1. 1-24 of 306 1 2 3 4 ... 11 12 13 »
    1. Murine chronic lymph node window for longitudinal intravital lymph node imaging

      Murine chronic lymph node window for longitudinal intravital lymph node imaging

      Chronic imaging windows in mice have been developed to allow intravital microscopy of many different organs and have proven to be of paramount importance in advancing our knowledge of normal and disease processes. A model system that allows long-term intravital imaging of lymph nodes would facilitate the study of cell behavior in lymph nodes during the generation of immune responses in a variety of disease settings and during the formation of metastatic lesions in cancer-bearing mice. We describe a chronic lymph node window (CLNW) surgical preparation that allows intravital imaging of the inguinal lymph node in mice. The CLNW is ...

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    2. Miniature probe for mapping mechanical properties of vascular lesions using acoustic radiation force optical coherence elastography

      Miniature probe for mapping mechanical properties of vascular lesions using acoustic radiation force optical coherence elastography

      Cardiovascular diseases are the leading cause of fatalities in the United States. Atherosclerotic plaques are one of the primary complications that can lead to strokes and heart attacks if left untreated. It is essential to diagnose the disease early and distinguish vulnerable plaques from harmless ones. Many methods focus on the structural or molecular properties of plaques. Mechanical properties have been shown to change drastically when abnormalities develop in arterial tissue. We report the development of an acoustic radiation force optical coherence elastography (ARF-OCE) system that uses an integrated miniature ultrasound and optical coherence tomography (OCT) probe to map the ...

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    3. Optical coherence microscopy as a novel, non-invasive method for the 4D live imaging of early mammalian embryos

      Optical coherence microscopy as a novel, non-invasive method for the 4D live imaging of early mammalian embryos

      Imaging of living cells based on traditional fluorescence and confocal laser scanning microscopy has delivered an enormous amount of information critical for understanding biological processes in single cells. However, the requirement for a high numerical aperture and fluorescent markers still limits researchers’ ability to visualize the cellular architecture without causing short- and long-term photodamage. Optical coherence microscopy (OCM) is a promising alternative that circumvents the technical limitations of fluorescence imaging techniques and provides unique access to fundamental aspects of early embryonic development, without the requirement for sample pre-processing or labeling. In the present paper, we utilized the internal motion of ...

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    4. Postoperative change in lateral rectus muscle insertion measured by anterior segment optical coherence tomography

      Postoperative change in lateral rectus muscle insertion measured by anterior segment optical coherence tomography

      Aims The aims of this study were to investigate the longitudinal change in lateral rectus (LR) muscle insertion after recession surgery, and to evaluate a relationship between insertion distance and postoperative amount of deviation. Methods We recruited 31 patients who underwent primary LR recession surgery with normal anterior segment structures. An AS-OCT scan of the LR muscle was performed at every visit. Data on sex, age, degree of deviation (prism diopter), and spur-LR insertion distance using AS-OCT were collected at preoperatively and postoperative months 1, 3, and 6. Spur-LR insertion was defined as the shortest distance between the insertion of ...

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    5. Optical coherence tomography analysis of evolution of Bruch’s membrane features in angioid streaks

      Optical coherence tomography analysis of evolution of Bruch’s membrane features in angioid streaks

      Purpose To describe optical coherence tomography (OCT) features in the Bruch’s membrane (BM) of eyes with angioid streaks (AS) and evaluate their evolution over the follow-up. Patients and methods Patients with AS presenting between March 2016 and September 2016 at two tertiary referral centers were consecutively recruited in this study. Eligibility criteria included prior spectral domain (SD)-OCT images, taken at least 3 months before at the same referral center, with automated eye tracking and image alignment modules. Alterations of BM were described and compared to previous scans over the follow-up. Multimodal imaging was used to identify alteration of ...

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    6. Speckle-modulating optical coherence tomography in living mice and humans

      Speckle-modulating optical coherence tomography in living mice and humans

      Optical coherence tomography (OCT) is a powerful biomedical imaging technology that relies on the coherent detection of backscattered light to image tissue morphology in vivo . As a consequence, OCT is susceptible to coherent noise (speckle noise), which imposes significant limitations on its diagnostic capabilities. Here we show speckle-modulating OCT (SM-OCT), a method based purely on light manipulation that virtually eliminates speckle noise originating from a sample. SM-OCT accomplishes this by creating and averaging an unlimited number of scans with uncorrelated speckle patterns without compromising spatial resolution. Using SM-OCT, we reveal small structures in the tissues of living animals, such as ...

