1. 73-96 of 501 « 1 2 3 4 5 6 7 ... 19 20 21 »
    1. M-mode swept source optical coherence tomography for quantification of salt concentration in blood: An in vitro study

      M-mode swept source optical coherence tomography for quantification of salt concentration in blood: An in vitro study

      We report the use of M-mode swept source optical coherence tomography (SS-OCT) for measuring sodium chloride (NaCl) salt concentrations in liquid phantoms and in drawn whole blood based on temporal dynamics of light scattering. The Brownian motion of scattering particle is affected due to the change in viscosity of liquid. An autocorrelation function was determined from the power spectrum of SS-OCT signal and then was fit by mono and double exponential function to obtain decorrelation time. These translational decorrelation times corresponding to translational diffusion coefficients enabled us to find the controlled viscosity of the medium. The viscosities of the media ...

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    2. Retinal optical coherence tomography manifestations of intraocular lymphoma

      Retinal optical coherence tomography manifestations of intraocular lymphoma

      Purpose Primary central nervous system lymphoma (PCNSL) is a rare disease. The index report describes a patient with intraocular lymphoma secondary to recurrent PCNSL and corresponding retinal findings on spectral domain optical coherence tomography (SD-OCT). Methods Case report. Results OCT changes were documented and correlated with the clinical course of intraocular lymphoma progression in the index patient. The OCT changes, manifested as hyperreflective material accumulation in the intraretinal and subretinal pigment epithelial spaces, were caused by lymphomatous infiltration. Conclusion SD-OCT can be useful in diagnosing and monitoring the progression or regression of intraocular lymphoma with retinal involvement.

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    3. Design of highly nonlinear dispersion flattened hexagonal photonic crystal fibers for dental optical coherence tomography applications

      Design of highly nonlinear dispersion flattened hexagonal photonic crystal fibers for dental optical coherence tomography applications

      In this paper, we propose a highly nonlinear dispersion flattened hexagonal photonic crystal fiber (HNDF-HPCF) with nonlinear coefficients as large as 57.5W−1 km−1 at 1.31 μm wavelength for dental optical coherence tomography (OCT) applications. This HNDF-HPCF offers not only large nonlinear coefficient but also very flat dispersion slope and very low confinement losses. Using these characteristics of our proposed PCF, it is shown through simulations by using finite difference method with an anisotropic perfectly matched boundary layer that this PCF offers the efficient supercontinuum (SC) generation for dental OCT applications at 1.31 μm wavelength using ...

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    4. Quantification of glucose levels in flowing blood using M-mode swept source optical coherence tomography

      Quantification of glucose levels in flowing blood using M-mode swept source optical coherence tomography

      Abstract  The increase of glucose levels in blood changes the viscosity of flowing fluids and shape of the erythrocytes. Both of these can affect the details of light scattering as can be quantified via decorrelation times measured by optical coherence tomography (OCT). The relative contributions of these competing effects have been studied by examining the motion dynamics of deformable asymmetrical (red blood cells, RBCs with ∼7 μm diameter and ∼2 μm thickness) and non deformable symmetrical (polystyrene microspheres, PSM with 1.4 μm diameter) flowing scattering particles. The fluid flow under the action of gravity was modulated by changing the ...

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    5. Visualization of hair follicles using high-speed optical coherence tomography based on a Fourier domain mode locking laser

      Visualization of hair follicles using high-speed optical coherence tomography based on a Fourier domain mode locking laser

      Abstract  In this study, a swept-source optical coherence tomography (SS-OCT) system with a Fourier domain mode locking (FDML) laser is proposed for a dermatology study. The homemade FDML laser is one kind of frequency-sweeping light source, which can provide output power of >20 mW and an output spectrum of 65 nm in bandwidth centered at 1300 nm, enabling imaging with an axial resolution of 12 μm in the OCT system. To eliminate the forward scans from the laser output and insert the delayed backward scans, a Mach-Zehnder configuration is implemented. Compared with conventional frequency-sweeping light sources, the FDML laser can ...

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    6. Enhanced depth imaging spectral-domain optical coherence tomography of subfoveal choroidal thickness in normal Japanese eyes

      Enhanced depth imaging spectral-domain optical coherence tomography of subfoveal choroidal thickness in normal Japanese eyes

      PURPOSE: To investigate the subfoveal choroidal thickness of healthy Japanese subjects using enhanced depth imaging optical coherence tomography and to evaluate the association between subfoveal choroidal thickness and age in a group of subjects with a wide age range. SUBJECTS AND METHODS: A total of 145 eyes of 145 healthy volunteers (85 women, 60 men, age range 5-88 years, mean age 45.7 years) with no ophthalmic or systemic symptoms were evaluated; 23 subjects were under the age of 20 years. Exclusion criteria included high myopia (greater than -6 D) of spherical equivalent refractive error. RESULTS: The mean subfoveal choroidal ...

