1. Articles from melissa c. skala

    1-24 of 24
    1. Photothermal Optical Coherence Tomography of Anti-Angiogenic Treatment in the Mouse Retina Using Gold Nanorods as Contrast Agents

      Photothermal Optical Coherence Tomography of Anti-Angiogenic Treatment in the Mouse Retina Using Gold Nanorods as Contrast Agents

      Purpose : Optical coherence tomography (OCT) is widely used for ocular imaging in clinical and research settings. OCT natively provides structural information based on the reflectivity of the tissues it images. We demonstrate the utility of photothermal OCT (PTOCT) imaging of gold nanorods (GNR) in the mouse retina in vivo in the laser-induced choroidal neovascularization (LCNV) model to provide additional image contrast within the lesion. Methods : Wild-type C57BL/6 mice were imaged following the intravenous injection of ICAM2-targeted or untargeted GNR. Mice were also imaged following the injection of ICAM2-targeted GNR with or without the additional ocular delivery of a neutralizing ...

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    2. Redox imaging and optical coherence tomography of the respiratory ciliated epithelium

      Redox imaging and optical coherence tomography of the respiratory ciliated epithelium

      Optical coherence tomography (OCT) is an emerging technology for in vivo< airway and lung imaging. However, OCT lacks sensitivity to the metabolic changes caused by inflammation, which drives chronic respiratory diseases such as asthma and chronic obstructive pulmonary disorder. Redox imaging (RI) is a label-free technique that uses the autofluorescence of the metabolic coenzymes NAD(P)H and flavin adenine dinucleotide (FAD) to probe cellular metabolism and could provide complimentary information to OCT for airway and lung imaging. We demonstrate OCT and RI of respiratory ciliated epithelial function in ex vivo mouse tracheae. We applied RI to measure cellular metabolism ...

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    3. Imaging Melanin Distribution in the Zebrafish Retina Using Photothermal Optical Coherence Tomography

      Imaging Melanin Distribution in the Zebrafish Retina Using Photothermal Optical Coherence Tomography

      Purpose : To demonstrate and validate that photothermal optical coherence tomography (PT-OCT) can image melanin in the retinal pigment epithelium (RPE) and can observe light-driven melanosome translocation in the zebrafish retina. Methods : A commercial spectral domain OCT system was modified to perform both OCT and PT-OCT. Four adult tyrosinase-mosaic zebrafish with varying levels of melanin expression across their retinas were imaged, and the PT-OCT signal for pigmented and nonpigmented regions were compared. Wild-type dark-adapted ( n = 11 fish) and light-adapted ( n = 10 fish) zebrafish were also imaged with OCT and PT-OCT. Longitudinal reflectivity and absorption profiles were generated from B-scans to compare ...

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    4. Photothermal optical coherence tomography of indocyanine green in ex vivo eyes

      Photothermal optical coherence tomography of indocyanine green in ex vivo eyes

      Indocyanine green (ICG) is routinely used during surgery to stain the inner limiting membrane (ILM) and provide contrast on white light surgical microscopy. While translation of optical coherence tomography (OCT) for intraoperative imaging during ophthalmic surgery has enhanced visualization, the ILM remains difficult to distinguish from underlying retinal structures and ICG does not provide additional OCT contrast. We present photothermal OCT (PT-OCT) for high-specificity detection of ICG on retinal OCT images. We demonstrate our technique by performing an ILM peel in ex vivo eyes using low ICG concentrations and laser powers. These results establish the feasibility of PT-OCT for intraoperative ...

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    5. Optical coherence tomography and autofluorescence microscopy of respiratory ciliated epithelia

      Optical coherence tomography and autofluorescence microscopy of respiratory ciliated epithelia

      Efficient mucociliary clearance is necessary to protect the respiratory tract from infection. Mucociliary dysfunction is common in respiratory diseases including asthma, chronic obstructive pulmonary disease, and cystic fibrosis. Rescuing mucociliary clearance by stimulating the metabolism of respiratory ciliated epithelia could offer new treatments for respiratory diseases. However, the coupling between cellular metabolism and mechanical output in respiratory ciliated epithelia is poorly understood. We propose to study this coupling with autofluorescence microscopy and optical coherence tomography (OCT), to measure cellular metabolism and ciliary motility, respectively. The autofluorescent metabolic co-enzymes NAD(P)H and FAD provide non-invasive measures of metabolism through the ...