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    7. Atrophy of retinal inner layers is associated with poor vision after endophthalmitis: a spectral domain optical coherence tomography study

      Atrophy of retinal inner layers is associated with poor vision after endophthalmitis: a spectral domain optical coherence tomography study

      urpose To investigate the retinal structural changes in endophthalmitis and their association with visual outcome. Patients and methods Forty-five eyes of 45 patients diagnosed with endophthalmitis were included. Spectral domain optical coherence tomography (SD-OCT) was performed after inflammation was controlled. The relationship between SD-OCT features and best-corrected visual acuity (BCVA) at the last follow-up was analyzed. Results The structural changes included inner segment ellipsoid (ISe) disruption (49 % ), atrophy of retinal inner layers (24 % ), epimacular membrane (24 % ), and macular edema (24 % ). BCVA was worse in patients with ISe disruption (P = 0.005) and retinal inner layers' atrophy (P = 0.004) compared ...

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    8. Determinants of Quantitative Optical Coherence Tomography Angiography Metrics in Patients with Diabetes

      Determinants of Quantitative Optical Coherence Tomography Angiography Metrics in Patients with Diabetes

      Early microvascular damage in diabetes (e.g. capillary nonperfusion and ischemia) can now be assessed and quantified with optical coherence tomography-angiography (OCT-A). The morphology of vascular tissue is indeed affected by different factors; however, there is a paucity of data examining whether OCT-A metrics are influenced by ocular, systemic and demographic variables in subjects with diabetes. We conducted an observational cross-sectional study and included 434 eyes from 286 patients with diabetes. Foveal avascular zone (FAZ) area, FAZ circularity, total and parafoveal vessel density (VD), fractal dimension (FD), and vessel diameter index (VDI) from the superficial capillary plexus OCT-angiogram were measured ...

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    9. When pressure meets light: detecting the photoacoustic effect at the origin

      When pressure meets light: detecting the photoacoustic effect at the origin

      Modern optical microscopy1, including confocal microscopy, two-photon microscopy and optical coherence tomography (OCT), has revolutionized life sciences by providing detailed information of biological samples with cellular and subcellular resolutions, and has become an essential tool for biomedical research labs. However, optical microscopy typically has a limited penetration depth of ~1mm in biological tissue due to strong optical scattering23. Moreover, with respective contrast mechanisms, confocal and two-photon microscopy usually rely on fluorescent labeling of the samples and OCT still lacks sensitivity to many biological functions. In contrast, optical-resolution photoacoustic microscopy (OR-PAM) has emerged over the last decade ...

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      Mentions: Duke University
    10. Supervised learning and dimension reduction techniques for quantification of retinal fluid in optical coherence tomography images

      Supervised learning and dimension reduction techniques for quantification of retinal fluid in optical coherence tomography images

      Purpose The purpose of the present study is to develop fast automated quantification of retinal fluid in optical coherence tomography (OCT) image sets. Methods We developed an image analysis pipeline tailored towards OCT images that consists of five steps for binary retinal fluid segmentation. The method is based on feature extraction, pre-segmention, dimension reduction procedures, and supervised learning tools. Results Fluid identification using our pipeline was tested on two separate patient groups: one associated to neovascular age-related macular degeneration, the other showing diabetic macular edema. For training and evaluation purposes, retinal fluid was annotated manually in each cross-section by human ...

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    11. Robust and fast characterization of OCT-based optical attenuation using a novel frequency-domain algorithm for brain cancer detection

      Robust and fast characterization of OCT-based optical attenuation using a novel frequency-domain algorithm for brain cancer detection

      Cancer is known to alter the local optical properties of tissues. The detection of OCT-based optical attenuation provides a quantitative method to efficiently differentiate cancer from non-cancer tissues. In particular, the intraoperative use of quantitative OCT is able to provide a direct visual guidance in real time for accurate identification of cancer tissues, especially these without any obvious structural layers, such as brain cancer. However, current methods are suboptimal in providing high-speed and accurate OCT attenuation mapping for intraoperative brain cancer detection. In this paper, we report a novel frequency-domain (FD) algorithm to enable robust and fast characterization of optical ...

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    12. Elastic turbulence in entangled semi-dilute DNA solutions measured with optical coherence tomography velocimetry

      Elastic turbulence in entangled semi-dilute DNA solutions measured with optical coherence tomography velocimetry

      The flow instabilities of solutions of high molecular weight DNA in the entangled semi-dilute concentration regime were investigated using optical coherence tomography velocimetry, a technique that provides high spatial (probe volumes of 3.4 pL) and temporal resolution (sub μs) information on the flow behaviour of complex fluids in a rheometer. The velocity profiles of the opaque DNA solutions (high and low salt) were measured as a function of the distance across the gap of a parallel plate rheometer, and their evolution over time was measured. At lower DNA concentrations and low shear rates, the velocity fluctuations were well described ...

