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    1. Smoothing Splines on Unit Ball Domains with Application to Corneal Topography

      Smoothing Splines on Unit Ball Domains with Application to Corneal Topography

      Abstract: Optical coherence tomography (OCT) is a non-invasive imaging technique used to study and understand internal structures of biological tissues such as the anterior chamber of the human eye. An interesting problem is the reconstruction of the shape of the biological tissue from OCT images, that is not only a good fit of the data but also respects the smoothness properties observed in the images. A similar problem arises in Magnetic Resonance Imaging (MRI). We cast the problem as a penalized weighted least squares regression with a penalty on the magnitude of the second derivative (Laplacian) of the surface. We ...

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    2. Efficient OCT volume reconstruction from slitlamp microscopes

      Efficient OCT volume reconstruction from slitlamp microscopes

      Since its introduction 25 years ago, Optical Coherence Tomography (OCT) has contributed tremendously to diagnostic and monitoring capabilities of pathologies in the field of ophthalmology. Despite rapid progress in hardware and software technology however, the price of OCT devices has remained high, limiting their use in private practice and in screening examinations. In this paper, we present a slitlamp-integrated OCT device, built with off-the-shelf components, which can generate high-quality volumetric images of the posterior eye segment. To do so, we present a novel strategy for 3D image reconstruction in this challenging domain that allows for state-ofthe- art OCT volumes to ...

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    3. Contrast Enhanced Subsurface Fingerprint Detection using High-speed Optical Coherence Tomography

      Contrast Enhanced Subsurface Fingerprint Detection using High-speed Optical Coherence Tomography

      Spectral-domain optical coherence tomography (SDOCT) has been demonstrated to be a viable tool in forensic science for fingerprint detection, yet it still suffers from certain practical issues, e.g., the limited scanning speed and low image contrast. In this letter, we report a high-speed SD-OCT together with an image contrast enhancement mechanism for reliable subsurface fingerprint detection. The constructed SDOCT system achieves a scanning rate up to 60K A-lines/s, and thus, both 3D volumetric images, reaching up to 20mm × 20mm × 1.2mm, and en face internal fingerprint furrow pattern images could be obtained. Based upon the analyses of the ...

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    4. Optical Coherence Tomography for Brain Imaging and Developmental Biology

      Optical Coherence Tomography for Brain Imaging and Developmental Biology

      Optical coherence tomography (OCT) is a promising research tool for brain imaging and developmental biology. Serving as a three-dimensional optical biopsy technique, OCT provides volumetric reconstruction of brain tissues and embryonic structures with micrometer resolution and video rate imaging speed. Functional OCT enables label-free monitoring of hemodynamic and metabolic changes in the brain in vitro and in vivo in animal models. Due to its noninvasiveness nature, OCT enables longitudinal imaging of developing specimens in vivo without potential damage from surgical operation, tissue fixation and processing, and staining with exogenous contrast agents. In this paper, various OCT applications in brain imaging ...

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    5. Performance analysis of a Hybrid fingerprint extracted from optical coherence tomography fingertip scans

      Performance analysis of a Hybrid fingerprint extracted from optical coherence tomography fingertip scans

      The Hybrid fingerprint is a local-quality-specific blend of the surface and internal fingerprints, extracted from optical coherence tomography scans. Owing to its origin, and the manner in which it is obtained, the Hybrid fingerprint is a high-quality and secure fingerprint acquisition solution. This research entails a detailed description of the Hybrid fingerprint, the techniques involved to produce it, and a performance analysis of it. A dataset of 282 fingertip scans was established. Two recognised minutiae extraction and fingerprint matching algorithms were applied to assess the performance of the Hybrid fingerprint. The best equal error rate measured was 1.25%. NIST ...

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      Mentions: Ann Singh
    6. Miniaturization of plastic lens by injection molding for disposable endoscopie optical coherence tomography system

      Miniaturization of plastic lens by injection molding for disposable endoscopie optical coherence tomography system

      Minimally invasive robotic surgery required disposable endoscopie optical coherence tomography (OCT) for high-resolution deep tissue imaging and cross-contamination prevention. Here, we developed a miniaturized plastic lens by injection molding for developing a disposable endoscopie optical coherence tomography system for the first time. Injection molding provided low-cost and high-production rate to produce a disposable plastic lens and enabled the miniaturization of plastic lens. Transmittance and curvature of the plastic lens was measured. The plastic lens was integrated with an endoscopie OCT system, and the images of human-skin and microspheres embedded in agarose gel were captured. We are currently trying to integrate ...

