1. All Articles

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    1. Feature of the Week 10/19/14: Automated Classification of Optical Coherence Tomography Images for the Diagnosis of Oral Malignancy in the Hamster Cheek Pouch

      Feature of the Week 10/19/14: Automated Classification of Optical Coherence Tomography Images for the Diagnosis of Oral Malignancy in the Hamster Cheek Pouch

      Most studies evaluating the potential of optical coherence tomography (OCT) for the diagnosis of oral cancer are based on visual assessment of OCT B-scans by trained experts. Human interpretation of the large pool of data acquired by modern high-speed OCT systems, however, can be cumbersome and extremely time consuming. Development of image analysis methods for automated and quantitative OCT image analysis could therefore facilitate the evaluation of such a large volume of data. We report automated algorithms for quantifying structural features that are associated with the malignant transformation of the oral epithelium based on image processing of OCT data. The ...

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    2. Fabrication method of ultra-small gradient-index fiber probe

      Fabrication method of ultra-small gradient-index fiber probe

      Fabrication method and device of ultra-small gradient-index (GRIN) fiber probe were investigated in order to explore the development of ultra-small probes for optical coherence tomography (OCT) imaging. The beam-expanding effect of no-core fiber (NCF) and the focusing properties of the GRIN fiber lens were analyzed based on the model of GRIN fiber probe consisting of single-mode fiber (SMF), NCF and GRIN fiber lens. A stereo microscope based system was developed to fabricate the GRIN fiber probe. A fiber fusion splicer and an ultrasonic cleaver were used to weld and cut the fiber respectively. A confocal microscopy was used to measure ...

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    3. All-fiber wavelength swept ring laser based on Fabry-Perot filter for optical frequency domain imaging

      All-fiber wavelength swept ring laser based on  Fabry-Perot filter for optical frequency domain  imaging

      Innovations in laser engineering have yielded several novel configurations for high repetition rate, broad sweep range, and long coherence length wavelength swept lasers. Although these lasers have enabled high performance frequency-domain optical coherence tomography, they are typically complicated and costly and many require access to proprietary materials or devices. Here, we demonstrate a simplified ring resonator configuration that is straightforward to construct from readily available materials at a low total cost. It was enabled by an insight regarding the significance of isolation against bidirectional operation and by configuring the sweep range of the intracavity filter to exceed its free spectral ...

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    4. Comparison of Circulating Dendritic Cells and Monocyte Subsets at Different Stages of Atherosclerosis: insights from optical coherence tomography

      Comparison of Circulating Dendritic Cells and Monocyte Subsets at Different Stages of Atherosclerosis: insights from optical coherence tomography

      Objectives Proinflammatory dendritic cells (DC) and monocytes are critically involved in the proceeding and destabilization of atherosclerosis. Recent studies have reported potential associations of specific patterns of circulating DCs and monocytes with the incidence of coronary artery disease (CAD) and ST-elevation myocardial infarction (STEMI); however, further information of DC and monocyte subsets on plaque morphology and vulnerability is uncertain and required. Methods Forty-seven CAD patients with borderline lesions (stenosis 50%-70%) by coronary angiography (CAG) were enrolled, while 31 subjects free of luminal diameter narrowing ≥ 50% served as controls. Likewise, 35 patients with STEMI were enrolled and confirmed with the ...

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    5. Swept-Source Optical Coherence Tomography Features of Choroidal Nevi

      Swept-Source Optical Coherence Tomography Features of Choroidal Nevi

      Purpose To investigate the morphological characteristics of choroidal nevi using swept-source optical coherence tomography and compare this with enhanced-depth optical coherence tomography. Design Retrospective observational case series Methods One choroidal nevus each from 30 eyes of 30 patients was included and received imaging with swept-source OCT (SS-OCT) and enhanced-depth imaging OCT (EDI-OCT). For SS-OCT, a scan acquisition protocol was utilized involving 12mm horizontal and vertical scans in the posterior fundus. The main outcome measures were morphological features of choroidal nevi obtained with SS-OCT imaging. These features were compared to images obtained with EDI-OCT. A two-tailed Fisher’s exact test was ...

