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    1. Postdoctoral or Research Scientist Position in Biomedical Optics at Baylor College of Medicine

      Postdoctoral or Research Scientist Position in Biomedical Optics at Baylor College of Medicine

      A postdoctoral or research scientist position is available in Larina Lab in the Department of Molecular Physiology and Biophysics at the Baylor College of Medicine, Houston, TX to develop functional optical imaging methods toward investigation of developmental mechanisms. We are a dynamic highly collaborative team of optical engineers and biologists, investigating biomechanical aspects of biological processes in mouse models of human disorders. Our studies bring together optical system design, OCT, confocal/multiphoton microscopy, optogenetics, technology development in functional optical imaging and data processing (4D angiography, cilia beat mapping, cardiodynamic analysis, elastography), vital fluorescent reporters, genetic mouse models of human disorders ...

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    2. Investigation of cell dynamics in 3D cell spheroids and cell interaction with 3D printed scaffolds by mOCT

      Investigation of cell dynamics in 3D cell spheroids and cell interaction with 3D printed scaffolds by mOCT

      Optical coherence tomography is a non-invasive and label-free imaging modality based on the detection of backscattered light in samples. As microscopic OCT (mOCT) combines high axial and lateral resolution, an investigation of biological and printed samples at subcellular level is feasible. The additional excellent depth resolution enables mOCT to be a suitable quality control of 3D printed samples. The use of speckle variance adds information about cell viability. Here we present the feasibility of investigating cell viability within a cell spheroid and monitoring the cell interaction with bioprinted scaffolds using mOCT.

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    3. Neoatherosclerosis ― Long-Term Assessment of Bioresorbable Vascular Scaffold ―

      Neoatherosclerosis ― Long-Term Assessment of Bioresorbable Vascular Scaffold ―

      Although metallic stents improved the safety and efficacy of percutaneous coronary intervention (PCI), even the latest generation of drug-eluting stents (DES) is still limited by several factors. The limitations of DES are mainly related to the permanent metallic caging in vessel, chronic inflammatory response to the polymer and adverse effects of antiproliferative drug on endothelial tissue, leading to impaired physiological vasomotor response and late stent-related adverse events such as stent thrombosis and neoatherosclerosis. Bioresorbable vascular scaffold (Absorb BVS; Abbott Vascular) was designed to overcome these drawbacks of DES by disappearing from the vessel wall. Absorb BVS, however, was withdrawn from ...

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    4. Intravascular Polarimetry for Tissue Characterization of Coronary Atherosclerosis

      Intravascular Polarimetry for Tissue Characterization of Coronary Atherosclerosis

      The microscopic tissue structure and organization influence the polarization of light. Intravascular polarimetry leverages this compelling intrinsic contrast mechanism by using polarization-sensitive optical frequency domain imaging to measure the polarization properties of the coronary arterial wall. Tissues rich in collagen and smooth muscle cells appear birefringent, while the presence of lipid causes depolarization, offering quantitative metrics related to the presence of important components of coronary atherosclerosis. Here, we review the basic principles, the interpretation of polarization signatures, and first clinical investigations of intravascular polarimetry and discuss how this extension of contemporary intravascular imaging may advance our knowledge and improve clinical ...

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    5. Efficacy and Reproducibility of Attenuation-Compensated Optical Coherence Tomography for Assessing External Elastic Membrane Border and Plaque Composition in Native and Stented Segments ― An In Vivo and Histology-Based Study ―

      Efficacy and Reproducibility of Attenuation-Compensated Optical Coherence Tomography for Assessing External Elastic Membrane Border and Plaque Composition in Native and Stented Segments ― An In Vivo and Histology-Based Study ―

      Background: Attenuation-compensated (AC) technique was recently introduced to improve the plaque characterization of optical coherence tomography (OCT). Histological validation demonstrated promising results but the efficacy and reproducibility of this technique for assessing in-vivo tissue composition remains unclear. Methods and Results: OCT images portraying native (n=200) and stented (n=200) segments and 31 histological cross-sections were analyzed. AC-OCT appeared superior to conventional (C)-OCT in detecting the external elastic lamina (EEM) borders (76% vs. 65.5%); AC-OCT enabled larger EEM arc detection compared with C-OCT (174.2±58.7° vs. 137.5±57.9°; P<0.001). There was poor ...

