1. Articles in category: Neurology

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    1. Longitudinal deep-brain imaging in mouse using visible-light optical coherence tomography through chronic microprism cranial window

      Longitudinal deep-brain imaging in mouse using visible-light optical coherence tomography through chronic microprism cranial window

      We longitudinally imaged both the superficial and deep cortical microvascular networks in brains of healthy mice and in a mouse model of stroke in vivo using visible-light optical coherence tomography (vis-OCT). We surgically implanted a microprism in mouse brains sealed by a chronic cranial window. The microprism enabled vis-OCT to image the entire depth of the mouse cortex. Following microprism implantation, we imaged the mice for 28 days and found that that it took around 15 days for both the superficial and deep cortical microvessels to recover from the implantation surgery. After the brains recovered, we introduced ischemic strokes by ...

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    2. Spatial analysis of thickness changes in ten retinal layers of Alzheimer’s disease patients based on optical coherence tomography

      Spatial analysis of thickness changes in ten retinal layers of Alzheimer’s disease patients based on optical coherence tomography

      The retina is an attractive source of biomarkers since it shares many features with the brain. Thickness differences in 10 retinal layers between 19 patients with mild Alzheimer’s disease (AD) and a control group of 24 volunteers were investigated. Retinal layers were automatically segmented and their thickness at each scanned point was measured, corrected for tilt and spatially normalized. When the mean thickness of entire layers was compared between patients and controls, only the outer segment layer of patients showed statistically significant thinning. However, when the layers were compared point-by point, patients showed statistically significant thinning in irregular regions ...

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    3. Researchers have identified areas of the retina that change in mild Alzheimer's disease

      Researchers have identified areas of the retina that change in mild Alzheimer's disease

      Researchers at the Complutense University of Madrid (UCM) have identified changes in retinal layer thickness, inflammation or thinning in patients with mild Alzheimer's disease, confirming that the retina is one of the most important biomarkers for early diagnosis of the disease. For the first time, researchers have determined the shape and size of the areas that present significant thinning in each retinal layer, which tend to occur in the same locations.

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    4. Optical coherence tomography and multiple sclerosis: Update on clinical application and role in clinical trials

      Optical coherence tomography and multiple sclerosis: Update on clinical application and role in clinical trials

      Optical coherence tomography (OCT) has emerged as a fast, non-invasive, inexpensive, high-resolution imaging technique in multiple sclerosis (MS). Retinal layer quantification by OCT facilitates a ‘window’ into not only local retinal pathology but also global neurodegenerative processes, recognised to be the principal substrates of disability accumulation in MS. While OCT measures in MS have been demonstrated to reflect visual function, inflammatory activity outside of the visual pathways, disability measures including the prediction of disability progression, whole brain atrophy, and the differential neuroprotective effects of disease-modifying therapies, debate continues regarding the clinical utility of OCT in everyday practice. This review presents ...

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    5. Retinal Nerve Fiber and Ganglion Cell Inner Plexiform Layer Analysis by Optical Coherence Tomography in Asymptomatic Empty Sella Patient

      Retinal Nerve Fiber and Ganglion Cell Inner Plexiform Layer Analysis by Optical Coherence Tomography in Asymptomatic Empty Sella Patient

      Purpose: To investigate the clinical importance of the thicknesses of the retinal nerve fiber (RNFL) and ganglion cell and inner plexiform layer (GCL+) by spectral domain optic coherence tomography (SD-OCT) in asymptomatic empty sella (ES) patients. Materials and Methods: In this cross-sectional, nonrandomized prospective study, 44 ES patients and 74 age- and sex-matched healthy individuals were evaluated. All the patients and controls competed an automated 30-2 visual field (VF) test. The mean deviation (MD), pattern standard deviation (PSD), RNFL, and GCL + thickness values obtained with SD-OCT were compared statistically between the two groups. Results : No marked VF defects were found ...

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    6. Functional-Optical Coherence Tomography: A non-invasive approach to assess the sympathetic nervous system and intrinsic vascular regulation

      Functional-Optical Coherence Tomography: A non-invasive approach to assess the sympathetic nervous system and intrinsic vascular regulation

      Sympathetic nervous system dysregulation and vascular impairment in neuronal tissue beds are hallmarks of prominent cardiorespiratory diseases. However, an accurate and convenient method of assessing SNA and local vascular regulation is lacking, hindering routine clinical and research assessments. To address this, we investigated whether spectral domain optical coherence tomography (OCT), that allows investigation of retina and choroid vascular responsiveness, reflects sympathetic activity in order to develop a quick, easy and non-invasive sympathetic index. Here, we compare choroid and retina vascular perfusion density (VPD) acquired with OCT and heart rate variability (HRV) to microneurography. We recruited 6 healthy males (26±3y ...

