The Experts below are selected from a list of 1788 Experts worldwide ranked by ideXlab platform
Per Kristian Eide - One of the best experts on this subject based on the ideXlab platform.
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the human visual pathway communicates directly with the subarachnoid Space
Investigative Ophthalmology & Visual Science, 2019Co-Authors: Henrik Holvin Jacobsen, Geir Ringstad, Oystein Kalsnes Jorstad, Tiril Sandell, Per Kristian EideAbstract:Purpose: Explore in vivo whether there is direct communication between the cerebrospinal fluid (CSF) and Extravascular compartment of human visual pathway structures. Methods: A prospective and observational study included 10 subjects who underwent intrathecal gadolinium-enhanced magnetic resonance imaging (MRI) for suspected CSF circulation disorder, but with a negative result and with no known ophthalmic diseases. After precontrast T1-weighted MRI, 0.5 mL of gadobutrol (Gadovist, 1.0 mmol/mL) was injected intrathecally. Gadobutrol distributes in the Extravascular Space, and served as a CSF tracer. Consecutive MRI scans were obtained throughout 24 to 48 hours. To assess gadobutrol contrast enrichment, regions of interest (ROIs) were placed at multiple locations along the visual pathway, from the primary visual cortex to the eye's vitreous body. CSF tracer dependent T1 signal was measured in each ROI. A linear mixed-model was used for statistical analyses. Results: CSF tracer enrichment was found within the optic nerve, optic chiasm, optic tract, and primary visual cortex (P < 0.001). Peak tracer enrichment in the visual pathway generally occurred after 24 hours and was preceded by peak enhancement in the prechiasmatic cistern after 4 to 6 hours. Conclusions: The results indicate direct communication between CSF of subarachnoid Space and the Extravascular Space of the human visual pathway. Extravascular entry of the CSF tracer is a prerequisite for a glymphatic system, the present findings may suggest its presence. The existence of a glymphatic system in the human visual pathway could bring novel perspectives on the pathophysiology and treatment of ophthalmic diseases.
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the human visual pathway communicates directly with the subarachnoid Space
Investigative Ophthalmology & Visual Science, 2019Co-Authors: Henrik Holvin Jacobsen, Geir Ringstad, Oystein Kalsnes Jorstad, Tiril Sandell, Per Kristian EideAbstract:Purpose: Explore in vivo whether there is direct communication between the cerebrospinal fluid (CSF) and Extravascular compartment of human visual pathway structures. Methods: A prospective and observational study included 10 subjects who underwent intrathecal gadolinium-enhanced magnetic resonance imaging (MRI) for suspected CSF circulation disorder, but with a negative result and with no known ophthalmic diseases. After precontrast T1-weighted MRI, 0.5 mL of gadobutrol (Gadovist, 1.0 mmol/mL) was injected intrathecally. Gadobutrol distributes in the Extravascular Space, and served as a CSF tracer. Consecutive MRI scans were obtained throughout 24 to 48 hours. To assess gadobutrol contrast enrichment, regions of interest (ROIs) were placed at multiple locations along the visual pathway, from the primary visual cortex to the eye's vitreous body. CSF tracer dependent T1 signal was measured in each ROI. A linear mixed-model was used for statistical analyses. Results: CSF tracer enrichment was found within the optic nerve, optic chiasm, optic tract, and primary visual cortex (P < 0.001). Peak tracer enrichment in the visual pathway generally occurred after 24 hours and was preceded by peak enhancement in the prechiasmatic cistern after 4 to 6 hours. Conclusions: The results indicate direct communication between CSF of subarachnoid Space and the Extravascular Space of the human visual pathway. Extravascular entry of the CSF tracer is a prerequisite for a glymphatic system, the present findings may suggest its presence. The existence of a glymphatic system in the human visual pathway could bring novel perspectives on the pathophysiology and treatment of ophthalmic diseases.
Sridhar Vajapeyam - One of the best experts on this subject based on the ideXlab platform.