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    6. Spectral domain - Optical coherence tomography (SD-OCT) as a monitoring tool for alterations in mouse lenses

      Spectral domain - Optical coherence tomography (SD-OCT) as a monitoring tool for alterations in mouse lenses

      The eye lens displayes a variety of phenotypes in the wake of genetical modifications or environmental influences. Therefore, a high-resolution in vivo imaging method for the lens is desirable. Optical coherence tomography (OCT) has become a powerful imaging tool in ophthalmology, especially for retinal imaging in small animal models such as mice. Here, we demonstrate an optimized approach specifically for anterior eye segment imaging with spectral domain OCT (SD-OCT) on several known murine lens cataract mutants. Scheimpflug and histological section images on the same eye were used in parallel to assess the observed pathologies. With SD-OCT images, we obtained detailed ...

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    7. Optical coherence tomography angiography in diabetic retinopathy: a review of current applications

      Optical coherence tomography angiography in diabetic retinopathy: a review of current applications

      Background Diabetic retinopathy (DR) is a leading cause of vision loss in adults. Currently, the standard imaging technique to monitor and prognosticate DR and diabetic maculopathy is dye-based angiography. With the introduction of optical coherence tomography angiography (OCTA), it may serve as a potential rapid, non-invasive imaging modality as an adjunct. Main text Recent studies on the role of OCTA in DR include the use of vascular parameters e.g., vessel density, intercapillary spacing, vessel diameter index, length of vessels based on skeletonised OCTA, the total length of vessels, vascular architecture and area of the foveal avascular zone. These quantitative ...

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    8. Optical coherence tomography allows 3D reconstruction of ablation lesions

      Optical coherence tomography allows 3D reconstruction of ablation lesions

      Radiofrequency catheter ablation (RFA) is an effective interventional treatment for atrial fibrillation. However, the immediate effect of RFA on the tissue is not directly visualized. This is a key limitation as only acute electrical measurements are taken into account and the atrial wall structure or ablation lesion form are neglected. Optical coherence tomography (OCT) is an imaging technique that uses light to capture histology-like images with a moderate penetration depth of 1–3 mm in the cardiac tissue. It is well-established to characterize plaques in patients with coronary artery disease. Therefore, it might also be used for high-precision imaging of ...

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    9. Early detection of enamel demineralization by optical coherence tomography

      Early detection of enamel demineralization by optical coherence tomography

      Enamel is the outermost layer of the tooth that protects it from invasion. In general, an acidic environment accelerates tooth demineralization, leading to the formation of cavities. Scanning electron microscopy (SEM) is conventionally used as an in vitro tool for the observation of tooth morphology changes with acid attacks. Yet, SEM has intrinsic limitations for the potential application of in vivo detection in the early demineralization process. In this study, a high-resolution optical coherence tomography (OCT) system with the axial and transverse resolutions of 2.0 and 2.7 μm in teeth has been utilized for characterizing the effect of ...

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    10. Deep spectral learning for label-free optical imaging oximetry with uncertainty quantification

      Deep spectral learning for label-free optical imaging oximetry with uncertainty quantification

      Measurement of blood oxygen saturation ( s O 2 ) by optical imaging oximetry provides invaluable insight into local tissue functions and metabolism. Despite different embodiments and modalities, all label-free optical-imaging oximetry techniques utilize the same principle of s O 2 -dependent spectral contrast from haemoglobin. Traditional approaches for quantifying s O 2 often rely on analytical models that are fitted by the spectral measurements. These approaches in practice suffer from uncertainties due to biological variability, tissue geometry, light scattering, systemic spectral bias, and variations in the experimental conditions. Here, we propose a new data-driven approach, termed deep spectral learning (DSL), to ...

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    11. AS-OCT Guided Treatment Of Diffuse Conjunctival Squamous Cell Carcinoma With Resection ...

      AS-OCT Guided Treatment Of Diffuse Conjunctival Squamous Cell Carcinoma With Resection ...

      Purpose: To evaluate the efficacy of combined limited surgical resection, amniotic membrane graft and topical mitomycin C in treatment of diffuse conjunctival squamous cell carcinoma (CSCC) diagnosed and followed up by anterior segment optical coherence tomography (AS-OCT). Subjects and methods: A prospective study was performed on 24 eyes with diffuse CSCC. Fifteen eyes underwent lesion limited resection followed by postoperative topical mitomycin C 0.04% eye drop (MMC group) while nine eyes underwent complete excision and cryotherapy (no MMC group). Amniotic membrane graft was applied in all cases. The diagnosis was based on clinical and AS-OCT specific criteria of CSCC ...

