1. All Articles

    25-48 of 15205 « 1 2 3 4 5 ... 632 633 634 »
    1. Optical microcavity scanning 3D tomography

      Optical microcavity scanning 3D tomography

      A scanning optical microcavity is exploited to achieve lens-free 3D tomography of microfluidic channels. The microcavity, powered by a low-coherence source, is realized by approaching a cleaved fiber to few tens of micrometers over the sample. The interference of scattered waves inside the cavity shapes the transverse field distribution by focusing the beam and overcoming the diffraction limit due to the optical-fiber numerical aperture. The focusing effect is also preserved in the inner layers of the sample, allowing optical 3D tomography. Analysis of microfluidic channels was demonstrated through this noninvasive technique. Although the experimental setup recalls the well-known fiber-optic Fourier-domain ...

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    2. In vivo functional microangiography by visible-light optical coherence tomography

      In vivo functional microangiography by visible-light optical coherence tomography

      Although hemoglobin oxygen saturation (sO 2 ) in the microvasculature is an essential physiological parameter of local tissue functions, non-invasive measurement of microvascular sO 2 is still challenging. Here, we demonstrated that visible-light optical coherence tomography (vis-OCT) can simultaneously provide three-dimensional anatomical tissue morphology, visualize microvasculature at the capillary level, and measure sO 2 from the microvasculature in vivo . We utilized speckle contrast caused by the moving blood cells to enhance microvascular imaging. We applied a series of short-time inverse Fourier transforms to obtain the spectroscopic profile of blood optical attenuation, from which we quantified sO 2 . We validated the sO ...

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    3. New York University School of Medicine Receives 2014 NIH Grant to Study Hyperspectral Imaging of the Normal and Age-Related Macular Degeneration Fundus

      New York University School of Medicine Receives  2014 NIH Grant to Study Hyperspectral Imaging of the Normal and Age-Related Macular Degeneration Fundus

      A team with world-class expertise in ophthalmic disease, imaging, retinal pathology, and biomedical engineering will utilize hyperspectral imaging to provide, for the first time, in vivo molecular probing, validated with histopathologic correlation, of age-related macular degeneration (AMD). Their system, a specially modified fundus camera harnessed to cutting-edge biomedical image analysis techniques, will revolutionize the field by identifying the distribution and spectral signature of the various chromophores and fluorophores associated with AMD lesions. Drusen, the hallmark lesions of AMD, are biochemically heterogeneous and are key to understanding this disease. However, their composition cannot be determined in vivo with even the current ...

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    4. University of Texas at Arlington Receives NIH Grant to Study All Optical Control and Monitoring of Neural Activity.

      University of Texas at Arlington Receives NIH Grant to Study All Optical Control and Monitoring of Neural Activity.

      University of Texas at Arlington Received at 2014 NIH Grant for $206,065 to Study All Optical Control and Monitoring of Neural Activity. The principal investigator is Samarendra Mohanty. The program began in 2014 and ends in 2015. Below is a summary of the propose work. Success of optogenetic intervention of neural activity requires optimization of delivery of genes encoding light sensitive proteins (opsins) to specific cells, and to record the changes in cells and tissue during optogenetic stimulation. The most-commonly used method for delivering opsin(s) is use of viral vector, which is prone to cause unexpected inflammatory responses ...

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    5. OCT STEMI: Optical Coherence Tomography Guidance During Primary PCI in AMI

      OCT STEMI: Optical Coherence Tomography Guidance During Primary PCI in AMI

      The OCT STEMI trial presented Sept. 14 at TCT 2014 looked at optical coherence tomography (OCT) guidance during drug-eluting stent implantation in patients with ST segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI), and was the first randomized trial to look at serial OCT in primary PCI, but ultimately showed that larger randomized trials are needed on this topic to assess potential benefit. Led by principal investigator Pavel Červinka, MD, PhD, First Department of Cardio-Angiology and Internal Medicine, Faculty Hospital Hradec Králové, Czech Republic, the trial enrolled 201 patients, who were pre-treated with aspirin, heparin and ...