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    7. Optical coherence tomography-based evaluation of malapposed strut coverage after drug-eluting stent implantation

      Optical coherence tomography-based evaluation of malapposed strut coverage after drug-eluting stent implantation

      Abstract  Minimal data exist regarding the use of optical coherence tomography (OCT) to evaluate malapposed strut coverage following implantation of drug-eluting stents (DESs). Follow-up OCT examination after DES implantation was performed in 368 patients with 406 lesions at our institute. We assessed the status of malapposed strut coverage that was identified via OCT in 92 (23 %) lesions. An absence of uncovered struts among malapposed struts was defined as completely covered (CC) malapposition; the presence of uncovered struts was defined as incompletely covered (IC) malapposition. Among the 92 lesions with malapposed DES struts, CC malapposition was detected in 47 lesions (51 ...

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    8. Fluorescein angiography, optical coherence tomography, and histopathologic findings in a VEGF165 animal model of retinal angiogenesis

      Fluorescein angiography, optical coherence tomography, and histopathologic findings in a VEGF165 animal model of retinal angiogenesis

      Background To establish an animal model of retinal neovascularization using vascular endothelial growth factor (VEGF165) and analyze the model using optical coherence tomography (OCT), fluorescein angiography (FA), and histopathologic evaluation. Methods Twelve rabbits were divided into groups as follows: group 1 (n = 3), sham intravitreous injections of 0.1 ml of balanced saline; group 2 (n = 6), one 10-μg intravitreal injection of VEGF165 on day 0; and group 3 (n = 3), two 10-μg intravitreal injections of VEGF165, one on day 0 and one on day 7. Follow-up evaluations (days 0, 3, 7, 14, 21, 28) included obtaining fundus color photographs ...

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    9. Microfluidic Phenotyping of Cilia-Driven Mixing for the Assessment of Respiratory Diseases

      Microfluidic Phenotyping of Cilia-Driven Mixing for the Assessment of Respiratory Diseases

      The function of ciliated surfaces to clear mucus from the respiratory system is important for many respiratory diseases and, therefore, has a high impact on public health. In this work, we present a quantitative method to evaluate mixing efficiency of cilia-driven microfluidic flow based on front line deformation as an integrated measurement of cilia function. So far, mixing efficiency has been used mainly for analyzing artificial cilia. Most of this work, however, was either bound to specific imaging modalities or done on simulated data. In this simulations, mixing efficiency has been quantified as the change in length of a virtual ...

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    10. 3D Optic Nerve Head Segmentation in Idiopathic Intracranial Hypertension

      3D Optic Nerve Head Segmentation in Idiopathic Intracranial Hypertension

      Patients with idiopathic intracranial hypertension (IIH) often present papilledema at the optic nerve head (ONH), associated with visual field losses. In order to quantify the edema, the computation of its volume is needed. Optical coherence tomography (OCT) is a noninvasive method for spatial imaging of retinal layer composition. However, current algorithms fail to segment the ONH in IIH patients satisfactorily. We developed an automatic method for segmenting the retinal pigment epithelium layer (RPE) from spatial high-resolution OCT ONH scans with robust performance in IIH patients. Using a hypothetical extension of the RPE through the ONH we were able to compute ...

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      Mentions: Friedemann Paul
    11. Neointimal tissue characteristics following sirolimus-eluting stent implantation: OCT quantitative tissue property analysis

      Neointimal tissue characteristics following sirolimus-eluting stent implantation: OCT quantitative tissue property analysis

      The neointimal tissue characteristics inside sirolimus-eluting stent (SES) were evaluated by optical coherence tomography (OCT) according to follow-up duration. One hundred and thirty-three Optical coherence tomography was performed in 96 patients with 143 SES which were retrospectively included and divided into 2 groups according to follow-up duration: Group 1, 24 months (35 stents in 25 patients). The neointimal tissue coverage pattern and characteristics were studied using a new OCT analysis system which can quantitatively analyze tissue property by measuring attenuation, backscatter and signal intensity in the region of interest. Using these parameters, a multivariable logistic regression model was constructed to ...

