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    1. A New Framework for the Integrative Analytics of Intravascular Ultrasound and Optical Coherence Tomography Images

      A New Framework for the Integrative Analytics of Intravascular Ultrasound and Optical Coherence Tomography Images

      The integrative analysis of multimodal medical images plays an important role in the diagnosis of coronary artery disease by providing additional comprehensive information that cannot be found in an individual source image. Intravascular Ultrasound (IVUS) and Optical Coherence Tomography (IV-OCT) are two imaging modalities that have been widely used in the medical practice for the assessment of arterial health and the detection of vascular lumen lesions. IV-OCT has a high resolution and poor penetration, while IVUS has a low resolution and high detection depth. This paper proposes a new approach for the fusion of intravascular ultrasound and optical coherence tomography ...

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    2. Evaluating micro-optical coherence tomography (μOCT) as a feasible imaging tool for pancreatic disease diagnosis

      Evaluating micro-optical coherence tomography (μOCT) as a feasible imaging tool for pancreatic disease diagnosis

      Pancreatic cancer is one of the leading causes of cancer mortality worldwide due to the lack of reliable tools for early diagnosis of this cancer. In this study, we evaluated the feasibility of micro-optical coherence tomography (μOCT) as an imaging tool for the diagnosis of pancreatic cancers. Specifically, we constructed a μOCT device that achieves a resolution of ∼1.67 μm and 1.79 μm in axial and lateral directions, respectively, and acquires three-dimensional μOCT images of mouse, rat and human pancreatic specimens ex vivo. We compared the results of μOCT with those of the corresponding histology. In μOCT images ...

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    3. Fully Automated Segmentation of Fluid/Cyst Regions in Optical Coherence Tomography Images With Diabetic Macular Edema Using Neutrosophic Sets and Graph Algorithms

      Fully Automated Segmentation of Fluid/Cyst Regions in Optical Coherence Tomography Images With Diabetic Macular Edema Using Neutrosophic Sets and Graph Algorithms

      This paper presents a fully automated algorithm to segment fluid-associated (fluid-filled) and cyst regions in optical coherence tomography (OCT) retina images of subjects with diabetic macular edema. The OCT image is segmented using a novel neutrosophic transformation and a graph-based shortest path method. In neutrosophic domain, an image g is transformed into three sets: T (true), I (indeterminate) that represents noise, and F (false). This paper makes four key contributions. First, a new method is introduced to compute the indeterminacy set I , and a new λ -correction operation is introduced to compute the set T in neutrosophic domain. Second, a graph ...

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    4. Magnetomotive Displacement of the Tympanic Membrane using Magnetic Nanoparticles: Toward Enhancement of Sound Perception

      Magnetomotive Displacement of the Tympanic Membrane using Magnetic Nanoparticles: Toward Enhancement of Sound Perception

      Objective: A novel hearing-aid scheme using magnetomotive nanoparticles (MNPs) as transducers in the tympanic membrane (TM) is proposed, aiming to noninvasively and directly induce a modulated vibration on the TM. Methods: In this feasibility study, iron-oxide (Fe<sub>3</sub>O<sub>4</sub>) nanoparticles were applied on ex vivo rat TM tissues and allowed to diffuse over ~2 hr. Subsequently, magnetic force was exerted on the MNP-laden TM via a programmable electromagnetic solenoid to induce the magnetomotion. Optical coherence tomography (OCT), along with its phase-sensitive measurement capabilities, was utilized to visualize and quantify the nanometer-scale vibrations generated on the ...

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    5. Macular OCT Classification Using a Multi-Scale Convolutional Neural Network Ensemble

      Macular OCT Classification Using a Multi-Scale Convolutional Neural Network Ensemble

      Computer-aided diagnosis (CAD) of retinal pathologies is a current active area in medical image analysis. Due to the increasing use of retinal optical coherence tomography (OCT) imaging technique, a CAD system in retinal OCT is essential to assist ophthalmologist in the early detection of ocular diseases and treatment monitoring. This paper presents a novel CAD system based on a multi-scale convolutional mixture of expert (MCME) ensemble model to identify normal retina, and two common types of macular pathologies, namely, dry age-related macular degeneration, and diabetic macular edema. The proposed MCME modular model is a data-driven neural structure, which employs a ...

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    6. Pixel-Reassigned Spectral-Domain Optical Coherence Tomography

      Pixel-Reassigned Spectral-Domain Optical Coherence Tomography

      A novel method of pixel reassignment (PRA) is proposed to achieve transverse superresolution in the confocal microscopy. Inspired by it, for the first time, we report a pixel-reassigned spectral-domain optical coherence tomography (OCT) with ∼ 1.5 times transverse resolution improvement both in numerical simulations and imaging experiments. PRA is implemented by transversely shifting the detection fiber from the on-axis position to five off-axis positions, capturing cross-sectional images at each shifting step of the detection fiber and digitally reassigning them together to give a sharper image with moderately extended depth of focus and enhanced intensity. So, we believe that the PRA ...

