1. 1-24 of 297 1 2 3 4 ... 11 12 13 »
    1. Supervised learning and dimension reduction techniques for quantification of retinal fluid in optical coherence tomography images

      Supervised learning and dimension reduction techniques for quantification of retinal fluid in optical coherence tomography images

      Purpose The purpose of the present study is to develop fast automated quantification of retinal fluid in optical coherence tomography (OCT) image sets. Methods We developed an image analysis pipeline tailored towards OCT images that consists of five steps for binary retinal fluid segmentation. The method is based on feature extraction, pre-segmention, dimension reduction procedures, and supervised learning tools. Results Fluid identification using our pipeline was tested on two separate patient groups: one associated to neovascular age-related macular degeneration, the other showing diabetic macular edema. For training and evaluation purposes, retinal fluid was annotated manually in each cross-section by human ...

      Read Full Article
    2. Robust and fast characterization of OCT-based optical attenuation using a novel frequency-domain algorithm for brain cancer detection

      Robust and fast characterization of OCT-based optical attenuation using a novel frequency-domain algorithm for brain cancer detection

      Cancer is known to alter the local optical properties of tissues. The detection of OCT-based optical attenuation provides a quantitative method to efficiently differentiate cancer from non-cancer tissues. In particular, the intraoperative use of quantitative OCT is able to provide a direct visual guidance in real time for accurate identification of cancer tissues, especially these without any obvious structural layers, such as brain cancer. However, current methods are suboptimal in providing high-speed and accurate OCT attenuation mapping for intraoperative brain cancer detection. In this paper, we report a novel frequency-domain (FD) algorithm to enable robust and fast characterization of optical ...

      Read Full Article
    3. Elastic turbulence in entangled semi-dilute DNA solutions measured with optical coherence tomography velocimetry

      Elastic turbulence in entangled semi-dilute DNA solutions measured with optical coherence tomography velocimetry

      The flow instabilities of solutions of high molecular weight DNA in the entangled semi-dilute concentration regime were investigated using optical coherence tomography velocimetry, a technique that provides high spatial (probe volumes of 3.4 pL) and temporal resolution (sub μs) information on the flow behaviour of complex fluids in a rheometer. The velocity profiles of the opaque DNA solutions (high and low salt) were measured as a function of the distance across the gap of a parallel plate rheometer, and their evolution over time was measured. At lower DNA concentrations and low shear rates, the velocity fluctuations were well described ...

      Read Full Article
    4. In Vivo Molecular Optical Coherence Tomography of Lymphatic Vessel Endothelial Hyaluronan Receptors

      In Vivo Molecular Optical Coherence Tomography of Lymphatic Vessel Endothelial Hyaluronan Receptors

      Optical Coherence Tomography (OCT) imaging of living subjects offers increased depth of penetration while maintaining high spatial resolution when compared to other optical microscopy techniques. However, since most protein biomarkers do not exhibit inherent contrast detectable by OCT, exogenous contrast agents must be employed for imaging specific cellular biomarkers of interest. While a number of OCT contrast agents have been previously studied, demonstrations of molecular targeting with such agents in live animals have been historically challenging and notably limited in success. Here we demonstrate for the first time that microbeads (µBs) can be used as contrast agents to target cellular ...

      Read Full Article
    5. Optical Coherence Tomography Angiography to Estimate Retinal Blood Flow in Eyes with Retinitis Pigmentosa

      Optical Coherence Tomography Angiography to Estimate Retinal Blood Flow in Eyes with Retinitis Pigmentosa

      Ophthalmologists sometimes face difficulties in identifying the origin of visual acuity (VA) loss in a retinitis pigmentosa (RP) patient, particularly before cataract surgery: cataract or the retinal disease state. Therefore, it is important to identify the significant factors correlating with VA. Nowadays, retinal blood flow in superficial and deep layers can be estimated non-invasively using optical coherence tomography angiography (OCTA). We estimated blood flow per retinal layer by using OCTA; investigated the correlation between VA and other parameters including blood flow and retinal thickness; and identified the most associated factor with VA in patients with RP. OCTA images in 68 ...

