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Xie Y, Fu Y, Shao Y, Qu L, Yang J, Yang C, Zhou K, Li K, Xu Z, Xu D, Cao K, Tian N, Lv K, Wang L, Wang Y, Wang N, Li Y. Quantitative ultrasound image assessment of the optic nerve subarachnoid space during 90-day head-down tilt bed rest. NPJ Microgravity 2024; 10:9. [PMID: 38233425 PMCID: PMC10794463 DOI: 10.1038/s41526-024-00347-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 01/03/2024] [Indexed: 01/19/2024] Open
Abstract
The elevation in the optic nerve sheath (ONS) pressure (ONSP) due to microgravity-induced headward fluid shift is the primary hypothesized contributor to SANS. This longitudinal study aims to quantify the axial plane of the optic nerve subarachnoid space area (ONSSA), which is filled with cerebrospinal fluid (CSF) and expands with elevated ONSP during and after head-down tilt (HDT) bed rest (BR). 36 healthy male volunteers (72 eyes) underwent a 90-day strict 6° HDT BR. Without obtaining the pre-HDT data, measurements were performed on days 30, 60, and 90 during HDT and at 6 recovery time points extended to 180-days (R + 180) in a supine position. Portable B-scan ultrasound was performed using the 12 MHz linear array probe binocularly. The measurements of the ONS and the calculation of the ONSSA were performed with ImageJ 1.51 analysis software by two experienced observers in a masked manner. Compared to R + 180, the ONSSA on HDT30, HDT60, and HDT90 exhibited a consistently significant distention of 0.44 mm2 (95% CI: 0.13 to 0.76 mm2, P = 0.001), 0.45 mm2 (95% CI: 0.15 to 0.75 mm2, P = 0.001), and 0.46 mm2 (95% CI: 0.15 to 0.76 mm2, P < 0.001), respectively, and recovered immediately after HDT on R + 2. Such small changes in the ONSSA were below the lateral resolution limit of ultrasound (0.4 mm) and may not be clinically relevant, possibly due to ONS hysteresis causing persistent ONS distension. Future research can explore advanced quantitative portable ultrasound-based techniques and establish comparisons containing the pre-HDT measurements to deepen our understanding of SANS.
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Affiliation(s)
- Yuan Xie
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing, 100730, China
| | - Yingdi Fu
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing, 100730, China
- Beijing Institute of Ophthalmology, Beijing Tongren Hospital, Capital Medical University, Beijing, 100005, China
| | - Yaqi Shao
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing, 100730, China
- Beijing Institute of Ophthalmology, Beijing Tongren Hospital, Capital Medical University, Beijing, 100005, China
| | - Lina Qu
- China Astronaut Research and Training Center, State Key Lab of Space Medicine Fundamentals and Application, No. 26 Beiqing Road, Haidian District, Beijing, 100094, China
| | - Jiangang Yang
- Xi'an No.1 Hospital; Shanxi Institute of Ophthalmology; Shanxi Key Laboratory of Ophthalmology; Clinical Research Center for Ophthalmology Diseases of Shanxi Province; the First Affiliated Hospital of Northwestern University, Xi'an, 710002, Shanxi Province, China
| | - Chengjia Yang
- China Astronaut Research and Training Center, State Key Lab of Space Medicine Fundamentals and Application, No. 26 Beiqing Road, Haidian District, Beijing, 100094, China
| | - Kun Zhou
- Xi'an No.1 Hospital; Shanxi Institute of Ophthalmology; Shanxi Key Laboratory of Ophthalmology; Clinical Research Center for Ophthalmology Diseases of Shanxi Province; the First Affiliated Hospital of Northwestern University, Xi'an, 710002, Shanxi Province, China
| | - Kai Li
- China Astronaut Research and Training Center, State Key Lab of Space Medicine Fundamentals and Application, No. 26 Beiqing Road, Haidian District, Beijing, 100094, China
| | - Zi Xu
- China Astronaut Research and Training Center, State Key Lab of Space Medicine Fundamentals and Application, No. 26 Beiqing Road, Haidian District, Beijing, 100094, China
| | - Dong Xu
- China Astronaut Research and Training Center, State Key Lab of Space Medicine Fundamentals and Application, No. 26 Beiqing Road, Haidian District, Beijing, 100094, China
| | - Kai Cao
- Beijing Institute of Ophthalmology, Beijing Tongren Hospital, Capital Medical University, Beijing, 100005, China
| | - Ning Tian
- Beijing Institute of Ophthalmology, Beijing Tongren Hospital, Capital Medical University, Beijing, 100005, China
| | - Ke Lv
- China Astronaut Research and Training Center, State Key Lab of Space Medicine Fundamentals and Application, No. 26 Beiqing Road, Haidian District, Beijing, 100094, China
| | - Linjie Wang
- China Astronaut Research and Training Center, State Key Lab of Space Medicine Fundamentals and Application, No. 26 Beiqing Road, Haidian District, Beijing, 100094, China
| | - Yaping Wang
- China Astronaut Research and Training Center, State Key Lab of Space Medicine Fundamentals and Application, No. 26 Beiqing Road, Haidian District, Beijing, 100094, China
| | - Ningli Wang
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing, 100730, China.
