1. Articles from bioRxiv.org

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  2. 1-19 of 19
    1. Full-field optical coherence tomography for the diagnosis of giant cell arteritis

      Full-field optical coherence tomography for the diagnosis of giant cell arteritis

      Histopathological examination of temporal artery biopsy (TAB) remains the gold standard for the diagnosis of giant cell arteritis (GCA) but is associated with essential limitations that emphasize the need for an upgraded pathological process. This study pioneered the use of full-field optical coherence tomography (FF-OCT) for rapid and automated on-site pathological diagnosis of GCA. Sixteen TABs (12 negative and 4 positive for GCA) were selected according to major histopathological criteria of GCA following hematoxylin-eosin-saffron-staining for subsequent acquisition with FF-OCT to compare structural modifications of the artery cell wall and thickness of each tunica. Gabor filtering of FF-OCT images was then ...

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    2. Visible light optical coherence tomography angiography (vis-OCTA)

      Visible light optical coherence tomography angiography (vis-OCTA)

      We report herein the first visible light optical coherence tomography angiography (vis-OCTA) for human retinal imaging. Compared to the existing vis-OCT systems, we devised a spectrometer with a narrower bandwidth to increase the spectral power density for OCTA imaging, while retaining the major spectral contrast in the blood. We achieved a 100 kHz A-line rate, the fastest acquisition speed reported so far for human retinal vis-OCT. We rigorously optimized the imaging protocol such that a single acquisition takes <6 seconds with a field of view (FOV) of 3x7.8 mm2. The angiography enables accurate localization of microvasculature down to the ...

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    3. In vivo characterization of chick embryo mesoderm by optical coherence tomography assisted microindentation

      In vivo characterization of chick embryo mesoderm by optical coherence tomography assisted microindentation

      Embryos are growing organisms with highly heterogeneous properties in space and time. Understanding the mechanical properties is a crucial prerequisite for the investigation of morphogenesis. During the last ten years, new techniques have been developed to evaluate the mechanical properties of biological tissues in vivo . To address this need, we employed a new instrument that, via the combination of micro-indentation with Optical Coherence Tomography (OCT), allows us to determine both, the spatial distribution of mechanical properties of chick embryos and the structural changes in real-time provided by OCT. We report here the stiffness measurements on live chicken mesoderm during somite ...

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    4. Long-term in vivo Monitoring of Gliotic Sheathing of Ultrathin Entropic Coated Brain Microprobes with Fiber-based Optical Coherence Tomography

      Long-term in vivo Monitoring of Gliotic Sheathing of Ultrathin Entropic Coated Brain Microprobes with Fiber-based Optical Coherence Tomography

      Microfabricated neuroprosthetic devices have made possible important observations on neuron activity; however, long-term high-fidelity recording performance of these devices has yet to be realized. Tissue-device interactions appear to be a primary source of lost recording performance. The current state of the art for visualizing the tissue response surrounding brain implants in animals is Immunohistochemistry + Confocal Microscopy, which is mainly performed after sacrificing the animal. Monitoring the tissue response as it develops could reveal important features of the response which may inform improvements in electrode design. Optical Coherence Tomography (OCT), an imaging technique commonly used in ophthalmology, has already been adapted ...

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    5. The influence of insulin therapy on measurements of optical coherence tomography parameters in diabetic patients without retinopathy

      The influence of insulin therapy on measurements of optical coherence tomography parameters in diabetic patients without retinopathy

      Purpose To determine whether there was a change in the fundus of the eye in diabetic patients without retinopathy after insulin therapy. Methods The diabetic patients without retinopathy were included in this study. A swept-source optical coherence tomography/angiography (SS-OCT/A) was used to obtain the measurements of macular retinal nerve fibre layer (mRNFL) thickness, ganglion cell-inner plexiform layer (GC-IPL) thickness, retinal thickness (RT), macular choroidal thickness (MCT), peripapillary retinal nerve fibre layer (pRNFL) thickness, peripapillary choroidal thickness (PCT), and perfused vascular density (PVD). Univariable and multivariable regression analyses were performed to explore the influence of insulin use on measurements ...

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    6. Accuracy of a deep convolutional neural network in the detection of myopic macular diseases using swept-source optical coherence tomography

      Accuracy of a deep convolutional neural network in the detection of myopic macular diseases using swept-source optical coherence tomography

      This study examined and compared outcomes of deep learning (DL) in identifying swept-source optical coherence tomography (OCT) images without myopic macular lesions [i.e., no high myopia (nHM) vs. high myopia (HM)], and OCT images with myopic macular lesions [e.g., myopic choroidal neovascularization (mCNV) and retinoschisis (RS)]. A total of 796 SS-OCT images were included in the study as follows and analyzed by k-fold cross-validation (k = 5) using DL's renowned model, Visual Geometry Group-16: nHM, 107 images; HM, 456 images; mCNV, 122 images; and RS, 111 images (n = 796). The binary classification of OCT images with or without ...

