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    1. Retinal pulse wave velocity measurement using spectral-domain optical coherence tomography

      Retinal pulse wave velocity measurement using spectral-domain optical coherence tomography

      In their latest publication on retinal pulse wave velocity measurement using optical co-herence tomography (OCT), Qian Li et al. propose a method to determine the pulse wave velocity in retinal arteries and veins [1]. This should enable a non-invasive determination of biomechanical properties of the vessel network, particularly the elasticity of the vessel walls [2].

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    2. Image-guided recording system for spatial and temporal mapping of neuronal activities in brain slice

      Image-guided recording system for spatial and temporal mapping of neuronal activities in brain slice

      In this study, we introduce the novel image-guided recording system (IGRS) for efficient interpretation of neuronal activities in the brain slice. IGRS is designed to combine microelectrode array (MEA) and optical coherence tomography at the customized upright microscope. It allows to record multi-site neuronal signals and image the volumetric brain anatomy in a single body configuration. For convenient interconnection between a brain image and neuronal signals, we developed the automatic mapping protocol which enables for projecting acquired neuronal signals on a brain image. In order to evaluate the performance of IGRS, hippocampal signals of the brain slice were monitored, and ...

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    3. Imaging of the lamina cribrosa and its role in glaucoma: a review

      Imaging of the lamina cribrosa and its role in glaucoma: a review

      The lamina cribrosa of the optic nerve head serves two contrasting roles; it must be porous to allow retinal ganglion cell axons to pass through, and yet at the same time, it must also provide adequate structural support to withstand the stresses and strains across it. Improvements in imaging such as optical coherence tomography image capture and image processing have allowed detailed in vivo studies of lamina cribrosa macro- and micro-architectural characteristics. This has aided our understanding of the optic nerve head as a complex biomechanical structure. In this review, we first aim to frame the biomechanical considerations of lamina ...

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    4. Polarization-multiplexed, dual-beam swept source optical coherence tomography angiography

      Polarization-multiplexed, dual-beam swept source optical coherence tomography angiography

      A polarization-multiplexed, dual-beam setup is proposed to expand the field of view for a swept source optical coherence tomography angiography (OCTA) system. This method used a Wollaston prism to split sample path light into two orthogonal-polarized beams. This allowed two beams to shine on the cornea at an angle separation of ~ 14 degrees, which led to a separation of ~ 4.2 mm on the retina. A 3-mm glass plate was inserted into one of the beam paths to set a constant path length difference between the two polarized beams so the interferogram from the two beams are coded at different ...

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    5. Multifunctional in vivo imaging for monitoring wound healing using swept-source polarization-sensitive optical coherence tomography

      Multifunctional in vivo imaging for monitoring wound healing using swept-source polarization-sensitive optical coherence tomography

      Background and Objective Wound healing involves a complex and dynamic biological process in response to tissue injury. Monitoring of the cascade of cellular events is useful for wound management and treatment. The aim of this study is to demonstrate the potential of multifunctional polarization-sensitive optical coherence tomography (PS-OCT) to longitudinally monitor the self-healing process in a murine cutaneous wound model. Materials and Methods A multi-functional PS-OCT system based on swept source OCT configuration (1,310 nm central wavelength) was designed to obtain simultaneously microstructural, blood perfusion, and birefringent information of a biological tissue in vivo . A 1-mm-diameter wound was generated ...

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    6. Role of anterior segment optical coherence tomography in angle closure disease: a review

      Role of anterior segment optical coherence tomography in angle closure disease: a review

      This article aims to review the published literature pertaining to the use of anterior segment optical coherence tomography (AS-OCT) in the evaluation of angle closure disease. Searches on the available published literature were last conducted on June 15, 2017. Rated as Level I evidence, we found that AS-OCT has shown good sensitivity and moderate diagnostic accuracy to detect narrow angles when compared with gonioscopy. AS-OCT quantitative and qualitative parameters demonstrated strong association with the presence of gonioscopically closed-angles. This technology provides an objective non-contact method of assessing the angle that is well tolerated by the patient and correlates well with ...

