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Parent O, Bussy A, Devenyi GA, Dai A, Costantino M, Tullo S, Salaciak A, Bedford S, Farzin S, Béland ML, Valiquette V, Villeneuve S, Poirier J, Tardif CL, Dadar M, Chakravarty MM. Assessment of white matter hyperintensity severity using multimodal magnetic resonance imaging. Brain Commun 2023; 5:fcad279. [PMID: 37953840 PMCID: PMC10636521 DOI: 10.1093/braincomms/fcad279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 09/05/2023] [Accepted: 10/17/2023] [Indexed: 11/14/2023] Open
Abstract
White matter hyperintensities are radiological abnormalities reflecting cerebrovascular dysfunction detectable using MRI. White matter hyperintensities are often present in individuals at the later stages of the lifespan and in prodromal stages in the Alzheimer's disease spectrum. Tissue alterations underlying white matter hyperintensities may include demyelination, inflammation and oedema, but these are highly variable by neuroanatomical location and between individuals. There is a crucial need to characterize these white matter hyperintensity tissue alterations in vivo to improve prognosis and, potentially, treatment outcomes. How different MRI measure(s) of tissue microstructure capture clinically-relevant white matter hyperintensity tissue damage is currently unknown. Here, we compared six MRI signal measures sampled within white matter hyperintensities and their associations with multiple clinically-relevant outcomes, consisting of global and cortical brain morphometry, cognitive function, diagnostic and demographic differences and cardiovascular risk factors. We used cross-sectional data from 118 participants: healthy controls (n = 30), individuals at high risk for Alzheimer's disease due to familial history (n = 47), mild cognitive impairment (n = 32) and clinical Alzheimer's disease dementia (n = 9). We sampled the median signal within white matter hyperintensities on weighted MRI images [T1-weighted (T1w), T2-weighted (T2w), T1w/T2w ratio, fluid-attenuated inversion recovery (FLAIR)] as well as the relaxation times from quantitative T1 (qT1) and T2* (qT2*) images. qT2* and fluid-attenuated inversion recovery signals within white matter hyperintensities displayed different age- and disease-related trends compared to normal-appearing white matter signals, suggesting sensitivity to white matter hyperintensity-specific tissue deterioration. Further, white matter hyperintensity qT2*, particularly in periventricular and occipital white matter regions, was consistently associated with all types of clinically-relevant outcomes in both univariate and multivariate analyses and across two parcellation schemes. qT1 and fluid-attenuated inversion recovery measures showed consistent clinical relationships in multivariate but not univariate analyses, while T1w, T2w and T1w/T2w ratio measures were not consistently associated with clinical variables. We observed that the qT2* signal was sensitive to clinically-relevant microstructural tissue alterations specific to white matter hyperintensities. Our results suggest that combining volumetric and signal measures of white matter hyperintensity should be considered to fully characterize the severity of white matter hyperintensities in vivo. These findings may have implications in determining the reversibility of white matter hyperintensities and the potential efficacy of cardio- and cerebrovascular treatments.
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Affiliation(s)
- Olivier Parent
- Cerebral Imaging Centre, Douglas Mental Health University Institute, Montreal, Quebec H4H 1R3, Canada
- Integrated Program in Neuroscience, McGill University, Montreal, Quebec H3A 1A1, Canada
| | - Aurélie Bussy
- Cerebral Imaging Centre, Douglas Mental Health University Institute, Montreal, Quebec H4H 1R3, Canada
- Integrated Program in Neuroscience, McGill University, Montreal, Quebec H3A 1A1, Canada
| | - Gabriel Allan Devenyi
- Cerebral Imaging Centre, Douglas Mental Health University Institute, Montreal, Quebec H4H 1R3, Canada
- Department of Psychiatry, McGill University, Montreal, Quebec H3A 1A1, Canada
| | - Alyssa Dai
- Cerebral Imaging Centre, Douglas Mental Health University Institute, Montreal, Quebec H4H 1R3, Canada
- Integrated Program in Neuroscience, McGill University, Montreal, Quebec H3A 1A1, Canada
- McConnell Brain Imaging Centre, Montreal Neurological Institute, Montreal, Quebec H3A 2B4, Canada
| | - Manuela Costantino
- Cerebral Imaging Centre, Douglas Mental Health University Institute, Montreal, Quebec H4H 1R3, Canada