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    6. Point-of-care and point-of-procedure optical imaging technologies for primary care and global health

      Point-of-care and point-of-procedure optical imaging technologies for primary care and global health

      Leveraging advances in consumer electronics and wireless telecommunications, low-cost, portable optical imaging devices have the potential to improve screening and detection of disease at the point of care in primary health care settings in both low- and high-resource countries. Similarly, real-time optical imaging technologies can improve diagnosis and treatment at the point of procedure by circumventing the need for biopsy and analysis by expert pathologists, who are scarce in developing countries. Although many optical imaging technologies have been translated from bench to bedside, industry support is needed to commercialize and broadly disseminate these from the patient level to the population ...

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    7. Feature Of The Week 9/14/14: UC Davis Investigates Brain Imaging with Optical Coherence Tomography

      Feature Of The Week 9/14/14: UC Davis Investigates Brain Imaging with Optical Coherence Tomography

      One of the nine high priority research areas in the recent BRAIN Initiative (executive summary available at HERE ) is to “Delineate mechanisms underlying human brain imaging technologies.” While empowering tools such as two-photon microscopy, used in conjunction with dyes and indicators, can image cellular and vascular activity, even measuring activity in all cells and vessels comprising a single voxel in a functional magnetic resonance imaging (fMRI) scanner remains a daunting task. Hence, mesoscopic imaging tools are needed to help bridge the gap between microscopic and macroscopic (human brain level) findings. Here, using Optical Coherence Tomography angiography at 1300 nm, we ...

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    8. Dependability of Posterior-Segment Spectral Domain Optical Coherence Tomography for Measuring Central Corneal Thickness

      Dependability of Posterior-Segment Spectral Domain Optical Coherence Tomography for Measuring Central Corneal Thickness

      Purpose: The aim of this study was to assess the intersession and interobserver reliability of central corneal thickness (CCT) measurements using a posterior-segment spectral domain optical coherence tomography (SD-OCT). Methods: Sixty patients were examined with a posterior-segment SD-OCT system (Topcon 3D-OCT). To analyze intersession reproducibility, 1 examiner measured CCT in 60 eyes 2 times 1 week apart, and to study interobserver reproducibility, a second examiner obtained another measurement during the first session. Within-subject reproducibility, coefficient of reproducibility (CR), and intraclass correlation coefficients (ICC) were calculated. Agreement between Topcon 3D OCT and ultrasound pachymetry (USP) was also assessed. Results: Posterior-segment SD-OCT ...

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    9. Assessment of Retinal Alterations after Intravitreal Ocriplasmin with Spectral Domain-Optical Coherence Tomography

      Assessment of Retinal Alterations after Intravitreal Ocriplasmin with Spectral Domain-Optical Coherence Tomography

      Ocriplasmin (Jetrea, Thrombogenics, Leuven, Belgium) was recently approved by the United States Food and Drug Administration for the treatment of symptomatic vitreomacular traction (VMT). The MIVI-TRUST phase III randomized, controlled trials revealed that intravitreal ocriplasmin had superior efficacy for VMT resolution compared with placebo vehicle injection. 1 Qualitative identification of outer retinal changes after ocriplasmin injection that were not previously recognized in the MIVI-TRUST trials have recently been described.

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    10. Optical Coherence Tomography Imaging of the Proximal Lacrimal System

      Optical Coherence Tomography Imaging of the Proximal Lacrimal System

      Abstract Introduction: There are currently no routinely used imaging modalities for the proximal lacrimal system. Optical Coherence Tomography (OCT) is a safe and non-invasive method of high resolution cross-sectional imaging of tissue microstructures using infra-red radiation. In this study we investigate whether OCT may be used to image the punctum and proximal canaliculus. Methods: A cohort of healthy subjects with normal ocular anatomy and no symptoms of epiphora were prospectively invited to enrol. Spectral OCT images of the lower punctae were captured with a Topcon 3D Optical Coherence Tomography 2000 machine. Measurements were made of the maximal punctal diameter, canalicular ...

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    11. Optical coherence tomography appears valuable for tracking MS patients over time

      Optical coherence tomography appears valuable for tracking MS patients over time

      Retinal changes over time mirror global central nervous system processes in patients with multiple sclerosis, according to findings from a longitudinal study comparing optical coherence tomography and magnetic resonance imaging findings. The results validate optical coherence tomography (OCT) measures for both clinical monitoring of patients, and as an outcome measure in clinical trials, and could have implications that reach beyond MS, Dr. Shiv Saidha said at the joint meeting of the European and Americas committees for Treatment and Research in Multiple Sclerosis. In 107 multiple sclerosis (MS) patients with a mean age of 44 years and median disease duration of ...