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    6. Noise characterization of broadband fiber Cherenkov radiation as a visible-wavelength source for optical coherence tomography and two-photon fluorescence microscopy

      Noise characterization of broadband fiber Cherenkov radiation as a visible-wavelength source for optical coherence tomography and two-photon fluorescence microscopy

      Optical sources in the visible region immediately adjacent to the near-infrared biological optical window are preferred in imaging techniques such as spectroscopic optical coherence tomography of endogenous absorptive molecules and two-photon fluorescence microscopy of intrinsic fluorophores. However, existing sources based on fiber supercontinuum generation are known to have high relative intensity noise and low spectral coherence, which may degrade imaging performance. Here we compare the optical noise and pulse compressibility of three high-power fiber Cherenkov radiation sources developed recently, and evaluate their potential to replace the existing supercontinuum sources in these imaging techniques.

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    7. Optical Coherence Tomography Assessment of Angle Anatomy Changes After Trabeculectomy in Primary Angle-Closure Glaucoma

      Optical Coherence Tomography Assessment of Angle Anatomy Changes After Trabeculectomy in Primary Angle-Closure Glaucoma

      Purpose: Using anterior chamber optical coherence tomography to evaluate changes in angle anatomy in patients with primary angle-closure glaucoma (PACG) before and after trabeculectomy. Methods: This is a prospective observational study in 38 eyes of 38 patients with PACG, who underwent trabeculectomy. We used customized software to analyze optical coherence tomography images (Visante) of all participants before and after the surgical treatment. Multivariate linear regression analysis was performed for predictors of percentage change in mean angle parameters, including scleral spur angle, angle opening distance, angle recess area, and trabecular-iris surface area. The main outcome measures were changes in angle parameters ...

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    8. OCT-Derived Comparison of Corneal Thickness Distribution and Asymmetry Differences Between Normal and Keratoconic Eyes

      OCT-Derived Comparison of Corneal Thickness Distribution and Asymmetry Differences Between Normal and Keratoconic Eyes

      Purpose: The aim of this study was to investigate the corneal thickness asymmetry indices in a large pool of patients with keratoconus derived using anterior segment optical coherence tomography (AS-OCT) in comparison with established Scheimpflug imaging-derived keratoconus classification indices. Methods: Six specific indices were comparatively investigated in this study encompassing 2 groups: keratoconic group A (175 eyes) and age- and gender-matched control group B (175 eyes). AS-OCT was used for corneal focal thinning and irregularity indices, namely the superior nasal minus inferior temporal (SN-IT), superior minus inferior (S-I), minimum minus median (Min-Med) focal thinning, and thickness range, defined as the ...

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    9. Supercontinuum optimization for dual-soliton based light sources using genetic algorithms in a grid platform

      Supercontinuum optimization for dual-soliton based light sources using genetic algorithms in a grid platform

      We present a numerical strategy to design fiber based dual pulse light sources exhibiting two predefined spectral peaks in the anomalous group velocity dispersion regime. The frequency conversion is based on the soliton fission and soliton self-frequency shift occurring during supercontinuum generation. The optimization process is carried out by a genetic algorithm that provides the optimum input pulse parameters: wavelength, temporal width and peak power. This algorithm is implemented in a Grid platform in order to take advantage of distributed computing. These results are useful for optical coherence tomography applications where bell-shaped pulses located in the second near-infrared window are ...

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    10. Noise-compensated Homotopic Non-local Regularized Reconstruction for Rapid Retinal Optical Coherence Tomography Image Acquisitions

      Noise-compensated Homotopic Non-local Regularized Reconstruction for Rapid Retinal Optical Coherence Tomography Image Acquisitions

      Background Optical coherence tomography (OCT) is a minimally invasive imaging technique, which utilizes the spatial and temporal coherence properties of optical waves backscattered from biological material. Recent advances in tunable lasers and infrared camera technologies have enabled an increase in the OCT imaging speed by a factor of more than 100, which is important for retinal imaging where we wish to study fast physiological processes in the biological tissue. However, the high scanning rate causes proportional decrease of the detector exposure time, resulting in a reduction of the system signal-to-noise ratio (SNR). One approach to improving the image quality of ...

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    11. Measurement of retinal blood flow in the rat by combining Doppler Fourier-domain optical coherence tomography with fundus imaging

      Measurement of retinal blood flow in the rat by combining Doppler Fourier-domain optical coherence tomography with fundus imaging

      A wide variety of ocular diseases are associated with abnormalities in ocular circulation. As such, there is considerable interest in techniques for quantifying retinal blood flow, among which Doppler optical coherence tomography (OCT) may be the most promising. We present an approach to measure retinal blood flow in the rat using a new optical system that combines the measurement of blood flow velocities via Doppler Fourier-domain optical coherence tomography and the measurement of vessel diameters using a fundus camera-based technique. Relying on fundus images for extraction of retinal vessel diameters instead of OCT images improves the reliability of the technique ...

