1. Articles in category: Neurology

    73-96 of 693 « 1 2 3 4 5 6 7 ... 27 28 29 »
    1. MICRO-IMAGING CATHETERS FOR HIGH-RESOLUTION, IMAGE-GUIDED, ENDOVASCULAR REPAIR OF BRAIN ANEURYSMS

      MICRO-IMAGING CATHETERS FOR HIGH-RESOLUTION, IMAGE-GUIDED, ENDOVASCULAR REPAIR OF BRAIN ANEURYSMS

      This program will commercialize a high-speed, high-resolution, neuroendovascular imaging platform that allows neurointerventionalists to directly visualize intravascular devices and their interaction with vessels during treatment of brain aneurysms. The miniaturization of the design features of neurovascular stents and flow-diverters has enabled an explosion of technologies available for endovascular treatment of stroke. However, imaging technology has not kept pace with device technology to enable endovascular surgeons sufficient resolution to adequately visualize the device-vessel relationship. As such, there is a critical need for high-resolution imaging specific to cerebrovascular disease and endovascular treatments. Optical coherence tomography (OCT) is a relatively new imaging technique ...

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    2. Can Optical Coherence Tomography Be Used to Guide Treatment Decisions in Adult or Pediatric Multiple Sclerosis?

      Can Optical Coherence Tomography Be Used to Guide Treatment Decisions in Adult or Pediatric Multiple Sclerosis?

      Purpose of review With the recognition that neurodegeneration represents the principal substrate of disability in multiple sclerosis (MS), there has been increased strives towards identifying biomarkers for accurately quantifying and tracking neurodegeneration during the disease course. The retina provides an opportune “window” into the central nervous system (CNS) in MS, with retinal changes in MS reflecting not only local, but also global aspects of neurodegeneration and inflammation operative in the disease. Optical coherence tomography (OCT) is a rapid, inexpensive, reproducible, high-resolution imaging technique allowing accurate quantification of discrete retinal layers. OCT determined thinning of inner retinal layers such as the ...

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    3. Visualization of neuritic plaques in Alzheimer’s disease by polarization-sensitive optical coherence microscopy

      Visualization of neuritic plaques in Alzheimer’s disease by polarization-sensitive optical coherence microscopy

      One major hallmark of Alzheimer’s disease (AD) and cerebral amyloid angiopathy (CAA) is the deposition of extracellular senile plaques and vessel wall deposits composed of amyloid-beta (A β ). In AD, degeneration of neurons is preceded by the formation of A β plaques, which show different morphological forms. Most of them are birefringent owing to the parallel arrangement of amyloid fibrils. Here, we present polarization sensitive optical coherence microscopy (PS-OCM) for imaging mature neuritic A β plaques based on their birefringent properties. Formalin-fixed, post-mortem brain samples of advanced stage AD patients were investigated. In several cortical brain regions, neuritic A β plaques were successfully ...

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    4. In vivo high-resolution cortical imaging with extended-focus optical coherence microscopy in the visible-NIR wavelength range

      In vivo high-resolution cortical imaging with extended-focus optical coherence microscopy in the visible-NIR wavelength range

      Visible light optical coherence tomography has shown great interest in recent years for spectroscopic and high-resolution retinal and cerebral imaging. Here, we present an extended-focus optical coherence microscopy system operating from the visible to the near-infrared wavelength range for high axial and lateral resolution imaging of cortical structures in vivo . The system exploits an ultrabroad illumination spectrum centered in the visible wavelength range (λ c   =  650  nm, Δλ  ∼  250  nm) offering a submicron axial resolution (∼0.85  μm in water) and an extended-focus configuration providing a high lateral resolution of ∼1.4  μm maintained over ∼150  μm in depth in water. The ...

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    5. Optic Nerve Head Parameters Measured with Spectral-Domain Optical Coherence Tomography in Healthy Turkish Children: Normal Values, Repeatability, and Interocular Symmetry

      Optic Nerve Head Parameters Measured with Spectral-Domain Optical Coherence Tomography in Healthy Turkish Children: Normal Values, Repeatability, and Interocular Symmetry

      To determine normal values, repeatability, and interocular symmetry of optic nerve head measurements, three spectral-domain optical coherence tomography (SD-OCT) scans were obtained from 128 healthy Turkish children aged 5–17 years consecutively and prospectively. The mean disc area, rim area, cup volume, cup to disc area ratio, and vertical and horizontal cup to disc ratios were 2.30 ± 0.42 mm 2 , 1.84 ± 0.45 mm 2 , 0.09 ± 0.10 mm 3 , 0.20 ± 0.13, 0.37 ± 0.17, and 0.45 ± 0.20, respectively. The intraclass correlation coefficients were >0.9 for repeatability and >0.75 ...