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    12. Automatic detection of bioresorbable vascular scaffold struts in intravascular optical coherence tomography pullback runs

      Automatic detection of bioresorbable vascular scaffold struts in intravascular optical coherence tomography pullback runs

      Bioresorbable vascular scaffolds (BVS) have gained significant interest in both the technical and clinical communities as a possible alternative to metallic stents. For accurate BVS analysis, intravascular optical coherence tomography (IVOCT) is currently the most suitable imaging technique due to its high resolution and the translucency of polymeric BVS struts for near infrared light. However, given the large number of struts in an IVOCT pullback run, quantitative analysis is only feasible when struts are detected automatically. In this paper, we present an automated method to detect and measure BVS struts based on their black cores in IVOCT images. Validated using ...

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    13. Fully automated detection of diabetic macular edema and dry age-related macular degeneration from optical coherence tomography images

      Fully automated detection of diabetic macular edema and dry age-related macular degeneration from optical coherence tomography images

      We present a novel fully automated algorithm for the detection of retinal diseases via optical coherence tomography (OCT) imaging. Our algorithm utilizes multiscale histograms of oriented gradient descriptors as feature vectors of a support vector machine based classifier. The spectral domain OCT data sets used for cross-validation consisted of volumetric scans acquired from 45 subjects: 15 normal subjects, 15 patients with dry age-related macular degeneration (AMD), and 15 patients with diabetic macular edema (DME). Our classifier correctly identified 100% of cases with AMD, 100% cases with DME, and 86.67% cases of normal subjects. This algorithm is a potentially impactful ...

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    14. Bioptigen Introduces Deep Imaging OCT System for Contact Lens Metrology

      Bioptigen Introduces Deep Imaging OCT System for Contact Lens Metrology

      Bioptigen announced today the availability of a newly developed deep imaging OCT system for the optical device metrology and pre-clinical ophthalmic research markets. The Envisu S4410 SDOCT for Contact Lens Metrology is designed for non-destructive, non-contact, full immersion measurements for standard and high complexity contact lens, IOL structures, and donor tissues. The metrology system allows imaging of a complete contact lens immersed in a hydration bath (saline), automated segmentation of anterior and posterior surfaces, and quantification of curvatures across both surfaces. The system delivers 5 um axial pixel resolution, 11 mm scan depth in saline, and a full 20mm lateral ...

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      Mentions: Bioptigen
    15. Automated retinal layers segmentation in SD-OCT images using dual-gradient and spatial correlation smoothness constraint

      Automated retinal layers segmentation in SD-OCT images using dual-gradient and spatial correlation smoothness constraint

      Automatic segmentation of retinal layers in spectral domain optical coherence tomography (SD-OCT) images plays a vital role in the quantitative assessment of retinal disease, because it provides detailed information which is hard to process manually. A number of algorithms to automatically segment retinal layers have been developed; however, accurate edge detection is challenging. We developed an automatic algorithm for segmenting retinal layers based on dual-gradient and spatial correlation smoothness constraint. The proposed algorithm utilizes a customized edge flow to produce the edge map and a convolution operator to obtain local gradient map in the axial direction. A valid search region ...

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    16. Generation of an octave-spanning supercontinuum in highly nonlinear fibers pumped by noise-like pulse

      Generation of an octave-spanning supercontinuum in highly nonlinear fibers pumped by noise-like pulse

      A supercontinuum generation system is developed, which consists of an erbium-doped fiber ring laser, an erbium-doped fiber amplifier, and a 100-m highly nonlinear fiber. Through nonlinear polarization rotation, the fiber ring laser generates a train of noise-like pulses in the form of repetitive picosecond pulse packets consisting of femtosecond noise-like fine temporal structures. The noise-like pulses are amplified before being sent into the highly nonlinear fiber. As a result, an octave-spanning supercontinuum from 1177 nm to 2449 nm is obtained, which has a 20-dB spectral width of 980 nm. Because of the nonlinearity of the fiber amplifier, the duration of ...