| | - Stephanie Tullo
- Cerebral Imaging Centre, Douglas Mental Health University Institute, Montreal, Quebec H4H 1R3, Canada
- Integrated Program in Neuroscience, McGill University, Montreal, Quebec H3A 1A1, Canada
| | - Alyssa Salaciak
- Cerebral Imaging Centre, Douglas Mental Health University Institute, Montreal, Quebec H4H 1R3, Canada
| | - Saashi Bedford
- Cerebral Imaging Centre, Douglas Mental Health University Institute, Montreal, Quebec H4H 1R3, Canada
- Department of Psychiatry, McGill University, Montreal, Quebec H3A 1A1, Canada
| | - Sarah Farzin
- Cerebral Imaging Centre, Douglas Mental Health University Institute, Montreal, Quebec H4H 1R3, Canada
| | - Marie-Lise Béland
- Cerebral Imaging Centre, Douglas Mental Health University Institute, Montreal, Quebec H4H 1R3, Canada
| | - Vanessa Valiquette
- Cerebral Imaging Centre, Douglas Mental Health University Institute, Montreal, Quebec H4H 1R3, Canada
- Integrated Program in Neuroscience, McGill University, Montreal, Quebec H3A 1A1, Canada
| | - Sylvia Villeneuve
- Cerebral Imaging Centre, Douglas Mental Health University Institute, Montreal, Quebec H4H 1R3, Canada
- Department of Psychiatry, McGill University, Montreal, Quebec H3A 1A1, Canada
- Center for the Studies in the Prevention of Alzheimer's Disease, Douglas Mental Health University Institute, Montreal, Quebec H4H 1R3, Canada
- McConnell Brain Imaging Centre, Montreal Neurological Institute, Montreal, Quebec H3A 2B4, Canada
| | - Judes Poirier
- Department of Psychiatry, McGill University, Montreal, Quebec H3A 1A1, Canada
- Center for the Studies in the Prevention of Alzheimer's Disease, Douglas Mental Health University Institute, Montreal, Quebec H4H 1R3, Canada
- Molecular Neurobiology Unit, Douglas Mental Health University Institute, Montreal, Quebec H4H 1R3, Canada
- Department of Medicine, McGill University, Montreal, Quebec H4A 3J1, Canada
| | - Christine Lucas Tardif
- McConnell Brain Imaging Centre, Montreal Neurological Institute, Montreal, Quebec H3A 2B4, Canada
- Department of Biomedical Engineering, McGill University, Montreal, Quebec H3A 2B4, Canada
- Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec H3A 1A1, Canada
| | - Mahsa Dadar
- Department of Psychiatry, McGill University, Montreal, Quebec H3A 1A1, Canada
| | - M Mallar Chakravarty
- Cerebral Imaging Centre, Douglas Mental Health University Institute, Montreal, Quebec H4H 1R3, Canada
- Integrated Program in Neuroscience, McGill University, Montreal, Quebec H3A 1A1, Canada
- Department of Psychiatry, McGill University, Montreal, Quebec H3A 1A1, Canada
- Department of Biomedical Engineering, McGill University, Montreal, Quebec H3A 2B4, Canada
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Wang JY, Sonico GJ, Salcedo-Arellano MJ, Hagerman RJ, Martinez-Cerdeno V. A Postmortem MRI Study of Cerebrovascular Disease and Iron Content at End-Stage of Fragile X-Associated Tremor/Ataxia Syndrome. Cells 2023; 12:1898. [PMID: 37508562 PMCID: PMC10377990 DOI: 10.3390/cells12141898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 07/03/2023] [Accepted: 07/14/2023] [Indexed: 07/30/2023] Open
Abstract
Brain changes at the end-stage of fragile X-associated tremor/ataxia syndrome (FXTAS) are largely unknown due to mobility impairment. We conducted a postmortem MRI study of FXTAS to quantify cerebrovascular disease, brain atrophy and iron content, and examined their relationships using principal component analysis (PCA). Intracranial hemorrhage (ICH) was observed in 4/17 FXTAS cases, among which one was confirmed by histologic staining. Compared with seven control brains, FXTAS cases showed higher ratings of T2-hyperintensities (indicating cerebral small vessel disease) in the cerebellum, globus pallidus and frontoparietal white matter, and significant atrophy in the cerebellar white matter, red nucleus and dentate nucleus. PCA of FXTAS cases revealed negative associations of T2-hyperintensity ratings with anatomic volumes and iron content in the white matter, hippocampus and amygdala, that were independent from a highly correlated number of regions with ICH and iron content in subcortical nuclei. Post-hoc analysis confirmed PCA findings and further revealed increased iron content in the white matter, hippocampus and amygdala in FXTAS cases compared to controls, after adjusting for T2-hyperintensity ratings. These findings indicate that both ischemic and hemorrhagic brain damage may occur in FXTAS, with the former being marked by demyelination/iron depletion and atrophy, and the latter by ICH and iron accumulation in basal ganglia.