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    6. Quantifying optical properties with visible and near-infrared optical coherence tomography to visualize esophageal microwave ablation zones

      Quantifying optical properties with visible and near-infrared optical coherence tomography to visualize esophageal microwave ablation zones

      Microwave ablation is a minimally invasive image guided thermal therapy for cancer that can be adapted to endoscope use in the gastrointestinal (GI) tract. Microwave ablation in the GI tract requires precise control over the ablation zone that could be guided by high resolution imaging with quantitative contrast. Optical coherence tomography (OCT) provides ideal imaging resolution and allows for the quantification of tissue scattering properties to characterize ablated tissue. Visible and near-infrared OCT image analysis demonstrated increased scattering coefficients ( μ s ) in ablated versus normal tissues (Vis: 347.8%, NIR: 415.0%) and shows the potential for both wavelength ranges to ...

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    7. In vivo photothermal optical coherence tomography of endogenous and exogenous contrast agents in the eye

      In vivo photothermal optical coherence tomography of endogenous and exogenous contrast agents in the eye

      Optical coherence tomography (OCT) has become a standard-of-care in retinal imaging. OCT allows non-invasive imaging of the tissue structure but lacks specificity to contrast agents that could be used for in vivo molecular imaging. Photothermal OCT (PT-OCT) is a functional OCT-based technique that has been developed to detect absorbers in a sample. We demonstrate in vivo PT-OCT in the eye for the first time on both endogenous (melanin) and exogenous (gold nanorods) absorbers. Pigmented mice and albino mice (n = 6 eyes) were used to isolate the photothermal signal from the melanin in the retina. Pigmented mice with laser-induced choroidal neovascularization ...

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    8. Depth-resolved analytical model and correction algorithm for photothermal optical coherence tomography

      Depth-resolved analytical model and correction algorithm for photothermal optical coherence tomography

      Photothermal OCT (PT-OCT) is an emerging molecular imaging technique that occupies a spatial imaging regime between microscopy and whole body imaging. PT-OCT would benefit from a theoretical model to optimize imaging parameters and test image processing algorithms. We propose the first analytical PT-OCT model to replicate an experimental A-scan in homogeneous and layered samples. We also propose the PT-CLEAN algorithm to reduce phase-accumulation and shadowing, two artifacts found in PT-OCT images, and demonstrate it on phantoms and in vivo mouse tumors.

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    9. Photothermal optical lock-in optical coherence tomography for in vivo imaging

      Photothermal optical lock-in optical coherence tomography for in vivo imaging

      Photothermal OCT (PTOCT) provides high sensitivity to molecular targets in tissue, and occupies a spatial imaging regime that is attractive for small animal imaging. However, current implementations of PTOCT require extensive temporal sampling, resulting in slow frame rates and a large data burden that limit its in vivo utility. To address these limitations, we have implemented optical lock-in techniques for photothermal optical lock-in OCT (poli-OCT), and demonstrated the in vivo imaging capabilities of this approach. The poli-OCT signal was assessed in tissue-mimicking phantoms containing indocyanine green (ICG), an FDA approved small molecule that has not been previously imaged in vivo ...

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    10. Quantifying the vascular response to ischemia with speckle variance optical coherence tomography

      Quantifying the vascular response to ischemia with speckle variance optical coherence tomography

      Longitudinal monitoring techniques for preclinical models of vascular remodeling are critical to the development of new therapies for pathological conditions such as ischemia and cancer. In models of skeletal muscle ischemia in particular, there is a lack of quantitative, non-invasive and long term assessment of vessel morphology. Here, we have applied speckle variance optical coherence tomography (OCT) methods to quantitatively assess vascular remodeling and growth in a mouse model of peripheral arterial disease. This approach was validated on two different mouse strains known to have disparate rates and abilities of recovering following induction of hind limb ischemia. These results establish ...

