1. Articles from Ruchit G. Shah

    1-7 of 7
    1. Use of Vibrational Optical Coherence Tomography to Image and Characterize a Squamous Cell Carcinoma

      Use of Vibrational Optical Coherence Tomography to Image and Characterize a Squamous Cell Carcinoma

      Previous literature reports suggest that tissue stiffness is a predictor of cancer and metastatic behavior. We have used optical coherence tomography and vibrational analysis (VOCT) to characterize normal skin, scar and a verrucous carcinoma, a squamous cell carcinoma subtype, non-invasively and nondestructively. The results suggest that epidermal thickening and increased keratin production occur in verrucous carcinoma and lead to increases in surface hills and valleys as well as subsequent increases in epidermal stiffness values. Increased stiffness of the epidermis is a result of increased keratin production while the stiffness of the dermis remains similar to that of normal skin, suggesting ...

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    2. Use of Vibrational Optical Coherence Tomography to Characterize Skin Lesions and a Congenital Nevus

      Use of Vibrational Optical Coherence Tomography to Characterize Skin Lesions and a Congenital Nevus

      We have used vibrational optical coherence tomography (VOCT) to image and measure the mechanical properties of normal skin and skin lesions. It is observed that in a congenital nevus and normal skin, the cellular epidermis is qualitatively not as bright as in skin lesions including basal cell carcinoma, actinic keratosis and a melanocytic nevus. Melanin and cytochrome c oxidase are reported to attenuate the reflection of near-infrared light at a wavelength of 810 nm and therefore may explain the reduced reflection of light in a congenital nevus and normal skin under conditions where cytochrome c oxidase levels would be expected ...

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    3. Comparative “virtual biopsies” of normal skin and skin lesions using vibrational optical coherence tomography

      Comparative “virtual biopsies” of normal skin and skin lesions using vibrational optical coherence tomography

      Background Increased tissue stiffness (also termed modulus) has been shown to be a characteristic of potential tumor metastasis. Measured values of the stiffness of tumors and cancer cells are reported in the literature to increase compared to neighboring normal tissues. Yet the relationship between the mechanical properties of cells and the extracellular matrix has yet to be correlated with the histopathology of cancerous lesions. Materials and Methods We have developed a technique to do virtual biopsies of skin lesions by combining images made using optical coherence tomography with stiffness measurements made simultaneously using vibrational analysis. The technique is termed vibrational ...

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      Mentions: OptoVibronex
    4. Non-Invasive and Non-Destructive Determination of Corneal and Scleral Biomechanics Using Vibrational Optical Coherence Tomography: Preliminary Observations

      Non-Invasive and Non-Destructive Determination of Corneal and Scleral Biomechanics Using Vibrational Optical Coherence Tomography: Preliminary Observations

      Experimental measurements made in this study on human and porcine eyes suggest that the resonant frequency for both cornea and sclera varies from 130 to 150 Hz and increases slightly with increasing intraocular pressure. The values of the moduli calculated using the experimental values of the thickness are close to 2 MPa. Similar values of the modulus for cornea and sclera suggest that there is very little stress concentration at the cornea-scleral junction and that any stress concentration that occurs probably resides at the scleral attachment laterally and posteriorly. These moduli are close to those measured in vivo on human ...

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    5. Biomechanical analysis of decellularized dermis and skin: Initial in vivo observations using OCT and vibrational analysis

      Biomechanical analysis of decellularized dermis and skin: Initial in vivo observations using OCT and vibrational analysis

      Measurement of the mechanical properties of skin in vivo has been complicated by the lack of methods that can accurately measure the viscoelastic properties without assuming values of Poisson's ratio and tissue density. In this paper, we present the results of preliminary studies comparing the mechanical properties of skin and scar tissue measured using a technique involving OCT and vibrational analysis. This technique has been reported to give values of the modulus that correlate with those obtained from tensile measurements made on decellularized dermis [1, 2]. The high correlation between moduli measured using vibrational studies and uniaxial tensile tests ...

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    6. Viscoelastic Behavior of Tissues and Implant Materials: Estimation of the Elastic Modulus and Viscous Contribution Using Optical Coherence Tomography and Vibrational Analysis

      Viscoelastic Behavior of Tissues and Implant Materials: Estimation of the Elastic Modulus and Viscous Contribution Using Optical Coherence Tomography and Vibrational Analysis

      Recently, we have reported use of Optical Coherence Tomography (OCT) and vibrational analysis to determine the resonant frequency of a material from which the moduli of decellularized dermis, pig skin, silicone rubber and chemically modified dermis were calculated. In this paper, we present data on viscoelastic mechanical properties of extracellular matrices and silicone rubber at frequencies above and below the resonant frequency. The results reported suggest that measurement of the modulus at the resonant frequency of a viscoelastic material provides a good estimate of the elastic modulus while measurements below and above the resonant frequency contain a larger viscous contribution ...

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    7. Analysis of Mechanical Behavior of Composite Tissues Using Vibrational Optical Coherence Tomography

      Analysis of Mechanical Behavior of Composite Tissues Using Vibrational Optical Coherence Tomography

      Extracellular matrices (ECMs) found in vertebrate tissues are fiber reinforced composite materials that prevent premature mechanical failure, store, transmit, and dissipate mechanical energy generated by the musculoskeletal system. We have developed a new method using optical cohesion tomography and vibrational analysis to non-destructively and non-invasively measure the mechanical properties of composite tissues and polymeric materials. In addition, this method can be used to measure the moduli of individual components of composite materials and perform “mechanical spectroscopy” on materials. In addition, we propose that measurement of the resonant frequency of a material minimizes the viscoelastic behavior of a composite material. This ...

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    1-7 of 7
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  2. Topics in the News

    1. (3 articles) National Institutes of Health
    2. (1 articles) OptoVibronex
    3. (1 articles) University of Pennsylvania
    4. (1 articles) National Eye Institute
    5. (1 articles) Columbia University
    6. (1 articles) University of Iowa
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    Analysis of Mechanical Behavior of Composite Tissues Using Vibrational Optical Coherence Tomography Viscoelastic Behavior of Tissues and Implant Materials: Estimation of the Elastic Modulus and Viscous Contribution Using Optical Coherence Tomography and Vibrational Analysis Biomechanical analysis of decellularized dermis and skin: Initial in vivo observations using OCT and vibrational analysis Non-Invasive and Non-Destructive Determination of Corneal and Scleral Biomechanics Using Vibrational Optical Coherence Tomography: Preliminary Observations Comparative “virtual biopsies” of normal skin and skin lesions using vibrational optical coherence tomography Use of Vibrational Optical Coherence Tomography to Characterize Skin Lesions and a Congenital Nevus Use of Vibrational Optical Coherence Tomography to Image and Characterize a Squamous Cell Carcinoma Vitreous Seeding in Retinocytoma: Importance of Optical Coherence Tomography Utility of Spectral-Domain Optical Coherence Tomography in Differentiating Papilledema From Pseudopapilledema: A Prospective Longitudinal Study Visualizing and quantifying cutaneous microvascular reactivity in humans using optical coherence tomography: Impaired dilator function in diabetes Optical Coherence Tomography of Outer Retinal Hyper-Reflectivity, Neovascularization and Pigment in Type 2 Macular Telangiectasia Early Detection of Incipient Retinal Pigment Epithelium Atrophy Overlying Drusen with Fundus Autofluorescence vs. Spectral Domain Optical Coherence Tomography