1. Articles from ingentaconnect.com

  2. 1-22 of 22
    1. Off-Line Fusion of Intravascular Ultrasound and Optical Coherence Tomography Images

      Off-Line Fusion of Intravascular Ultrasound and Optical Coherence Tomography Images

      Intravascular ultrasound (IVUS) and optical coherence tomography (IV-OCT) are widely used interventional imaging modalities to visualize vascular morphologies and identify atherosclerotic plaques. IVUS has high detection depth and low spatial resolution while IV-OCT has high resolution and poor tissue penetration. This work presents a registration and fusion method for IV-OCT and IVUS images acquired on a same vessel segment by separate imaging catheters. First, an IVUS image matched with an IV-OCT image is retrieved from the image sequence based on the Fourier descriptor of the detected lumen contour. Then, the IVUS image elastically deforms according to the geometrical transformation parameters ...

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    2. Detection and Classification of Retinal Diseases in Spectral Domain Optical Coherence Tomography Images Using Texture Analysis of Macula

      Detection and Classification of Retinal Diseases in Spectral Domain Optical Coherence Tomography Images Using Texture Analysis of Macula

      Optical coherence tomography (OCT) is becoming one of the most important modalities for noninvasive assessment of retinal eye diseases. With the introduction of spectral domain OCT (SD-OCT), complete macular scanning is achieved compared to the previous time-domain OCT technique. Recent advancement in the computer field, various methods and techniques in automatic image segmentation, processing and analysis gives us the opportunity to detect automatically the changes and degenerations in retinal images. Segmentation of retinal layers is extremely important for determining various retinal diseases affecting macula in computer aided retinal disease diagnosis systems. Our work aims for efficient and accurate segmentation of ...

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    3. Vessel Intimal Extraction of Coronary Optical Coherence Tomography Imagery Based on an Improved CV Model

      Vessel Intimal Extraction of Coronary Optical Coherence Tomography Imagery Based on an Improved CV Model

      Optical coherence tomography (OCT) is a novel technology used in coronary artery disease diagnosis for its high resolution. It has numerous advantages in 3D vessel modeling and vulnerable plaque quantification. This paper proposes a robust vessel intimal extraction algorithm using active contours. A pre-processing module, that takes into consideration the characteristics of coronary OCT imagery, is introduced to eliminate a variety of visual disruptions. Then, a monotonically decreasing function is added into the Chan-Vese (CV) method in order to avoid over segmentation. This is done by controlling the evolution speed in closing the boundary area. A postprocess is followed after ...

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    4. Suppression of Cardiac Motion Artifacts in Sequential Intracoronary Optical Coherence Images

      Suppression of Cardiac Motion Artifacts in Sequential Intracoronary Optical Coherence Images

      Background : Intracoronary optical coherence tomography (IC-OCT), an interventional imaging modality, has been used in clinical diagnosis of cardiac vessel diseases for decades. Motion artifacts caused by cardiac motion and pulsatile blood flow always hamper the visualization of sequential IC-OCT images acquired by continuously pulling back the imaging catheter within the vascular lumen. Method : Suppression of cardiac motion artifacts in an IC-OCT image sequence was addressed in this study. A signal implying cardiac phases was detected based on the cyclic variation of gray-scale features or the location of the lumen contour centroid along the overall image sequence. The local extrema of ...

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    5. Plasmon Resonant Silica-Coated Silver Nanoplates as Contrast Agents for Optical Coherence Tomography

      Plasmon Resonant Silica-Coated Silver Nanoplates as Contrast Agents for Optical Coherence Tomography

      Silica-coated silver nanostructures are identified as potential contrast agents for visible and near-infrared bio-imaging applications due to their high optical extinction caused by localized surface plasmon resonance (LSPR), improved chemical stability, and lower toxicity. We demonstrate the potential of plasmon resonant silica-coated silver nanoplates as a contrast agent for optical coherence tomography (OCT). It is shown that, triangular-shaped silica-coated silver nanoplates (SSNPs) with a side length of 170 ± 5 nm, base silver thickness of 10 ± 1 nm, and silica shell thickness of 40 ± 2 nm, exhibit higher optical extinction at a 1300 nm wavelength range, thus making them an excellent ...