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    7. In Vivo Fascicle Bifurcation Imaging of Rat Sciatic Nerve Using Swept-Source Optical Coherence Tomography

      In Vivo Fascicle Bifurcation Imaging of Rat Sciatic Nerve Using Swept-Source Optical Coherence Tomography

      The sciatic nerve is the longest and widest single nerve in the human body and is responsible for the signal transduction of the entire hind limb region. Its wide nerve dynamic range and size makes it sensitive to injury. The branching and location of the sciatic nerve are important, and unlike histology, optical coherence tomography (OCT) can provide rapid non-destructive cross-sectional images. The sciatic nerves of ten rats were analyzed using swept-source (SS)-OCT. The sufficient depth penetration of the SS-OCT system allowed clear identification of the internal bifurcation point of the external branching and the internal route for the ...

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    8. Conjugate transformation for dispersion compensation in optical coherence tomography imaging

      Conjugate transformation for dispersion compensation in optical coherence tomography imaging

      In optical coherence tomography (OCT), the sample dispersion tends to increase the signal width and hence lower down the resolution, resulting in serious image quality degradation, especially for imaging over a large depth range or media with large dispersion coefficient. In this letter, instead of the conventional Fourier transformation for dispersion compensation that can compensate the image only ideally at a certain depth, a novel transformation, as called conjugate transformation, is proposed to achieve high resolution at all depth by utilizing the conjugate function of the signal itself as an optimized integral kernel. A large dispersion media of ZnSe is ...

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    9. Multi-Scale Segmentation and Surface Fitting for Measuring 3-D Macular Holes

      Multi-Scale Segmentation and Surface Fitting for Measuring 3-D Macular Holes

      Macular holes are blinding conditions, where a hole develops in the central part of retina, resulting in reduced central vision. The prognosis and treatment options are related to a number of variables, including the macular hole size and shape. High-resolution spectral domain optical coherence tomography allows precise imaging of the macular hole geometry in three dimensions, but the measurement of these by human observers is time-consuming and prone to high inter- and intra-observer variability, being characteristically measured in 2-D rather than 3-D. We introduce several novel techniques to automatically retrieve accurate 3-D measurements of the macular hole, including: surface area ...

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    10. Speckle Removal Using Diffusion Potential for Optical Coherence Tomography Images

      Speckle Removal Using Diffusion Potential for Optical Coherence Tomography Images

      We propose a fast and accurate solution to speckle reduction targeted specifically at optical coherence tomography images. The proposed speckle removing filter is designed using a novel potential function based on the gradient of the local variance of intensity. After filtering, the spatially neighboring pixels with close values of intensities converge to uniform gray values while the edges remain intact. This filtering process results in removal of speckle without destroying the edges of the desired object. The proposed filter also prevents the generation of any false edges. Detailed experimental analysis shows at least 1 dB improvement in peak signal-to-noise ratio ...

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    11. Detection of Glaucoma using Cup to Disc Ratio from Spectral Domain Optical Coherence Tomography Images

      Detection of Glaucoma using Cup to Disc Ratio from Spectral Domain Optical Coherence Tomography Images

      Glaucoma is an asymptomatic neurological disease. It causes damage to optic nerve due to increased fluid pressure with in eyes. In the proposed system, Cup-to-Disc-Ratio (CDR) has been computed considering internal layers of the retina using Spectral Domain Optical Coherence Tomography (SD-OCT) images. In the Cup-Diameter-Calculation (CDC) process, cup contour has been extracted from InnerLimiting-Membrane (ILM) layer. The paper introduces a new method to improve the precision of the ILMlayer extraction. It also employs a novel technique to refine contour of ILM layer. The novel method has outperformed interpolation and Bezier curve fitting in term of outliers removal and surface ...

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    12. Automated Detection and Measurement of Corneal Haze and Demarcation Line in Spectral-Domain Optical Coherence Tomography Images

      Automated Detection and Measurement of Corneal Haze and Demarcation Line in Spectral-Domain Optical Coherence Tomography Images

      Keratoconus is a progressive eye disease that may lead to significant loss of visual acuity. Corneal cross-linking (CXL) is a surgical procedure that halts the progression of Keratoconus. One commonly used clinical indicator of CXL success, albeit being an indirect one, is the presence and depth of stromal demarcation line. In addition, corneal haze beyond the demarcation line can be an ominous sign of loss of corneal transparency, which is a much-dreaded side-effect of CXL. To date, ophthalmologists evaluate the presence and depth of the demarcation line, and grade corneal haze using slit lamp biomicroscopy and/or optical coherence tomography ...

