1. All Articles

    1-24 of 15212 1 2 3 4 ... 632 633 634 »
    1. Feature Of The Week 9/21/14: National Univerity of Singapore Investigates OCT as a Tool for Characterization of Complex Biological Surfaces Including Morphology of Crab Shells

      Feature Of The Week 9/21/14: National Univerity of Singapore Investigates OCT as a Tool for Characterization of Complex Biological Surfaces Including Morphology of Crab Shells

      The advent of scanning electron microscopy has facilitated our understanding of the In recent years, there has been a growing interest in the study of natural biological surfaces in the search for novel solutions in surface engineering design from nature. Most methods for surface imaging of natural biological samples are however, sacrificial and require that samples be sectioned and prepared for characterization. One example is the use of the scanning electron microscope (SEM) to obtain detailed images of microtopography, where a section of the specimen is cut and sputter coated with electrically conductive material like gold or platinum for scanning ...

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    2. Wavelet transform-based method of compensating dispersion for high-resolution imaging in SDOCT

      Wavelet transform-based method of compensating dispersion for high-resolution imaging in SDOCT

      The axial resolution is an important parameter in Optical Coherence Tomography (OCT). In OCT a broadband light source is used to achieve high axial resolution imaging. However the dispersion results in a broadening of the coherence envelope. The dispersion mismatch between reference and sample arms then needs to be minimized to achieve optimal axial resolution for OCT. In this work we propose a new numerical dispersion compensation method to obtain ultrahigh resolution in SDOCT, in which wavelet transform instead of Fourier transform is used to obtain the signal in different frequency domain. And a series of the phase signals of ...

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    3. 3D Polymer Weld Seam Characterization Based on Optical Coherence Tomography for Laser Transmission Welding Applications

      3D Polymer Weld Seam Characterization Based on Optical Coherence Tomography for Laser Transmission Welding Applications

      Laser transmission welding is an established single-stage plastic joining process, which enables hermetically sealed joints under the workpiece surface. The process requires joining partners with proper degrees of transmission and absorption to the processing wavelength. For reaching a stable process an in-process quality assurance is very valuable. Current monitoring systems have a limited usage, as no quantitative information of the weld itself is obtained without its destruction. In medical and pharmaceutical applications a weld with leakage is e.g. unacceptable. The main objective of this paper is the presentation of the optical coherence tomography as a tool for the quality ...

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    4. Relation of joint spectral and time domain optical coherence tomography (jSTdOCT) and phase-resolved Doppler OCT

      Relation of joint spectral and time domain optical coherence tomography (jSTdOCT) and phase-resolved Doppler OCT

      A variety of promising approaches for quantitative flow velocity measurement in OCT have been proposed in recent years. The question is: Which method gets the most precise flow velocity out of the interference signals detected. We have compared the promising joint spectral and time domain optical coherence tomography (jSTdOCT) and the commonly used phase-resolved Doppler OCT (DOCT) and describe the link between these two proven methods for OCT in the Fourier domain (FD OCT). First, we show that jSTdOCT can be significantly improved by calculating the center of gravity via an unbiased complex algorithm instead of detecting the maximum intensity ...

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    5. Optimization of compute unified device architecture for real-time ultrahigh-resolution optical coherence tomography

      Optimization of compute unified device architecture for real-time ultrahigh-resolution optical coherence tomography

      We propose an optimized signal processing scheme that utilizes the compute unified device architecture (CUDA) for real-time spectral domain optical coherence tomography (OCT). Because linear spline interpolation and the direct spectral reshaping method have low data and control dependencies, these algorithms maximally utilize graphic processing unit (GPU) resources for dispersion control. In addition, data transfer between main memory and GPU, regarded as one of the most wasteful and time-consuming processes in GPU computing, is executed in parallel with the signal processing by overlapping kernel execution and data transfers. Experimental results obtained from application of the proposed scheme to a laboratory ...

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      Mentions: Korea University
    6. In vivo analysis of burns in a mouse model using spectroscopic optical coherence tomography

      In vivo analysis of burns in a mouse model using spectroscopic optical coherence tomography

      Spectroscopic analysis of biological tissues can provide insight into changes in structure and function due to disease or injury. Depth-resolved spectroscopic measurements can be implemented for tissue imaging using optical coherence tomography (OCT). Here, spectroscopic OCT is applied to in vivo measurement of burn injury in a mouse model. Data processing and analysis methods are compared for their accuracy. Overall accuracy in classifying burned tissue was found to be as high as 91%, producing an area under the curve of a receiver operating characteristic curve of 0.97. The origins of the spectral changes are identified by correlation with histopathology.