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      Mentions: Yasushi Ikuno
    7. A Spectral De-mixing Model for Triplex In Vivo Imaging of Optical Coherence Tomography Contrast Agents

      A Spectral De-mixing Model for Triplex In Vivo Imaging of Optical Coherence Tomography Contrast Agents

      The ability to detect multiple contrast agents simultaneously would greatly enhance Optical Coherence Tomography (OCT) images, providing nuanced biological context to physiological structures. However, previous OCT contrast agent work has been limited to scenarios where only a single contrast agent could be robustly detected within each voxel. We present a novel spectroscopic technique for de-mixing the spectral signal from multiple OCT contrast agents within a single voxel. We validate our technique in vitro and also demonstrate in vivo imaging of three spectrally distinct gold nanobipyramids, trafficking within the lymphatic system of a live mouse. This approach opens the door to ...

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    8. Gold Nanobipyramids as Second Near Infrared Optical Coherence Tomography Contrast Agents for Multiplexed In Vivo Lymphangiography

      Gold Nanobipyramids as Second Near Infrared Optical Coherence Tomography Contrast Agents for Multiplexed In Vivo Lymphangiography

      Developing contrast-enhanced optical coherence tomography (OCT) techniques is important for specific imaging of tissue lesions, molecular imaging, cell-tracking, and highly sensitive microangiography and lymphangiography. Multiplexed OCT imaging in the second near infrared (NIR-II) window is highly desirable since it allows simultaneous imaging and tracking of multiple biological events in high resolution with deeper tissue penetration in vivo. Here we demonstrate that gold nanobipyramids can function as OCT multiplexing contrast agents, allowing the visualization of two separate lymphatic flows occurring simultaneously from different drainage basins into the same lymph node in a live mouse. Contrast-enhanced multiplexed lymphangiography of a melanoma tumor ...

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    9. Exploring the association of collaterals and vessel density using optical coherence tomography angiography in retinal vein occlusions

      Exploring the association of collaterals and vessel density using optical coherence tomography angiography in retinal vein occlusions

      Purpose: Using optical coherence tomography angiography (OCTA) to characterize the types of collaterals in eyes with retinal vein occlusion (RVO) and further investigate their correlations with vessel densities of the superficial (SCP) and the deep capillary plexus (DCP). Methods: This cross-sectional study included 25 eyes of 23 patients with RVO. 3 x 3 mm2 OCTA macular scans were used to quantify the parafoveal vessel density (VD) of the SCP and DCP, and to classify the collaterals into one of four types (true superficial, true deep, superficial diving, and foveal collateral). Poisson regression model was used to identify significant associations between ...

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    10. Micro-indentation and optical coherence tomography for the mechanical characterization of embryos: Experimental setup and measurements on fixed chicken embryos.

      Micro-indentation and optical coherence tomography for the mechanical characterization of embryos: Experimental setup and measurements on fixed chicken embryos.

      The investigation of the mechanical properties of embryos is expected to provide valuable information on the phenomenology of morphogenesis. It is thus believed that, by mapping the viscoelastic features of an embryo at different stages of growth, it may be possible to shed light on the role of mechanics in embryonic development. To contribute to this field, we present a new instrument that can determine spatiotemporal distributions of mechanical properties of embryos over a wide area and with unprecedented accuracy. The method relies on combining ferrule-top micro-indentation, which provides local measurements of viscoelasticity, with Optical Coherence Tomography, which can reveal ...

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    11. Micro-indentation and optical coherence tomography for the mechanical characterization of embryos

      Micro-indentation and optical coherence tomography for the mechanical characterization of embryos

      The investigation of the mechanical properties of embryos is expected to provide valuable information on the phenomenology of morphogenesis. It is thus believed that, by mapping the viscoelastic features of an embryo at different stages of growth, it may be possible to shed light on the role of mechanics in embryonic development. To contribute to this field, we present a new instrument that can determine spatiotemporal distributions of mechanical properties of embryos over a wide area and with unprecedented accuracy. The method relies on combining ferrule-top micro-indentation, which provides local measurements of viscoelasticity, with Optical Coherence Tomography, which can reveal ...

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    12. Aperture Phase Modulation with Adaptive Optics: A Novel Approach for Speckle Reduction and Structure Extraction in Optical Coherence Tomography

      Aperture Phase Modulation with Adaptive Optics: A Novel Approach for Speckle Reduction and Structure Extraction in Optical Coherence Tomography

      Speckle is an inevitable consequence of the use of coherent light in optical coherence tomography (OCT), and often acts as noise that obscures micro-structures of biological tissue. We here present a novel method of suppressing speckle noise intrinsically compatible with adaptive optics (AO) in OCT system: by modulating the phase inside the imaging system pupil aperture with a segmented deformable mirror, thus producing minor perturbations in the point spread function (PSF) to create un-correlated speckle pattern between B-scans, and further averaging to wash out the speckle but maintain the structures. It is a well-controlled and universal method which can efficiently ...