- Beijing Institute of Ophthalmology, Beijing Tongren Hospital, Capital Medical University, Beijing, 100005, China.
| | - Yinghui Li
- China Astronaut Research and Training Center, State Key Lab of Space Medicine Fundamentals and Application, No. 26 Beiqing Road, Haidian District, Beijing, 100094, China.
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Visualization of human optic nerve by diffusion tensor mapping and degree of neuropathy. PLoS One 2022; 17:e0278987. [PMID: 36508429 PMCID: PMC9744320 DOI: 10.1371/journal.pone.0278987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 11/28/2022] [Indexed: 12/14/2022] Open
Abstract
Diffusion-weighted magnetic resonance imaging of the human optic nerve and tract is technically difficult because of its small size, the inherent strong signal generated by the surrounding fat and the cerebrospinal fluid, and due to eddy current-induced distortions and subject movement artifacts. The effects of the bone canal through which the optic nerve passes, and the proximity of blood vessels, muscles and tendons are generally unknown. Also, the limited technical capabilities of the scanners and the minimization of acquisition times result in poor quality diffusion-weighted images. It is challenging for current tractography methods to accurately track optic pathway fibers that correspond to known anatomy. Despite these technical limitations and low image resolution, here we show how to visualize the optic nerve and tract and quantify nerve atrophy. Our visualization method based on the analysis of the diffusion tensor shows marked differences between a healthy male subject and a male subject with progressive optic nerve neuropathy. These differences coincide with diffusion scalar metrics and are not visible on standard morphological images. A quantification of the degree of optic nerve atrophy in a systematic way is provided and it is tested on 9 subjects from the Human Connectome Project.
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Holmlund P, Støverud KH, Eklund A. Mathematical modelling of the CSF system: effects of microstructures and posture on optic nerve subarachnoid space dynamics. Fluids Barriers CNS 2022; 19:67. [PMID: 36042452 PMCID: PMC9426285 DOI: 10.1186/s12987-022-00366-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 08/18/2022] [Indexed: 11/21/2022] Open
Abstract
Background The pressure difference between the eye and brain in upright postures may be affected by compartmentalization of the optic nerve subarachnoid space (ONSAS). Both pressure and deformation will depend on the microstructures of the ONSAS, and most likely also on ocular glymphatic clearance. Studying these factors could yield important knowledge regarding the translaminar pressure difference, which is suspected to play a role in normal-tension glaucoma. Methods A compartment model coupling the ONSAS with the craniospinal CSF system was used to investigate the effects of microstructures on the pressure transfer through the ONSAS during a posture change from supine to upright body postures. ONSAS distensibility was based on MRI measurements. We also included ocular glymphatic flow to investigate how local pressure gradients alter this flow with changes in posture. Results A compartmentalization of the ONSAS occurred in the upright posture, with ONSAS porosity (degree of microstructural content) affecting the ONSAS pressure (varying the supine/baseline porosity from 1.0 to 0.75 yielded pressures between − 5.3 and − 2 mmHg). Restricting the minimum computed porosity (occurring in upright postures) to 0.3 prevented compartmentalization, and the ONSAS pressure could equilibrate with subarachnoid space pressure (− 6.5 mmHg) in \documentclass[12pt]{minimal}
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\begin{document}$$\le$$\end{document}≤ 1 h. The ocular glymphatics analysis predicted that substantial intraocular-CSF flows could occur without substantial changes in the ONSAS pressure. The flow entering the ONSAS in supine position (both from the intraocular system and from the cranial subarachnoid space) exited the ONSAS through the optic nerve sheath, while in upright postures the flow through the ONSAS was redirected towards the cranial subarachnoid space. Conclusions Microstructures affect pressure transmission along the ONSAS, potentially contributing to ONSAS compartmentalization in upright postures. Different pathways for ocular glymphatic flow were predicted for different postures.