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    13. Automatic Subretinal Fluid Segmentation of Retinal SD-OCT Images With Neurosensory Retinal Detachment Guided by Enface Fundus Imaging

      Automatic Subretinal Fluid Segmentation of Retinal SD-OCT Images With Neurosensory Retinal Detachment Guided by Enface Fundus Imaging

      Objective: Accurate segmentation of neurosensory retinal detachment (NRD) associated subretinal fluid in spectral domain optical coherence tomography (SD-OCT) is vital for the assessment of central serous chorioretinopathy (CSC). A novel two-stage segmentation algorithm was proposed, guided by Enface fundus imaging. Methods: In the first stage, Enface fundus image was segmented using thickness map prior to detecting the fluid-associated abnormalities with diffuse boundaries. In the second stage, the locations of the abnormalities were used to restrict the spatial extent of the fluid region, and a fuzzy level set method with a spatial smoothness constraint was applied to subretinal fluid segmentation in ...

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    14. Automatic Side Branch Ostium Detection and Main Vascular Segmentation in Intravascular Optical Coherence Tomography Images

      Automatic Side Branch Ostium Detection and Main Vascular Segmentation in Intravascular Optical Coherence Tomography Images

      Intravascular optical coherence tomography (IVOCT) is the state-of-the-art imaging modality in percutaneous coronary intervention (PCI) planning and evaluation, in which side branch ostium and main vascular measurements play critical roles. However, manual measurement is time consuming and labor intensive. In this paper, we propose a fully automatic method for side branch ostium detection and main vascular segmentation to make up manual deficiency. In our method, side branch ostium points are firstly detected and subsequently used to divide the lumen contour into side branch and main vascular regions. Based on the division, main vascular contour is then smoothly fitted for segmentation ...

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    15. Statistical Models of Signal and Noise and Fundamental Limits of Segmentation Accuracy in Retinal Optical Coherence Tomography

      Statistical Models of Signal and Noise and Fundamental Limits of Segmentation Accuracy in Retinal Optical Coherence Tomography

      Optical coherence tomography (OCT) has revolutionized diagnosis and prognosis of ophthalmic diseases by visualization and measurement of retinal layers. To speed up quantitative analysis of disease biomarkers, an increasing number of automatic segmentation algorithms have been proposed to estimate the boundary locations of retinal layers. While the performance of these algorithms has significantly improved in recent years, a critical question to ask is how far we are from a theoretical limit to OCT segmentation performance. In this paper, we present the Cramèr-Rao lower bounds (CRLBs) for the problem of OCT layer segmentation. In deriving the CRLBs, we address the ...

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    16. Optimized computer-aided segmentation and 3D reconstruction using intracoronary optical coherence tomography

      Optimized computer-aided segmentation and 3D reconstruction using intracoronary optical coherence tomography

      We present a novel and time-efficient method for intracoronary lumen detection which produces three-dimensional (3D) coronary arteries using Optical Coherence Tomographic (OCT) images. OCT images are acquired for multiple patients and longitudinal cross-section (LOCS) images are reconstructed using different acquisition angles. The lumen contours for each LOCS image are extracted and translated to 2D cross-sectional images. Using two angiographic projections the centerline of the coronary vessel is reconstructed in 3D and the detected 2D contours are transformed to 3D and placed perpendicular to the centerline. To validate the proposed method, 613 manual annotations from medical experts were used as gold ...

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    17. Monitoring Kidney Microanatomy Changes During Ischemia-Reperfusion Process Using Texture Analysis of OCT Images

      Monitoring Kidney Microanatomy Changes During Ischemia-Reperfusion Process Using Texture Analysis of OCT Images

      Impact Statement: Tubular diameter has been developed previously as a potential biomarker for the transplant kidney. However, the tubular lumens were segmented out based on an empirically-determined threshold. In our study, a fully automatic texture analysis algorithm has been developed for OCT image analysis of kidney microanatomy during ischemia-reperfusion process. Our method can potentially be applicable in evaluating the status of donor kidneys prior to and after their transplantation. Abstract: Kidney ischemia-reperfusion (I/R) accounts for the majority of acute kidney injury cases, whose consequences are commonly encountered after kidney transplantation. Optical coherence tomography (OCT) has been applied to image ...

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    18. Sensitivity enhancement for low coherence interferometry

      Sensitivity enhancement for low coherence interferometry

      In this letter, a sensitivity improvement for systems combining low coherence interferometry (LCI) and microwave photonics (MWP) is demonstrated. This improvement is due to the introduction of a different modulation format and an exhaustive control of the optical source profile compared to previous MWP-LCI schemes. Our proposal allows to retrieve the visibility of low-coherence interferograms through the analysis of the interference pattern using a dispersive element. We demonstrate that the use of a phase modulator offers better stability and lower insertion loss since a bias point configuration is not needed compared to the intensity modulators typically used in these schemes ...

