1. Articles from Roberto Reif

    1-16 of 16
    1. Platform to investigate aqueous outflow system structure and pressure-dependent motion using high-resolution spectral domain optical coherence tomography

      Platform to investigate aqueous outflow system structure and pressure-dependent motion using high-resolution spectral domain optical coherence tomography

      The aqueous outflow system (AOS) is responsible for maintaining normal intraocular pressure (IOP) in the eye. Structures of the AOS have an active role in regulating IOP in healthy eyes and these structures become abnormal in the eyes with glaucoma. We describe a newly developed system platform to obtain high-resolution images of the AOS structures. By incorporating spectral domain optical coherence tomography (SD-OCT), the platform allows us to systematically control, image, and quantitate the responses of AOS tissue to pressure with a millisecond resolution of pulsed flow. We use SD-OCT to image radial limbal segments from the surface of the ...

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    2. Motion artifact and background noise suppression on optical microangiography frames using a naïve Bayes mask

      Motion artifact and background noise suppression on optical microangiography frames using a naïve Bayes mask

      Optical coherence tomography (OCT) is a technique that allows for the three-dimensional (3D) imaging of small volumes of tissue (a few millimeters) with high resolution ( ∼ 10     μ m ). Optical microangiography (OMAG) is a method of processing OCT data, which allows for the extraction of the tissue vasculature with capillary resolution from the OCT images. Cross-sectional B-frame OMAG images present the location of the patent blood vessels; however, the signal-to-noise-ratio of these images can be affected by several factors such as the quality of the OCT system and the tissue motion artifact. This background noise can appear in the en face projection ...

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    3. Improved microcirculation imaging of human skin in vivo using optical microangiography with a correlation mapping mask

      Improved microcirculation imaging of human skin in vivo using optical microangiography with a correlation mapping mask

      Optical microangiography based on optical coherence tomography (OCT) is prone to noise that arises from a static tissue region. Here, we propose a method that can significantly reduce this noise. The method is developed based on an approach that uses the magnitude information of OCT signals to produce tissue microangiograms, especially suitable for the case where a swept-source OCT system is deployed. By combined use of two existing OCT microangiography methods—ultrahigh-sensitive optical microangiography (UHS-OMAG) and correlation mapping OCT (cmOCT)—the final tissue microangiogram is generated by masking UHS-OMAG image using the binary representation of cmOCT image. We find that ...

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    4. Analysis of cross-sectional image filters for evaluating nonaveraged optical microangiography images

      Analysis of cross-sectional image filters for evaluating nonaveraged optical microangiography images

      Optical microangiography (OMAG) is a method that enables the noninvasive extraction of blood vessels within biological tissues. OMAG B-frames are prone to noise; therefore, techniques such as B-frame averaging have been applied to reduce these effects. A drawback of this method is that the total acquisition time and amount of data collected are increased; hence, the data are susceptible to motion artifacts and decorrelation. In this paper we propose using an image filter on a nonaveraged OMAG B-frame to reduce its noise. Consequently, B-frames comparable to the averaged OMAG B-frame are obtained, while reducing the total acquisition and processing time ...

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    5. Changes in cochlear blood flow in mice due to loud sound exposure measured with Doppler optical microangiography and laser Doppler flowmetry

      Changes in cochlear blood flow in mice due to loud sound exposure measured with Doppler optical microangiography and laser Doppler flowmetry

      In this work we determined the contributions of loud sound exposure (LSE) on cochlear blood flow (CoBF) in an in vivo anesthetized mouse model. A broadband noise system (20 kHz bandwidth) with an intensity of 119 dB SPL, was used for a period of one hour to produce a loud sound stimulus. Two techniques were used to study the changes in blood flow, a Doppler optical microangiography (DOMAG) system; which can measure the blood flow within individual cochlear vessels, and a laser Doppler flowmetry (LDF) system; which averages the blood flow within a volume (a hemisphere of ~1.5 mm ...

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    6. Wide velocity range Doppler optical microangiography using optimized step-scanning protocol with phase variance mask

      Wide velocity range Doppler optical microangiography using optimized step-scanning protocol with phase variance mask

      We propose a simple and optimized method for acquiring a wide velocity range of blood flow using Doppler optical microangiography. After characterizing the behavior of the scanner in the fast scan axis, a step-scanning protocol is developed by utilizing repeated A-scans at each step. Multiple velocity range images are obtained by the high-pass filtering and Doppler processing of complex signals between A-scans within each step with different time intervals. A phase variance mask is then employed to segment meaningful Doppler flow signals from noisy phase background. The technique is demonstrated by imaging in vivo mouse brain with skull left intact ...