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    11. In vivo imaging of nanoparticle delivery and tumor microvasculature with multimodal optical coherence tomography

      In vivo imaging of nanoparticle delivery and tumor microvasculature with multimodal optical coherence tomography

      Current imaging techniques capable of tracking nanoparticles in vivo supply either a large field of view or cellular resolution, but not both. Here, we demonstrate a multimodality imaging platform of optical coherence tomography (OCT) techniques for high resolution, wide field of view in vivo imaging of nanoparticles. This platform includes the first in vivo images of nanoparticle pharmacokinetics acquired with photothermal OCT (PTOCT), along with overlaying images of microvascular and tissue morphology. Gold nanorods (51.8 ± 8.1 nm by 15.2 ± 3.3 nm) were intravenously injected into mice, and their accumulation into mammary tumors was non-invasively imaged in ...

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    12. Longitudinal study of arteriogenesis with swept source optical coherence tomography and hyperspectral imaging

      Longitudinal study of arteriogenesis with swept source optical coherence tomography and hyperspectral imaging

      Peripheral arterial disease (PAD) is an atherosclerotic disease of the extremities that leads to high rates of myocardial infarction and stroke, increased mortality, and reduced quality of life. PAD is especially prevalent in diabetic patients, and is commonly modeled by hind limb ischemia in mice to study collateral vessel development and test novel therapies. Current techniques used to assess recovery cannot obtain quantitative, physiological data non-invasively. Here, we have applied hyperspectral imaging and swept source optical coherence tomography (OCT) to study longitudinal changes in blood oxygenation and vascular morphology, respectively, intravitally in the diabetic mouse hind limb ischemia model. Additionally ...

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    13. Feature Of The Week 10/06/13: Vanderbilt University Investigates Gold Nanorod Contrast Agents for Photothermal OCT

      Feature Of The Week 10/06/13: Vanderbilt University Investigates Gold Nanorod Contrast Agents for Photothermal OCT

      Photothermal OCT (PTOCT) is a functional extension of OCT that images oscillations in optical path length due to heat release from an absorber. These oscillations are induced by an amplitude-modulated photothermal laser that is incident on the sample. After photon absorption, heat is released into the microenvironment, which alters the local geometric path length and index of refraction. Phase-sensitive PTOCT is then used to map these index of refraction oscillations. We demonstrate that PTOCT is especially sensitive to near infrared absorbing gold nanorods, a promising contrast agent and drug carrier. The PTOCT signal is also characterized with respect to imaging ...

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    14. Quantitative Optical Imaging of Vascular Response in vivo in a Model of Peripheral Arterial Disease

      Quantitative Optical Imaging of Vascular Response in vivo in a Model of Peripheral Arterial Disease

      The mouse hind limb ischemia (HLI) model is well established for studying collateral vessel formation and testing therapies for peripheral arterial disease, but there is a lack of quantitative techniques for intravitally analyzing blood vessel structure and function. To address this need, non-invasive, quantitative optical imaging techniques were developed to assess the time-course of recovery in the mouse HLI model. Hyperspectral imaging and optical coherence tomography (OCT) were used to non-invasively image hemoglobin oxygen saturation and microvessel morphology plus blood flow, respectively, in the anesthetized mouse after induction of HLI. Hyperspectral imaging detected significant increases in hemoglobin saturation in the ...

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    15. Three-Dimensional Molecular Imaging with Photothermal Optical Coherence Tomography

      Three-Dimensional Molecular Imaging with Photothermal Optical Coherence Tomography

      Optical coherence tomography (OCT) is a three-dimensional optical imaging technique that has been successfully implemented in ophthalmology for imaging the human retina, and in studying animal models of disease. OCT can nondestructively visualize structural features in tissue at cellular-level resolution, and can exploit contrast agents to achieve molecular contrast. Photothermal OCT relies on the heat-producing capabilities of antibody-conjugated gold nanoparticles to achieve molecular contrast. A pump laser at the nanoparticle resonance wavelength is used to heat the nanoparticles in the sample, and the resulting changes in the index of refraction around the nanoparticles are detected by phase-sensitive OCT. Lock-in detection ...