      Read Full Article
    6. Crowded optic nerve head evaluation with optical coherence tomography in anterior ischemic optic neuropathy

      Crowded optic nerve head evaluation with optical coherence tomography in anterior ischemic optic neuropathy

      Purpose To characterize the optic nerve head (ONH) structure in patients with non-arteritic anterior ischemic optic neuropathy (NAION) compared to healthy control subjects using spectral domain optical coherence tomography (SD-OCT) via the enhanced depth imaging method. Methods In this prospective, cross-sectional, comparative study, we assessed 66 eyes of 33 patients with unilateral NAION and 31 eyes of 31 healthy normal subjects in an academic institution. The peripapillary nerve fiber layer thickness, disc area, and quantitative parameters of the ONH structures, including the Bruch’s membrane opening (BMO) area, anterior laminar depth, and prelaminar thickness and depth were compared between the ...

      Read Full Article
    7. The emergence of optical elastography in biomedicine

      The emergence of optical elastography in biomedicine

      Optical elastography, the use of optics to characterize and map the mechanical properties of biological tissue, involves measuring the deformation of tissue in response to a load. Such measurements may be used to form an image of a mechanical property, often elastic modulus, with the resulting mechanical contrast complementary to the more familiar optical contrast. Optical elastography is experiencing new impetus in response to developments in the closely related fields of cell mechanics and medical imaging, aided by advances in photonics technology, and through probing the microscale between that of cells and whole tissues. Two techniques — optical coherence elastography and ...

      Read Full Article
    8. Illuminating dynamic neutrophil trans-epithelial migration with micro-optical coherence tomography

      Illuminating dynamic neutrophil trans-epithelial migration with micro-optical coherence tomography

      A model of neutrophil migration across epithelia is desirable to interrogate the underlying mechanisms of neutrophilic breach of mucosal barriers. A co-culture system consisting of a polarized mucosal epithelium and human neutrophils can provide a versatile model of trans-epithelial migration in vitro , but observations are typically limited to quantification of migrated neutrophils by myeloperoxidase correlation, a destructive assay that precludes direct longitudinal study. Our laboratory has recently developed a new isotropic 1-μm resolution optical imaging technique termed micro-optical coherence tomography (μOCT) that enables 4D (x,y,z,t) visualization of neutrophils in the co-culture environment. By applying μOCT to ...

      Read Full Article
    9. Visual dysfunction and its correlation with retinal changes in patients with Alzheimer's disease

      Visual dysfunction and its correlation with retinal changes in patients with Alzheimer's disease

      Aim To evaluate visual dysfunction and its correlation with structural changes in the retina in patients with Alzheimer's disease (AD). Methods Patients with AD (n = 24) and controls (n = 24) underwent evaluation of visual acuity (VA), color vision (using the Farnsworth and L’Anthony desaturated (D) 15 color tests), and contrast sensitivity vision (CSV; using the Pelli-Robson chart and CSV-1000E test) to measure visual dysfunction. Structural measurements of the retinal nerve fiber layer (RNFL) and macular thickness were obtained using spectral domain-optical coherence tomography (SD-OCT). Results CSV at three of the four spatial frequencies was significantly worse in AD ...

      Read Full Article
    10. Surgical treatment and optical coherence tomographic evaluation for accidental laser-induced full-thickness macular holes

      Surgical treatment and optical coherence tomographic evaluation for accidental laser-induced full-thickness macular holes

      Purpose To report OCT appearance and surgical outcomes of full-thickness macular holes (MHs) accidentally caused by laser devices. Patients and methods This retrospective case series included 11 eyes of 11 patients with laser-induced MHs treated by pars plana vitrectomy, internal limiting membrane (ILM) peeling, and gas or silicone oil tamponade. Evaluations included a full ophthalmic examination, macular spectral-domain optical coherence tomography (SD-OCT), and fundus photography. Main outcome measures is MH closure and final visual acuity; the secondary outcome was the changes of retinal pigment epithelium and photoreceptor layer evaluated by sequential post-operative SD-OCT images. Results Five patients were accidentally injured ...