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    6. White matter atrophy in spinocerebellar ataxia type 1 mouse models revealed by serial optical coherence scanner

      White matter atrophy in spinocerebellar ataxia type 1 mouse models revealed by serial optical coherence scanner

      Spinocerebellar ataxia type 1 (SCA1) is a fatal inherited neurodegenerative disease. Post-mortem studies showed neurodegeneration involving white matter components in the cerebral lobes, the cerebellar peduncles and the more distal cranial nerves in human patients. However, the progression of SCA1 in the brain remains unclear. We present the study of white matter atrophy of SCA1 mouse models using serial optical coherence scanner (SOCS). SOCS consists of a polarization sensitive optical coherence tomography and a tissue slicer (vibratome) with associated controls for serial imaging. The optical system has 5.5 µm axial resolution and utilizes a scan lens or a water-immersion ...

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    7. Multicenter reliability of semiautomatic retinal layer segmentation using OCT

      Multicenter reliability of semiautomatic retinal layer segmentation using OCT

      Objective To evaluate the inter-rater reliability of semiautomated segmentation of spectral domain optical coherence tomography (OCT) macular volume scans. Methods Macular OCT volume scans of left eyes from 17 subjects (8 patients with MS and 9 healthy controls) were automatically segmented by Heidelberg Eye Explorer (v1.9.3.0) beta-software (Spectralis Viewing Module v6.0.0.7), followed by manual correction by 5 experienced operators from 5 different academic centers. The mean thicknesses within a 6-mm area around the fovea were computed for the retinal nerve fiber layer, ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer, outer ...

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    8. Optical coherence tomography in autosomal recessive spastic ataxia of Charlevoix-Saguenay

      Optical coherence tomography in autosomal recessive spastic ataxia of Charlevoix-Saguenay

      Autosomal recessive spastic ataxia of Charlevoix-Saguenay is a rare neurodegenerative disorder caused by mutations in the SACS gene. Thickened retinal nerve fibres visible on fundoscopy have previously been described in these patients; however, thickening of the retinal nerve fibre layer as demonstrated by optical coherence tomography appears to be a more sensitive and specific feature. To test this observation, we assessed 292 individuals (191 patients with ataxia and 101 control subjects) by peripapillary time-domain optical coherence tomography. The patients included 146 with a genetic diagnosis of ataxia (17 autosomal spastic ataxia of Charlevoix-Saguenay, 59 Friedreich’s ataxia, 53 spinocerebellar ataxias ...

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    9. Optical Coherence Tomography versus Visual Evoked Potentials for Detecting Visual Pathway Abnormalities in Patients with Neuromyelitis Optica Spectrum Disorder

      Optical Coherence Tomography versus Visual Evoked Potentials for Detecting Visual Pathway Abnormalities in Patients with Neuromyelitis Optica Spectrum Disorder

      Background and Purpose Optical coherence tomography (OCT) and visual evoked potentials (VEPs) can be used to detect optic neuritis (ON). However, the comparative sensitivities of OCT and VEPs for detecting ON in neuromyelitis optica spectrum disorder (NMOSD) are unclear, and so we assessed these sensitivities. Methods This cross-sectional study included 73 patients with aquaporin-4 antibody-seropositive NMOSD, and 101 eyes with ON. The clinical characteristics, visual acuity (VA), Expanded Disability Status Scale (EDSS) scores, OCT peripapillary retinal nerve fiber layer (RNFL) thickness, and VEPs of the patients were evaluated. Results OCT and VEPs were abnormal in 68% and 73% of eyes ...

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    10. A pilot study assessing retinal pathology in psychosis using optical coherence tomography: choroidal and macular thickness

      A pilot study assessing retinal pathology in psychosis using optical coherence tomography: choroidal and macular thickness

      Mounting evidence supports a genetic-vascular-inflammatory etiology of schizophrenia. The retina provides an indirect assessment of inflammation and degeneration in the brain. In particular, the use of spectral domain optical coherence tomography (SD-OCT) has emerged as a powerful tool for examining single retinal nerve cell layers and the choroid, the vascular layer supplying the outer retina. In this study, choroidal and macular thicknesses were measured in six patients with psychosis with either schizophrenia or bipolar disorder, and in 18 age- and sex-matched healthy controls. Mean choroidal thickness was reduced in psychosis, though not significantly so. There was a statistically significant decrease ...