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    17. Ultrasensitive detection of 3D cerebral microvascular network dynamics in vivo

      Ultrasensitive detection of 3D cerebral microvascular network dynamics in vivo

      Despite widespread applications of multiphoton microscopy in microcirculation, its small field of view and inability to instantaneously quantify cerebral blood flow velocity (CBFv) in vascular networks limit its utility in investigating the heterogeneous responses to brain stimulations. Optical Doppler tomography (ODT) provides 3D images of CBFv networks, but it suffers poor sensitivity for measuring capillary flows. Here we report on a new method, contrast-enhanced ODT with Intralipid that significantly improves quantitative CBFv imaging of capillary networks by obviating the errors from long latency between flowing red blood cells (low hematocrit ~ 20% in capillaries). This enhanced sensitivity allowed us to measure ...

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    18. The calculation of the coherence time of spectral supercontinuum at the output of the fused silica with different parameters of the initial pulse

      The calculation of the coherence time of spectral supercontinuum at the output of the fused silica with different parameters of the initial pulse

      In this paper the dependence of the coherence time of a femtosecond spectral supercontinuum from different initial pulse parameters - wavelength, peak intensity and duration is studied. The obtained dependences and ratio of the coherence time of the pulse to the duration of the pulse at the output are analyzed. It is shown that in the case of femtosecond spectral supercontinuum generation in fused silica in the areas of normal, anomalous and zero group velocity dispersion, with an increase of the central wavelength of the femtosecond laser pulse at the input, the coherence time of the radiation with ultra-wide spectrum is ...

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    19. Measurement of the temperature dependence of Young's modulus of cartilage by phase-sensitive optical coherence elastograph

      Measurement of the temperature dependence of Young's modulus of cartilage by phase-sensitive optical coherence elastograph

      The development of an effective system to monitor the changes in the elastic properties of cartilage tissue with increasing temperature in laser reconstruction is an urgent practical task. In this paper, the use of phase-sensitive optical coherence elastography for detection of elastic waves in the sample has allowed Young's modulus of cartilage tissue to be measured directly during heating. Young's modulus was calculated from the group velocity of propagation of elastic waves excited by means of a system supplying focused air pulses. The measurement results are in agreement with the results of measurements of the modulus of elasticity ...

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    20. Tornado Spectral Systems Announces Investment by Beauvest & Roadmap Captial

      Tornado Spectral Systems Announces Investment by Beauvest & Roadmap Captial

      Strategic Growth Round to Accelerate Global Expansion of Process Analyzers and Spectrometers-On-Chip Tornado Spectral Systems Inc., an emerging tech company developing radically superior tools for measuring the chemical composition and structure of materials in real-time for a variety of demanding industrial processes, announced additional funding led by venture capital firms BeauVest and Roadmap Capital. The new investments will be used to finance Tornado’s continued growth in North America and globally. With proprietary optical and nanophotonic technologies that overcome the limitations of conventional spectroscopy-based analyzers, Tornado Spectral Systems has developed a new class of instruments that can acquire chemical signatures ...

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    21. Study of cystoid macular edema by optical coherent tomography following uneventful cataract surgery

      Study of cystoid macular edema by optical coherent tomography following uneventful cataract surgery

      The objective of this paper is to study the incidence of cystoid macular edema (CME) using optical coherence tomography (OCT) following uneventful small incision cataract surgery (SICS) and phacoemulsification. This was a descriptive, prospective study where 200 patients undergoing cataract surgery were randomly divided into two groups over a period of 1 year. Patients undergoing uneventful small incision cataract surgery were included in group I and patient undergoing uneventful phacoemulsification were included in group II, with 100 patients in each group. Preoperative assessment included best corrected visual acuity, detailed anterior segment and posterior segment evaluation, and intraocular pressure measurement. Macular ...

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    22. Optical coherence tomography: A new strategy to image planarian regeneration

      Optical coherence tomography: A new strategy to image planarian regeneration

      The planarian is widely used as a model for studying tissue regeneration. In this study, we used optical coherence tomography (OCT) for the real-time, high-resolution imaging of planarian tissue regeneration. Five planaria were sliced transversely to produce 5 head and 5 tail fragments. During a 2-week regeneration period, OCT images of the planaria were acquired to analyze the signal attenuation rates, intensity ratios, and image texture features (including contrast, correlation, homogeneity, energy, and entropy) to compare the primitive and regenerated tissues. In the head and tail fragments, the signal attenuation rates of the regenerated fragments decreased from −0.2 dB ...

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