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      Mentions: Ki Hean Kim
    7. Imaging Spinal Structures With Polarization-Sensitive Optical Coherence Tomography

      Imaging Spinal Structures With Polarization-Sensitive Optical Coherence Tomography

      Impact Statement: We investigate polarization-sensitive optical coherence tomography (PS-OCT) to obtain both intensity and polarization contrast images of in vivo and ex vivo spinal structures like subcutaneous fat, supraspinous ligament, interspinous ligament, ligamentum flavum, dura, and spinal cord in a piglet model. The PS-OCT can provide enhanced contrast characteristic structures compared to the intensity OCT; therefore it has the potential for guidance in spine interventional procedures. Abstract: We investigate polarization-sensitive optical coherence tomography (PS-OCT) to obtain both intensity and polarization contrast images of in vivo and ex vivo spinal structures like subcutaneous fat, supraspinous ligament, interspinous ligament, ligamentum flavum, dura ...

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    8. Segmentation Based Sparse Reconstruction of Optical Coherence Tomography Images

      Segmentation Based Sparse Reconstruction of Optical Coherence Tomography Images

      We demonstrate the usefulness of utilizing a segmentation step for improving the performance of sparsity based image reconstruction algorithms. In specific, we will focus on retinal optical coherence tomography (OCT) reconstruction and propose a novel segmentation based reconstruction framework with sparse representation, termed segmentation based sparse reconstruction (SSR). The SSR method uses automatically segmented retinal layer information to construct layer-specific structural dictionaries. In addition, the SSR method efficiently exploits patch similarities within each segmented layer to enhance the reconstruction performance. Our experimental results on clinical-grade retinal OCT images demonstrate the effectiveness and efficiency of the proposed SSR method for both ...

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    9. Toward High-Speed Imaging of Cellular Structures in Rat Colon Using Micro-optical Coherence Tomography

      Toward High-Speed Imaging of Cellular Structures in Rat Colon Using Micro-optical Coherence Tomography

      The mucosal microanatomy of the large intestine is characterized by the presence of crypts of Lieberkühn, which is associated predominantly with goblet cells. Such cellular-level intestinal microstructures undergo morphological changes during the progression of bowel diseases, such as colon cancer or ulcerative colitis. As an indicator of gastric cancers, intestinal metaplasia in the large intestine is characterized by the appearance of goblet cells in gastric epithelium, and therefore, visualization of intestinal microstructure changes in cross-sectional view, particularly in vivo, in a highspeed fashion would assist early disease diagnosis and its treatment. In this paper, we investigated the capability of ...

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    10. Magnetic and Plasmonic Contrast Agents in Optical Coherence Tomography

      Magnetic and Plasmonic Contrast Agents in Optical Coherence Tomography

      Optical coherence tomography (OCT) has gained widespread application for many biomedical applications, yet the traditional array of contrast agents used in incoherent imaging modalities do not provide contrast in OCT. Owing to the high biocompatibility of iron oxides and noble metals, magnetic and plasmonic nanoparticles, respectively, have been developed as OCT contrast agents to enable a range of biological and pre-clinical studies. Here, we provide a review of these developments within the past decade, including an overview of the physical contrast mechanisms and classes of OCT system hardware add-ons needed for magnetic and plasmonic nanoparticle contrast . A comparison of the ...

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    11. Ghost Reduction in CP-SSOCT Having Multiple References Using Fourier-Domain Shift and Sum

      Ghost Reduction in CP-SSOCT Having Multiple References Using Fourier-Domain Shift and Sum

      We propose, test, and validate a novel Fourier-domain-based method for ghost image artifacts reduction in a common-path SSOCT system having multiple adjacent reference planes. Common-path probes with imaging systems containing high-index sapphire ball or other lenses produce multiple fixed references due to Fresnel reflections from the lens surfaces. The multiple reference planes produce multiple and overlapping optical coherence tomography (OCT) images. Since such ghost artifacts are the result of the superposition of multiple identical images having different amplitudes and spatial shifts, one can correctly shift and sum the images in the Fourier-domain once the relative amplitude and lateral position between ...

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    12. Statistical Modeling of Retinal Optical Coherence Tomography

      Statistical Modeling of Retinal Optical Coherence Tomography

      In this paper, a new model for retinal Optical Coherent Tomography (OCT) images is proposed. This statistical model is based on introducing a nonlinear transform, namely Gaussianization, to convert the probability distribution function (pdf) of each OCT intra-retinal layer to a Gaussian distribution. According to retina anatomy, the retina is a layered structure and in OCT images each of these layers has a specific pdf which is corrupted by speckle noise, therefore a mixture model for statistical modeling of OCT images is proposed. A Normal-Laplace distribution, which is a convolution of a Laplace pdf and Gaussian noise, is proposed as ...