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    13. Functional retinal imaging using adaptive optics swept-source OCT at 1.6MHz

      Functional retinal imaging using adaptive optics swept-source OCT at 1.6MHz

      bjective optical assessment of photoreceptor function may permit earlier diagnosis of retinal disease than current methods such as perimetry, electrophysiology, and clinical imaging. In this work, we describe an adaptive optics (AO) optical coherence tomography (OCT) system designed to measure functional responses of single cones to visible stimuli. The OCT subsystem consisted of a raster-scanning Fourier-domain mode-locked laser that acquires A-scans at 1.64MHz with a center wavelength of 1063nm, and an AO subsystem providing diffraction-limited imaging. Analysis of serial volumetric images revealed phase changes of cone photoreceptors consistent with outer segment elongation and proportional to stimulus intensity, as well ...

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    14. Spectral Contrast Optical Coherence Tomography Angiography Enables Single-Scan Vessel Imaging

      Spectral Contrast Optical Coherence Tomography Angiography Enables Single-Scan Vessel Imaging

      Optical Coherence Tomography angiography relies on motion for contrast and requires at least two data acquisitions per point-wise scanning location. We present a method termed Spectral Contrast Optical Coherence Tomography Angiography using visible light which relies on the spectral signatures of blood to obtain angiography from a single scan using endogenous contrast. We demonstrate the molecular sensitivity of this method enabling lymphatic, blood, and tissue discrimination.

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    15. Microscale light management and inherent optical properties of intact corals studied with optical coherence tomography

      Microscale light management and inherent optical properties of intact corals studied with optical coherence tomography

      Coral reefs are highly productive photosynthetic systems and coral optics studies suggest that such high efficiency is due to optimised light scattering by coral tissue and skeleton. Here, we characterise the inherent optical properties, i.e., the scattering coefficient, μ s , and the anisotropy of scattering, g , of 8 intact coral species using optical coherence tomography (OCT). Specifically, we describe light scattering by coral skeletons, coenoarc tissues, polyp tentacles and areas covered by fluorescent pigments (FP). Our results reveal that light scattering between coral species ranges from μ s = 3 mm -1 ( Stylophora pistillata ) to μ s = 25 mm -1 ( Echinopora lamelosa ). For ...

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    16. Generating perfusion maps from structural optical coherence tomography with artificial intelligence

      Generating perfusion maps from structural optical coherence tomography with artificial intelligence

      Despite significant advances in artificial intelligence (AI) for computer vision, its application in medical imaging has been limited by the burden and limits of expert-generated labels. We used images from optical coherence tomography angiography (OCTA), a relatively new imaging modality that measures perfusion of the retinal vasculature, to train an AI algorithm to generate vasculature maps from standard structural optical coherence tomography (OCT) images of the same retinae, both exceeding the ability and bypassing the need for expert labeling. Deep learning was able to infer perfusion of microvasculature from structural OCT images with similar fidelity to OCTA and significantly better ...

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    17. Optical Coherence Tomography Reveals Mechanobiologically Stable Self-Organizing Di-Fork Architecture of Mice Cutaneous Scars

      Optical Coherence Tomography Reveals Mechanobiologically Stable Self-Organizing Di-Fork Architecture of Mice Cutaneous Scars

      Scientific studies report crucial impacts of biomechanical effectors to modulate wound healing either by scarring or regeneration. Further, the biological decision to predominantly favor the former is still cryptic. Real-time visualization of biomechanical manifestations in situ in scarring is hence necessary. Endorsed by nanostructural testing, synthetic phantom analysis, and computational simulations, we found strong mechanobiological correlates for Swept Source Optical Coherence Tomography (SS-OCT) speckles in mice cutaneous repair (full-thickness) up to 10 months. The theoretical basis of the optomechanics to provide insights into scar form-factor and evolution is proposed. Optomechanical changes have been considered as the resultant of intrinsic (e ...

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    18. In vivo imaging of coral tissue and skeleton with optical coherence tomography

      In vivo imaging of coral tissue and skeleton with optical coherence tomography

      Optical coherence tomography (OCT) is a non-invasive three-dimensional imaging technique with micrometer resolution allowing microstructural characterization of tissues in vivo and in real time. We present the first application of OCT for in vivo imaging of tissue and skeleton structure of intact living corals spanning a variety of morphologies and tissue thickness. OCT visualized different coral tissue layers (e.g. endoderm vs ectoderm), special structures such as mesenterial filaments and skeletal cavities, as well as mucus release from living corals. We also developed a new approach for non-invasive imaging and quantification of chromatophores containing green fluorescent protein (GFP)-like host ...

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    1-19 of 19
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