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    16. Cross-Sectional Tracking of Particle Motion in Evaporating Drops: Flow Fields and Interfacial Accumulation

      Cross-Sectional Tracking of Particle Motion in Evaporating Drops: Flow Fields and Interfacial Accumulation

      The lack of an effective technique for three-dimensional flow visualization has limited the experimental exploration of the “coffee ring effect” to the two dimensional, top-down viewpoint. In this report, high-speed, cross-sectional imaging of the flow fields was obtained by using optical coherence tomography to track particle motion in an evaporating colloidal water drop. This approach enables z-dimensional mapping of primary and secondary flow fields and changes in these fields over time. These sectional images show that 1μm diameter polystyrene particles have a highly non-uniform vertical distribution with particles accumulating at both the air-water interface and water-glass interface during drop ...

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    17. Optical coherence tomography and hyperspectral imaging of vascular recovery in a model of peripheral arterial disease

      Optical coherence tomography and hyperspectral imaging of vascular recovery in a model of peripheral arterial disease

      Peripheral arterial disease (PAD) leads to an increased risk of myocardial infarction and stroke, increased mortality, and reduced quality of life. The mouse hind limb ischemia (HLI) model is the most commonly used system for studying the mechanisms of collateral vessel formation and for testing new PAD therapies, but there is a lack of techniques for acquiring physiologically-relevant, quantitative data intravitally in this model. In this work, non-invasive, quantitative optical imaging techniques were applied to the mouse HLI model over a time course. Optical coherence tomography (OCT) imaged changes in blood flow (Doppler OCT) and microvessel morphology (speckle variance OCT ...

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    18. In vivo imaging of gold nanorod contrast agents using photothermal optical coherence tomography

      In vivo imaging of gold nanorod contrast agents using photothermal optical coherence tomography

      Photothermal optical coherence tomography (PT-OCT) has the potential to increase the molecular specificity of OCT for in vivo pre-clinical studies of cancer, in order to better understand drug uptake and treatment response. However, the use of PT-OCT to image contrast agents in vivo has yet to be demonstrated. Here, we characterize PT-OCT imaging of gold nanorod (GNR) contrast agents, and we further apply these techniques for in vivo imaging. The PT-OCT signal was characterized and compared to a numerical model of the bio-heat equation with respect to varying photothermal chop frequency, photothermal laser power, OCT image reflectivity, and concentration of ...

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    19. Dual-modality photothermal optical coherence tomography and magnetic-resonance imaging of carbon nanotubes

      Dual-modality photothermal optical coherence tomography and magnetic-resonance imaging of carbon nanotubes

      We demonstrate polyethylene-glycol-coated single-walled carbon nanotubes (CNTs) as contrast agents for both photothermal optical coherence tomography (OCT) and magnetic-resonance imaging (MRI). Photothermal OCT was accomplished with a spectral domain OCT system with an amplitude-modulated 750 nm pump beam using 10 mW of power, and T2 MRI was achieved with a 4.7 T animal system. Photothermal OCT and T2 MRI achieved sensitivities of nanomolar concentrations to CNTs dispersed in amine-terminated polyethylene glycol, thus establishing the potential for dual-modality molecular imaging with CNTs.

