1. All Articles

    25-48 of 15674 « 1 2 3 4 5 ... 651 652 653 »
    1. Evaluation of Corneal Stromal Demarcation Line after Two Different Protocols of Accelerated Corneal Collagen Cross-Linking Procedures Using Anterior Segment Optical Coherence Tomography and Confocal Microscopy

      Evaluation of Corneal Stromal Demarcation Line after Two Different Protocols of Accelerated Corneal Collagen Cross-Linking Procedures Using Anterior Segment Optical Coherence Tomography and Confocal Microscopy

      Purpose . To evaluate the depth of corneal stromal demarcation line using AS-OCT and confocal microscopy after two different protocols of accelerated corneal collagen cross-linking procedures (CXL). Methods . Patients with keratoconus were divided into two groups. Peschke CXL device (Peschke CCL-VARIO Meditrade GmbH) applied UVA light with an intended irradiance of 18.0 mW/cm 2 for 5 minutes after applying riboflavin for 20 minutes (group 1) and 30 minutes (group 2). One month postoperatively, corneal stromal demarcation line was measured using AS-OCT and confocal microscopy. Results . This study enrolled 34 eyes of 34 patients (17 eyes in group 1 and ...

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    2. Optical coherence tomography imaging of microfluidic pattern with different refractive index contrast

      Optical coherence tomography imaging of microfluidic pattern with different refractive index contrast

      Optical coherence tomography (OCT) technology is analogous to ultrasound imaging, except that OCT employs light instead of sound. The non-invasive imaging method works by projecting light on test target and detecting the backscattering from the underlying layers. As the OCT technology is based on optical interference, the internal structural features and inhomogeneities induced by different refractive index contrast could be detected and displayed in the form of a gray scale or false color image. In this paper, a typical microfluidic device was produced and measured by a spectral domain OCT instrument. The internal dimensions of the lab-on-chip device were determined ...

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    3. Intraoperative Optical Coherence Tomography Using the RESCAN 700: Preliminary Results in Collagen Crosslinking

      Intraoperative Optical Coherence Tomography Using the RESCAN 700: Preliminary Results in Collagen Crosslinking

      Purpose . To compare the penetration of riboflavin using a microscope-integrated real time spectral domain optical coherence tomography (ZEISS OPMI LUMERA 700 and ZEISS RESCAN 700) in keratoconus patients undergoing accelerated collagen crosslinking (ACXL) between epithelium on (epi-on) and epithelium off (epi-off). Methods . Intraoperative images were obtained during each of the procedures. Seven keratoconus patients underwent epi-on ACXL and four underwent epi-off ACXL. A software tool was developed using Microsoft.NET and Open Computer Vision (OpenCV) libraries for image analysis. Pre- and postprocedure images were analyzed for changes in the corneal hyperreflectance pattern as a measure of the depth of riboflavin ...

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    4. Simultaneous measurement of localized diffusion and flow using optical coherence tomography

      Simultaneous measurement of localized diffusion and flow using optical coherence tomography

      We report on the simultaneous and localized measurements of the diffusion coefficient and flow velocity based on the normalized autocorrelation function using optical coherence tomography (OCT). Our results on a flowing solution of polystyrene spheres show that the flow velocity and the diffusion coefficient can be reliably estimated in a regime determined by the sample diffusivity, the local flow velocity, and the Gaussian beam waist. We experimentally show that a smaller beam waist results in an improvement of the velocity sensitivity at cost of the precision and accuracy of the estimation of the diffusion coefficient. Further, we show that the ...

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    5. Optical Coherence Tomography for Prostate Cancer and Beyond (Book Chapter)

      Optical Coherence Tomography for Prostate Cancer and Beyond (Book Chapter)

      Since it was first used to evaluate human genitourinary tissue in 1997, OCT has emerged as a promising modality to provide real-time, high-resolution imaging of urologic organs. In the bladder, it has demonstrated a high sensitivity in identifying regions of the bladder suspicious for CIS and between invasive and noninvasive malignancy; it has been studied as an “optical biopsy” both during the initial cystoscopic diagnosis and intraoperatively in bladder-preserving surgery. Several small, ex vivo studies have shown promising results in the ability of OCT to demonstrate histopathologic alterations to renal morphology such as in renal ischemia and malignancy. It may ...