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    6. Retrospective Respiratory Gating for Intravascular Ultrasound/Intravascular Optical Coherence Tomography Images

      Retrospective Respiratory Gating for Intravascular Ultrasound/Intravascular Optical Coherence Tomography Images

      Clinically acquired free-breathing interventional cardiac images are usually polluted by cardiac and respiratory motion artifacts. ECG-gating is one of widely used strategies to suppress cardiac motion artifacts in clinic. In this study, retrospective respiratory gating is addressed to suppress respiratory motion artifacts in ECG-gated free-breathing intravascular ultrasound (IVUS) and intravascular optical coherence tomography (IV-OCT) image sequences. The dimensionality of the data matrix representing the image sequence is firstly reduced with Laplacian Eigenmaps algorithm. A signal reflecting the respiratory phases is then detected. Gating frames in the same respiratory phase are finally selected by detecting local extrema of the respiratory motion ...

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    7. Improving image quality in intensity-interferometric spectral-domain optical coherence tomography

      Improving image quality in intensity-interferometric spectral-domain optical coherence tomography

      Intensity-interferometric spectral-domain optical coherence tomography (I-SD-OCT), devised recently as a classical analog of quantum OCT, enables axially scanless cross-sectional imaging with an immunity to group-velocity dispersion and a factor-of-sqrt{2}; resolution improvement. However, unwanted artifacts inevitably emerge in the resultant image. In this paper, it is demonstrated theoretically and experimentally that such artifacts can be reduced without any difficulty by means of either a mechanical displacement of the detector for capturing spectral intensity patterns or a numerical displacement of the spectral intensity patterns stored in a computer. Furthermore, it is proved that the I-SD-OCT signal can be extracted from the ...

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    8. Three-dimensional image reconstruction of macula from stratus optical coherence tomography (OCT) for diagnosis of macular degeneration

      Three-dimensional image reconstruction of macula from stratus optical coherence tomography (OCT) for diagnosis of macular degeneration

      Diagnosis of macular degeneration using a Stratus OCT with a fast macular thickness map (FMTM) method produced six B-scan images of macula from different angles. The images were converted into a retinal thickness chart to be evaluated by normal distribution percentile of data so that it can be classified as normal thickness of macula or as experiencing abnormality (e.g. thickening and thinning). Unfortunately, the diagnostic images only represent the retinal thickness in several areas of the macular region. Thus, this study is aims to obtain the entire retinal thickness in the macula area from Status OCT's output images ...

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    9. Optical Coherence Tomography of Pulmonary Arterial Walls in Humans and Pigs (Sus scrofa domesticus)

      Optical Coherence Tomography of Pulmonary Arterial Walls in Humans and Pigs (Sus scrofa domesticus)

      Pulmonary arterial hypertension (PAH) is a devastating disorder characterized by progressive elevation of the pulmonary pressures that, in the absence of therapy, results in chronic right-heart failure and premature death. The vascular pathology of PAH is characterized by progressive loss of small (diameter, less than 50 μm) peripheral pulmonary arteries along with abnormal medial thickening, neointimal formation, and intraluminal narrowing of the remaining pulmonary arteries. Vascular pathology correlates with disease severity, given that hemodynamic effects and disease outcomes are worse in patients with advanced compared with lower-grade lesions. Novel imaging tools are urgently needed that demonstrate the extent of vascular ...

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    10. Image Enhancement of Common-Path Fourier-Domain Optical Coherence Tomography for Monitoring Osteoarthritis in Rats Using a Non-Linear Anisotropic Filter

      Image Enhancement of Common-Path Fourier-Domain Optical Coherence Tomography for Monitoring Osteoarthritis in Rats Using a Non-Linear Anisotropic Filter

      We utilized internally developed common-path Fourier-domain optical coherence tomography (CP-FDOCT) to monitor the deterioration of articular cartilage in rats with osteoarthritis (OA), Monosodium iodoacetate (MIA) was injected into the knee joint to observe the progression of OA. We terminated rats at intervals of one, two, and three weeks, and acquired subsequent CP-FDOCT and histological images. The histological images demonstrated similar patterns to OCT images. These results indicated the significant potential of CP-FDOCT for use in the non-invasive diagnosis of OA. The image quality was greatly improved by using a non-linear anisotropic filter on the OCT images acquired from the developed ...