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multiparametric analysis of permeability and adc histogram metrics for classification of pediatric brain tumors by tumor grade
American Journal of Neuroradiology, 2018Co-Authors: Sridhar Vajapeyam, Douglas Brown, P R Johnston, Kelsey I Ricci, Mark W Kieran, Hart G W Lidov, Tina Young PoussaintAbstract:BACKGROUND AND PURPOSE: Accurate tumor grading is essential for treatment planning of pediatric brain tumors. We hypothesized that multiparametric analyses of a combination of permeability metrics and ADC histogram metrics would differentiate high- and low-grade tumors with high accuracy. MATERIALS AND METHODS: DTI and dynamic contrast-enhanced MR imaging using T1-mapping with flip angles of 2°, 5°, 10°, and 15°, followed by a 0.1-mmol/kg body weight gadolinium-based bolus was performed on all patients in addition to standard MR imaging. Permeability data were processed and transfer constant from the blood plasma into the extracellular Extravascular Space, rate constant from the extracellular Extravascular Space back into blood plasma, Extravascular extracellular volume fraction, and fractional blood plasma volume were calculated from 3D tumor volumes. Apparent diffusion coefficient histogram metrics were calculated for 3 separate tumor volumes derived from T2-FLAIR sequences, T1 contrast-enhanced sequences, and permeability maps, respectively. RESULTS: Results from 41 patients (0.3–16.76 years of age; mean, 6.22 years) with newly diagnosed contrast-enhancing brain tumors (16 low-grade; 25 high-grade) were included in the institutional review board–approved retrospective analysis. Wilcoxon tests showed a higher transfer constant from blood plasma into extracellular Extravascular Space and rate constant from extracellular Extravascular Space back into blood plasma, and lower extracellular Extravascular volume fraction ( P P CONCLUSIONS: ADC histogram metrics combined with permeability metrics differentiate low- and high-grade pediatric brain tumors with high accuracy.
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automated processing of dynamic contrast enhanced mri correlation of advanced pharmacokinetic metrics with tumor grade in pediatric brain tumors
American Journal of Neuroradiology, 2017Co-Authors: Sridhar Vajapeyam, Kelsey I Ricci, Mark W Kieran, Catherine Stamoulis, Young T PoussaintAbstract:BACKGROUND AND PURPOSE: Pharmacokinetic parameters from dynamic contrast-enhanced MR imaging have proved useful for differentiating brain tumor grades in adults. In this study, we retrospectively reviewed dynamic contrast-enhanced perfusion data from children with newly diagnosed brain tumors and analyzed the pharmacokinetic parameters correlating with tumor grade. MATERIALS AND METHODS: Dynamic contrast-enhanced MR imaging data from 38 patients were analyzed by using commercially available software. Subjects were categorized into 2 groups based on pathologic analyses consisting of low-grade (World Health Organization I and II) and high-grade (World Health Organization III and IV) tumors. Pharmacokinetic parameters were compared between the 2 groups by using linear regression models. For parameters that were statistically distinct between the 2 groups, sensitivity and specificity were also estimated. RESULTS: Eighteen tumors were classified as low-grade, and 20, as high-grade. Transfer constant from the blood plasma into the extracellular Extravascular Space ( K trans ), rate constant from extracellular Extravascular Space back into blood plasma (K ep ), and extracellular Extravascular volume fraction (V e ) were all significantly correlated with tumor grade; high-grade tumors showed higher K trans , higher K ep , and lower V e . Although all 3 parameters had high specificity (range, 82%–100%), K ep had the highest specificity for both grades. Optimal sensitivity was achieved for V e , with a combined sensitivity of 76% (compared with 71% for K trans and K ep ). CONCLUSIONS: Pharmacokinetic parameters derived from dynamic contrast-enhanced MR imaging can effectively discriminate low- and high-grade pediatric brain tumors.
Henrik Holvin Jacobsen - One of the best experts on this subject based on the ideXlab platform.