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    7. Hypoxia challenge test and retinal circulation changes – a study using ocular coherence tomography angiography

      Hypoxia challenge test and retinal circulation changes – a study using ocular coherence tomography angiography

      Purpose Previous studies report that the response of retinal vessels to a decrease in oxygen (hypoxia) is vasodilation, thus increasing blood flow. We aimed to characterize the changes in retinal microvasculature induced by a mild hypoxia stress test in a healthy population, using ocular coherence tomography angiography (OCT-A) technology. Methods Interventional repeated-measures study. The standardized hypoxia challenge test (HCT) was performed to all volunteers, according to the British Thoracic Society protocol. Ocular coherence tomography angiography (OCT-A) was performed at three time-points (baseline, during HCT and 30′ posthypoxia). Macular and peripapillary vessel densities were assessed using the built-in software. To minimize ...

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    8. Paravascular abnormalities observed by spectral domain optical coherence tomography are risk factors for retinoschisis in eyes with high myopia

      Paravascular abnormalities observed by spectral domain optical coherence tomography are risk factors for retinoschisis in eyes with high myopia

      Purpose To investigate the retinal features and distribution of paravascular abnormalities (PVAs) and their relationship with retinoschisis in eyes with high myopia. Methods One hundred and fifty-two eyes of 88 patients with high myopia [refractive error greater than −6 dioptres (D) or axial length (AL) ≥26.5 mm] who had undergone comprehensive ophthalmic examinations were evaluated in this cross-sectional study. Multiple optical coherence tomography (OCT) scans were performed to study the microstructural alterations adjacent to the retinal vascular arcades and the entire macular area. The presence and distribution patterns of various PVAs, retinoschisis and the association between these parameters were ...

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    9. In vitro determination of Mexican Mestizo hair shaft diameter using optical coherence tomography

      In vitro determination of Mexican Mestizo hair shaft diameter using optical coherence tomography

      Background Mexican mestizo population has a pluriethnic mixture of Amerindian, European and African ancestry, predominant in most Latin American countries. Until now, there are no reports about hair characteristics in this population, necessary to define normal values, for hair diseases evaluation and comparison among other ethnic groups. Methods The VivoSight ® swept-source multibeam optical coherence tomography system was used to evaluate hair diameter and shape in 30 females. Three hair samples from each volunteer were measured transversely along three distances, generating nine cross-sectional images, two measurements per image and 18 measurements per patient for a total of 540 diameter measurements. Results ...

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    10. Multi-contrast Endomyocardial Imaging By Single-channel High Resolution Cross-polarization Optical Coherence Tomography

      Multi-contrast Endomyocardial Imaging By Single-channel High Resolution Cross-polarization Optical Coherence Tomography

      A single-channel high-resolution cross-polarization (CP) optical coherence tomography (OCT) system is presented for multi-contrast imaging of human myocardium in one-shot measurement. The intensity contrast and functional contrasts, including the ratio between the cross- and co- polarization channels as well as the cumulative retardation, are reconstructed from the CP-OCT readout. By comparing the CP-OCT results with histological analysis, it is shown that the system can successfully delineate micro-structures in the myocardium and differentiate the fibrotic myocardium from normal or ablated myocardium based the functional contrasts provided by the CP-OCT system. The feasibility of using A-line profiles from the two orthogonal polarization ...

