1. Articles in category: Neurology

    1-24 of 506 1 2 3 4 ... 19 20 21 »
    1. Optical Coherence Tomography for the Noninvasive Detection of Elevated Intracranial Pressure A New Role for the Ophthalmologist?

      Optical Coherence Tomography for the Noninvasive Detection of Elevated Intracranial Pressure A New Role for the Ophthalmologist?

      Lumbar puncture is the usual confirmatory procedure for the diagnosis of idiopathic intracranial hypertension. However, the lumbar cerebrospinal fluid pressure does not always reflect the intracranial pressure (ICP), especially in children. 1 Therefore, direct ICP monitoring is the gold standard for ascertainment of ICP. However, this procedure is more invasive, requiring general anesthesia and hospital admission to monitor ICP over a period of days. It also carries low risk for central nervous system infection or injury. Consequently, newer techniques are being devised to noninvasively monitor ICP. 2

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    2. Rat brain imaging using full field optical coherence microscopy with short multimode fiber probe

      Rat brain imaging using full field optical coherence microscopy with short multimode fiber probe

      We demonstrated FF OCM(full field optical coherence microscopy) using an ultrathin forward-imaging SMMF (short multimode fiber) probe of 50 μm core diameter, 125 μm diameter, and 7.4 mm length, which is a typical graded-index multimode fiber for optical communications. The axial resolution was measured to be 2.20 μm, which is close to the calculated axial resolution of 2.06 μm. The lateral resolution was evaluated to be 4.38 μm using a test pattern. Assuming that the FWHM of the contrast is the DOF (depth of focus), the DOF of the signal is obtained at 36 μm ...

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    3. Spectroscopic optical coherence tomography for ex vivo brain tumor analysis

      Spectroscopic optical coherence tomography for ex vivo brain tumor analysis

      For neurosurgeries precise tumor resection is essential for the subsequent recovery of the patients since nearby healthy tissue that may be harmed has a huge impact on the life quality after the surgery. However, so far no satisfying methodology has been established to assist the surgeon during surgery to distinguish between healthy and tumor tissue. Optical Coherence Tomography (OCT) potentially enables non-contact in vivo image acquisition at penetration depths of 1-2 mm with a resolution of approximately 1-15 μm. To analyze the potential of OCT for distinction between brain tumors and healthy tissue, we used a commercially available Thorlabs Callisto ...

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    4. Retinal structure assessed by OCT as a biomarker of brain development in children born small for gestational age

      Retinal structure assessed by OCT as a biomarker of brain development in children born small for gestational age

      Purpose To identify differences in neuronal tissue from retinal and brain structures in children born small for gestational age (SGA) with no abnormality in neonatal brain ultrasonography and no previous neurological impairment, and to evaluate the relationship between retinal structure and brain changes in school-age children born SGA. Methods Two cohorts of children were recruited: 25 children born SGA and 25 children born with an appropriate birth weight according to gestational age. All the children underwent an ophthalmic examination, which included retinal imaging using spectral-domain optical coherence tomography, and a brain MRI. MRI images were automatically segmented and global and ...

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    5. Semiautomated segmentation and analysis of retinal layers in three-dimensional spectral-domain optical coherence tomography images of patients with atrophic age-related macular degeneration

      Semiautomated segmentation and analysis of retinal layers in three-dimensional spectral-domain optical coherence tomography images of patients with atrophic age-related macular degeneration

      Historically, regular drusen and geographic atrophy (GA) have been recognized as the hallmarks of nonneovascular age-related macular degeneration (AMD). Recent imaging developments have revealed another distinct nonneovascular AMD phenotype, reticular pseudodrusen (RPD). We develop an approach to semiautomatically quantify retinal surfaces associated with various AMD lesions (i.e., regular drusen, RPD, and GA) in spectral domain (SD) optical coherence tomography (OCT) images. More specifically, a graph-based algorithm was used to segment multiple retinal layers in SD-OCT volumes. Varying surface feasibility constraints based on the presegmentation were applied on the double-surface graph search to refine the surface segmentation. The thicknesses of ...