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Affiliation(s)
- Petter Holmlund
- Department of Radiation Sciences, Radiation Physics, Biomedical Engineering, Umeå University, 901 87, Umeå, Sweden.
| | - Karen-Helene Støverud
- Department of Radiation Sciences, Radiation Physics, Biomedical Engineering, Umeå University, 901 87, Umeå, Sweden.,Department of Health Research, SINTEF Digital, Trondheim, Norway
| | - Anders Eklund
- Department of Radiation Sciences, Radiation Physics, Biomedical Engineering, Umeå University, 901 87, Umeå, Sweden.,Umeå Center for Functional Brain Imaging, Umeå University, 901 87, Umeå, Sweden
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Mendoza M, Shotbolt M, Faiq MA, Parra C, Chan KC. Advanced Diffusion MRI of the Visual System in Glaucoma: From Experimental Animal Models to Humans. BIOLOGY 2022; 11:454. [PMID: 35336827 PMCID: PMC8945790 DOI: 10.3390/biology11030454] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 03/10/2022] [Indexed: 11/18/2022]
Abstract
Glaucoma is a group of ophthalmologic conditions characterized by progressive retinal ganglion cell death, optic nerve degeneration, and irreversible vision loss. While intraocular pressure is the only clinically modifiable risk factor, glaucoma may continue to progress at controlled intraocular pressure, indicating other major factors in contributing to the disease mechanisms. Recent studies demonstrated the feasibility of advanced diffusion magnetic resonance imaging (dMRI) in visualizing the microstructural integrity of the visual system, opening new possibilities for non-invasive characterization of glaucomatous brain changes for guiding earlier and targeted intervention besides intraocular pressure lowering. In this review, we discuss dMRI methods currently used in visual system investigations, focusing on the eye, optic nerve, optic tract, subcortical visual brain nuclei, optic radiations, and visual cortex. We evaluate how conventional diffusion tensor imaging, higher-order diffusion kurtosis imaging, and other extended dMRI techniques can assess the neuronal and glial integrity of the visual system in both humans and experimental animal models of glaucoma, among other optic neuropathies or neurodegenerative diseases. We also compare the pros and cons of these methods against other imaging modalities. A growing body of dMRI research indicates that this modality holds promise in characterizing early glaucomatous changes in the visual system, determining the disease severity, and identifying potential neurotherapeutic targets, offering more options to slow glaucoma progression and to reduce the prevalence of this world's leading cause of irreversible but preventable blindness.
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Affiliation(s)
- Monica Mendoza
- Department of Biomedical Engineering, Tandon School of Engineering, New York University, New York, NY 11201, USA; (M.M.); (M.S.)
| | - Max Shotbolt
- Department of Biomedical Engineering, Tandon School of Engineering, New York University, New York, NY 11201, USA; (M.M.); (M.S.)
| | - Muneeb A. Faiq
- Department of Ophthalmology, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, NY 10017, USA; (M.A.F.); (C.P.)
| | - Carlos Parra
- Department of Ophthalmology, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, NY 10017, USA; (M.A.F.); (C.P.)
| | - Kevin C. Chan
- Department of Biomedical Engineering, Tandon School of Engineering, New York University, New York, NY 11201, USA; (M.M.); (M.S.)
- Department of Ophthalmology, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, NY 10017, USA; (M.A.F.); (C.P.)