      Read Full Article
    11. Accuracy and safety verification of ovarian reserve assessment technique for ovarian tissue transplantation using optical coherence tomography in mice ovary

      Accuracy and safety verification of ovarian reserve assessment technique for ovarian tissue transplantation using optical coherence tomography in mice ovary

      Except for histological study, there are currently no suitable techniques available for the detection and identification of primordial follicles in ovary of primary ovarian insufficiency patients who have undetectable AMH levels. Also, the ability to locate and quantify follicles on ovarian cortex strips, without fixation, is valuable for patients who could undergo subsequent successful ovarian tissue transplantation. Although optical coherence tomography (OCT) is a well-established high resolution imaging technique without fixation commonly applied in biomedicine, few reports are available on ovarian tissue imaging. In present study, we established standard OCT follicle images at each developmental stage, including the primordial follicle ...

      Read Full Article
    12. Design of a k-space spectrometer for ultra-broad waveband spectral domain optical coherence tomography

      Design of a k-space spectrometer for ultra-broad waveband spectral domain optical coherence tomography

      Nonlinear sampling of the interferograms in wavenumber ( k ) space degrades the depth-dependent signal sensitivity in conventional spectral domain optical coherence tomography (SD-OCT). Here we report a linear-in-wavenumber ( k -space) spectrometer for an ultra-broad bandwidth (760 nm–920 nm) SD-OCT, whereby a combination of a grating and a prism serves as the dispersion group. Quantitative ray tracing is applied to optimize the linearity and minimize the optical path differences for the dispersed wavenumbers. Zemax simulation is used to fit the point spread functions to the rectangular shape of the pixels of the line-scan camera and to improve the pixel sampling rates ...

      Read Full Article
    13. Optical coherence tomography evaluation of pulmonary arterial vasculopathy in Systemic Sclerosis

      Optical coherence tomography evaluation of pulmonary arterial vasculopathy in Systemic Sclerosis

      Our current understanding of the pathophysiology of pulmonary vascular disease is incomplete, since information about alterations of the pulmonary vasculature in pulmonary arterial hypertension (PAH) is primarily provided by autopsy or tissue specimens. The aim of this study was to compare the distal pulmonary vasculature of <2 mm in diameter in Systemic Sclerosis (SSc) patients with (n = 17) and without (n = 5) associated PAH using Optical Coherence Tomography during Right Heart catheterization. SSc-PAH patients showed significant thickening of Intima Media Thickening Area compared to patients without PAH (27 +/− 5.8% vs. 21 +/− 1.4%, p = 0.024). A good haemodynamic ...

      Read Full Article
    14. Evaluation of choroidal tumors with optical coherence tomography: enhanced depth imaging and OCT-angiography features

      Evaluation of choroidal tumors with optical coherence tomography: enhanced depth imaging and OCT-angiography features

      Aim To describe the vascular features of choroidal tumors using enhanced depth imaging (EDI), optical coherence tomography (OCT), and OCT-angiography. Methods In this prospective study, we evaluated 116 Caucasian patients with choroidal tumors (60 eyes with choroidal nevi, 40 with choroidal melanoma, 6 with choroidal hemangioma, 2 with optic disc melanocytoma, 6 with choroidal osteoma, and 2 with retinal metastases). Patients underwent a complete ophthalmic examination including bulbar echography, EDI-OCT, OCT-angiography, and multicolor imaging. Sixteen patients also underwent fluorescein and indocyanine angiography. Results The left eye was more involved than the right eye. The mean tumor thickness was 1.23 ...