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    6. Using OCT with your diabetes patients

      Using OCT with your diabetes patients

      Patients with diabetes may present a variety of interesting findings best unveiled by use of spectral domain optical coherence tomography (SD-OCT). OCT is one of the best way to assess patients for the presence of diabetic macular edema (DME). It is extremely useful for monitoring responses to treatments such as anti-VEGF injections, grid or focal laser, intravitreal steroids, or any combination thereof in patients with DME involving or threatening the fovea (center-involved DME). However, detecting and monitoring increased retinal thickness associated with diabetes is not the only relevant anatomical feature best visualized and appreciated with OCT. Let’s consider a ...

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    7. Multimodal optical coherence tomography for in vivo imaging of brain tissue structure and microvascular network at glioblastoma

      Multimodal optical coherence tomography for in vivo imaging of brain tissue structure and microvascular network at glioblastoma

      In the case of infiltrative brain tumors the surgeon faces difficulties in determining their boundaries to achieve total resection. The aim of the investigation was to evaluate the performance of multimodal OCT (MM OCT) for differential diagnostics of normal brain tissue and glioma using an experimental model of glioblastoma. The spectral domain OCT device that was used for the study provides simultaneously two modes: cross-polarization and microangiographic OCT. The comparative analysis of the both OCT modalities images from tumorous and normal brain tissue areas concurrently with histologic correlation shows certain difference between when accordingly to morphological and microvascular tissue features.

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    8. Optical coherence tomography segmentation analysis in relapsing remitting versus progressive multiple sclerosis

      Optical coherence tomography segmentation analysis in relapsing remitting versus progressive multiple sclerosis

      Introduction Optical coherence tomography (OCT) with retinal segmentation analysis is a valuable tool in assessing axonal loss and neuro-degeneration in multiple sclerosis (MS) by in-vivo imaging, delineation and quantification of retinal layers. There is evidence of deep retinal involvement in MS beyond the inner retinal layers. The ultra-structural retinal changes in MS in different MS phenotypes can reflect differences in the pathophysiologic mechanisms. There is limited data on the pattern of deeper retinal layer involvement in progressive MS (PMS) versus relapsing remitting MS (RRMS). We have compared the OCT segmentation analysis in patients with relapsing-remitting MS and progressive MS. Methods ...

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    9. Northwestern University Receives a NIH Grant for A Clinically Applicable Model Of Retinal Oxygen Metabolism

      Northwestern University Receives a NIH Grant for A Clinically Applicable Model Of Retinal Oxygen Metabolism

      Northwestern University Receives at 2017 NIH Grant for $195,625 for A Clinically Applicable Model Of Retinal Oxygen Metabolism. The principal investigator is Robert Linsenmeier. The program began in 2017 and ends in 2019. Below is a summary of the proposed work. This proposal seeks to establish a correlation between the metabolism of the inner retina and the oxygen supply from the inner retinal vascular network measured by optical coherence tomography. This work will be done in rats, but will have immediate clinical application. Several important diseases cause damage to the inner retina, including diabetes, glaucoma, and vascular occlusion. Considerable ...

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    10. Polarization-sensitive optical coherence tomography of the human brain connectome

      Polarization-sensitive optical coherence tomography of the human brain connectome

      The human brain is composed of approximately 100 billion neurons that ‘communicate’ through an intricate network of axons and dendrites. 1 The difficulty of tracing these 3D neuronal pathways, however, has been a critical barrier for standard histology (the study of microscopic anatomy) over the past 100 years. Indeed, there is still no technology that can be used to acquire microscopic images in undistorted 3D space for mapping human brain connectivity. Currently available techniques for 3D brain mapping include histological staining and polarized light imaging. 2, 3 In these approaches, 2D image slices are obtained, but these must be physically ...