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the human visual pathway communicates directly with the subarachnoid Space
Investigative Ophthalmology & Visual Science, 2019Co-Authors: Henrik Holvin Jacobsen, Geir Ringstad, Oystein Kalsnes Jorstad, Tiril Sandell, Per Kristian EideAbstract:Purpose: Explore in vivo whether there is direct communication between the cerebrospinal fluid (CSF) and Extravascular compartment of human visual pathway structures. Methods: A prospective and observational study included 10 subjects who underwent intrathecal gadolinium-enhanced magnetic resonance imaging (MRI) for suspected CSF circulation disorder, but with a negative result and with no known ophthalmic diseases. After precontrast T1-weighted MRI, 0.5 mL of gadobutrol (Gadovist, 1.0 mmol/mL) was injected intrathecally. Gadobutrol distributes in the Extravascular Space, and served as a CSF tracer. Consecutive MRI scans were obtained throughout 24 to 48 hours. To assess gadobutrol contrast enrichment, regions of interest (ROIs) were placed at multiple locations along the visual pathway, from the primary visual cortex to the eye's vitreous body. CSF tracer dependent T1 signal was measured in each ROI. A linear mixed-model was used for statistical analyses. Results: CSF tracer enrichment was found within the optic nerve, optic chiasm, optic tract, and primary visual cortex (P < 0.001). Peak tracer enrichment in the visual pathway generally occurred after 24 hours and was preceded by peak enhancement in the prechiasmatic cistern after 4 to 6 hours. Conclusions: The results indicate direct communication between CSF of subarachnoid Space and the Extravascular Space of the human visual pathway. Extravascular entry of the CSF tracer is a prerequisite for a glymphatic system, the present findings may suggest its presence. The existence of a glymphatic system in the human visual pathway could bring novel perspectives on the pathophysiology and treatment of ophthalmic diseases.
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the human visual pathway communicates directly with the subarachnoid Space
Investigative Ophthalmology & Visual Science, 2019Co-Authors: Henrik Holvin Jacobsen, Geir Ringstad, Oystein Kalsnes Jorstad, Tiril Sandell, Per Kristian EideAbstract:Purpose: Explore in vivo whether there is direct communication between the cerebrospinal fluid (CSF) and Extravascular compartment of human visual pathway structures. Methods: A prospective and observational study included 10 subjects who underwent intrathecal gadolinium-enhanced magnetic resonance imaging (MRI) for suspected CSF circulation disorder, but with a negative result and with no known ophthalmic diseases. After precontrast T1-weighted MRI, 0.5 mL of gadobutrol (Gadovist, 1.0 mmol/mL) was injected intrathecally. Gadobutrol distributes in the Extravascular Space, and served as a CSF tracer. Consecutive MRI scans were obtained throughout 24 to 48 hours. To assess gadobutrol contrast enrichment, regions of interest (ROIs) were placed at multiple locations along the visual pathway, from the primary visual cortex to the eye's vitreous body. CSF tracer dependent T1 signal was measured in each ROI. A linear mixed-model was used for statistical analyses. Results: CSF tracer enrichment was found within the optic nerve, optic chiasm, optic tract, and primary visual cortex (P < 0.001). Peak tracer enrichment in the visual pathway generally occurred after 24 hours and was preceded by peak enhancement in the prechiasmatic cistern after 4 to 6 hours. Conclusions: The results indicate direct communication between CSF of subarachnoid Space and the Extravascular Space of the human visual pathway. Extravascular entry of the CSF tracer is a prerequisite for a glymphatic system, the present findings may suggest its presence. The existence of a glymphatic system in the human visual pathway could bring novel perspectives on the pathophysiology and treatment of ophthalmic diseases.
Wolfgang Weninger - One of the best experts on this subject based on the ideXlab platform.