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    11. Spectrally Encoded Coherence Tomography and Reflectometry (SECTR): simultaneous en face and cross-sectional imaging at 2 gigapixels-per-second

      Spectrally Encoded Coherence Tomography and Reflectometry (SECTR): simultaneous en face and cross-sectional imaging at 2 gigapixels-per-second

      Non-invasive biological imaging is crucial for understanding in vivo structure and function. Optical coherence tomography (OCT) and reflectance confocal microscopy are two of the most widely used optical modalities for exogenous contrast-free high-resolution three-dimensional imaging in non-fluorescent scattering tissues. However, sample motion remains a critical barrier to raster-scanned acquisition and reconstruction of wide-field anatomically accurate volumetric datasets. We introduce spectrally encoded coherence tomography and reflectometry (SECTR), a high-speed multimodality system for simultaneous OCT and spectrally-encoded reflectance (SER) imaging. SECTR utilizes a robust system design consisting of shared optical relays, scanning mirrors, swept-laser, and digitizer to achieve the fastest reported in ...

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    12. An overview of methods to mitigate artifacts in optical coherence tomography imaging of the skin

      An overview of methods to mitigate artifacts in optical coherence tomography imaging of the skin

      Background Optical coherence tomography (OCT) of skin delivers three-dimensional images of tissue microstructures. Although OCT imaging offers a promising high-resolution modality, OCT images suffer from some artifacts that lead to misinterpretation of tissue structures. Therefore, an overview of methods to mitigate artifacts in OCT imaging of the skin is of paramount importance. Speckle, intensity decay, and blurring are three major artifacts in OCT images. Speckle is due to the low coherent light source used in the configuration of OCT. Intensity decay is a deterioration of light with respect to depth, and blurring is the consequence of deficiencies of optical components ...

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    13. In-line optical fiber metallic mirror reflector for monolithic common path optical coherence tomography probes

      In-line optical fiber metallic mirror reflector for monolithic common path optical coherence tomography probes

      Background and Objectives Endoscopic optical coherence tomography probes suffer from various artifacts due to dispersion imbalance and polarization mismatch between reference and sample arm light. Such artifacts can be minimized using a common path approach. In this work, we demonstrate a miniaturized common path probe for optical coherence tomography using an inline fiber mirror. Materials and Methods A common path optical fiber probe suitable for performing high-resolution endoscopic optical coherence tomography imaging was developed. To achieve common path functionality, an inline fiber mirror was fabricated using a thin gold layer. A commercially available swept source engine was used to test ...

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    14. Transverse partial stent ablation with rotational atherectomy for suboptimal culotte technique in left main stem bifurcation

      Transverse partial stent ablation with rotational atherectomy for suboptimal culotte technique in left main stem bifurcation

      Longitudinal rotational atherectomy of metal struts is well described as bail-out strategy to treat undilatable instent restenosis. Ablation of metal stent struts jailing the ostium of a major side branch in a coronary bifurcation is not described. In the current report, we describe a case of “transverse” rotational atherectomy to treat a failure of culotte stenting in a left main stem bifurcation. We document for the first time in vivo and in man the effect of this strategy using optical coherence tomography.

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    15. Ganglion cell-inner plexiform layer and retinal nerve fibre layer changes within the macula in retinitis pigmentosa: a spectral domain optical coherence tomography study

      Ganglion cell-inner plexiform layer and retinal nerve fibre layer changes within the macula in retinitis pigmentosa: a spectral domain optical coherence tomography study

      Purpose To investigate how macular ganglion cell-inner plexiform layer (GCIPL) and retinal nerve fibre layer (RNFL) thicknesses within the macula change with retinitis pigmentosa (RP) severity. Methods Spectral domain optical coherence tomography (SD-OCT) was used to examine 177 patients with RP and 177 normal controls. An optical coherence tomography (OCT) line scan was used to grade RP severity. Retinitis pigmentosa (RP) was categorized as more advanced if there was no identifiable inner segment ellipsoid (ISe) band (NISE) and as less advanced if an ISe band could be identified and peripheral loss of ISe was apparent (IISE). Ganglion cell-inner plexiform layer ...