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    12. In vivo assessment of retinal neuronal layers in multiple sclerosis with manual and automated optical coherence tomography segmentation techniques

      In vivo assessment of retinal neuronal layers in multiple sclerosis with manual and automated optical coherence tomography segmentation techniques

      Macular optical coherence tomography (OCT) segmentation, enabling quantification of retinal axonal and neuronal subpopulations, may help elucidate the neuroretinal pathobiology of multiple sclerosis (MS). This study aimed to determine the agreement, reproducibility, and visual correlations of retinal layer thicknesses measured by different OCT segmentation techniques, on two spectral-domain OCT devices. Macular scans of 52 MS patients and 30 healthy controls from Spectralis OCT and Cirrus HD-OCT were segmented using fully manual (Spectralis), computer-aided manual (Spectralis and Cirrus), and fully automated (Cirrus) segmentation techniques. Letter acuity was recorded. Bland-Altman analyses revealed low mean differences across OCT segmentation techniques on both devices ...

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    13. Reproducibility of qualitative assessment of stent struts coverage by optical coherence tomography

      Reproducibility of qualitative assessment of stent struts coverage by optical coherence tomography

      Abstract  Assessment of stent strut coverage by optical coherence tomography (OCT) is not standardized. The methodology most commonly used is based on a visual binary qualitative assessment (strut covered or not). However, the influence of magnification (zoom setting) to the inter- and intra-observer agreements has not yet been evaluated. Aim of our study was therefore to evaluate the agreements of this approach, taking into account various zoom settings. 126 struts from 10 selected frames were independently evaluated by four observers using a stepwise approach increasing the zoom setting as following: (1) full view of the lumen (FV), (2) half view ...

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    14. Optical features for chronological aging and photoaging skin by optical coherence tomography

      Optical features for chronological aging and photoaging skin by optical coherence tomography

      Abstract  The characteristics of skins in different aging processes were obtained by optical coherence tomography (OCT) single scattering model, and their optical parameters were analyzed quantitatively. Significant differences were found in epidermis thickness and attenuation coefficients in chronological aging skins and photonaging skins. These parameters can be served as indicators of skin type as well as the progress of aging. These results are valuable to the study of aging skin, and they could further help to understand the mechanism of aging.

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    15. Wavy and elevated retinal pigment epithelial line in optical coherence tomographic images of eyes with atypical Vogt-Koyanagi-Harada disease

      Wavy and elevated retinal pigment epithelial line in optical coherence tomographic images of eyes with atypical Vogt-Koyanagi-Harada disease

      Purpose We report the changes of the retinal pigment epithelium (RPE) determined by optical coherence tomography in a patient with atypical Vogt–Koyanagi–Harada (VKH) disease during the recovery phase. Method Case presentation. Results A 74-year-old woman presented with a central scotoma associated with disc hyperemia, serous retinal detachment, and scleral thickening in her left eye, and was diagnosed with VKH. OCT showed a serous retinal detachment and a wavy RPE contour that corresponded to the choroidal folds. The OCT images clearly showed the dynamic changes of the retina, RPE, and choroid during the recovery phase. Conclusions The OCT was ...

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    16. Deletion of Siah-interacting protein gene in Drosophila causes cardiomyopathy

      Deletion of Siah-interacting protein gene in Drosophila causes cardiomyopathy

      Drosophila is a useful model organism in which the genetics of human diseases, including recent advances in identification of the genetics of heart development and disease in the fly, can be studied. To identify novel genes that cause cardiomyopathy, we performed a deficiency screen in adult Drosophila. Using optical coherence tomography to phenotype cardiac function in awake adult Drosophila, we identified Df(1)Exel6240 as having cardiomyopathy. Using a number of strategies including customized smaller deletions, screening of mutant alleles, and transgenic rescue, we identified CG3226 as the causative gene for this deficiency. CG3226 is an uncharacterized gene in Drosophila ...

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      Mentions: Duke University
    17. Optical coherence tomography using broad-bandwidth XUV and soft X-ray radiation

      Optical coherence tomography using broad-bandwidth XUV and soft X-ray radiation

      We present a novel approach to extend optical coherence tomography (OCT) to the extreme ultraviolet (XUV) and soft X-ray (SXR) spectral range. With a simple setup based on Fourier-domain OCT and adapted for the application of XUV and SXR broadband radiation, cross-sectional images of semiconductors and organic samples becomes feasible with current synchrotron or laser-plasma sources. For this purpose, broadband XUV radiation is focused onto the sample surface, and the reflected spectrum is recorded by an XUV spectrometer. The proposed method has the particular advantage that the axial spatial resolution only depends on the spectral bandwidth. As a consequence, the ...