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leukocyte migration in the interstitial Space of non lymphoid organs
Nature Reviews Immunology, 2014Co-Authors: Wolfgang Weninger, Maté Biro, Rohit JainAbstract:This Review follows neutrophils and T cells as they journey from the blood into tissues in search of sites of infection or injury. It highlights the mediators, which form temporally and spatially coordinated gradients within the tissues, and the mechanisms, including physical structures, that guide this directional migration. Leukocyte migration through interstitial tissues is essential for mounting a successful immune response. Interstitial motility is governed by a vast array of cell-intrinsic and cell-extrinsic factors that together ensure the proper positioning of immune cells in the context of specific microenvironments. Recent advances in imaging modalities, in particular intravital confocal and multi-photon microscopy, have helped to expand our understanding of the cellular and molecular mechanisms that underlie leukocyte navigation in the Extravascular Space. In this Review, we discuss the key factors that regulate leukocyte motility within three-dimensional environments, with a focus on neutrophils and T cells in non-lymphoid organs.
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immune cell migration as a means to control immune privilege lessons from the cns and tumors
Immunological Reviews, 2006Co-Authors: Paulus Mrass, Wolfgang WeningerAbstract:Summary: Certain organs, such as the brain, eye, and gonads, are particularly sensitive to damage by inflammation. Therefore, these tissues have developed unique immunological properties that curtail inflammatory responses, a phenomenon termed immune privilege. In addition, by co-opting some of the regulatory cues operant in immune privilege in normal organs, tumors can evade immunosurveillance. While many different mechanisms contribute to immune privilege, there is evidence that leukocyte migration is an important checkpoint in its control. This hypothesis is based on the fact that leukocyte entry into these organs is restricted by physical barriers and that the collapse of these obstacles marks a critical step in the development of inflammatory/autoimmune disease at these sites. Numerous studies in a variety of experimental systems have characterized the molecular and cellular mechanisms involved in leukocyte homing to immune-privileged organs. Recently, two-photon microscopy has revealed critical insights into the events occurring in the Extravascular Space of immune-privileged organs, including locomotion patterns and interactive behavior of leukocytes in the interstitial Space. Here, we review our current understanding of immune cell migration to and within immune-privileged organs and highlight how this knowledge may be exploited for immunotherapeutic purposes.
Young T Poussaint - One of the best experts on this subject based on the ideXlab platform.
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automated processing of dynamic contrast enhanced mri correlation of advanced pharmacokinetic metrics with tumor grade in pediatric brain tumors
American Journal of Neuroradiology, 2017Co-Authors: Sridhar Vajapeyam, Kelsey I Ricci, Mark W Kieran, Catherine Stamoulis, Young T PoussaintAbstract:BACKGROUND AND PURPOSE: Pharmacokinetic parameters from dynamic contrast-enhanced MR imaging have proved useful for differentiating brain tumor grades in adults. In this study, we retrospectively reviewed dynamic contrast-enhanced perfusion data from children with newly diagnosed brain tumors and analyzed the pharmacokinetic parameters correlating with tumor grade. MATERIALS AND METHODS: Dynamic contrast-enhanced MR imaging data from 38 patients were analyzed by using commercially available software. Subjects were categorized into 2 groups based on pathologic analyses consisting of low-grade (World Health Organization I and II) and high-grade (World Health Organization III and IV) tumors. Pharmacokinetic parameters were compared between the 2 groups by using linear regression models. For parameters that were statistically distinct between the 2 groups, sensitivity and specificity were also estimated. RESULTS: Eighteen tumors were classified as low-grade, and 20, as high-grade. Transfer constant from the blood plasma into the extracellular Extravascular Space ( K trans ), rate constant from extracellular Extravascular Space back into blood plasma (K ep ), and extracellular Extravascular volume fraction (V e ) were all significantly correlated with tumor grade; high-grade tumors showed higher K trans , higher K ep , and lower V e . Although all 3 parameters had high specificity (range, 82%–100%), K ep had the highest specificity for both grades. Optimal sensitivity was achieved for V e , with a combined sensitivity of 76% (compared with 71% for K trans and K ep ). CONCLUSIONS: Pharmacokinetic parameters derived from dynamic contrast-enhanced MR imaging can effectively discriminate low- and high-grade pediatric brain tumors.