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    11. The role of optical coherence tomography in Alzheimer’s disease

      The role of optical coherence tomography in Alzheimer’s disease

      Background Alzheimer’s disease (AD) is the most common cause of dementia and its incidence is increasing worldwide along with population aging. Previous clinical and histologic studies suggest that the neurodegenerative process, which affects the brain, may also affect the retina of AD patients. Main body Optical coherence tomography (OCT) is a non-invasive technology that acquires cross-sectional images of retinal structures allowing neural fundus integrity assessment. Several previous studies demonstrated that both peripapillary retinal nerve fiber layer and macular thickness measurements assessed by OCT were able to detect neuronal loss in AD. Moreover, recent advances in OCT technology, have allowed ...

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    12. The University of Houston Receives NIH Grant for Optical Coherence Tomography to Study Effect of Poly-Drug Exposure on Fetal Brain Development

      The University of Houston Receives NIH Grant for Optical Coherence Tomography to Study Effect of Poly-Drug Exposure on Fetal Brain Development

      The University of Houston Receives a 2017 NIH Grant for $311,241 for Optical Coherence Tomography to Study Effect of Poly-Drug Exposure on Fetal Brain Development. The principal investigator is Kirll Larin. The program began in 2016 and ends in 2020. Below is a summary of the proposed work. The overall objective of this study is to develop an optical coherence tomography (OCT) based high- resolution mouse embryonic brain imaging and analysis approach, and to use this method in correlation with molecular analysis to understand the interplay between ethanol (EtOH) and nicotine (NIC) effects on embryonic brain development. Maternal exposures ...

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    13. Sensitivity of visual evoked potentials and spectral domain optical coherence tomography in early relapsing remitting multiple sclerosis

      Sensitivity of visual evoked potentials and spectral domain optical coherence tomography in early relapsing remitting multiple sclerosis

      Background Visual evoked potentials and spectral-domain optical coherence tomography are common ancillary studies that assess the visual pathways from a functional and structural aspect, respectively. Objective To compare prevalence of abnormalities of Visual evoked potentials (VEP) and spectral-domain optical coherence tomography (SDOCT) in patients with relapsing remitting multiple sclerosis (RRMS). Methods A cross-sectional study of 100 eyes with disease duration of less than 5 years since the diagnosis. Correlation between retinal nerve fiber layer and ganglion-cell/inner plexiform layer with pattern-reversal visual evoked potentials amplitude and latency and contrast sensitivity was performed. Results The prevalence of abnormalities in pattern-reversal visual ...

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    14. Dynamic imaging and quantitative analysis of cranial neural tube closure in the mouse embryo using optical coherence tomography

      Dynamic imaging and quantitative analysis of cranial neural tube closure in the mouse embryo using optical coherence tomography

      Neural tube closure is a critical feature of central nervous system morphogenesis during embryonic development. Failure of this process leads to neural tube defects, one of the most common forms of human congenital defects. Although molecular and genetic studies in model organisms have provided insights into the genes and proteins that are required for normal neural tube development, complications associated with live imaging of neural tube closure in mammals limit efficient morphological analyses. Here, we report the use of optical coherence tomography (OCT) for dynamic imaging and quantitative assessment of cranial neural tube closure in live mouse embryos in culture ...

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    15. Polarization-Maintaining Fiber-Based Optical Coherence Tomography on Functional Imaging in Dense Nerve (Student Thesis)

      Polarization-Maintaining Fiber-Based Optical Coherence Tomography on Functional Imaging in Dense Nerve (Student Thesis)

      The technology and applications of optical coherence tomography (OCT) have been developed rapidly for structural and functional investigations of biological tissues. The use of light yields outstanding resolution and simultaneous measurements from a range of targeted locations without physical contact with tissue. The objective of this thesis was to investigate the feasibility of utilizing polarization-maintaining-fiber (PMF) based OCT to image the microstructure and functional (neural activity) of pike olfactory nerve. A dual-wavelength polarization-sensitive spectral-domain OCT system has been designed and constructed in house for depth-resolved optical recordings. The olfactory nerves dissected from pike were used with or without voltage-sensitive dye ...