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    13. Speckle Reduction in 3D Optical Coherence Tomography of Retina by A-Scan Reconstruction

      Speckle Reduction in 3D Optical Coherence Tomography of Retina by A-Scan Reconstruction

      Optical coherence tomography (OCT) is a micrometer-scale, cross-sectional imaging modality for biological tissue. It has been widely used for retinal imaging in ophthalmology. Speckle noise is problematic in OCT. A raw OCT image/volume usually has very poor image quality due to speckle noise, which often obscures the retinal structures. Overlapping scan is often used for speckle reduction in a 2D line-scan. However, it leads to an increase of the data acquisition time. Therefore, it is unpractical in 3D scan as it requires a much longer data acquisition time. In this paper, we propose a new method for speckle reduction ...

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    14. 4D imaging of cardiac trabeculae contracting in vitro using gated OCT

      4D imaging of cardiac trabeculae contracting in vitro using gated OCT

      Cardiac trabeculae are widely used as experimental muscle preparations for studying heart muscle. However, their geometry (diameter, length, and shape) can vary not only amongst samples, but also within a sample, leading to inaccuracies in estimating their stress production, volumetric energy output, and/or oxygen consumption. Hence, it is desirable to have a system that can accurately image each trabecula in vitro during an experiment. To this end, we constructed an optical coherence tomography (OCT) system and implemented a gated imaging procedure to image actively contracting trabeculae and reconstruct their time-varying geometry. By imaging a single cross section while monitoring ...

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    15. The Application of Full-Field Optical Coherence Tomography on Evaluating Film Coating of Pharmaceutical Pellets

      The Application of Full-Field Optical Coherence Tomography on Evaluating Film Coating of Pharmaceutical Pellets

      This paper focuses on the application of full-field optical coherence tomography (FF-OCT) imaging on quantifying coating thickness and characterizing coating structures of two layer pharmaceutical pellets. This FF-OCT system used aninexpensive infrared light-emitting diode (LED) as the opticalsource and a commercial high speed complementary metal-oxidesemiconductor (CMOS) camera as the detector. A total volume of700 × 50 × 200 μm3 (x-y-z) were imaged by using the FF-OCTdevice. A high spatial resolution of 4.0 × 5.0 μm2 (axial × lateral)was achieved. In the cross-sectional image the internal structuredetails can be clearly observed and in particular particle-likefeatures can be clearly ...

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    16. Simulation of cellular changes on Optical Coherence Tomography of human retina

      Simulation of cellular changes on Optical Coherence Tomography of human retina

      We present a methodology to assess cell level alterations on the human retina responsible for functional changes observable in the Optical Coherence Tomography data in healthy ageing and in disease conditions, in the absence of structural alterations. The methodology is based in a 3D multilayer Monte Carlo computational model of the human retina . The optical properties of each layer are obtained by solving the Maxwell's equations for 3D domains representative of small regions of those layers, using a Discontinuous Galerkin Finite Element Method (DG-FEM). Here we present the DG-FEM Maxwell 3D model and its validation against Mie's theory ...

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    17. Highly functional ultrashort pulse fiber laser sources and applications for optical coherence tomography

      Highly functional ultrashort pulse fiber laser sources and applications for optical coherence tomography

      We have been investigating highly functional ultrashort pulse fiber laser sources for highly sensitive, ultrahigh resolution optical coherence tomography (UHR-OCT). The coherent, low-noise, and Gaussian like wideband super-continuum (SC) sources were developed at five different wavelength regions between 0.8 and 1.7 um in order to investigate the wavelength dependence of OCT imaging. A real-time imaging was achieved with spectral domain OCT system. A fiber laser based, rapid, widely wavelength tunable narrow linewidth source was also developed. The UHR-OCT imaging of biological samples were demonstrated using the developed OCT systems.

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    18. Introducing Augmented Reality to Optical Coherence Tomography in Ophthalmic Microsurgery

      Introducing Augmented Reality to Optical Coherence Tomography in Ophthalmic Microsurgery

      Augmented Reality (AR) in microscopic surgery has been subject of several studies in the past two decades. Nevertheless, AR has not found its way into everyday microsurgical workflows. The introduction of new surgical microscopes equipped with Optical Coherence Tomography (OCT) enables the surgeons to perform multimodal (optical and OCT) imaging in the operating room. Taking full advantage of such elaborate source of information requires sophisticated intraoperative image fusion, information extraction, guidance and visualization methods. Medical AR is a unique approach to facilitate utilization of multimodal medical imaging devices. Here we propose a novel medical AR solution to the long-known problem ...