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    7. Novel insights provided by spectral-domain coherent tomography in pediatric ophthalmology

      Novel insights provided by spectral-domain coherent tomography in pediatric ophthalmology

      Tilted disk syndrome (TDS) is observed in approximately 1 % to 2 % of the population. This percentage appears to be highly variable according to the clinical and imaging features retained for establishing the accurate diagnosis. It is of paramount importance to distinguish isolated tilted optic disk from TDS. This syndrome has a number of alternative nomenclatures such as the nasal fundus ectasia syndrome, inversion of the optic disk, inverse myopia, and dysversion of the optic disk. TDS may be a variant of colobomatous defects. The definition of TDS has often been inaccurate in many studies which did not take account of ...

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    8. Orion is in Beta - Voxeleron prepares the release of their advanced OCT analysis software

      Orion is in Beta - Voxeleron prepares the release of their advanced OCT analysis software

      Orion™, Voxeleron’s advanced optical coherence tomography (OCT) analysis software, is currently being beta tested at a number of sites in the USA and Europe in preparation for release. Orion™ is an application that offers fully-automated, rapid and accurate segmentation of seven layers in OCT images of the human retina. Following the successful release of InSight , Voxeleron’s animal OCT package, Orion™ establishes Voxeleron as leaders in the development of OCT image analysis software. "The Orion software gives us the ability to measure the thickness of the nuclear layers in isolation, so is a welcome addition to our quantification tools ...

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    9. Two-dimensional optical coherence tomography for real-time structural dynamical characterization

      Two-dimensional optical coherence tomography for real-time structural dynamical characterization

      We present a two-dimensional optical coherence vibration tomography (2DOCVT) system with an ultra-precision displacement resolution of ~0.1 nm that is capable of in site real-time absolute displacement measurement of structural line vibrations. Experimental results of sinusoidal, sweep and impulse vibrations were reported. The key figures of merit such as the 2DOCVT system could obtain fast line vibration measurement without scanning and it also could be used to capture structural modal parameters in one single impulse excitation measurement without any vibration excitation input information, making it attractive for the application in low-frequency vibration measurement and response-only modal analysis.

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    10. A novel method to assess coronary artery bifurcations by OCT: cut-plane analysis for side-branch ostial assessment from a main-vessel pullback

      A novel method to assess coronary artery bifurcations by OCT: cut-plane analysis for side-branch ostial assessment from a main-vessel pullback

      Aims In coronary bifurcations assessment, evaluation of side-branch (SB) ostia by an optical coherence tomography (OCT) pullback performed in the main branch (MB) could speed up lesion evaluation and minimize contrast volume. Dedicated software that reconstructs the cross-sections perpendicular to the SB centreline could improve this assessment. We aimed to validate a new method for assessing the SB ostium from an OCT pullback performed in the MB. Methods and results Thirty-one sets of frequency-domain OCT pullbacks from 28 patients, both from the MB and the SB of a coronary artery bifurcation were analysed. Measurements of the SB ostium from the ...

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    11. Repeatability of peripapillary retinal nerve fiber layer and inner retinal thickness among 2 spectral domain optical coherence tomography devices

      Repeatability of peripapillary retinal nerve fiber layer and inner retinal thickness among 2 spectral domain optical coherence tomography devices

      PURPOSE. To compare measurement of macular inner retina and peripapillary retinal nerve fiber layer (pRNFL) thickness using 2 spectral-domain optical coherence tomography (OCT) devices in glaucoma patients, patients with ocular hypertension, idiopathic and atypical Parkinson's disease and healthy controls. METHODS. One-hundred seventy-one eyes of 146 participants underwent successful pRNFL and macular scanning and automated measurement of ganglion cell layer + inner plexiform layer (GCL-IPL) using Cirrus® HD-OCT or retinal nerve fiber layer + ganglion cell layer + inner plexiform layer (RNFL-GCL-IPL) using RTVue-100®. Macular RNFL was added to the GCL-IPL thickness measured by Cirrus and was compared to the RNFL-GCL-IPL thickness of ...

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    12. Effect of elevated intraocular pressure on the thickness changes of cat laminar and prelaminar tissue using optical coherence tomography

      Effect of elevated intraocular pressure on the thickness changes of cat laminar and prelaminar tissue using optical coherence tomography

      The aim of this study was to examine shape the changes of the lamina cribrosa (LC) under different intraocular pressures (IOPs) with different periods. Images of the optic nerve head were obtained using enhanced depth imaging spectral domain optical coherence tomography (EDI SD-OCT). After an initial scan of the IOP at native pressure, subsequent scanning was taken when the IOP values reached 40, 60, 80 and 100 mm Hg. Then scans continued with the IOP maintained at 100 mm Hg for 1 hour, 2 hours, 3 hours and 4 hours. The thicknesses of the LC and prelaminar tissue were measured ...