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    18. Surface epithelialization of the type I Boston keratoprosthesis front plate: immunohistochemical and high-definition optical coherence tomography characterization

      Surface epithelialization of the type I Boston keratoprosthesis front plate: immunohistochemical and high-definition optical coherence tomography characterization

      Background The aim of this work is to characterize a transparent tissue layer partially covering the anterior surface of the type I Boston permanent keratoprosthesis front plate in four patients. Methods The tissue over the front plate was easily scrolled back as a single transparent layer using a sponge. In two cases, histopathologic analysis was undertaken and immunofluorescent staining with a cytokeratin 3-specific antibody was performed. The relationship of the tissue to the keratoprosthesis device was further characterized using spectral domain high-definition optical coherence tomography (HD-OCT). Results Histopathologic analysis revealed the tissue to be non-keratinized squamous epithelium. No goblet cells ...

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    19. Laser hyperthermia of tumors using gold nanoparticles monitored by optical coherence tomography and acoustic thermometry

      Laser hyperthermia of tumors using gold nanoparticles monitored by optical coherence tomography and acoustic thermometry

      Local laser hyperthermia of grafted RShM-5 tumors in mice with the use of plasmon resonant gold nanoparticles has been carried out. Accumulation of particles in the tumor was monitored in vivo noninvasively by optical coherence tomography. Thereby it was determined that the maximal content of nanoparticles in the tumor was reached within 5 h after intravenous administration, and laser hyperthermia was performed at this time. Monitoring the tumor temperature during the treatment by IR thermography and acoustic thermometry showed that the nanoparticles provided efficient temperature elevation inside the tumor as well as more selective heating. Local laser hyperthermia with gold ...

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    20. Visualization and measurement of capillary-driven blood flow using spectral domain optical coherence tomography

      Visualization and measurement of capillary-driven blood flow using spectral domain optical coherence tomography

      Capillary-driven flow (CD-flow) in microchannels plays an important role in many microfluidic devices. These devices, the most popular being those based in lateral flow, are becoming increasingly used in health care and diagnostic applications. CD-flow can passively pump biological fluids as blood, serum or plasma, in microchannels and it can enhance the wall mass transfer by exploiting the convective effects of the flow behind the meniscus. The flow behind the meniscus has not been experimentally identified up to now because of the lack of high-resolution, non-invasive, cross-sectional imaging means. In this study, spectral-domain Doppler optical coherence tomography is used to ...

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    21. Stent strut coverage of titanium-nitride-oxide coated stent compared to paclitaxel-eluting stent in acute myocardial infarction: TITAX-OCT study

      Stent strut coverage of titanium-nitride-oxide coated stent compared to paclitaxel-eluting stent in acute myocardial infarction: TITAX-OCT study

      Drug-eluting stents (DES) have reduced the rate of restenosis but recent studies have raised concern over the risk of late stent thrombosis (LST). Incomplete stent endothelialization and delayed vascular healing have been associated with LST. The titanium-nitride-oxide coated bio-active stent (BAS) has shown promising results in patients with acute coronary syndromes, but there is little long-term optical coherence tomography (OCT) data comparing BAS with DES. The TITAX-AMI trial is a prospective, randomized, multicenter trial comparing BAS to paclitaxel-eluting stent (PES) in 425 patients with acute myocardial infarction. A total of 18 patients (9 per group) with no major cardiac events ...

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    22. Factors affecting imaging of spectral-domain optical coherence tomography in gas-filled eyes after macular-hole surgery

      Factors affecting imaging of spectral-domain optical coherence tomography in gas-filled eyes after macular-hole surgery

      Purpose We investigated factors affecting imaging of spectral-domain optical coherence tomography (SD-OCT) in gas-filled eyes after macular-hole (MH) surgery. Methods The study comprised 25 eyes in 23 patients, eight men and 15 women, with a mean age of 66.9 (48–77) years, all of whom had undergone vitrectomy for MH. Sulfur hexafluoride (SF6) gas was used as a tamponade, and the patients were maintained in a prone position after surgery. The SD-OCT imaging was performed on postoperative days 1 and 2. Results The success rate of imaging was 88.0% (22/25 eyes) on postoperative day 1 and 95 ...

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    73-96 of 501 « 1 2 3 4 5 6 7 ... 19 20 21 »
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