      Read Full Article
    15. Research Engineer Opening - Probe-based Imaging Diagnostic Tool for In vivo Atherosclerotic Biomarker Detection

      Research Engineer Opening - Probe-based Imaging Diagnostic Tool for In vivo Atherosclerotic Biomarker Detection

      The International Iberian Nanotechnology Laboratory – INL ( http://www.inl.int ), was founded under an international legal framework to perform interdisciplinary research and to deploy and articulate nanotechnology for the benefit of society. INL aims to become the world-wide hub for nanotechnology addressing society's grand challenges with specific emphasis on Aging & Wellbeing, Mobility & Urban Living and a Safe & Secure Society. The work undertaken by our research centre has a significant impact on people's lives and societal benefit. The objective is to ensure that staff is employed on the basis of skills and requirements for the job and that there ...

      Read Full Article
    16. Detailed Vascular Anatomy of the Human Retina by Projection-Resolved Optical Coherence Tomography Angiography

      Detailed Vascular Anatomy of the Human Retina by Projection-Resolved Optical Coherence Tomography Angiography

      Optical coherence tomography angiography (OCTA) is a noninvasive method of 3D imaging of the retinal and choroidal circulations. However, vascular depth discrimination is limited by superficial vessels projecting flow signal artifact onto deeper layers. The projection-resolved (PR) OCTA algorithm improves depth resolution by removing projection artifact while retaining in-situ flow signal from real blood vessels in deeper layers. This novel technology allowed us to study the normal retinal vasculature in vivo with better depth resolution than previously possible. Our investigation in normal human volunteers revealed the presence of 2 to 4 distinct vascular plexuses in the retina, depending on location ...

      Read Full Article
    17. Analysis of Craniocardiac Malformations in Xenopus using Optical Coherence Tomography : Scientific Reports

      Analysis of Craniocardiac Malformations in Xenopus using Optical Coherence Tomography : Scientific Reports

      Birth defects affect 3% of children in the United States. Among the birth defects, congenital heart disease and craniofacial malformations are major causes of mortality and morbidity. Unfortunately, the genetic mechanisms underlying craniocardiac malformations remain largely uncharacterized. To address this, human genomic studies are identifying sequence variations in patients, resulting in numerous candidate genes. However, the molecular mechanisms of pathogenesis for most candidate genes are unknown. Therefore, there is a need for functional analyses in rapid and efficient animal models of human disease. Here, we coupled the frog Xenopus tropicalis with Optical Coherence Tomography (OCT) to create a fast and ...

      Read Full Article
    18. Visualizing dynamics of angiogenic sprouting from a three-dimensional microvasculature model using stage-top optical coherence tomography

      Visualizing dynamics of angiogenic sprouting from a three-dimensional microvasculature model using stage-top optical coherence tomography

      Three-dimensional (3D) in vitro microvasculature in a polydimethylsiloxane-based microdevice was developed as a physiologically relevant model of angiogenesis. The angiogenic process is monitored using stage-top optical coherence tomography (OCT). OCT allows non-invasive monitoring of the 3D structures of the prepared host microvasculature and sprouted neovasculature without fluorescence staining. OCT monitoring takes only a few minutes to scan through the several-millimetre scale range, which provides the advantage of rapid observation of living samples. The obtained OCT cross-sectional images capture 3D features of the angiogenic sprouting process and provide information on the dynamics of luminal formation. The stage-top system used in this ...

      Read Full Article
    19. Open-source algorithm for automatic choroid segmentation of OCT volume reconstructions

      Open-source algorithm for automatic choroid segmentation of OCT volume reconstructions

      The use of optical coherence tomography (OCT) to study ocular diseases associated with choroidal physiology is sharply limited by the lack of available automated segmentation tools. Current research largely relies on hand-traced, single B-Scan segmentations because commercially available programs require high quality images, and the existing implementations are closed, scarce and not freely available. We developed and implemented a robust algorithm for segmenting and quantifying the choroidal layer from 3-dimensional OCT reconstructions. Here, we describe the algorithm, validate and benchmark the results, and provide an open-source implementation under the General Public License for any researcher to use ( https://www.mathworks ...