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    7. Noninvasive, in vivo rodent brain optical coherence tomography at 2.1  microns

      Noninvasive, in vivo rodent brain optical coherence tomography at 2.1  microns

      n biological tissue, longer near-infrared wavelengths generally experience less scattering and more water absorption. Here we demonstrate an optical coherence tomography (OCT) system centered at 2.1 microns, whose bandwidth falls in the 2.2 micron water absorption optical window, for in vivo imaging of the rodent brain. We show in vivo that at 2.1 microns, the OCT signal is actually attenuated less in cranial bone than at 1.3 microns, and is also less susceptible to multiple scattering tails. We also show that the 2.2 micron window enables direct spectroscopic OCT assessment of tissue water content. We ...

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    8. Optical coherence tomography imaging after endovascular thrombectomy for basilar artery occlusion: report of 3 cases

      Optical coherence tomography imaging after endovascular thrombectomy for basilar artery occlusion: report of 3 cases

      Studies evaluating individuals for endothelial injury after endovascular thrombectomy (EVT) have been done by means of retrieved human thrombus, MR vessel-wall imaging, and animal histopathological studies. These techniques have limitations, because MR imaging has insufficient spatial resolution to directly visualize endothelium, and histopathological examinations are performed ex vivo and are unable to provide real-time patterns of injury. The purpose of the current study was to obtain in vivo intraluminal imaging after EVT by using optical coherence tomography (OCT), examining for evidence of endothelial injury in real time. Three consecutive patients with acute basilar artery occlusion underwent OCT imaging immediately after ...

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    9. Glioma cell migration dynamics in brain tissue assessed by multimodal optical imaging

      Glioma cell migration dynamics in brain tissue assessed by multimodal optical imaging

      Glioblastoma is a primary malignant brain tumor characterized by highly infiltrative glioma cells. Vasculature and white matter tracts are considered to be the preferred and fastest routes for glioma invasion through brain tissue. In this study, we systematically quantified the routes and motility of the U251 human glioblastoma cell line in mouse brain slices by multimodal imaging. Specifically, we used polarization-sensitive optical coherence tomography to delineate nerve fiber tracts while confocal fluorescence microscopy was used to image cell migration and brain vasculature. Somewhat surprisingly, we found that in mouse brain slices, U251 glioma cells do not follow white matter tracts ...

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    10. Comparison of Retinal Microvasculature in Patients With Alzheimer's Disease and Primary Open-Angle Glaucoma by Optical Coherence Tomography Angiography

      Comparison of Retinal Microvasculature in Patients With Alzheimer's Disease and Primary Open-Angle Glaucoma by Optical Coherence Tomography Angiography

      Purpose : Comparison of retinal microvasculature within the macula and the optic nerve head in the eyes of patients with Alzheimer's disease (AD), primary open-angle glaucoma (POAG), and in a healthy control (HC) group, using optical coherence tomography angiography (OCTA). Methods : In this cross-sectional study, 27 patients with AD, 27 with POAG, and 27 healthy controls were enrolled. The Mini-Mental State Examination test was used to assess cognitive function. Ophthalmic examination included OCTA, which was used for the imaging of vascular flow within the layer of radial peripapillary capillaries (RPCs), and also in the superficial vascular plexus (SVP) and deep ...

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    11. Subclinical neurodegeneration in multiple sclerosis and neuromyelitis optica spectrum disorder revealed by optical coherence tomography

      Subclinical neurodegeneration in multiple sclerosis and neuromyelitis optica spectrum disorder revealed by optical coherence tomography

      Background: Neuroretinal atrophy is associated with whole-brain atrophy and disease activity in multiple sclerosis (MS). Recent findings support that subclinical visual pathway involvement might also occur in neuromyelitis optica spectrum disorders (NMOSDs). Objective: The objective of this study is to assess retinal thinning in MS and NMOSD and its association with disease activity. Methods: In total, 27 NMOSD and 54 propensity-score-matched MS patients underwent optical coherence tomography, visual acuity, and visual-evoked potentials at 2.4 years apart, in addition to routine clinical and magnetic resonance imaging (MRI) assessment. We excluded eyes with acute optic neuritis. Results: In NMOSD, we detected ...

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    12. Dynamic Contrast Optical Coherence Tomography reveals laminar microvascular hemodynamics in the mouse neocortex in vivo

      Dynamic Contrast Optical Coherence Tomography reveals laminar microvascular hemodynamics in the mouse neocortex in vivo

      Studies of flow-metabolism coupling often presume that microvessel architecture is a surrogate for blood flow. To test this assumption, we introduce an in vivo Dynamic Contrast Optical Coherence Tomography (DyC-OCT) method to quantify layer-resolved microvascular blood flow and volume across the full depth of the mouse neocortex, where the angioarchitecture has been previously described . First, we cross-validate average DyC-OCT cortical flow against conventional Doppler OCT flow. Next, with laminar DyC-OCT, we discover that layer 4 consistently exhibits the highest microvascular blood flow, approximately two-fold higher than the outer cortical layers. While flow differences between layers are well-explained by microvascular volume ...