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    12. CHOROIDAL THICKNESS MEASURED WITH SWEPT SOURCE OPTICAL COHERENCE TOMOGRAPHY BEFORE AND AFTER VITRECTOMY WITH INTERNAL LIMITING MEMBRANE PEELING FOR IDIOPATHIC EPIRETINAL MEMBRANES

      CHOROIDAL THICKNESS MEASURED WITH SWEPT SOURCE OPTICAL COHERENCE TOMOGRAPHY BEFORE AND AFTER VITRECTOMY WITH INTERNAL LIMITING MEMBRANE PEELING FOR IDIOPATHIC EPIRETINAL MEMBRANES

      Purpose: In eyes with epiretinal membranes (ERMs), retinal arteries become dilated and tortuous. This may correlate with the hemodynamics of the affected areas and possibly with choroidal thickness. The aim of this study was to estimate choroidal thickness before and after vitrectomy for idiopathic ERM in the operated eye and in the unaffected fellow eye. Methods: A prospective study of 21 patients with idiopathic ERMs. We obtained swept source optical coherence tomography images that simultaneously evaluated the vitreous, retina, and choroid. We performed choroidal thickness measurements before pars plana vitrectomy with ERM removal and internal limiting membrane peeling. We took ...

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    13. A comprehensive model for correcting RNFL readings of varying signal strengths in CIRRUS Optical Coherence Tomography (OCT)

      A comprehensive model for correcting RNFL readings of varying signal strengths in CIRRUS Optical Coherence Tomography (OCT)

      Purpose. Develop a model for the CIRRUSTM HD-OCT that allows for the comparison of retinal nerve fiber layer (RNFL) thickness measurements with dissimilar signal strengths (SS) and accounts for test-re-test variability. Methods. RNFLs were obtained in normals using the CIRRUSTM optic disc cube 200x200 protocol during a single encounter. Five RNFL scans were obtained with a SS of 9-10. Diffusion lens filters were used to degrade SS to obtain five scans at each SS group of 7-8, 5-6, and 3-4. The relationship between average RNFL thickness and SS was established and an equation was developed to allow for adjustment of ...

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    14. Evaluating Dissociated Optic Nerve Fiber Layer Appearance Using En Face Layer Imaging Produced by Optical Coherence Tomography

      Evaluating Dissociated Optic Nerve Fiber Layer Appearance Using En Face Layer Imaging Produced by Optical Coherence Tomography

      Purpose: To investigate the incidence of and risk factors for a dissociated optic nerve fiber layer (DONFL) appearance after pars plana vitrectomy (PPV). Methods: We retrospectively reviewed 189 eyes that underwent PPV with internal limiting membrane removal and judged the presence/absence of an apparent DONFL based on en face layer images produced by spectral-domain optical coherence tomography (SD-OCT). Results: An apparent DONFL was observed in 47 (24.9%) eyes. The incidence of an apparent DONFL was significantly higher in the macular hole (MH) group (76.5%) than in the non-MH group (epiretinal membrane, diabetic macular edema, retinal vein occlusion ...

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    15. The cellular origins of the outer retinal bands in optical coherence tomography images

      The cellular origins of the outer retinal bands in optical coherence tomography images

      Purpose: To test the recently proposed hypothesis that the second OCT outer retinal band originates from the inner segment ellipsoid, by measuring: 1) thickness of this band within single cones, and 2) its respective distance from the external limiting membrane and outer segment tips. Methods: Adaptive optics OCT images were obtained from four normal subjects. Images were obtained at foveal (2∘) and perifoveal (5∘) locations. Cones (n = 9593) were identified and segmented in three dimensions using custom software. Features corresponding to bands 1, 2, and 3 were automatically identified. Thickness of band 2 was assessed in each cell by fitting ...

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    16. Endoscopic Eradication Therapy for Barrett's Esophagus

      Endoscopic Eradication Therapy for Barrett's Esophagus

      B arrett’s esophagus (BE) is the precursor lesion to esophageal adenocarcinoma, which in an invasive stage causes significant morbidity and mortality. Surgery was the mainstay of treatment for patients with high-grade dysplasia (HGD) and adenocarcinoma associated with BE. However, surgery in itself carries substantial morbidity. There has been tremendous progress in the minimally invasive treatment of BE in the past decade. The premise to be aggressive in treating dysplastic BE and early-stage adenocarcinoma is to prevent progression to an advanced-stage cancer. Most interventional endoscopists are comfortable treating dysplasia and intramucosal esophageal cancer, although recently there have been emerging data ...