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    11. Optical Coherence Tomography of Pulmonary Arterial Walls in Humans and Pigs (Sus scrofa domesticus)

      Optical Coherence Tomography of Pulmonary Arterial Walls in Humans and Pigs (Sus scrofa domesticus)

      Pulmonary arterial hypertension (PAH) is a devastating disorder characterized by progressive elevation of the pulmonary pressures that, in the absence of therapy, results in chronic right-heart failure and premature death. The vascular pathology of PAH is characterized by progressive loss of small (diameter, less than 50 μm) peripheral pulmonary arteries along with abnormal medial thickening, neointimal formation, and intraluminal narrowing of the remaining pulmonary arteries. Vascular pathology correlates with disease severity, given that hemodynamic effects and disease outcomes are worse in patients with advanced compared with lower-grade lesions. Novel imaging tools are urgently needed that demonstrate the extent of vascular ...

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    12. Group Refractive Index Measurement of Liquids Using Common-Path Swept Source Optical Coherence Tomography

      Group Refractive Index Measurement of Liquids Using Common-Path Swept Source Optical Coherence Tomography

      A fiber-optic based common-path swept source optical coherence tomography for a simple and high-resolution measurement of the group refractive indices of liquids has been investigated. The group refractive index measurement has been based on the optical length change before and after injection of liquid into a transparent glass tube. The gas-cell referenced fiber based common-path swept source optical coherence tomography instrument was utilized to obtain the group refractive indices of liquids. The standard deviations of the group refractive indices measured by this method were about 1 × 10–4. The measurement results on the group refractive indices of liquids showed an ...

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    13. Iterative Nonlocal Means Method for Despeckling Optical Coherence Tomography Images

      Iterative Nonlocal Means Method for Despeckling Optical Coherence Tomography Images

      Speckle reduction in optical coherence tomography (OCT) images plays an important role in facilitating further image analysis. Existing despeckling methods generally tend to provide insufficient speckle suppression or limited detail preservation especially at high speckle corruption. To address this problem, this paper proposes a novel iterative nonlocal means (NLM) method to restore OCT images. Different from the classical NLM method, the proposed method computes the weight using an improved weight function in an iterative way and it determines the decay parameter based on the classification of image pixels. The experiments on the clinical OCT images indicate that the proposed method ...

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    14. Development of the Opto-Mechanical Scanning System for Biological Imaging Applications

      Development of the Opto-Mechanical Scanning System for Biological Imaging Applications

      An opto-mechanical scanning system has been widely used for many biological applications such as in optical coherence tomography, confocal microscopy, and digital imaging system. This study was to design and build an optical scanning system, a pre-objective scanning, which allows the lateral scanning as well as depth scanning. The scanning lenses were determined by considering all possible aberrations. To verify the scanning lens system, a test was performed both computationally and experimentally. From overall the results that acquired both computationally and experimentally, the spot diameters were relatively consistent. Integration of the optical scanning system in various lab-based imaging systems like ...

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    15. Depth-Resolved Multilayer Pigment Identification in Paintings: Combined Use of Laser-Induced Breakdown Spectroscopy (LIBS) and Optical Coherence Tomography (OCT)

      Depth-Resolved Multilayer Pigment Identification in Paintings: Combined Use of Laser-Induced Breakdown Spectroscopy (LIBS) and Optical Coherence Tomography (OCT)

      A detailed feasibility study on the combined use of laser-induced breakdown spectroscopy with optical coherence tomography (LIBS/OCT), aiming at a realistic depth-resolved elemental analysis of multilayer stratigraphies in paintings, is presented. Merging a high spectral resolution LIBS system with a high spatial resolution spectral OCT instrument significantly enhances the quality and accuracy of stratigraphic analysis. First, OCT mapping is employed prior to LIBS analysis in order to assist the selection of specific areas of interest on the painting surface to be examined in detail. Then, intertwined with LIBS, the OCT instrument is used as a precise profilometer for the ...

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    16. Calluses, Corns and Heel Fissures

      Calluses, Corns and Heel Fissures

      Hypertrophy of the plantar stratum corneum (SC) of the epidermis (also known as hyperkeratosis) is one of the skin's primary protective responses, triggered by either physiological stresses, a result of underlying disease (eg, psoriasis, palmoplantar keratoderma), or external mechanical stresses. In the case of the foot the most common presentations of hyperkeratosis are: anhidrosis, calluses, corns and heel fissures. This article reviews the current evidence in the field of hyperkeratosis of the foot and will present the treatment options available to practitioners and patients. The gaps in the knowledge surrounding the efficacy of treatments are discussed and novel methods ...