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    13. In Vivo Three-Dimensional Characterization of the Healthy Human Lamina Cribrosa with Adaptive Optics Spectral-Domain Optical Coherence Tomography

      In Vivo Three-Dimensional Characterization of the Healthy Human Lamina Cribrosa with Adaptive Optics Spectral-Domain Optical Coherence Tomography

      Purpose: To characterize the in vivo 3D lamina cribrosa (LC) microarchitecture of healthy eyes using adaptive optics spectral-domain optical coherence tomography (AO-SDOCT). Methods: One randomly selected eye from each of 18 healthy subjects was scanned with Cirrus HD-OCT and AO-SDOCT centered on the optic nerve head. LC microarchitecture, imaged by the later device, was semi-automatically segmented and quantified for connective tissue volume fraction (CTVF), beam thickness, pore diameter, pore area and pore aspect ratio. The LC was assessed in central and peripheral regions of equal areas, quadrants and with depth. A linear mixed-effects model weighted by the fraction of visible ...

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    14. Accommodation-induced variations in retinal thickness measured by spectral domain optical coherence tomography

      Accommodation-induced variations in retinal thickness measured by spectral domain optical coherence tomography

      To research retinal stretching or distortion with accommodation, accommodation-induced changes in retinal thickness (RT) in the macular area were investigated in a population of young adults ( n = 23 ) by using a dual-channel spectral domain optical coherence tomography (SD-OCT) system manufactured in-house for this study. This dual-channel SD-OCT is capable of imaging the cornea and retina simultaneously with an imaging speed of 24 kHz A-line scan rate, which can provide the anatomical dimensions of the eye, including the RT and axial length. Thus, the modification of the RT with accommodation can be calculated. A significant decrease in the RT ( 13.50 ...

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    15. High-definition optical coherence tomography of melanocytic skin lesions

      High-definition optical coherence tomography of melanocytic skin lesions

      High-definition optical coherence tomography and the corresponding vertically sectioned histology of a compound naevus. High-definition optical coherence tomography (HD-OCT) scanners have recently been developed. We assessed micromorphological HD-OCT correlates of benign naevi (BN) and malignant melanoma (MM). 28 BN and 20 MM were studied using HD-OCT and histology. Epidermal honeycomb/cobblestone pattern, regular junctional cell nests, and edged papillae are more often observed in BN, whereas fusion of rete ridges, pagetoid cells and junctional and/or dermal nests with atypical cells are more frequently seen in MM. A high overlap of HD-OCT features in BN and MM was observed and ...

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    16. Latest Data Shows OrbusNeich's COMBO™ Dual Therapy Stent has Excellent

      Latest Data Shows OrbusNeich's COMBO™ Dual Therapy Stent has Excellent

      Prof. Stephen W.L. Lee presented two-year optical coherence tomography (OCT) findings and three-year clinical follow up from the EGO COMBO study, providing further evidence to support the healing benefits of the COMBO Dual Therapy Stent, the only drug eluting stent (DES) with active EPC capture technology. The findings were presented during the 26th Annual Transcatheter Cardiovascular Therapeutics (TCT) meeting, held in Washington, D.C. , September 13-17, 2014 . "This is the first study to assess the healing profile of a dual therapy stent by optical coherence tomography," said Prof. Stephen W.L. Lee , M.D., of the Queen Mary Hospital ...

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    17. New Study Assesses the Utility of Optical Coherence Tomography During Stent Implantation in Primary PCI

      New Study Assesses the Utility of Optical Coherence Tomography During Stent Implantation in Primary PCI

      The first randomized trial to examine serial optical coherence tomography (OCT) in primary percutaneous coronary intervention (PCI) was reported today at the 26 th annual Transcatheter Cardiovascular Therapeutics (TCT) scientific symposium. Sponsored by the Cardiovascular Research Foundation (CRF), TCT is the world’s premier educational meeting specializing in interventional cardiovascular medicine. OCT uses light emitted from an intravascular catheter to capture high-resolution cross sectional imaging from within coronary arteries. OCT STEMI is the first randomized multicenter study to examine routine use of OCT guidance during stent implantation in patients with ST-elevation myocardial infarction (STEMI, the most serious form of a ...