- Department of Radiology, Neuroscience Institute, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, NY 10016, USA
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Martin Paez Y, Mudie LI, Subramanian PS. Spaceflight Associated Neuro-Ocular Syndrome (SANS): A Systematic Review and Future Directions. Eye Brain 2020; 12:105-117. [PMID: 33117025 PMCID: PMC7585261 DOI: 10.2147/eb.s234076] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 09/22/2020] [Indexed: 12/24/2022] Open
Abstract
Purpose To present a systematic review of the current body of literature surrounding spaceflight associated neuro-ocular syndrome (SANS) and highlight priorities for future research. Methods Three major biomedical databases were searched with the following terms: ((neuro ocular) OR ((brain) AND (eye))) AND ((spaceflight) OR (astronaut) OR (microgravity)) AND (ENGLISH[Language]). Once duplicates were removed, 283 papers were left. Articles were excluded if they were not written in English or conference abstracts only. We avoided including review papers which did not provide any new information; however, two reviews on the pathophysiology of SANS were included for completeness. No limitations on date of publication were used. All included entries were then summarized for their contribution to knowledge about SANS. Results Four main themes among the publications emerged: papers defining the clinical entity of SANS, its pathophysiology, technology used to study SANS, and publications on possible prevention of SANS. The key clinical features of SANS include optic nerve head elevation, hyperopic shifts, globe flattening, choroidal folds, and increased cerebrospinal fluid (CSF) volume in optic nerve sheaths. Two main hypotheses are proposed for the pathophysiology of SANS. The first being elevated intracranial pressure and the second compartmentalization of CSF to the globe. These hypotheses are not mutually exclusive, and our understanding of the pathophysiology of SANS is still evolving. The use of optical coherence tomography (OCT) has greatly furthered our knowledge about SANS, and with the deployment of OCT to the International Space Station, we now have ability to collect intraflight data. No effective prevention for SANS has been found, although fortunately, even with persistent anatomic and physiologic neuro-ocular changes, any functional impact has been correctable with spectacles. Conclusion This is the first systematic review of SANS. Despite the limitations of studying a syndrome that can only occur in a small, discrete population, we present a thorough overview of the literature surrounding SANS and several key areas important for future research are identified.
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Affiliation(s)
- Yosbelkys Martin Paez
- Sue Anschutz-Rodgers/UCHealth Eye Center and Departments of Ophthalmology, Aurora, CO, 80045, USA.,Neurology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Lucy I Mudie
- Sue Anschutz-Rodgers/UCHealth Eye Center and Departments of Ophthalmology, Aurora, CO, 80045, USA
| | - Prem S Subramanian
- Sue Anschutz-Rodgers/UCHealth Eye Center and Departments of Ophthalmology, Aurora, CO, 80045, USA.,Neurology, University of Colorado School of Medicine, Aurora, CO 80045, USA.,Neurosurgery, University of Colorado School of Medicine, Aurora, CO 80045, USA
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6
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Jordan J, Hellweg CE, Mulder E, Stern C. [From human terrestrial models to new preventive measures for ocular changes in astronauts : Results of the German Aerospace Center studies]. Ophthalmologe 2020; 117:740-745. [PMID: 32519116 DOI: 10.1007/s00347-020-01133-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
BACKGROUND Ocular changes in astronauts, particularly the spaceflight associated neuro-ocular syndrome (SANS), pose a medical challenge for which no suitable preventive measures exist. During long-duration spaceflight missions, e.g. to the Moon and Mars, SANS and radiation-induced cataract could affect the health and performance of crews and jeopardize the success of missions. Mechanistic studies and development of preventive measures require suitable terrestrial models. OBJECTIVE Overview on the most recent research and future plans in space medicine. MATERIAL AND METHODS Search for relevant publications using PubMed. RESULTS Bed rest studies at the German Aerospace Center (DLR) demonstrated that strict bed rest in a -6° head down tilt position reproduces changes just like SANS on Earth. This model including creation of optic disc edema is applied in human studies testing influences of artificial gravity through short arm centrifugation as a preventive method. The unique research facility :envihab provides the opportunity to also simulate the ambient conditions of the International Space Station during bed rest studies. CONCLUSION Future head down tilt bed rest studies will serve to systematically test preventive measures for SANS. Similar investigations would be difficult to realize under real space conditions. Through close collaboration between space medicine and terrestrial ophthalmology, this research can benefit patients on Earth.