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    16. Structural and Functional Analyses in Nonarteritic Anterior Ischemic Optic Neuropathy: Optical Coherence Tomography Angiography Study

      Structural and Functional Analyses in Nonarteritic Anterior Ischemic Optic Neuropathy: Optical Coherence Tomography Angiography Study

      Background: Retinal and optic disc perfusion in nonarteritic anterior ischemic optic neuropathy (NAION) is incompletely understood. Our aim was to investigate the characteristics of the microvascular structures at the peripapillary area and optic disc, and their associations with retinal structure and function in patients with NAION. Methods: We conducted a prospective, observational case series study. Thirty-four eyes, consisting of 15 NAION eyes and 19 normal eyes, were included. Optical coherence tomography (OCT) angiography was used to measure the vessel densities in the peripapillary superficial retina and whole-depth mode inside the optic disc. Measurement of circumpapillary retinal nerve fiber layer (cpRNFL ...

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    17. Optical coherence tomography: A quantitative tool to measure neurodegeneration and facilitate testing of novel treatments for tissue protection in multiple sclerosis

      Optical coherence tomography: A quantitative tool to measure neurodegeneration and facilitate testing of novel treatments for tissue protection in multiple sclerosis

      Optical coherence tomography (OCT) is a relatively new imaging technology that has been introduced as a powerful biomarker in neurological disease, including multiple sclerosis. In this review, OCT as an imaging technique, its reproducibility and validation in multiple sclerosis, application to other neurodegenerative diseases and future technological directions are discussed.

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    18. 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 ...

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    19. Optical Coherence Tomography: Research that’s Revealing More than Meets the Eye

      Optical Coherence Tomography: Research that’s Revealing More than Meets the Eye

      A simple eye exam can reveal a lot about your health, helping doctors diagnose existing conditions or to spot indicators before there’s even a problem. Dr. Kostadinka Bizheva is advancing medical care by bringing high resolution imaging technology to Optical Coherence Tomography (OCT). At her research clinic at the University of Waterloo, she and her team are researching how to take OCT beyond detecting common eye diseases like glaucoma and macular degeneration.

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    20. Using light to map the circuitry of the brain

      Using light to map the circuitry of the brain

      Lehigh University bio-engineers are first to explore the use of highly-sensitive, non-invasive optical coherence tomography (OCT) to examine neuron-to-neuron communication in live tissue. Scientific progress has provided a solid understanding of the anatomy of the brain. However, there is still no reliable way to examine neuron to neuron communication, as it happens--a key to understanding the correlation between brain structure and brain function. Chao Zhou , assistant professor of bioengineering at Lehigh University, likens our current brain-mapping ability to a Global Positioning System (GPS) that can help a user locate a city, but cannot offer a street-level view. With current imaging ...

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    21. Optical coherence tomography imaging of capillary reperfusion after ischemic stroke

      Optical coherence tomography imaging of capillary reperfusion after ischemic stroke

      Although progress has been made for recanalization therapies after ischemic stroke, post-treatment imaging studies show that tissue reperfusion cannot be attained despite satisfactory recanalization in a significant percentage of patients. Hence, investigation of microcirculatory changes in both surface and deep cortical levels after ischemia reperfusion is important for understanding the post-stroke blood flow dynamics. In this study, we applied optical coherence tomography (OCT) imaging of cerebral blood flow for the quantification of the microcirculatory changes. We obtained OCT microangiogram of the brain cortex in a mouse stroke model and analyzed the data to trace changes in the capillary perfusion level ...

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    1-24 of 506 1 2 3 4 ... 19 20 21 »
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