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    6. Optical Coherence Tomography in Bladder Cancer (Book Chapter)

      Optical Coherence Tomography in Bladder Cancer (Book Chapter)

      The current diagnostic standard for grading and staging of non-muscle-invasive bladder cancer (NMIBC) is based on the histopathology obtained during transurethral resection of the bladder tumour (TURBT) or biopsies. Although considered reference standard, this technique has some limitations: First, no real-time intraoperative histological information is obtained on stage and grade. Real-time intraoperative histological information could be helpful when NMIBC is treated by electric coagulation or laser ablation. The urologist has to rely on his/her judgement of stage and grade since no tissue is harvested for histological confirmation. In addition, in many centres, patients with a history of low-grade, non-invasive ...

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    7. Optical coherence tomography: a potential tool for prediction of treatment response for port wine stain after photodynamic therapy

      Optical coherence tomography: a potential tool for prediction of treatment response for port wine stain after photodynamic therapy

      Response of port wine stain (PWS) to photodynamic therapy treatment (PDT) is variable and depends on treatment setting used and anatomic sites as well as on size and depth of ectatic vessels. Optical coherence tomography (OCT) is a non-destructive imaging modality which can reveal the layered structure of the upper part of the skin. The structural features of the PWS skin such as the diameter and depth of the blood vessels in different anatomic sites can be showed in the OCT images. In this study, the possible role of PWS skin structure in the response to PDT is assessed. 82 ...

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    8. Longitudinal Analysis of Reticular Drusen Associated with Age-Related Macular Degeneration Using Combined Confocal Scanning Laser Ophthalmoscopy and Spectral-Domain Optical Coherence Tomography Imaging

      Longitudinal Analysis of Reticular Drusen Associated with Age-Related Macular Degeneration Using Combined Confocal Scanning Laser Ophthalmoscopy and Spectral-Domain Optical Coherence Tomography Imaging

      Purpose: To evaluate longitudinal variations of reticular drusen (RDR) in age-related macular degeneration using confocal scanning laser ophthalmoscopy (cSLO), near-infrared reflectance (NIR) and spectral-domain optical coherence tomography (SD-OCT) imaging. Methods: Eighteen eyes of 12 patients with RDR (median observational time 5 months, range 3-10) were included. Changes over time in the en face cSLO NIR images, the identical SD-OCT B scan (simple approach) and the dense SD-OCT volume scans (11 µm between B scans, detailed approach) for 5 preselected RDR lesions were analysed, respectively. Results: Nineteen of 90 (21%) lesions were no longer detectable at the follow-up examination with the ...

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    9. Additive Diagnostic Role of Imaging in Glaucoma: Optical Coherence Tomography and Retinal Nerve Fiber Layer Photography

      Additive Diagnostic Role of Imaging in Glaucoma: Optical Coherence Tomography and Retinal Nerve Fiber Layer Photography

      Purpose: To investigate the additive diagnostic role of spectral-domain optical coherence tomography (SD-OCT) and red-free retinal nerve fiber layer photography (RNFLP) in making clinical glaucoma diagnosis. Methods: Four diagnostic combination sets, including the most recent image from each measurement of 196 glaucoma eyes (including the 44 preperimetric glaucoma eyes) and 101 healthy eyes, were prepared: (1) stereo disc photography and Humphrey visual field (SH); (2) SH and SD-OCT (SHO); (3) SH and RNFLP (SHR); 4) SHR and SD-OCT (SHRO). Each randomly sorted set was serially presented at one-month intervals to five glaucoma specialists who were asked to evaluate them in ...