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    11. Brain tissue analysis using texture features based on optical coherence tomography images

      Brain tissue analysis using texture features based on optical coherence tomography images

      Brain tissue differentiation is highly demanded in neurosurgeries, i.e. tumor resection. Exact navigation during the surgery is essential in order to guarantee best life quality afterwards. So far, no suitable method has been found that perfectly covers this demands. With optical coherence tomography (OCT), fast three dimensional images can be obtained in vivo and contactless with a resolution of 1-15 μm. With these specifications OCT is a promising tool to support neurosurgeries. Here, we investigate ex vivo samples of meningioma, healthy white and healthy gray matter in a preliminary study towards in vivo brain tumor removal assistance. Raw OCT ...

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    12. In Vivo Fascicle Bifurcation Imaging of Rat Sciatic Nerve Using Swept-Source Optical Coherence Tomography

      In Vivo Fascicle Bifurcation Imaging of Rat Sciatic Nerve Using Swept-Source Optical Coherence Tomography

      The sciatic nerve is the longest and widest single nerve in the human body and is responsible for the signal transduction of the entire hind limb region. Its wide nerve dynamic range and size makes it sensitive to injury. The branching and location of the sciatic nerve are important, and unlike histology, optical coherence tomography (OCT) can provide rapid non-destructive cross-sectional images. The sciatic nerves of ten rats were analyzed using swept-source (SS)-OCT. The sufficient depth penetration of the SS-OCT system allowed clear identification of the internal bifurcation point of the external branching and the internal route for the ...

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    13. Automated differentiation between meningioma and healthy brain tissue based on optical coherence tomography ex vivo images using texture features

      Automated differentiation between meningioma and healthy brain tissue based on optical coherence tomography ex vivo images using texture features

      Brain tissue analysis is highly desired in neurosurgery, such as tumor resection. To guarantee best life quality afterward, exact navigation within the brain during the surgery is essential. So far, no method has been established that perfectly fulfills this need. Optical coherence tomography (OCT) is a promising three-dimensional imaging tool to support neurosurgical resections. We perform a preliminary study toward in vivo brain tumor removal assistance by investigating meningioma, healthy white, and healthy gray matter. For that purpose, we utilized a commercially available OCT device (Thorlabs Callisto) and measured eight samples of meningioma, three samples of healthy white, and two ...

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    14. Retinal signs and 20-year cognitive decline in the Atherosclerosis Risk in Communities Study

      Retinal signs and 20-year cognitive decline in the Atherosclerosis Risk in Communities Study

      Objective To test the hypothesis that retinal vascular signs are associated with greater cognitive decline over 20 years in 12,317 men and women 50 to 73 years of age at baseline. Methods A composite cognitive score was created with 3 neuropsychological tests measured at 3 time points (1990–1992 to 2011–2013). Retinal signs were measured with fundus photography (1993–1995). Differences in cognitive change by retinal signs status were estimated with linear mixed models. Cognitive scores were imputed for living participants with incomplete cognitive testing. Results In multivariable-adjusted analyses that controlled for attrition, loss of vascular integrity (retinopathy ...

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    15. Optic Nerve Head and Macular Optical Coherence Tomography Measurements in Papilledema Compared With Pseudopapilledema

      Optic Nerve Head and Macular Optical Coherence Tomography Measurements in Papilledema Compared With Pseudopapilledema

      Background: To compare macular and optic nerve head optical coherence tomography (OCT) measurements in mild to moderate papilledema and pseudopapilledema. Methods: One hundred nineteen eyes of 61 patients with mild to moderate papilledema, 84 eyes of 48 patients with pseudopapilledema, and 60 eyes of 60 healthy normal individuals were enrolled in this cross-sectional study. Using Spectralis SD-OCT, macular scans with macular ganglion cell–inner plexiform layer (GCIPL) and macular retinal nerve fiber layer (RNFL) segmentation were performed and divided into 2 regions (inner and outer, with a diameter of 3 and 6 mm, respectively); in addition, Bruch membrane opening (BMO ...