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    13. In Vivo Molecular Optical Coherence Tomography of Lymphatic Vessel Endothelial Hyaluronan Receptors

      In Vivo Molecular Optical Coherence Tomography of Lymphatic Vessel Endothelial Hyaluronan Receptors

      Optical Coherence Tomography (OCT) imaging of living subjects offers increased depth of penetration while maintaining high spatial resolution when compared to other optical microscopy techniques. However, since most protein biomarkers do not exhibit inherent contrast detectable by OCT, exogenous contrast agents must be employed for imaging specific cellular biomarkers of interest. While a number of OCT contrast agents have been previously studied, demonstrations of molecular targeting with such agents in live animals have been historically challenging and notably limited in success. Here we demonstrate for the first time that microbeads (µBs) can be used as contrast agents to target cellular ...

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    14. Optical Coherence Tomography Angiography to Estimate Retinal Blood Flow in Eyes with Retinitis Pigmentosa

      Optical Coherence Tomography Angiography to Estimate Retinal Blood Flow in Eyes with Retinitis Pigmentosa

      Ophthalmologists sometimes face difficulties in identifying the origin of visual acuity (VA) loss in a retinitis pigmentosa (RP) patient, particularly before cataract surgery: cataract or the retinal disease state. Therefore, it is important to identify the significant factors correlating with VA. Nowadays, retinal blood flow in superficial and deep layers can be estimated non-invasively using optical coherence tomography angiography (OCTA). We estimated blood flow per retinal layer by using OCTA; investigated the correlation between VA and other parameters including blood flow and retinal thickness; and identified the most associated factor with VA in patients with RP. OCTA images in 68 ...

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    15. Crowded optic nerve head evaluation with optical coherence tomography in anterior ischemic optic neuropathy

      Crowded optic nerve head evaluation with optical coherence tomography in anterior ischemic optic neuropathy

      Purpose To characterize the optic nerve head (ONH) structure in patients with non-arteritic anterior ischemic optic neuropathy (NAION) compared to healthy control subjects using spectral domain optical coherence tomography (SD-OCT) via the enhanced depth imaging method. Methods In this prospective, cross-sectional, comparative study, we assessed 66 eyes of 33 patients with unilateral NAION and 31 eyes of 31 healthy normal subjects in an academic institution. The peripapillary nerve fiber layer thickness, disc area, and quantitative parameters of the ONH structures, including the Bruch’s membrane opening (BMO) area, anterior laminar depth, and prelaminar thickness and depth were compared between the ...

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    16. The emergence of optical elastography in biomedicine

      The emergence of optical elastography in biomedicine

      Optical elastography, the use of optics to characterize and map the mechanical properties of biological tissue, involves measuring the deformation of tissue in response to a load. Such measurements may be used to form an image of a mechanical property, often elastic modulus, with the resulting mechanical contrast complementary to the more familiar optical contrast. Optical elastography is experiencing new impetus in response to developments in the closely related fields of cell mechanics and medical imaging, aided by advances in photonics technology, and through probing the microscale between that of cells and whole tissues. Two techniques — optical coherence elastography and ...

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    17. Illuminating dynamic neutrophil trans-epithelial migration with micro-optical coherence tomography

      Illuminating dynamic neutrophil trans-epithelial migration with micro-optical coherence tomography

      A model of neutrophil migration across epithelia is desirable to interrogate the underlying mechanisms of neutrophilic breach of mucosal barriers. A co-culture system consisting of a polarized mucosal epithelium and human neutrophils can provide a versatile model of trans-epithelial migration in vitro , but observations are typically limited to quantification of migrated neutrophils by myeloperoxidase correlation, a destructive assay that precludes direct longitudinal study. Our laboratory has recently developed a new isotropic 1-μm resolution optical imaging technique termed micro-optical coherence tomography (μOCT) that enables 4D (x,y,z,t) visualization of neutrophils in the co-culture environment. By applying μOCT to ...

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    18. Visual dysfunction and its correlation with retinal changes in patients with Alzheimer's disease

      Visual dysfunction and its correlation with retinal changes in patients with Alzheimer's disease

      Aim To evaluate visual dysfunction and its correlation with structural changes in the retina in patients with Alzheimer's disease (AD). Methods Patients with AD (n = 24) and controls (n = 24) underwent evaluation of visual acuity (VA), color vision (using the Farnsworth and L’Anthony desaturated (D) 15 color tests), and contrast sensitivity vision (CSV; using the Pelli-Robson chart and CSV-1000E test) to measure visual dysfunction. Structural measurements of the retinal nerve fiber layer (RNFL) and macular thickness were obtained using spectral domain-optical coherence tomography (SD-OCT). Results CSV at three of the four spatial frequencies was significantly worse in AD ...