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    19. Automated, Depth-Resolved Estimation of the Attenuation Coefficient From Optical Coherence Tomography Data

      Automated, Depth-Resolved Estimation of the Attenuation Coefficient From Optical Coherence Tomography Data

      We present a method for automated, depth-resolved extraction of the attenuation coefficient from Optical Coherence Tomography (OCT) data. In contrast to previous automated, depth-resolved methods, the Depth-Resolved Confocal (DRC) technique derives an invertible mapping between the measured OCT intensity data and the attenuation coefficient while considering the confocal function and sensitivity fall-off, which are critical to ensure accurate measurements of the attenuation coefficient in practical settings (e.g., clinical endoscopy). We also show that further improvement of the estimated attenuation coefficient is possible by formulating image denoising as a convex optimization problem that we term Intensity Weighted Horizontal Total Variation ...

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    20. Moving beam shear wave reconstruction for both ultrasound and optical coherence tomography applications

      Moving beam shear wave reconstruction for both ultrasound and optical coherence tomography applications

      Shear wave elasticity imaging can quantitatively estimate a stiffness map of biological tissues based on speckle-tracking shear wave propagation. However, current approaches cannot directly reconstruct elasticity properties in speckle-less or speckle-free regions, for example within the crystalline lens in ophthalmology. We propose an imaging sequence to reconstruct the elastic properties in speckle-free regions by sequentially launching shear waves with a laterally moving acoustic radiation force, and then detecting the displacement at a specific speckle-generating position. The imaging sequence was tested for both ultrasound and phase-sensitive optical coherence tomography imaging. Tissue-mimicking phantom studies were performed and results demonstrate that elastic properties ...

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    21. Live Acquisition of Internal Fingerprint with Automated Detection of Subsurface Layers Using OCT

      Live Acquisition of Internal Fingerprint with Automated Detection of Subsurface Layers Using OCT

      Recently, optical coherence tomography (OCT) was introduced as a novel fingerprint scanning technique. This approach is resistant to fake fingerprint attacks, and is robust against poor fingertip conditions – i.e., wet or stained fingers. The method proceeds by scanning a fingertip in three dimensions and capturing a fingerprint from the subsurface layer. Although OCT has the potential to be widely used as a new standard in fingerprint scanning, it is hindered by its low scanning speed and the lack of computing power available for reproducing raw OCT data into images in real-time; for instance, this process can take minutes to ...

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      Mentions: Korea University
    22. A neural network approach to retinal layer boundary identification from optical coherence tomography images

      A neural network approach to retinal layer boundary identification from optical coherence tomography images

      In this paper, we propose a method by which the boundaries of retinal layers in optical coherence tomography (OCT) images can be identified from a simple initial user input. The proposed method is a neural network approach in which the neural networks are trained to identify points within each layer, from which, the boundaries between the retinal layers are estimated. This method focuses on training neural networks to identify layers themselves, instead of boundaries, because the available date is richer and more cohesive as compared to boundary identification. Results are presented, demonstrating the effectiveness of this method.

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    23. Review of OCT and fundus images for detection of Macular Edema

      Review of OCT and fundus images for detection of Macular Edema

      Macula is an oval shaped area near the center of human retina that covers the area of 5500 microns and at its center, there is a small pit known as fovea with the diameter of 1500 microns. Macular disorders involve group of diseases that damages macula resulting in blindness or vision loss. Macular Edema ‘ME’ is the most common disease related to macula. The symptoms for this disease usually appear in final stages to patient when it is very difficult to cure it and at that time it causes severe damage to central vision. However if it is detected in ...

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    24. Non-destructive cross-sectional imaging of tomato using ultra-high resolution optical coherence tomography

      Non-destructive cross-sectional imaging of tomato using ultra-high resolution optical coherence tomography

      Optical coherence tomography is an optical imaging technique that performs non-destructive cross-sectional imaging of micrometer-scale structures in samples. In this report, we demonstrated the visualization of inner structures in tomato fruits and leaves with ultra-high resolution optical coherence tomography (UHR-OCT) using fiber based laser source with ultra-broadband continuous spectrum around 1.7 μm wavelength. We confirmed that our UHR-OCT system allows us to perform cross-sectional imaging of tomato fruits and leaves at ∼ 2.8 μm axial resolution.

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