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    10. Optical Coherence Tomography Study of Retinal Changes in Normal Aging and after Ischemia

      Optical Coherence Tomography Study of Retinal Changes in Normal Aging and after Ischemia

      Purpose. Age-related thinning of the retinal ganglion cell axons in the nerve fiber layer has been measured in humans using optical coherence tomography (OCT). In this study, we used OCT to measure inner retinal changes in 3-months-, one-year, and two-year-old mice and after experimental anterior ischemic optic neuropathy (AION). Methods. We used OCT to quantify retinal thickness in over 200 eyes at different ages before and after photochemical thrombosis model of AION. The scans were manually or automatically segmented. Results. In normal aging, there was 1.3 µm thinning of the ganglion cell complex (GCC) between 3-months and 1-year (P ...

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    11. Noninvasive monitoring of photodynamic therapy on skin neoplastic lesions using the optical attenuation coefficient measured by optical coherence tomograph

      Noninvasive monitoring of photodynamic therapy on skin neoplastic lesions using the optical attenuation coefficient measured by optical coherence tomograph

      Photodynamic therapy (PDT) has become a promising alternative for treatment of skin lesions such as squamous cell carcinoma. We propose a method to monitor the effects of PDT in a noninvasive way by using the optical attenuation coefficient (OAC) calculated from optical coherence tomography (OCT) images. We conducted a study on mice with chemically induced neoplastic lesions and performed PDT on these lesions using homemade photosensitizers. The response of neoplastic lesions to therapy was monitored using, at the same time, macroscopic clinical visualization, histopathological analysis, OCT imaging, and OCT-based attenuation coefficient measurement. Results with all four modalities demonstrated a positive ...

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    12. Monitoring of strain-dependent responsiveness to TLR activation in the mouse anterior segment using SD-OCT

      Monitoring of strain-dependent responsiveness to TLR activation in the mouse anterior segment using SD-OCT

      Purpose: To determine whether spectral-domain optical coherence tomography (SD-OCT) can be used to longitudinally monitor inflammation in the mouse anterior segment and to identify any strain-dependent differences in responsiveness to distinct toll-like receptor ligands. Methods: Corneal inflammation was induced in BALB/c and C57BL/6 mice following central corneal abrasions and topical application of saline, toll-like receptor (TLR)-4 ligand, lipopolysaccharide (LPS) or TLR9 ligand, CpG-ODN (CpG). Anterior-segment images were captured using SD-OCT at baseline, 24 hours and one-week post-treatment. Corneal thickness, stromal haze and the number of keratic precipitates (KP) and anterior chamber (AC) cells were longitudinally compared to ...

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    13. International crew set for launch to space station Sunday

      International crew set for launch to space station Sunday

      “Now we’re finding that 60 percent of long duration fliers have vision (problems) and some of those don’t correct, I mean they can still see, but you have degraded vision,” he said. “So one of the main experiments I’m doing is going to be a pretty comprehensive study of vision. I’ll be doing ultrasound on my eyes, an OCT scan (optical coherence tomography), a fundascope, several different cameras looking inside the eye, some ultrasound of my brain and heart and pressure and blood flow into the eye. “So there’s a very intense focus on that ...

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    14. Evaluation of IVOCT imaging of coronary artery metallic stents with neointimal coverage

      Evaluation of IVOCT imaging of coronary artery metallic stents with neointimal coverage

      Accuracy of IVOCT for measurement of neointimal thickness and effect of neointima in the appearance of metallic struts in IVOCT images was investigated. Phantom vessels were constructed and coronary stents were deployed and covered with thick (250–400 μm) and thin (30–70 μm) phantom neointima. High resolution Micro-CT images of the stent struts were recorded as a gold standard. IVOCT images of the phantom vessels were acquired with various luminal blood scattering strengths and measured neointimal thicknesses from IVOCT and Micro-CT images were compared. In transparent lumen, comparison of IVOCT and Micro-CT neointima thickness measurements found no significant difference ...