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    20. Longitudinal optical imaging of tumor metabolism and hemodynamics

      Longitudinal optical imaging of tumor metabolism and hemodynamics
      An important feature of tumor hypoxia is its temporal instability, or “cycling hypoxia.” The primary consequence of cycling hypoxia is increased tumor aggressiveness and treatment resistance beyond that of chronic hypoxia. Longitudinal imaging of tumor metabolic demand, hemoglobin oxygen saturation, and blood flow would provide valuable insight into the mechanisms and distribution of cycling hypoxia in tumors. Fluorescence imaging of metabolic demand via the optical redox ratio (fluorescence intensity of FAD/NADH), absorption microscopy of hemoglobin oxygen saturation, and Doppler optical coherence tomography of vessel morphology and blood flow are combined to noninvasively monitor changes in oxygen supply and demand ...
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    21. Photothermal optical coherence tomography of epidermal growth factor receptor in live cells using immunotargeted gold nanospheres

      Molecular imaging is a powerful tool for investigating disease processes and potential therapies in both in vivo and in vitro systems. However, high resolution molecular imaging has been limited to relatively shallow penetration depths that can be accessed with microscopy. Optical coherence tomograp ... [Proc. SPIE 7168, 71680S (2009)] published Thu Feb 19, 2009.
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    22. Combined hyperspectral and spectral domain optical coherence tomography microscope for non-invasive hemodynamic imaging

      Melissa C. Skala, Hansford Hendargo, Andrew Fontanella et al. We have combined hyperspectral imaging with spectral domain optical coherence tomography (SDOCT) to non-invasively image changes in hemoglobin saturation, blood flow, microvessel morphology and sheer rate on the vessel wall with tumor growth. Changes in these hemodynamic variables were measured over ... [Proc. SPIE 7174, 71740I (2009)] published Thu Feb 12, 2009.
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    23. Combined hyperspectral and spectral domain optical coherence tomography microscope for noninvasive hemodynamic imaging

      Combined hyperspectral and spectral domain optical coherence tomography microscope for noninvasive hemodynamic imaging
      We have combined hyperspectral imaging with spectral domain optical coherence tomography (SDOCT) to noninvasively image changes in hemoglobin saturation, blood flow, microvessel morphology, and sheer rate on the vessel wall with tumor growth. Changes in these hemodynamic variables were measured over 24 h in dorsal skin fold window chamber tumors. There was a strong correlation between volumetric flow and hemoglobin saturation (ρ=0.89, p=9×10−6, N=15) and a moderate correlation between shear rate on the vessel wall and hemoglobin saturation (ρ=0.56, p=0.03, N=15).
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    24. Photothermal Optical Coherence Tomography of Epidermal Growth Factor Receptor in Live Cells Using Immunotargeted Gold Nanospheres

      Photothermal Optical Coherence Tomography of Epidermal Growth Factor Receptor in Live Cells Using Immunotargeted Gold Nanospheres
      Molecular imaging is a powerful tool for investigating disease processes and potential therapies in both in vivo and in vitro systems. However, high resolution molecular imaging has been limited to relatively shallow penetration depths that can be accessed with microscopy. Optical coherence tomography (OCT) is an optical analogue to ultrasound with relatively good penetration depth (1−2 mm) and resolution (~1−10 μm). We have developed and characterized photothermal OCT as a molecular contrast mechanism that allows for high resolution molecular imaging at deeper penetration depths than microscopy. Our photothermal system consists of an amplitude-modulated heating beam that spatially overlaps ...
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    1-24 of 24
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    1. (23 articles) Melissa C. Skala
    2. (20 articles) Vanderbilt University
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    Photothermal Optical Coherence Tomography of Epidermal Growth Factor Receptor in Live Cells Using Immunotargeted Gold Nanospheres Combined hyperspectral and spectral domain optical coherence tomography microscope for noninvasive hemodynamic imaging Longitudinal optical imaging of tumor metabolism and hemodynamics Dual-modality photothermal optical coherence tomography and magnetic-resonance imaging of carbon nanotubes Optical coherence tomography and hyperspectral imaging of vascular recovery in a model of peripheral arterial disease Cross-Sectional Tracking of Particle Motion in Evaporating Drops: Flow Fields and Interfacial Accumulation Feature Of The Week 10/06/13: Vanderbilt University Investigates Gold Nanorod Contrast Agents for Photothermal OCT In vivo imaging of nanoparticle delivery and tumor microvasculature with multimodal optical coherence tomography 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