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    16. Thickness mapping of individual retinal layers and sectors by Spectralis SD-OCT in Autosomal Dominant Optic Atrophy

      Thickness mapping of individual retinal layers and sectors by Spectralis SD-OCT in Autosomal Dominant Optic Atrophy

      Purpose To assess layer- and location-specific retinal thickness deficits in autosomal dominant optic atrophy (ADOA) using Spectralis SD-OCT. Methods This cross-sectional study included 41 ADOA patients with OPA1 exon 28 (2826delT) mutation [age, 8.6–83.5 years; best-corrected visual acuity (BCVA), 8–89 Early Treatment Diabetic Retinopathy Study (ETDRS) letters] and 55 mutation-free first-degree relatives as healthy controls (age, 8.9–68.7; BCVA, 80–99). Participants underwent routine examination and optical coherence tomography (OCT) with segmentation of the whole retina, inner retinal layers (IRL) and outer retinal layers (ORL). Individual segmentation was performed of the perifoveal retinal nerve ...

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    17. Optical coherence tomography for margin definition of basal cell carcinoma before micrographic surgery—recommendations regarding the marking and scanning technique

      Optical coherence tomography for margin definition of basal cell carcinoma before micrographic surgery—recommendations regarding the marking and scanning technique

      Background/purpose Mohs Micrographic Surgery (MMS) is the preferred therapeutic treatment for high-risk basal cell carcinoma (BCC). Optical Coherence Tomography (OCT) is a non-invasive imaging technique that enables the diagnosis of BCC. We thought to determine the margins of BCCs with OCT, prior to MMS, to reduce the number of surgical steps. Methods Different permanent markers were tested on the skin regarding line width, resistance against disinfection and brightness in the OCT image. The visible tumor margins of BCCs were defined by dermoscopy, adding a safety margin of 2 mm and labeled using the selected pen, causing a signal shadow ...

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    18. Optical coherence tomography: An efficient imaging method for the visualization of human epidermis orientation

      Optical coherence tomography: An efficient imaging method for the visualization of human epidermis orientation

      Recently, it has been shown that epidermal sheets taken from suction blisters are very appropriate skin samples for Multi-Photon (MP) microscopy. However, we observed that image quality was much better when the sample was visualized through the basale side. Thus, the epidermis orientation needs to be controlled before MP imaging. We observed that the use of standard laboratory binoculars led to a high rate of false results. In this context, we showed that optical coherence tomography provided clear images of the epidermis orientation without loss of sample integrity and thus represents an effective technique before slide sealing and MP analysis.

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    19. In vivo imaging of the internal nasal valve during different conditions using optical coherence tomography

      In vivo imaging of the internal nasal valve during different conditions using optical coherence tomography

      Objective Previously, we proposed long-range optical coherence tomography (LR-OCT) to be an effective method for the quantitative evaluation of the nasal valve geometry. Here, the objective was to quantify the reduction in the internal nasal valve angle and cross-sectional area that results in subjective nasal airway obstruction and to evaluate the dynamic behavior of the valve during respiration using LR-OCT. Methods For 16 healthy individuals, LR-OCT was performed in each naris during: 1) normal respiration, 2) peak forced inspiration, 3) lateral nasal wall depression (to the onset of obstructive symptoms), and 4) after application of a topical decongestant. The angle ...

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    20. Visibility of Fiducial Markers used for Image-Guided Radiation Therapy on Optical Coherence Tomography for Registration with CT: an Esophageal Phantom Study

      Visibility of Fiducial Markers used for Image-Guided Radiation Therapy on Optical Coherence Tomography for Registration with CT: an Esophageal Phantom Study

      Purpose Optical coherence tomography (OCT) is of interest to visualize microscopic esophageal tumor extensions to improve tumor delineation for radiation therapy (RT) planning. Fiducial marker placement is a common method to ensure target localization during planning and treatment. Visualization of these fiducial markers on OCT permits integrating OCT and computed tomography (CT) images used for RT planning via image registration. We studied the visibility of 13 (8 types) commercially available solid and liquid fiducial markers in OCT images at different depths using dedicated esophageal phantoms and evaluated marker placement depth in clinical practice. Materials and Methods We designed and fabricated ...

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