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    17. Living Brain Optical Imaging: Technology, Methods and Applications

      Living Brain Optical Imaging: Technology, Methods and Applications

      Within the last few decades, optical imaging methods have yielded revolutionary results when applied to all parts of the central nervous system. The purpose of this review is to analyze research possibilities and limitations of several novel imaging techniques and show some of the most interesting achievements obtained by these methods. Here we covered intrinsic optical imaging, voltage-sensitive dye, photoacoustic, optical coherence tomography, near-infrared spectroscopy and some other techniques. All of them are mainly applicable for experimental neuroscience but some of them also suitable for the clinical studies.

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    18. The Role of Optical Coherence Tomography Raster Imaging as a Valuable Diagnostic Tool in the Differential Between Optic Disc Hemorrhage and Vitreopapillary Traction

      The Role of Optical Coherence Tomography Raster Imaging as a Valuable Diagnostic Tool in the Differential Between Optic Disc Hemorrhage and Vitreopapillary Traction

      An acute presentation of an optic disc hemorrhage can indicate true optic nerve head damage or can be a result of tractional forces on the vitreopapillary interface. An isolated optic disc hemorrhage secondary to vitreopapillary traction (VPT) can mimic the clinical presentation of a glaucomatous process or that of an underlying ocular or systemic condition. This article highlights the use of spectral domain optical coherence tomography (SD-OCT) 5 line raster (5LR) in differentiating true optic disc hemorrhages from those as a result of tractional forces. Two examples are given of patients presenting to our clinic with unilateral optic disc hemorrhages ...

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    19. Endoscopic Microscopy Using Optical Coherence Tomography

      Endoscopic Microscopy Using Optical Coherence Tomography

      Optical coherence tomography (OCT) can perform high-speed, micron-level high resolution imaging of tissue microstructures in vivo and in real time and can function as a type of optical biopsy to visualize the structural and functional alterations associated with various diseases. The advances in endoscopic OCT and optical coherence microscopy (OCM) provide an exciting avenue for many promising clinical applications with the potential of enhancing diagnostic capabilities and treatment efficacies. In this review paper, we first review the basic principles for time- and Fourierdomain OCT. We then survey the various endoscopic OCT technologies followed by the review of several representative clinical ...

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    20. Using optical coherence tomography to characterize thick-glaze structure: Chinese Southern Song Guan glaze case study

      Using optical coherence tomography to characterize thick-glaze structure: Chinese Southern Song Guan glaze case study

      This study explores the structure characteristics of thick glaze, in terms of the case study of Chinese Southern Song Guan (SSG) ware, focusing on the bubble and its media structure, using a novel focus-tracking optical coherence tomography (OCT) system. The OCT images we obtained not only unveil the structural uniqueness of the thick-glaze SSG sample, but also establish a distinguishable structural pattern for aiding authentication. In addition, information revealed in our images provides a logical explanation for the subtle texture and tone of SSG glaze as well as insights into the technologies used in layering and firing these thick glazes.

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    21. Effect of Composition, Dimension and Shape on the Optical Properties of Gold Nanoparticles—A Theoretical Analysis

      Effect of Composition, Dimension and Shape on the Optical Properties of Gold Nanoparticles—A Theoretical Analysis

      Gold nanoparticles have great potential towards optical investigations in biological tissues which include imaging applications as well as therapeutic applications. However, the effectiveness of these techniques is greatly governed by the optical properties of the nanoparticles which are determined by its shape, size and composition and a variety of computational methods can be adopted to determine their optical efficiencies. A systematic study based on the finite-difference time-domain (FDTD) method was carried out to determine the trends in the optical properties of gold nanoparticles of varying sizes, shapes and compositions over a wavelength range of 380 nm-1064 nm. The finite difference ...

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    22. Optical Coherence Tomography of the Anterior Segment

      Perhaps no diagnostic technology has emerged as rapidly in ophthalmology as optical coherence tomography (OCT). A single clinical device for this noninvasive imaging technique was first released in 1996, and now at least ten clinical devices are available. Although the first clinical anterior segment OCT was marketed only 2 years ago, a substantial amount of work has been done using modified retinal imagers or prototype laboratory-based imagers. In this review, we discuss OCT imaging primarily o
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    1-22 of 22
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