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    7. Label-free imaging of blood vessel morphology with capillary resolution using optical microangiography

      Label-free imaging of blood vessel morphology with capillary resolution using optical microangiography
      Several tissue pathologies are correlated with changes in the blood vessel morphology and microcirculation that supplies the tissue. Optical coherence tomography (OCT) is an imaging technique that enables acquiring non-invasive three-dimensional images of biological structures with micrometer resolution. Optical microangiography (OMAG) is a method of processing OCT data which enables visualizing the three-dimensional blood vessel morphology within biological tissues. OMAG has high spatial resolution which allows visualizing single capillary vessels, and does not require the use of contrast agents. The intrinsic optical signals backscattered by the moving blood cells inside blood vessels are used as the contrast for which OMAG ...
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    8. Phase-sensitive optical coherence tomography characterization of pulse-induced trabecular meshwork displacement in ex vivo nonhuman primate eyes

      Phase-sensitive optical coherence tomography characterization of pulse-induced trabecular meshwork displacement in ex vivo nonhuman primate eyes

      Glaucoma is a blinding disease for which intraocular pressure (IOP) is the only treatable risk factor. The mean IOP is regulated through the aqueous outflow system, which contains the trabecular meshwork (TM). Considerable evidence indicates that trabecular tissue movement regulates the aqueous outflow and becomes abnormal during glaucoma; however, such motion has thus far escaped detection. The purpose of this study is to describe anovel use of a phase-sensitive optical coherence tomography (PhS-OCT) method to assess pulse-dependent TM movement. For this study, we used enucleated monkey eyes, each mounted in an anterior segment holder. A perfusion system was used to ...

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    9. Quantifying Optical Microangiography Images Obtained from a Spectral Domain Optical Coherence Tomography System

      Quantifying Optical Microangiography Images Obtained from a Spectral Domain Optical Coherence Tomography System

      The blood vessel morphology is known to correlate with several diseases, such as cancer, and is important for describing several tissue physiological processes, like angiogenesis. Therefore, a quantitative method for characterizing the angiography obtained from medical images would have several clinical applications. Optical microangiography (OMAG) is a method for obtaining three-dimensional images of blood vessels within a volume of tissue. In this study we propose to quantify OMAG images obtained with a spectral domain optical coherence tomography system. A technique for determining three measureable parameters (the fractal dimension, the vessel length fraction, and the vessel area density) is proposed and ...

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    10. Multifunctional nanoprobe to enhance the utility of optical based imaging techniques

      Multifunctional nanoprobe to enhance the utility of optical based imaging techniques

      Several imaging modalities such as optical coherence tomography, photothermal, photoacoustic and magnetic resonance imaging, are sensitive to different physical properties (i.e. scattering, absorption and magnetic) that can provide contrast within biological tissues. Usually exogenous agents are designed with specific properties to provide contrast for these imaging methods. In nano-biotechnology there is a need to combine several of these properties into a single contrast agent. This multifunctional contrast agent can then be used by various imaging techniques simultaneously or can be used to develop new imaging modalities. We reported and characterized a multifunctional nanoparticle, made from gold nanoshells, which exhibits ...

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    11. Depth profile absorber concentration reconstruction using photothermal optical coherence tomography

      Depth profile absorber concentration reconstruction using photothermal optical coherence tomography

      The concentration of photothermal (light-to-heat converters) compounds as a function of depth is determined in solid agar gel phantoms. The system contains an 808nm pump laser, which excites the photothermal compound, and a phase sensitive spectral domain optical coherence tomography system, which detects the changes in the optical pathlength of the sample induced by the temperature increase. The derivation of the model is described, and its parameters are empirically determined. The concentration of photothermal compounds are observed from double layer agar gel phantoms.