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    16. Predictors of Retinal Atrophy in Multiple Sclerosis: A Longitudinal Study Using Spectral Domain Optical Coherence Tomography with Segmentation Analysis

      Predictors of Retinal Atrophy in Multiple Sclerosis: A Longitudinal Study Using Spectral Domain Optical Coherence Tomography with Segmentation Analysis

      Background Multiple sclerosis is an inflammatory demyelinating disease characterized by progressive axonal loss affecting mainly the inner retinal layers. Optical coherence tomography (OCT) provides in-vivo quantification of the retinal layers and allows measuring progressive retinal changes. Our objective was to assess the longitudinal changes in the retina using spectral domain OCT (SDOCT) and to identify independent predictors affecting retinal thinning in MS patients. Methods A prospective study in a tertiary care MS center was conducted to study the longitudinal retinal changes in MS patients. All subjects underwent baseline and follow up OCT assessment with segmentation analysis. Regression analysis was performed ...

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    17. Imaging whole mouse brains with a dual resolution serial swept-source optical coherence tomography scanner

      Imaging whole mouse brains with a dual resolution serial swept-source optical coherence tomography scanner

      High resolution imaging of whole rodent brains using serial OCT scanners is a promising method to investigate microstructural changes in tissue related to the evolution of neuropathologies. Although micron to sub-micron sampling resolution can be obtained by using high numerical aperture objectives and dynamic focusing, such an imaging system is not adapted to whole brain imaging. This is due to the large amount of data it generates and the significant computational resources required for reconstructing such volumes. To address this limitation, a dual resolution serial OCT scanner was developed. The optical setup consists in a swept-source OCT made of two ...

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    18. Bedside optical coherence tomography for Terson’s syndrome screening in acute subarachnoid hemorrhage: a pilot study

      Bedside optical coherence tomography for Terson’s syndrome screening in acute subarachnoid hemorrhage: a pilot study

      OBJECTIVE Approximately 10% of patients with subarachnoid hemorrhage (SAH) become permanently, legally blind. The average cost of lifetime support and unpaid taxes for each blind person amounts to approximately $900,000. This study evaluates the feasibility and potential role of bedside optical coherence tomography (OCT) in Terson’s syndrome (TS) in patients with acute SAH (aSAH) and its potential role in blindness prevention. METHODS The authors conducted an open-label pilot study, in which 31 patients with an angiographic diagnosis of aSAH were first screened for TS with dilated funduscopy and then with OCT in the acute phase and at 6-week ...

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    19. Optical coherence tomography in multiple sclerosis

      Optical coherence tomography in multiple sclerosis

      To summarize recent findings regarding the utility of optical coherence tomography in multiple sclerosis. We searched PubMed for relevant articles using the keywords ‘optical coherence tomography multiple sclerosis’. Additional articles were found via references in these articles. We selected articles based on relevance. Optical coherence tomography has contributed to greater insights into the pathophysiology of multiple sclerosis. Loss of retinal nerve fibre layer and ganglion cell layer thickness correlate with clinical and paraclinical parameters such as visual function, disability and magnetic resonance imaging. Some studies indicate that OCT parameters may be able to predict disability progression and visual function in ...

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    20. Photodynamic opening of the blood-brain barrier and pathways of brain clearing

      Photodynamic opening of the blood-brain barrier and pathways of brain clearing

      A new application of the photodynamic treatment (PDT) is presented for the opening of blood-brain barrier (BBB) and the brain clearing activation that is associated with it, including the use of gold nanoparticles as emerging photosensitizer carriers in PDT. The obtained results clearly demonstrate two pathways for the brain clearing: 1) using PDT-opening of BBB and intravenous injection of FITC-dextran we showed a clearance of this tracer via the meningeal lymphatic system in the subdural space; 2) using optical coherence tomography and intra-parenchymal injection of gold nanorods we observed their clearance through the exit gate of cerebral spinal fluid from ...

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    21. Correlations among multifocal electroretinography and optical coherence tomography findings in patients with Parkinson’s disease

      Correlations among multifocal electroretinography and optical coherence tomography findings in patients with Parkinson’s disease

      To assess the correlation between functional and anatomical evaluations with multifocal electroretinography (mfERG) and spectral-domain optical coherence tomography (SD-OCT) in patients with Parkinson’s disease (PD). This cross-sectional study involved 116 eyes of 58 patients with PD and 30 age- and sex-matched control subjects. All study participants underwent a comprehensive neuro-ophthalmic examination, retinal single-layer thicknesses and volumes, and peripapillary retinal nerve fiber layer (pRNFL) measurements with SD-OCT, and the patients’ mfERG recordings were evaluated. The macular retinal nerve fiber layer (mRNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), outer nuclear layer (ONL), retinal pigment epithelium (RPE), and photoreceptor layer ...

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