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Affiliation(s)
- J Jordan
- Institut für Luft- und Raumfahrtmedizin, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Linder Höhe, 51147, Köln, Deutschland. .,Lehrstuhl für Luft- und Raumfahrtmedizin, Medizinische Fakultät, Universität zu Köln, Köln, Deutschland.
| | - C E Hellweg
- Institut für Luft- und Raumfahrtmedizin, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Linder Höhe, 51147, Köln, Deutschland
| | - E Mulder
- Institut für Luft- und Raumfahrtmedizin, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Linder Höhe, 51147, Köln, Deutschland
| | - C Stern
- Institut für Luft- und Raumfahrtmedizin, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Linder Höhe, 51147, Köln, Deutschland
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Stenger MB, Laurie SS, Sadda SR, Sadun AA, Macias BR, Huang AS. Focus on the Optic Nerve Head in Spaceflight-Associated Neuro-ocular Syndrome. Ophthalmology 2020; 126:1604-1606. [PMID: 31759496 DOI: 10.1016/j.ophtha.2019.09.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 09/04/2019] [Accepted: 09/11/2019] [Indexed: 10/25/2022] Open
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Roth S, Dreixler J, Newman NJ. Haemodilution and head-down tilting induce functional injury in the rat optic nerve: A model for peri-operative ischemic optic neuropathy. Eur J Anaesthesiol 2019; 35:840-847. [PMID: 29771733 DOI: 10.1097/eja.0000000000000829] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND Mechanisms of peri-operative ischaemic optic neuropathy remain poorly understood. Both specific pre-operative and intra-operative factors have been examined by retrospective studies, but no animal model currently exists. OBJECTIVES To develop a rodent model of peri-operative ischaemic optic neuropathy. In rats, we performed head-down tilt and/or haemodilution, theorising that the combination damages the optic nerve. DESIGN Animal study. SETTING Laboratory. ANIMALS A total of 36 rats, in four groups, completed the functional examination of retina and optic nerve after the interventions. INTERVENTIONS Anaesthetised groups (n>8) were supine (SUP) for 5 h, head-down tilted 70° for 5 h, head-down tilted/haemodiluted for 5 h or SUP/haemodiluted for 5 h. We measured blood pressure, heart rate, intra-ocular pressure and maintained constant temperature. MAIN OUTCOME MEASUREMENTS Retinal function (electroretinography), scotopic threshold response (STR) (for retinal ganglion cells) and visual evoked potentials (VEP) (for transmission through the optic nerve). We imaged the optic nerve in vivo and evaluated retinal histology, apoptotic cells and glial activation in the optic nerve. Retinal and optic nerve function were followed to 14 and 28 days after experiments. RESULTS At 28 days in head down tilted/haemodiluted rats, negative STR decreased (about 50% amplitude reduction, P = 0.006), VEP wave N2-P3 decreased (70% amplitude reduction, P = 0.01) and P2 latency increased (35%, P = 0.003), optic discs were swollen and glial activation was present in the optic nerve. SUP/haemodiluted rats had decreases in negative STR and increased VEP latency, but no glial activation. CONCLUSION An injury partly resembling human ischaemic optic neuropathy can be produced in rats by combining haemodilution and head-down tilt. Significant functional changes were also present with haemodilution alone. Future studies with this partial optic nerve injury may enable understanding of mechanisms of peri-operative ischaemic optic neuropathy and could help discover preventive or treatment strategies.
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Affiliation(s)
- Steven Roth
- From the Department of Anesthesiology (SR), Department of Ophthalmology and Visual Sciences, University of Illinois (SR), Anesthesia and Critical Care, University of Chicago, Chicago, Illinois (JD), Department of Ophthalmology and Neurology (NJN) and Department of Neurological Surgery, Emory University School of Medicine, Atlanta, Georgia, USA (NJN)
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Kim JW, Andersson JL, Seifert AC, Sun P, Song SK, Dula C, Naismith RT, Xu J. Incorporating non-linear alignment and multi-compartmental modeling for improved human optic nerve diffusion imaging. Neuroimage 2019; 196:102-113. [PMID: 30930313 DOI: 10.1016/j.neuroimage.2019.03.058] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 03/22/2019] [Accepted: 03/25/2019] [Indexed: 12/19/2022] Open
Abstract
In vivo human optic nerve diffusion magnetic resonance imaging (dMRI) is technically challenging with two outstanding issues not yet well addressed: (i) non-linear optic nerve movement, independent of head motion, and (ii) effect from partial-volumed cerebrospinal fluid or interstitial fluid such as in edema. In this work, we developed a non-linear optic nerve registration algorithm for improved volume alignment in axial high resolution optic nerve dMRI. During eyes-closed dMRI data acquisition, optic nerve dMRI measurements by diffusion tensor imaging (DTI) with and without free water elimination (FWE), and by diffusion basis spectrum imaging (DBSI), as well as optic nerve motion, were characterized in healthy adults at various locations along the posterior-to-anterior dimension. Optic nerve DTI results showed consistent trends in microstructural parametric measurements along the posterior-to-anterior direction of the entire intraorbital optic nerve, while the anterior portion of the intraorbital optic nerve exhibited the largest spatial displacement. Multi-compartmental dMRI modeling, such as DTI with FWE or DBSI, was less subject to spatially dependent biases in diffusivity and anisotropy measurements in the optic nerve which corresponded to similar spatial distributions of the estimated fraction of isotropic diffusion components. DBSI results derived from our clinically feasible (∼10 min) optic nerve dMRI protocol in this study are consistent with those from small animal studies, which provides the basis for evaluating the utility of multi-compartmental dMRI modeling in characterizing coexisting pathophysiology in human optic neuropathies.