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    15. Diagnostic accuracy of the parameters from ganglion cell complex map, evaluated with SD-OCT in primary open-angle glaucoma

      Diagnostic accuracy of the parameters from ganglion cell  complex map, evaluated with SD-OCT in primary open-angle  glaucoma

      Purpose: To evaluate the sensitivity and specificity of ganglion cell complex (GCC) parameters, obtained with optical coherence tomography (OCT) and to determine their role in diagnosis of primary open-angle glaucoma patients. Materials and methods: The study included 84 eyes of patients with primary open-angle glaucoma (POAG) and 40 eyes of healthy individuals. All of them underwent complete eye examination, including standard automated perimetry (HFA II) and OCT (RTVue-100). Avg. GCC (average GCC), Sup. GCC (superior GCC), Inf. GCC (inferior GCC), GLV (globаl loss volume), FLV (focal loss volume) and RNFL (retinal nerve fiber layer — ONH map) were measured. ROC curves ...

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    16. Scaffold and Edge Vascular Response Following Implantation of Everolimus-Eluting Bioresorbable Vascular Scaffold : A 3-Year Serial Optical Coherence Tomography Study

      Scaffold and Edge Vascular Response Following Implantation of Everolimus-Eluting Bioresorbable Vascular Scaffold : A 3-Year Serial Optical Coherence Tomography Study

      Objectives This study sought to investigate the in-scaffold vascular response (SVR) and edge vascular response (EVR) after implantation of an everolimus-eluting bioresorbable scaffold (BRS) using serial optical coherence tomography (OCT) imaging. Background Although studies using intravascular ultrasound have evaluated the EVR in metal stents and BRSs, there is a lack of OCT-based SVR and EVR assessment after BRS implantation. Methods In the ABSORB Cohort B (ABSORB Clinical Investigation, Cohort B) study, 23 patients (23 lesions) in Cohort B1 and 17 patients (18 lesions) in Cohort B2 underwent truly serial OCT examinations at 3 different time points (Cohort B1: post-procedure, 6 ...

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    17. Recanalized Thrombus Treated With Bioresorbable Vascular Scaffold Insights From Optical Coherence Tomography

      Recanalized Thrombus Treated With Bioresorbable Vascular Scaffold Insights From Optical Coherence Tomography

      A 29-year-old man underwent coronary angiography after non–ST-segment elevation myocardial infarction. He was a current smoker and did not have any other relevant medical history. Coronary angiography revealed a lesion with contrast filling defect and irregular lumen border at the mid-segment of the left anterior descending artery (Figure 1 ). Coronary distal flow was partially preserved. Optical coherence tomography (OCT) was performed to characterize the lesion. Lesion was crossed with a BMW Coronary guidewire (Abbott Vascular, Abbott Park, Illinois) and placed in the distal left anterior descending artery. An OCT catheter (C7-XR, Dragon Fly, LightLab, St. Jude Medical, St. Paul ...

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    18. Leading Irish University Bio-Photonics Laboratory And Compact Imaging Extend Agreement For Innovative Research Collaboration

      Leading Irish University Bio-Photonics Laboratory And Compact Imaging Extend Agreement For Innovative Research Collaboration

      NUI Galway’s TOMI Lab Provides Globally-Recognized Scientific Leadership for Advanced Development of Company’s Mobile OCT Technology The National University of Ireland Galway (NUI Galway) ( www.nuigalway.com.ie ) and Compact Imaging, Inc. (CI) ( www.compactimaging.com ) today jointly announced the extension of their innovative research collaboration in the field of optical coherence tomography (OCT) for a variety of applications, including mobile health monitoring and identity verification. The research agreement will continue the advanced development of CI’s novel multiple reference OCT sensor technology, MRO™, very small, low cost, low operating power OCT architecture ideal for high volume mobile ...