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    12. Depth profiling of photothermal compound concentrations using phase sensitive optical coherence tomography

      Depth profiling of photothermal compound concentrations using phase sensitive optical coherence tomography
      A model that describes the concentration of photothermal (light-to-heat converters) compounds as a function of depth in a turbid medium is developed. The system consists of a pump laser (808 nm modulated at 400 Hz), which heats a photothermal compound, and a phase sensitive spectral domain optical coherence tomography system, which detects the changes in the optical path length of the sample induced by the temperature increase. The model is theoretically derived and the coefficients are empirically determined using solid homogeneous gel phantoms. The model is validated by reconstructing the concentration of a photothermal compound in thick single and double ...
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    13. Determining elastic properties of skin by measuring surface waves from an impulse mechanical stimulus using phase-sensitive optical coherence tomography

      Determining elastic properties of skin by measuring surface waves from an impulse mechanical stimulus using phase-sensitive optical coherence tomography

      The mechanical properties of skin are important tissue parameters that are useful for understanding skin patho-physiology, which can aid disease diagnosis and treatment. This paper presents an innovative method that employs phase-sensitive spectral-domain optical coherence tomography (PhS-OCT) to characterize the biomechanical properties of skin by measuring surface waves induced by short impulses from a home-made shaker. Experiments are carried out on single and double-layer agar–agar phantoms, of different concentrations and thickness, and on in vivo human skin, at the forearm and the palm. For each experiment, the surface wave phase-velocity dispersion curves were calculated, from which the elasticity of ...

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    14. In vivo microstructural and microvascular imaging of the human corneo-scleral limbus using optical coherence tomography

      In vivo microstructural and microvascular imaging of the human corneo-scleral limbus using optical coherence tomography

      The corneo-scleral limbus contains several biological components, which are important constituents for understanding, diagnosing and managing several ocular pathologies, such as glaucoma and corneal abnormalities. An anterior segment optical coherence tomography (AS-OCT) system integrated with optical microangiography (OMAG) is used in this study to non-invasively visualize the three-dimensional microstructural and microvascular properties of the limbal region. Advantages include first the ability to correct optical distortion of microstructural images enabling quantification of relationships in the anterior chamber angle. Second, microvascular images enable the visualization of the microcirculation in the limbal area without the use of exogenous contrast agents. Third, by combining ...

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    15. A tomography system for imaging deep tissues

      A tomography system for imaging deep tissues
      An innovative fast optical coherence tomography system obtains high-resolution 3D images of deep retinal tissue structures and their vascularization. The number of people with major eye disease, such as glaucoma, age-related macular degeneration (ARMD), and diabetic retinopathy, is set to increase and to become a major public health problem.1 Several methods are used to diagnose and monitor the progression of such diseases. Optical coherence tomography (OCT) is a noninvasive method for obtaining 3D images of biological tissues. Such images contain information about the microstructures and microvasculature (small vessels and capillaries of the circulatory system) composition of the tissue that ...
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    16. Three-Dimensional High-Resolution Imaging of Gold Nanorods Uptake in Sentinel Lymph Nodes

      Three-Dimensional High-Resolution Imaging of Gold Nanorods Uptake in Sentinel Lymph Nodes
      n this paper, we demonstrate an application of a noninvasive imaging modality, photothermal optical coherence tomography (PT-OCT), for imaging gold nanorods (GNRs) uptake in sentinel lymph node (SLN) of mice in situ. This application enables us to obtain higher quality images of SLN structures due to the photothermal contrast properties of the GNRs. It is also demonstrated that GNRs accumulate differently within several SLN structures, and this uptake is time dependent. Finally, we determine the average concentration of GNRs within the whole SLN which is used to demonstrate uptake kinetics of the nanoparticles.
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    1-16 of 16
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    1. (16 articles) University of Washington
    2. (16 articles) Ruikang K. Wang
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    Three-Dimensional High-Resolution Imaging of Gold Nanorods Uptake in Sentinel Lymph Nodes A tomography system for imaging deep tissues In vivo microstructural and microvascular imaging of the human corneo-scleral limbus using optical coherence tomography Determining elastic properties of skin by measuring surface waves from an impulse mechanical stimulus using phase-sensitive optical coherence tomography Depth profiling of photothermal compound concentrations using phase sensitive optical coherence tomography Multifunctional nanoprobe to enhance the utility of optical based imaging techniques Quantifying Optical Microangiography Images Obtained from a Spectral Domain Optical Coherence Tomography System Phase-sensitive optical coherence tomography characterization of pulse-induced trabecular meshwork displacement in ex vivo nonhuman primate eyes Label-free imaging of blood vessel morphology with capillary resolution using optical microangiography Changes in cochlear blood flow in mice due to loud sound exposure measured with Doppler optical microangiography and laser Doppler flowmetry Non-invasive diagnosis of acquired lymphangiectases using optical coherence tomography Depth-resolved investigation of multiple optical properties and wrinkle morphology in eye-corner areas with multi-contrast Jones matrix optical coherence tomography