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Affiliation(s)
- Joo-Won Kim
- Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA; Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA; Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
| | - Jesper Lr Andersson
- Wellcome Center for Integrative Neuroimaging, University of Oxford, Oxford, UK
| | - Alan C Seifert
- Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA; Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA; Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Peng Sun
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Sheng-Kwei Song
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Courtney Dula
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA
| | - Robert T Naismith
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA
| | - Junqian Xu
- Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA; Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA; Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA; Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
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10
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Diffusion tensor imaging of the optic disc in idiopathic intracranial hypertension. Neuroradiology 2018; 60:1159-1166. [DOI: 10.1007/s00234-018-2078-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 08/07/2018] [Indexed: 12/11/2022]
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Marshall-Goebel K, Terlević R, Gerlach DA, Kuehn S, Mulder E, Rittweger J. Lower body negative pressure reduces optic nerve sheath diameter during head-down tilt. J Appl Physiol (1985) 2017; 123:1139-1144. [PMID: 28818998 DOI: 10.1152/japplphysiol.00256.2017] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 08/14/2017] [Accepted: 08/14/2017] [Indexed: 01/06/2023] Open
Abstract
The microgravity ocular syndrome (MOS) results in significant structural and functional ophthalmic changes during 6-mo spaceflight missions consistent with an increase in cerebrospinal fluid (CSF) pressure compared with the preflight upright position. A ground-based study was performed to assess two of the major hypothesized contributors to MOS, headward fluid shifting and increased ambient CO2, on intracranial and periorbital CSF. In addition, lower body negative pressure (LBNP) was assessed as a countermeasure to headward fluid shifting. Nine healthy male subjects participated in a crossover design study with five head-down tilt (HDT) conditions: -6, -12, and -18° HDT, -12° HDT with -20 mmHg LBNP, and -12° HDT with a 1% CO2 environment, each for 5 h total. A three-dimensional volumetric scan of the cranium and transverse slices of the orbita were collected with MRI, and intracranial CSF volume and optic nerve sheath diameter (ONSD) were measured after 4.5 h HDT. ONSD increased during -6° (P < 0.001), -12° (P < 0.001), and -18° HDT (P < 0.001) and intracranial CSF increased during -12° HDT (P = 0.01) compared with supine baseline. Notably, LBNP was able to reduce the increases in ONSD and intracranial CSF during HDT. The addition of 1% CO2 during HDT, however, had no further effect on ONSD, but rather ONSD increased from baseline in a similar magnitude to -12° HDT with ambient air (P = 0.001). These findings demonstrate the ability of LBNP, a technique that targets fluid distribution in the lower limbs, to directly influence CSF and may be a promising countermeasure to help reduce increases in CSF.NEW & NOTEWORTHY This is the first study to demonstrate the ability of lower body negative pressure to directly influence cerebrospinal fluid surrounding the optic nerve, indicating potential use as a countermeasure for increased cerebrospinal fluid on Earth or in space.
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Affiliation(s)
- Karina Marshall-Goebel
- Neural Systems Group, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts; .,Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany
| | - Robert Terlević
- Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany.,International Space University, Illkirch-Graffenstaden, France; and
| | - Darius A Gerlach
- Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany
| | - Simone Kuehn
- University Clinic Hamburg-Eppendorf, Clinic for Psychiatry and Psychotherapy, Hamburg, Germany
| | - Edwin Mulder
- Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany
| | - Jörn Rittweger
- Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany
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