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    13. Optical coherence tomography and cognitive dysfunction in Parkinson disease

      Optical coherence tomography and cognitive dysfunction in Parkinson disease

      Background Parkinson’s disease (PD) is a progressive neurodegenerative disease of aging. Optical coherence tomography (OCT) is a simple noninvasive imaging technique to estimate the retinal nerve fiber layer (RNFL) thickness. The aim of this study is to measure the changes of the RNFL thickness in patients with Parkinson disease in comparison with the control group and to detect the relationship between these changes in RNFL with cognitive functions and physical disability in Parkinson patients. Methods 20 PD patients (40 eyes) and 20 healthy persons (40 eyes) were enrolled according to the defined criteria. The diagnosis of the patient's ...

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    14. Optical coherence tomography in myelin-oligodendrocyte-glycoprotein antibody-seropositive patients: a longitudinal study

      Optical coherence tomography in myelin-oligodendrocyte-glycoprotein antibody-seropositive patients: a longitudinal study

      Background Serum antibodies against myelin-oligodendrocyte-glycoprotein (MOG-IgG) are detectable in a proportion of patients with acute or relapsing neuroinflammation. It is unclear, if neuro-axonal damage occurs only in an attack-dependent manner or also progressively. Therefore, this study aimed to investigate longitudinally intra-retinal layer changes in eyes without new optic neuritis (ON) in MOG-IgG-seropositive patients. Methods We included 38 eyes of 24 patients without ON during follow-up (F/U) [median years (IQR)] 1.9 (1.0–2.2) and 56 eyes of 28 age- and sex-matched healthy controls (HC). The patient group’s eyes included 18 eyes without (Eye ON- ) and 20 ...

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      Mentions: Friedemann Paul
    15. Contrast-enhanced serial optical coherence scanner with deep learning network reveals vasculature and white matter organization of mouse brain

      Contrast-enhanced serial optical coherence scanner with deep learning network reveals vasculature and white matter organization of mouse brain

      Optical coherence tomography provides volumetric reconstruction of brain structure with micrometer resolution. Gray matter and white matter can be highlighted using conventional and polarization-based contrasts; however, vasculature in ex-vivo fixed brain has not been investigated at large scale due to lack of intrinsic contrast. We present contrast enhancement to visualize the vasculature by perfusing titanium dioxide particles transcardially into the mouse vascular system. The brain, after dissection and fixation, is imaged by a serial optical coherence scanner. Accumulation of particles in blood vessels generates distinguishable optical signals. Among these, the cross-polarization images reveal the vasculature organization remarkably well. The conventional ...

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    16. Analysis of low-scattering regions in optical coherence tomography

      Analysis of low-scattering regions in optical coherence tomography

      Analysis of semi-transparent low scattering biological structures in optical coherence tomography (OCT) has been actively pursued in the context of lymphatic imaging, with most approaches relying on the relative absence of signal as a means of detection. Here we present an alternate methodology based on spatial speckle statistics, utilizing the similarity of a distribution of given voxel intensities to the power distribution function of pure noise, to visualize the low-scattering biological structures of interest. In a human tumor xenograft murine model, we show that these correspond to lymphatic vessels and nerves; extensive histopathologic validation studies are reported to unequivocally establish ...

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    17. Massachusetts General Hospital Receives NIH Grant for Multimodal Mapping of the Neurocircuitry of the Human Prefrontal Cortex

      Massachusetts General Hospital Receives NIH Grant for Multimodal Mapping of the Neurocircuitry of the Human Prefrontal Cortex

      Massachusetts General Hospital Receives a 2019 NIH Grant for $463,473 for Multimodal Mapping of the Neurocircuitry of the Human Prefrontal Cortex. The principal investigator is Anastasia Yendiki. The program began in 2016 and ends in 2020. Below is a summary of the proposed work. The objective of the proposed research is to map the organization of human white matter (WM) with cutting-edge ex vivo imaging technologies. This work will produce microscopic-level information on several long-range WM projections, as well as a more targeted mapping of circuits that serve the prefrontal cortex (PFC). These circuits are of particular interest in ...

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    18. AI-Assisted In Situ Detection of Human Glioma Infiltration Using a Novel Computational Method for Optical Coherence Tomography

      AI-Assisted In Situ Detection of Human Glioma Infiltration Using a Novel Computational Method for Optical Coherence Tomography

      Purpose: In glioma surgery, it is critical to maximize tumor resection without compromising adjacent non-cancerous brain tissue. Optical Coherence Tomography (OCT) is a non-invasive, label-free, real-time, high-resolution imaging modality that has been explored for glioma infiltration detection. Here we report a novel artificial intelligence (AI) assisted method for automated, real-time, in situ detection of glioma infiltration at high spatial resolution. Experimental Design: Volumetric OCT datasets were intraoperatively obtained from resected brain tissue specimens of 21 patients with glioma tumors of different stages and labeled as either non-cancerous or glioma-infiltrated based on histopathology evaluation of the tissue specimens (gold standard). Labeled ...