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    12. The Eyes Behind Surgical Robots

      The Eyes Behind Surgical Robots

      By the turn of the century, Intuitive Surgical Inc.’s da Vinci surgical system, which was approved by the FDA in 2000, was used for general laparoscopic surgical procedures and even cardiovascular surgeries — a high watermark in the early years. The system is still in wide use today. Intuitive Surgical Inc.’s da Vinci is among the most well-known surgical robotic systems. Courtesy of Intuitive Surgical Inc. Fast forward two decades, and today’s surgical robots are more precise and user-friendly, and capable of highly delicate microsurgeries, thanks to advancements in optical technology that have allowed for safe and effective ...

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    13. Optical Coherence Tomography Angiography Assessed Retinal and Choroidal Microvasculature Features in Patients with Retinitis Pigmentosa: A Meta-Analysis

      Optical Coherence Tomography Angiography Assessed Retinal and Choroidal Microvasculature Features in Patients with Retinitis Pigmentosa: A Meta-Analysis

      Background . The aim of this study was to assess the retinal and choroidal microvasculature features using optical coherence tomography angiography (OCTA) in patients with retinitis pigmentosa (RP). Methods . This study was a meta-analysis of relevant published studies that were included after a comprehensive search of PubMed, Embase, Cochrane Library, and Web of Science databases. Mean difference (MD) with a 95% confidence interval was used to assess continuous variable outcomes. Heterogeneity was evaluated using the chi-squared test based on the values of and I 2 . Results . Seven studies were included in this meta-analysis. The vessel density values measured in the superficial ...

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    14. The vascular densities of the macula and optic disc in normal eyes from children by optical coherence tomography angiography

      The vascular densities of the macula and optic disc in normal eyes from children by optical coherence tomography angiography

      Purpose This study aims to describe the variation and characteristics of vessel density (VD) of the macula and optic disc in the normal eyes of children. Methods This was a retrospective study where subjects aged 5–18 years with normal eyes were enrolled. The macula and optic disc were scanned by optical coherence tomography angiography (OCTA). The influences of age, gender, and axial length (AL) on VD were analyzed. Results A total of 71 normal eyes from 71 subjects were enrolled. For the macula, the mean VD of fovea, parafovea, and perifovea at superficial retina and deep retina were 20 ...

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    15. Three-dimensional choroidal vascularity index in acute central serous chorioretinopathy using swept-source optical coherence tomography

      Three-dimensional choroidal vascularity index in acute central serous chorioretinopathy using swept-source optical coherence tomography

      Purpose To evaluate the three-dimensional choroidal vascularity index (CVI) in the eyes with treatment-naïve acute central serous chorioretinopathy (CSC) using swept-source optical coherence tomography (SS OCT). Methods In this prospective cross-sectional study, OCT and OCT angiography covered an area of 12 × 12 mm centered on the fovea. Three-dimensional CVI was defined as the ratio of the choroidal vascular luminal volume to the total choroidal volume. The location of pigment epithelial detachment (PED) and the area with abnormal perfusion at choriocapillary layer were compared with the distribution of the three-dimensional CVI. Results Thirty-two eyes with treatment-naïve acute CSC, 18 ...

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    16. Optical coherence tomography angiography assessment of retinal microvascular changes in diabetic eyes in an urban safety-net hospital

      Optical coherence tomography angiography assessment of retinal microvascular changes in diabetic eyes in an urban safety-net hospital

      PURPOSE To determine whether quantitative optical coherence tomography angiography (OCTA) parameters can be used to distinguish among eyes at various stages of diabetic retinopathy (DR) in an urban safety-net hospital population. DESIGN Prospective cross-sectional study PARTICIPANTS 329 eyes from 329 patients were included in this study; 90 nondiabetic patients, 170 diabetic patients without retinopathy, 57 diabetes with mild to moderate NPDR, and 12 diabetes with severe NPDR to PDR. METHODS Patients underwent OCTA imaging and ultra-widefield fundus photography at Zuckerberg San Francisco General Hospital and Trauma Center between April and October 2018. For participants with diabetes, imaging was classified according ...

