assess tissue material properties in affected individuals. Regional variations in tissue properties were quantified before and after CXL in rabbit eyes using optical coherence elastography (OCE) imaging. Low-amplitude (<1µm) elastic waves were generated using micro air-pulse stimulation and the resulting wave amplitude and speed were measured using phase-stabilized swept-source OCE. OCE imaging following CXL treatment demonstrates increased corneal stiffness through faster elastic wave propagation speeds and lower wave amplitudes.

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    6. Combining optical coherence tomography with acoustic radiation force for depth-dependent biomechanics of crystalline lens

      Combining optical coherence tomography with acoustic radiation force for depth-dependent biomechanics of crystalline lens

      Noninvasively probing the biomechanical properties of crystalline lens has been challenging due to its unique features such as location inside the eye and being optically and ultrasonically transparent. Here we introduce a method of relying on the spectral analysis of the lens surface response to a mechanical stimulation for the depthdependent assessment of lens biomechanical properties. In this method, acoustic radiation force (ARF) is used to remotely induce the deformation on the surface of the crystalline lens, and a phase-sensitive optical coherence tomography (PhS-OCT) system, co-focused with ARF, utilized to monitor the localized temporal response of ARFinduced deformations on the ...

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    7. Assessing the mechanical properties of tissue-mimicking phantoms at different depths as an approach to measure biomechanical gradient of crystalline lens

      Assessing the mechanical properties of tissue-mimicking phantoms at different depths as an approach to measure biomechanical gradient of crystalline lens

      We demonstrate the feasibility of using the dominant frequency of the sample surface response to a mechanical stimulation as an effective indicator for sensing the depthwise distribution of elastic properties in transparent layered phantom samples simulating the cortex and nucleus of the crystalline lens. Focused ultrasound waves are used to noninvasively interrogate the sample surface. A phase-sensitive optical coherence tomography system is utilized to capture the surface dynamics over time with nanometer scale sensitivity. Spectral analysis is performed on the sample surface response to ultrasound stimulation and the dominant frequency is calculated under particular loading parameters. Pilot experiments were conducted ...

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    8. Dynamic optical coherence tomography measurements of elastic wave propagation in tissue-mimicking phantoms and mouse cornea in vivo

      Dynamic optical coherence tomography measurements of elastic wave propagation in tissue-mimicking phantoms and mouse cornea in vivo

      We demonstrate the use of phase-stabilized swept-source optical coherence tomography to assess the propagation of low-amplitude (micron-level) waves induced by a focused air-pulse system in tissue-mimicking phantoms, a contact lens, a silicone eye model, and the mouse cornea in vivo. The results show that the wave velocity can be quantified from the analysis of wave propagation, thereby enabling the estimation of the sample elasticity using the model of surface wave propagation for the tissue-mimicking phantoms. This noninvasive, noncontact measurement technique involves low-force methods of tissue excitation that can be potentially used to assess the biomechanical properties of ocular and other ...

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    9. Dynamic OCT measurements of corneal biomechanical properties after UV cross-linking in the rabbit

      Dynamic OCT measurements of corneal biomechanical properties after UV cross-linking in the rabbit

      Structural properties of the cornea determine the shape and optical quality of the eye. Keratoconus, a structural degeneration of the cornea, is often treated with UV-induced collagen cross-linking to increase tissue resistance to further deformation and degeneration. Optimal treatments would be customized to the individual and consider preexisting structural properties as well as the effects induced by treatment and this requires the capability to noninvasively measure tissue properties. The purpose of this study is to use novel methods of optical elastography to study the effects of UV-induced corneal collagen cross-linking in the rabbit eye. Low-amplitude (<1μm) elastic flexural waves ...

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    10. Measurement of vibrations induced on the surface of crystalline eye lens using PhS-SDOCT

      Measurement of vibrations induced on the surface of crystalline eye lens using PhS-SDOCT

      Experimental assessment of stiffness of crystalline lens of the eye can help in understanding several ocular diseases. Studies have shown that stiffness of the eye lens increases with age that might contribute to loss of accommodation. The stiffness of the lens could be assessed by measuring mechanically induced surface waves propagating on its surface. Here we present preliminary results on phase sensitive spectral domain optical coherence tomography (PhS-SDOCT) measurements of the vibrations induced on surface of an eye lens. The system shows an axial resolution of 8 µm, phase sensitivity of 0.01 radians, imaging depth of up to 3 ...

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    1-10 of 10
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    Measurement of vibrations induced on the surface of crystalline eye lens using PhS-SDOCT Dynamic OCT measurements of corneal biomechanical properties after UV cross-linking in the rabbit Dynamic optical coherence tomography measurements of elastic wave propagation in tissue-mimicking phantoms and mouse cornea in vivo Assessing the mechanical properties of tissue-mimicking phantoms at different depths as an approach to measure biomechanical gradient of crystalline lens Combining optical coherence tomography with acoustic radiation force for depth-dependent biomechanics of crystalline lens Spatial characterization of corneal biomechanical properties with optical coherence elastography after UV cross-linking Assessing age-related changes in the biomechanical properties of rabbit lens using a co-aligned ultrasound and optical coherence elastography system Assessing Age-Related Changes in the Biomechanical Properties of Rabbit Lens Using a Coaligned Ultrasound and Optical Coherence Elastography System Feature Of The Week 03/22/15: Assessing Age-Related Changes in the Biomechanical Properties of Rabbit Lens using a Co-Focused Ultrasound and Optical Coherence Elastography System Hybrid intravascular imaging: recent advances, technical considerations, and current applications in the study of plaque pathophysiology Cascade Optical Coherence Tomography (C-OCT) for Surface Form Metrology of - ProQuest Comparison of Anterior Segment Measurements with a New Multifunctional Unit and Five Other Devices