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    19. Optical Coherence Tomography Angiography of Macula in Chronic Anterior Ischaemic Optic Neuropathy Associated with Giant Cell Arteritis

      Optical Coherence Tomography Angiography of Macula in Chronic Anterior Ischaemic Optic Neuropathy Associated with Giant Cell Arteritis

      A 74-year-old man presented with bilateral optic nerve atrophy related to arteritic anterior ischaemic optic neuropathy (AION) which started 22 years ago. Atrophic papilla was noted in both eyes and optical coherence tomography showed thinning of the retinal nerve fibres layer as well as the macular ganglion cell complex. Optical coherence tomography angiography of the macula found a decreased density of the superficial capillary complex, whereas deep capillary complex was well-preserved. Inner retinal layer atrophy in chronic arteritic AION is followed by a loss of vascularisation in these layers as a consequence of the neurodegeneration.

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    20. Veterans Affairs Medical Center in San Francisco Receives a 2019 NIH Grant for Collateral Flow and Stroke Outcome

      Veterans Affairs Medical Center in San Francisco Receives a 2019 NIH Grant for Collateral Flow and Stroke Outcome

      Veterans Affairs Medical Center in San Francisco Receives a 2019 NIH Grant for Collateral Flow and Stroke Outcome. The principal investigator is Jialing Liu. . Below is a summary of the proposed work. Collateral status is an independent predictor of stroke outcome, as well as response to thrombolytic therapies in patients with ischemic stroke. Genetic factors contribute to the extent and development of native collaterals, whereas patients with metabolic syndromes are associated with poor collateral status during acute ischemic stroke. Diabetes increases the risk of stroke and exacerbates ischemic brain damage, although the impact of diabetes on collateral dynamics remains to ...

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    21. Optical coherence tomography angiography in preclinical neuroimaging

      Optical coherence tomography angiography in preclinical neuroimaging

      Preclinical neuroimaging allows for the assessment of brain anatomy, connectivity, and function in laboratory animals, such as mice and this imaging field has been a rapidly growing aimed at bridging the translation gap between animal and human research. The progress in the animal research could be accelerated by high-resolution in vivo optical imaging technologies. Optical coherence tomography-based angiography (OCTA) estimates the scattering from moving red blood cells, providing the visualization of functional micro-vessel networks within tissue beds in vivo without a need for exogenous contrast agents. Recent advancement of OCTA methods have expanded its application to neuroimaging of small animal ...

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      Mentions: Woo June Choi
    22. No alteration of optical coherence tomography and multifocal visual evoked potentials in eyes with symptomatic carotid artery disease

      No alteration of optical coherence tomography and multifocal visual evoked potentials in eyes with symptomatic carotid artery disease

      Background Symptomatic carotid artery disease (CAD) may cause modified blood supply to the retina possibly leading to retinal structure changes. Results of previous studies in asymptomatic CAD were heterogeneous in retinal layer changes measured by OCT. The objectives of this prospective, non-interventional study were to investigate if structural retinal changes occur in symptomatic CAD patients with macroangiopathic ischemic stroke or transient ischemic attack (TIA). Methods We used spectral-domain optical coherence tomography (SD-OCT) to cross-sectionally and longitudinally analyze the retinal morphology of CAD patients with macroangiopathic ischemic stroke or TIA not permanently affecting the visual pathway. We employed semi-automated segmentation of ...

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    23. Spatiotemporal Tracking of Brain-Tumor-Associated Myeloid Cells in Vivo through Optical Coherence Tomography with Plasmonic Labeling and Speckle Modulation

      Spatiotemporal Tracking of Brain-Tumor-Associated Myeloid Cells in Vivo through Optical Coherence Tomography with Plasmonic Labeling and Speckle Modulation

      By their nature, tumors pose a set of profound challenges to the immune system with respect to cellular recognition and response coordination. Recent research indicates that leukocyte subpopulations, especially tumor-associated macrophages (TAMs), can exert substantial influence on the efficacy of various cancer immunotherapy treatment strategies. To better study and understand the roles of TAMs in determining immunotherapeutic outcomes, significant technical challenges associated with dynamically monitoring single cells of interest in relevant live animal models of solid tumors must be overcome. However, imaging techniques with the requisite combination of spatiotemporal resolution, cell-specific contrast, and sufficient signal-to-noise at increasing depths in tissue ...

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