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    19. Automatic Identification of Weave Patterns of Checked and Colored Fabrics Using Optical Coherence Tomography

      Automatic Identification of Weave Patterns of Checked and Colored Fabrics Using Optical Coherence Tomography

      Identifying the weave pattern of fabrics can be done manually or automatically. Carrying out the weave recognition automatically will reduce the procedure time and error rates since automatic systems can perform successive measurements at high speeds and with great repeatability and quality. Woven fabric repeat identification systems that are automatic, usually work by employing complex algorithms and techniques. It is known that these automatic techniques struggle when trying to identify highly complex patterns, composing of a combination of different structures, figures, and colors. For example, image processing algorithms are known to make errors when dealing with checked and colored fabrics ...

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    20. Predicting Macular Edema Recurrence from Spatio-Temporal Signatures in Optical Coherence Tomography Images

      Predicting Macular Edema Recurrence from Spatio-Temporal Signatures in Optical Coherence Tomography Images

      Prediction of treatment responses from available data is key to optimizing personalized treatment. Retinal diseases are treated over long periods and patients’ response patterns differ substantially, ranging from a complete response to a recurrence of the disease and need for re-treatment at different intervals. Linking observable variables in high-dimensional observations to outcome is challenging. In this paper, we present and evaluate two different data-driven machine learning approaches operating in a high-dimensional feature space: sparse logistic regression and random forests-based extra trees (ET). Both identify spatio-temporal signatures based on retinal thickness features measured in longitudinal spectral-domain optical coherence tomography (OCT) imaging ...

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    21. Segmentation and Quantification for Angle-Closure Glaucoma Assessment in Anterior Segment OCT

      Segmentation and Quantification for Angle-Closure Glaucoma Assessment in Anterior Segment OCT

      Angle-closure glaucoma is a major cause of irreversible visual impairment and can be identified by measuring the anterior chamber angle (ACA) of the eye. The ACA can be viewed clearly through anterior segment optical coherence tomography (AS-OCT), but the imaging characteristics and the shapes and locations of major ocular structures can vary significantly among different AS-OCT modalities, thus complicating image analysis. To address this problem, we propose a data-driven approach for automatic AS-OCT structure segmentation, measurement, and screening. Our technique first estimates initial markers in the eye through label transfer from a hand-labeled exemplar data set, whose images are collected ...

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    22. Optimization of the Source Power Usage in Spectral Domain Optical Coherence Tomography

      Optimization of the Source Power Usage in Spectral Domain  Optical Coherence Tomography

      Source power consumption and system sensitivity of a spectrometer based optical coherence tomography (SD-OCT) system are investigated. Our study shows that the performance of SD-OCT system can be classified into two categories based on the beam splitting ratio R between the sample and reference rams in the Michelson interferometer. For the classic SD-OCT configuration, R is less than 1.0, and improvement of sample light collection efficiency through reducing R will increase the cost of OCT source power. We find that through combining the detection and source arms of a Michelson interferometer together with a fiber optic circulator and choosing ...

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    23. Size-Dependent Multiple-Scattering Effects of Mesoporous TiO2 Beads Distinguished by Optical Coherence Tomography

      Size-Dependent Multiple-Scattering Effects of Mesoporous TiO2 Beads Distinguished by Optical Coherence Tomography

      In this study, we propose a new analysis method using optical coherence tomography to further use the diffusive reflectance measurement to quantify the contribution of the size dependent multiple scattering effects of mesoporous TiO2 beads. The diffusive reflectance results from the complex interactions between light and the scattering particles, and influences the slopes of the associated depth dependent A-scan profiles, which can be fitted based on the extended Huygens-Fresnel model to quantify the contribution ratio of the multiple-scattering effects to the single scattering effects. The mesoporous TiO2 beads with average diameter of 300 nm show higher contribution percentage of multiple ...

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    24. Fully-Automated Segmentation of Fluid/Cyst Regions in Optical Coherence Tomography Images with Diabetic Macular Edema using Neutrosophic Sets and Graph Algorithm

      Fully-Automated Segmentation of Fluid/Cyst Regions in Optical Coherence Tomography Images with Diabetic Macular Edema using Neutrosophic Sets and Graph Algorithm

      This paper presents a fully-automated algorithm to segment fluid-associated (fluid-filled) and cyst regions in optical coherence tomography (OCT) retina images of the subjects with diabetic macular edema (DME). The OCT image is segmented using a novel neutrosophic transformation and a graph-based shortest path method. In neutrosophic domain, an image g is transformed into three sets: T (true), I (indeterminate) that represents noise, and F (false). This paper makes four key contributions. First, a new method is introduced to compute the indeterminacy set I, and a new λ-correction operation is introduced to compute the set T in neutrosophic domain. Second, a ...

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    1-24 of 269 1 2 3 4 ... 10 11 12 »
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