      Read Full Article
    20. Optical coherence tomography angiography microvascular findings in macular edema due to central and branch retinal vein occlusions

      Optical coherence tomography angiography microvascular findings in macular edema due to central and branch retinal vein occlusions

      The aim of this study was to evaluate retinal and choriocapillaris vessel density using optical coherence tomography angiography (OCTA) in eyes with central retinal vein occlusion (CRVO) and branch retinal vein occlusion (BRVO) complicated by macular edema (ME). Sixty eyes of 60 patients with CRVO or BRVO and ME and 40 healthy subjects underwent measurements of superficial and deep foveal and parafoveal vessel density (FVD, PFVD) and choricapillary density using OCTA at baseline and 60 days after intravitreal dexamethasone implant (IVDEX). FVD and PFVD of the superficial plexus were not significantly lower in CRVO group compared to the controls while ...

      Read Full Article
    21. Acoustic micro-tapping for non-contact 4D imaging of tissue elasticity

      Acoustic micro-tapping for non-contact 4D imaging of tissue elasticity

      Elastography plays a key role in characterizing soft media such as biological tissue. Although this technology has found widespread use in both clinical diagnostics and basic science research, nearly all methods require direct physical contact with the object of interest and can even be invasive. For a number of applications, such as diagnostic measurements on the anterior segment of the eye, physical contact is not desired and may even be prohibited. Here we present a fundamentally new approach to dynamic elastography using non-contact mechanical stimulation of soft media with precise spatial and temporal shaping. We call it acoustic micro-tapping (A ...

      Read Full Article
    22. Anatomically correct visualization of the human upper airway using a high-speed long range optical coherence tomography system with an integrated positioning sensor

      Anatomically correct visualization of the human upper airway using a high-speed long range optical coherence tomography system with an integrated positioning sensor

      The upper airway is a complex tissue structure that is prone to collapse. Current methods for studying airway obstruction are inadequate in safety, cost, or availability, such as CT or MRI, or only provide localized qualitative information such as flexible endoscopy. Long range optical coherence tomography (OCT) has been used to visualize the human airway in vivo , however the limited imaging range has prevented full delineation of the various shapes and sizes of the lumen. We present a new long range OCT system that integrates high speed imaging with a real-time position tracker to allow for the acquisition of an ...

      Read Full Article
    23. High-speed swept source optical coherence Doppler tomography for deep brain microvascular imaging

      High-speed swept source optical coherence Doppler tomography for deep brain microvascular imaging

      Noninvasive microvascular imaging using optical coherence Doppler tomography (ODT) has shown great promise in brain studies; however, high-speed microcirculatory imaging in deep brain remains an open quest. A high-speed 1.3 μm swept-source ODT (SS-ODT) system is reported which was based on a 200 kHz vertical-cavity-surface-emitting laser. Phase errors induced by sweep-trigger desynchronization were effectively reduced by spectral phase encoding and instantaneous correlation among the A-scans. Phantom studies have revealed a significant reduction in phase noise, thus an enhancement of minimally detectable flow down to 268.2 μm/s. Further in vivo validation was performed, in which 3D cerebral-blood-flow (CBF ...

      Read Full Article
    1-24 of 297 1 2 3 4 ... 11 12 13 »
  1. Categories

    1. Applications:

      Art, Cardiology, Dentistry, Dermatology, Developmental Biology, Gastroenterology, Gynecology, Microscopy, NDE/NDT, Neurology, Oncology, Ophthalmology, Other Non-Medical, Otolaryngology, Pulmonology, Urology
    2. Business News:

      Acquisition, Clinical Trials, Funding, Other Business News, Partnership, Patents
    3. Technology:

      Broadband Sources, Probes, Tunable Sources
    4. Miscellaneous:

      Jobs & Studentships, Student Theses, Textbooks