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    19. Post Doctoral Position Opening at The Coherence Imaging Laboratory at the University of North Carolina at Chapel Hill

      Post Doctoral Position Opening at The Coherence Imaging Laboratory at the University of North Carolina at Chapel Hill

      The Coherence Imaging Laboratory at the University of North Carolina at Chapel Hill seeks a highly motivated Postdoc to perform research in ultrahigh-resolution optical coherence tomography (UHR-OCT). Research activities will involve optical system construction and data acquisition hardware and software. They will also involve biological studies of cells and tissues primarily related to our lab's ongoing efforts in Marine Biology. Candidates with a strong background in optics and data acquisition are particularly sought, but should also demonstrate a genuine interest in biological and biomedical science. A demonstrated record of publication in peer-reviewed journals is required to be competitive for ...

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    20. In vitro assessment of effects of hyperglycemia on the optical properties of blood during coagulation using optical coherence tomography

      In vitro assessment of effects of hyperglycemia on the optical properties of blood during coagulation using optical coherence tomography

      No published reports have demonstrated the capability of the optical coherence tomography technique for quantifying the optical coherence tomography signal slope, 1/e light penetration depth, and attenuation coefficient of hyperglycemic blood by an in vitro assessment. The purpose of this study was to investigate the effects of hyperglycemia on optical properties during in vitro blood coagulation by optical coherence tomography. Normal whole blood acted as the control group. After 1-h coagulation, the average optical coherence tomography signal slope decreased approximately 23.3 and 16.7 %, and the 1/e light penetration depths increased approximately 21.5 and 19.2 ...

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    21. Intraocular optical coherence tomography

      Intraocular optical coherence tomography

      Since its introduction as a diagnostic instrument, optical coherence tomography (OCT) has become an essential instrument for ophthalmologists as it offers accurate details on both the vitreoretinal interface and the retinal layers. Initially designed as a pre- and post-operative instrument, today we are attending to its introduction as an intraoperative tool. Inspired by the intravascular use of the OCT, we developed a prototype spectral domain OCT probe for intraocular use. It is therefore possible to make dynamic real-time scans from the vitreous and retina at the posterior pole and in the peripheral retina. This type of endo-OCT may therefore help ...

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    22. Depth-encoded all-fiber swept source polarization sensitive OCT

      Depth-encoded all-fiber swept source polarization sensitive OCT

      Polarization sensitive optical coherence tomography (PS-OCT) is a functional extension of conventional OCT and can assess depth-resolved tissue birefringence in addition to intensity. Most existing PS-OCT systems are relatively complex and their clinical translation remains difficult. We present a simple and robust all-fiber PS-OCT system based on swept source technology and polarization depth-encoding. Polarization multiplexing was achieved using a polarization maintaining fiber. Polarization sensitive signals were detected using fiber based polarization beam splitters and polarization controllers were used to remove the polarization ambiguity. A simplified post-processing algorithm was proposed for speckle noise reduction relaxing the demand for phase stability. We ...

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    23. Endoscopic imaging in Barrett's esophagus

      Endoscopic imaging in Barrett's esophagus

      Barrett’s esophagus is the only known precursor that predisposes patients to the development of esophageal adenocarcinoma. The current recommended surveillance method is targeted biopsies of any abnormalities followed by random four-quadrant biopsies every 2 cm using standard white light endoscopy. Compliance with this and sampling error are two of the biggest problems. Several novel imaging technologies have been developed to aid the diagnosis of early neoplasia in Barrett’s esophagus. There are emerging data that some of these new modalities can increase the yield of detecting dysplasia. This review will discuss some of the present available techniques and technologies ...

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    24. Application of Improved Homogeneity Similarity-Based Denoising in Optical Coherence Tomography Retinal Images

      Application of Improved Homogeneity Similarity-Based Denoising in Optical Coherence Tomography Retinal Images

      Image denoising is a fundamental preprocessing step of image processing in many applications developed for optical coherence tomography (OCT) retinal imaging—a high-resolution modality for evaluating disease in the eye. To make a homogeneity similarity-based image denoising method more suitable for OCT image removal, we improve it by considering the noise and retinal characteristics of OCT images in two respects: (1) median filtering preprocessing is used to make the noise distribution of OCT images more suitable for patch-based methods; (2) a rectangle neighborhood and region restriction are adopted to accommodate the horizontal stretching of retinal structures when observed in OCT ...

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