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    19. Surgical treatment and optical coherence tomographic evaluation for accidental laser-induced full-thickness macular holes

      Surgical treatment and optical coherence tomographic evaluation for accidental laser-induced full-thickness macular holes

      Purpose To report OCT appearance and surgical outcomes of full-thickness macular holes (MHs) accidentally caused by laser devices. Patients and methods This retrospective case series included 11 eyes of 11 patients with laser-induced MHs treated by pars plana vitrectomy, internal limiting membrane (ILM) peeling, and gas or silicone oil tamponade. Evaluations included a full ophthalmic examination, macular spectral-domain optical coherence tomography (SD-OCT), and fundus photography. Main outcome measures is MH closure and final visual acuity; the secondary outcome was the changes of retinal pigment epithelium and photoreceptor layer evaluated by sequential post-operative SD-OCT images. Results Five patients were accidentally injured ...

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    20. Accuracy and safety verification of ovarian reserve assessment technique for ovarian tissue transplantation using optical coherence tomography in mice ovary

      Accuracy and safety verification of ovarian reserve assessment technique for ovarian tissue transplantation using optical coherence tomography in mice ovary

      Except for histological study, there are currently no suitable techniques available for the detection and identification of primordial follicles in ovary of primary ovarian insufficiency patients who have undetectable AMH levels. Also, the ability to locate and quantify follicles on ovarian cortex strips, without fixation, is valuable for patients who could undergo subsequent successful ovarian tissue transplantation. Although optical coherence tomography (OCT) is a well-established high resolution imaging technique without fixation commonly applied in biomedicine, few reports are available on ovarian tissue imaging. In present study, we established standard OCT follicle images at each developmental stage, including the primordial follicle ...

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    21. Design of a k-space spectrometer for ultra-broad waveband spectral domain optical coherence tomography

      Design of a k-space spectrometer for ultra-broad waveband spectral domain optical coherence tomography

      Nonlinear sampling of the interferograms in wavenumber ( k ) space degrades the depth-dependent signal sensitivity in conventional spectral domain optical coherence tomography (SD-OCT). Here we report a linear-in-wavenumber ( k -space) spectrometer for an ultra-broad bandwidth (760 nm–920 nm) SD-OCT, whereby a combination of a grating and a prism serves as the dispersion group. Quantitative ray tracing is applied to optimize the linearity and minimize the optical path differences for the dispersed wavenumbers. Zemax simulation is used to fit the point spread functions to the rectangular shape of the pixels of the line-scan camera and to improve the pixel sampling rates ...

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    22. Optical coherence tomography evaluation of pulmonary arterial vasculopathy in Systemic Sclerosis

      Optical coherence tomography evaluation of pulmonary arterial vasculopathy in Systemic Sclerosis

      Our current understanding of the pathophysiology of pulmonary vascular disease is incomplete, since information about alterations of the pulmonary vasculature in pulmonary arterial hypertension (PAH) is primarily provided by autopsy or tissue specimens. The aim of this study was to compare the distal pulmonary vasculature of <2 mm in diameter in Systemic Sclerosis (SSc) patients with (n = 17) and without (n = 5) associated PAH using Optical Coherence Tomography during Right Heart catheterization. SSc-PAH patients showed significant thickening of Intima Media Thickening Area compared to patients without PAH (27 +/− 5.8% vs. 21 +/− 1.4%, p = 0.024). A good haemodynamic ...

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    23. Evaluation of choroidal tumors with optical coherence tomography: enhanced depth imaging and OCT-angiography features

      Evaluation of choroidal tumors with optical coherence tomography: enhanced depth imaging and OCT-angiography features

      Aim To describe the vascular features of choroidal tumors using enhanced depth imaging (EDI), optical coherence tomography (OCT), and OCT-angiography. Methods In this prospective study, we evaluated 116 Caucasian patients with choroidal tumors (60 eyes with choroidal nevi, 40 with choroidal melanoma, 6 with choroidal hemangioma, 2 with optic disc melanocytoma, 6 with choroidal osteoma, and 2 with retinal metastases). Patients underwent a complete ophthalmic examination including bulbar echography, EDI-OCT, OCT-angiography, and multicolor imaging. Sixteen patients also underwent fluorescein and indocyanine angiography. Results The left eye was more involved than the right eye. The mean tumor thickness was 1.23 ...

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