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      Mentions: UCSF
    17. Imaging Artifacts and Segmentation Errors With Wide-Field Swept-Source Optical Coherence Tomography Angiography in Diabetic Retinopathy

      Imaging Artifacts and Segmentation Errors With Wide-Field Swept-Source Optical Coherence Tomography Angiography in Diabetic Retinopathy

      Purpose : To analyze imaging artifacts and segmentation errors with wide-field swept-source optical coherence tomography angiography (SS-OCTA) in diabetic retinopathy (DR). Methods : We conducted a prospective, observational study at Massachusetts Eye and Ear from December 2018 to March 2019. Proliferative diabetic retinopathy (PDR), nonproliferative diabetic retinopathy (NPDR), diabetic patients with no diabetic retinopathy (DR), and healthy control eyes were included. All patients were imaged with a SS-OCTA and the Montage Angio (15 × 9 mm) was used for analysis. Images were independently evaluated by two graders using the motion artifact score (MAS). All statistical analyses were performed using SPSS 25.0 and ...

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    18. Correlation of optical attenuation coefficient estimated using optical coherence tomography with changes in astrocytes and neurons in a chronic photothrombosis stroke model

      Correlation of optical attenuation coefficient estimated using optical coherence tomography with changes in astrocytes and neurons in a chronic photothrombosis stroke model

      The optical attenuation coefficient (OAC) estimated using optical coherence tomography (OAC-OCT) offers a label-free 3D mapping of tissue infarction, but the physiological origin of the OAC contrast remains unclear. For effectively suppressing OAC fluctuations, we propose a hybrid (wavelength/angle) division multiplexing (HDM) method, which improved the OAC contrast by 70.7% in tissue phantoms. To test the feasibility of OAC-based infarction detection, triphenyltetrazolium chloride (TTC) staining was performed on fresh ex vivo brain slices, and the TTC-defined infarction was used as the ground truth. Sharp OAC contrast was observed between the TTC-defined infarction (1.09 mm −1 ) and normal ...

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    19. Full‐field swept‐source optical coherence tomography and neural tissue classification for deep brain imagingv

      Full‐field swept‐source optical coherence tomography and neural tissue classification for deep brain imagingv

      Optical coherence tomography can differentiate brain regions with intrinsic contrast and at a micron scale resolution. Such a device can be particularly useful as a realtime neurosurgical guidance tool. We present, to our knowledge, the first full‐field swept‐source optical coherence tomography system operating near a wavelength of 1310 nm. The proof‐of‐concept system was integrated with an endoscopic probe tip, that is compatible with deep brain stimulation keyhole neurosurgery. Neuroimaging experiments were performed on ex vivo brain tissues and in vivo in rat brains. Using classification algorithms involving texture features and optical attenuation, images were successfully classified ...

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    20. Etching-enabled extreme miniaturization of graded-index fiber-based optical coherence tomography probes

      Etching-enabled extreme miniaturization of graded-index fiber-based optical coherence tomography probes

      We introduced and validated a method to miniaturize graded-index (GRIN) fiber-based optical coherence tomography (OCT) probes down to 70  μm in diameter. The probes consist in an assembly of single-mode (SM), coreless (CL), and graded-index (GRIN) fibers. We opted for a probe design enabling controlled size reduction by hydrogen fluoride etching. The fabrication approach prevents nonuniform etching for both the GRIN and SM fiber components, while it requires no probe polishing postetching. We found that the miniaturized probes present insignificant loss of sensitivity (∼1  dB) compared to their thicker (125  μm) counterparts. We also showed that their focusing capabilities remain ...

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    21. Repeatability of Optical Coherence Tomography Angiography in Uveitic Eyes

      Repeatability of Optical Coherence Tomography Angiography in Uveitic Eyes

      Purpose : To investigate the intravisit repeatability of optical coherence tomography angiography (OCTA) in a cohort of uveitis patients. Methods : One hundred ten patients were imaged twice per eye, per visit, using the Zeiss Cirrus HD-OCT Model 5000 device. To calculate choriocapillaris flow void area (CC FV) 6 × 6-mm images were used, and 3 × 3-mm images were used to calculate vessel density (VD) and the foveal avascular zone area (FAZ) of the superficial capillary plexus (SCP) and deep capillary plexus (DCP). Repeatability was measured using Bland-Altman analyses and intraclass correlation coefficients (ICC) with associated coefficient of variation (CV). Results : The level ...

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