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    18. Causes of very late stent thrombosis investigated using optical coherence tomograph

      Causes of very late stent thrombosis investigated using optical coherence tomograph

      Objective Very late stent thrombosis (VLST) remains an unresolved problem, and recent reports have indicated that VLST onset can occur in patients treated with both drug-eluting stents (DES) and bare metal stents (BMS). We evaluated the causes of VLST using optical coherence tomography (OCT). Methods OCT was performed in 22 patients (12 DES-treated patients, 10 BMS-treated patients). Because two instances of VLST occurred simultaneously in one case in the DES group, the DES group comprised 13 lesions, while the BMS group comprised 10 lesions. All struts were counted in each frame, and the proportion of uncovered or malapposed struts was ...

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    19. Optical coherence tomography in the diagnosis of basal cell carcinoma

      Optical coherence tomography in the diagnosis of basal cell carcinoma

      Since its introduction in dermatology in the late 1990s optical coherence tomography (OCT) has been used to study many skin diseases, in particular non-melanoma skin cancer and it s precursors. Special attention has been paid to superficial basal cell carcinoma (BCC), and a number of smaller observational studies have been published. The diagnostic criteria for BCC of these studies are systematically reviewed. A systemic review of English language studies was performed using PubMed, Google Scholar and Royal Danish Library, to search for primary papers on OCT and BCC. The references of retrieved papers were searched by hand for further relevant ...

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    20. Corneal assessment technologies: Current status

      Corneal assessment technologies: Current status

      There are now many devices that acquire data about the cornea: shape, power, pachymetry at any desired point of the cornea, corneal hysteresis, flap thickness (in LASIK procedures), endothelial cell count and morphology, and so forth. We review the literature on corneal assessment techniques and devices available in clinical practice. Specifically, we discuss slit lamp biomicroscopy, specular microscopy, ultrasound pachymetry, confocal microscopy, very-high-frequency digital ultrasound biomicroscopy, optical coherence tomography, Placido disk-based keratoscopy, slit-scanning elevation topography, Scheimpflug imaging, and dynamic applanation procedures—all of which can be used to assess the morphology of the cornea. In addition, we present a critical ...

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    21. Treatment Outcomes and Spectral Domain Optical Coherence Tomography Findings of Eyes with Symptomatic Vitreomacular Adhesion Treated with Intravitreal Ocriplasmin

      Treatment Outcomes and Spectral Domain Optical Coherence Tomography Findings of Eyes with Symptomatic Vitreomacular Adhesion Treated with Intravitreal Ocriplasmin

      Purpose To determine treatment outcomes of intravitreal ocriplasmin in symptomatic vitreomacular adhesion Design Retrospective interventional case series Methods: Setting Private practice Study population 35 eyes (35 subjects) with symptomatic vitreomacular adhesion Intervention/Observation Intravitreal ocriplasmin injection from February-November 2013 Main Outcome Measure Vitreomacular adhesion resolution rate. Secondary endpoints included post-injection visual acuity, and rates of outer retinal attenuation and full thickness macular hole (MH) closure. Results The 35 subjects included were of mean age 69 years, 66% female, and 71% phakic. Eleven (31%) cases had macular co-morbidities. Average adhesion diameter was 571 micrometers (μm), with mean 7.9 months duration ...

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    22. Macular Thickness Measurements in Normal Eyes Using Spectral Domain Optical Coherence Tomography

      Macular Thickness Measurements in Normal Eyes Using Spectral Domain Optical Coherence Tomography

      BACKGROUND AND OBJECTIVE: Knowledge of the macular thickness in a normal population is important for the evaluation of pathological macular change. The purpose of this study was to define and measure macular thickness in normal eyes using spectral domain optical coherence tomography (OCT). PATIENTS AND METHODS: Fifty eyes from 50 normal subjects (29 men and 21 women, aged 22 to 68 years) were scanned with a prototype Cirrus HD-OCT system (5 µm axial resolution) (Carl Zeiss Meditec, Inc.). The proprietary Cirrus segmentation algorithm was used to produce retinal thickness maps, which were then averaged over 9 regions defined by a ...

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    23. Preliminary Design and Evaluation of a B-Scan OCT-Guided Needle

      Preliminary Design and Evaluation of a B-Scan OCT-Guided Needle

      Real-time intraoperative B-scan optical coherence tomography (OCT) visualization of intraocular tissues is a desired ophthalmic feature during retinal procedures. A novel intraocular 25-gauge B-mode forward-imaging OCT probe was combined with a 36-gauge needle into a prototype instrument. Imaging of the needle tip itself and the effects of saline injection into a gelatin phantom were performed. A combined B-scan forward-imaging OCT-needle prototype was capable of real-time-imaging of saline injection into a gelatin phantom. Additional future miniaturization may permit this instrument to be an adjunctive real-time imaging and procedure tool for vitreoretinal surgery.

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