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    17. Advanced Colonoscopic Imaging: Do New Technologies Improve Adenoma Detection?

      Advanced Colonoscopic Imaging: Do New Technologies Improve Adenoma Detection?

      C olorectal cancer (CRC) is the second leading cause of cancer-related mortality in the Western world. 1 Screening colonoscopy and polypectomy have become widely accepted as the most effective available methods for early detection and prevention of CRC and have shown a reduction in mortality in the screened population. 2 However, colonoscopy remains imperfect and several studies have raised concerns about the miss rate of adenomatous polyps during screening. The overall miss rate is approximately 20%, and ranges from 6% for large (10 mm) adenomas to 26% for diminutive (<5 mm) lesions. 3 Missing these adenomas is one of the ...

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    18. Abbott Expands Cataract Surgery Product Portfolio through U.S. Distribution Agreement with Carl Zeiss Meditec

      Abbott Expands Cataract Surgery Product Portfolio through U.S. Distribution Agreement with Carl Zeiss Meditec

      Abbott and Carl Zeiss Meditec announced today that they have entered into a nonexclusive commercial collaboration in the United States. Under this agreement, Abbott will offer each company’s suite of cataract surgery products when developing clinical and contracting solutions with customers in the United States. This comprehensive offering, including synergistic diagnostics, visualization systems, lens extraction systems, and intraocular lenses, provides surgeons with access to a complete cataract surgery portfolio to assist them in maximizing visual outcomes and streamlining patient flow. "Together with surgeons, Abbott is committed to delivering unsurpassed visual outcomes to patients," said Murthy Simhambhatla, Ph.D., senior ...

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    19. Automated Three-Dimensional Image Segmentation of Retinal OCT Images (Thesis)

      Automated Three-Dimensional Image Segmentation of Retinal OCT Images (Thesis)

      Optical coherence tomography (OCT) has become an essential tool in ophthalmology. The macular OCT images are three dimensional, high resolution and cross-sectional image of macula, which provides detailed structural information of various macular layers. Moreover macular OCT imaging is non-contact, noninvasive and real-time. OCT images can be obtained quickly and multiple times, this allows easy diagnosis and treatment progress monitoring. With advances in technology acquired dataset size is also increasing, which makes it impractical to manually segment macular layers in clinical environment. Thus need of fast and accurate segmentation algorithm is ever increasing. In this thesis two segmentation algorithms have ...

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    20. The Role of Multimodality Imaging Approach in Diagnosis and Stratification of Aborted Sudden Cardiac Death

      The Role of Multimodality Imaging Approach in Diagnosis and Stratification of Aborted Sudden Cardiac Death

      A 34-year-old man was admitted after an episode of aborted SCD. The initial investigation including electrocardiogram, chest X-ray, transthoracic echocardiogram and biomarkers were normal. Although coronary angiography showed non-severe stenosis, optical coherence tomography revealed severe obstruction in the artery with a layered appearance of the vessel wall; it was consistent with the presence of mural thrombus.

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    21. Progress of Intravascular Optical Coherence Tomography Image Technology and Vascular Three-Dimensional Reconstruction

      Progress of Intravascular Optical Coherence Tomography Image Technology and Vascular Three-Dimensional Reconstruction

      Intravascular optical coherence tomography (IV-OCT) is a new intervention imaging technology for the diagnosis of coronary heart disease. Because of its high-resolution and non-invasive characteristics, it is widely used in clinical medicine. It has a revolutionary impact on coronary artery disease diagnosis, prognosis and treatment decisions. This paper studied this hot topic, gave the basic concepts of intravascular OCT image sequences. In accordance with current development studies, the key technology for three-dimensional reconstruction of the coronary vascular system is proposed and analyzed. On this basis, we proposed future research directions on IV-OCT vascular three-dimensional reconstruction, including clinical trial frequency domain ...

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    22. Optical Coherence Tomography: A new era in dentistry

      Optical Coherence Tomography: A new era in dentistry

      Dental prostheses are very complex systems, heterogenous in structure, made up from various materials, with different physical properties. They have to satisfy high stress requirements as well as aesthetic challenges. The failures of dental prostheses lead to functional, aesthetic and phonetic disturbances which finally render the prosthetic treatment inefficient. OCT is a tomography imaging technology capable of producing high-resolution cross-sectional images of the internal architecture of materials and tissues. This includes not only the images of normal and abnormal dental hard tissue structures but also teeth after several treatment methods. It can be used for non-invasive investigations for both in-vivo ...

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