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Affiliation(s)
- Jun Yi Wang
- Center for Mind and Brain, University of California Davis, Davis, CA 95618, USA
| | - Gerard J. Sonico
- Imaging Research Center, University of California Davis, Sacramento, CA 95817, USA;
| | - Maria Jimena Salcedo-Arellano
- Department of Pathology and Laboratory Medicine, University of California Davis School of Medicine, Sacramento, CA 95817, USA;
- MIND Institute, University of California Davis Health, Sacramento, CA 95817, USA;
- Institute for Pediatric Regenerative Medicine and Shriners Hospitals for Children Northern California, Sacramento, CA 95817, USA
| | - Randi J. Hagerman
- MIND Institute, University of California Davis Health, Sacramento, CA 95817, USA;
- Department of Pediatrics, University of California Davis School of Medicine, Sacramento, CA 95817, USA
| | - Veronica Martinez-Cerdeno
- Department of Pathology and Laboratory Medicine, University of California Davis School of Medicine, Sacramento, CA 95817, USA;
- MIND Institute, University of California Davis Health, Sacramento, CA 95817, USA;
- Institute for Pediatric Regenerative Medicine and Shriners Hospitals for Children Northern California, Sacramento, CA 95817, USA
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3
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Pang Y. Phase-shifted transverse relaxation orientation dependences in human brain white matter. NMR IN BIOMEDICINE 2023:e4925. [PMID: 36908074 DOI: 10.1002/nbm.4925] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 02/24/2023] [Accepted: 03/02/2023] [Indexed: 06/18/2023]
Abstract
This work aimed to demonstrate an essential phase shift ε 0 $$ {\varepsilon}_0 $$ for better quantifying R 2 $$ {R}_2 $$ and R 2 * $$ {R}_2^{\ast } $$ in human brain white matter (WM), and to further elucidate its origin related to the directional diffusivities from standard diffusion tensor imaging (DTI). ε 0 $$ {\varepsilon}_0 $$ was integrated into a proposed generalized transverse relaxation model for characterizing previously published R 2 $$ {R}_2 $$ and R 2 * $$ {R}_2^{\ast } $$ orientation dependence profiles in brain WM, and then comparisons were made with those without ε 0 $$ {\varepsilon}_0 $$ . It was theorized that anisotropic diffusivity direction ε $$ \varepsilon $$ was collinear with an axon fiber subject to all eigenvalues and eigenvectors from an apparent diffusion tensor. To corroborate the origin of ε 0 $$ {\varepsilon}_0 $$ , R 2 $$ {R}_2 $$ orientation dependences referenced by ε $$ \varepsilon $$ were compared with those referenced by the standard principal diffusivity direction Φ $$ \Phi $$ at b-values of 1000 and 2500 (s/mm2 ). These R 2 $$ {R}_2 $$ orientation dependences were obtained from T 2 $$ {T}_2 $$ -weighted images (b = 0) of ultrahigh-resolution Connectome DTI datasets in the public domain. A normalized root-mean-square error ( NRMSE % $$ NRMSE\% $$ ) and an F $$ F $$ -test were used for evaluating curve-fittings, and statistical significance was considered to be a p of 0.05 or less. A phase-shifted model resulted in significantly reduced NRMSE % $$ NRMSE\% $$ compared with that without ε 0 $$ {\varepsilon}_0 $$ in quantifying various R 2 $$ {R}_2 $$ and R 2 * $$ {R}_2^{\ast } $$ profiles, both in vivo and ex vivo at multiple B 0 $$ {B}_0 $$ fields. The R 2 $$ {R}_2 $$ profiles based on Φ $$ \Phi $$ manifested a right-shifted phase ( ε 0 > 0 $$ {\varepsilon}_0>0 $$ ) at two b-values, while those based on ε $$ \varepsilon $$ became free from ε 0 $$ {\varepsilon}_0 $$ . For all phase-shifted R 2 $$ {R}_2 $$ and R 2 * $$ {R}_2^{\ast } $$ profiles, ε 0 $$ {\varepsilon}_0 $$ generally depended on the directional diffusivities by tan - 1 D ⊥ / D ∥ $$ {\tan}^{-1}\left({D}_{\perp }/{D}_{\parallel}\right) $$ , as predicted. In summary, a ubiquitous phase shift ε 0 $$ {\varepsilon}_0 $$ has been demonstrated as a prerequisite for better quantifying transverse relaxation orientation dependences in human brain WM. Furthermore, the origin of ε 0 $$ {\varepsilon}_0 $$ associated with the directional diffusivities from DTI has been elucidated. These findings could have a significant impact on interpretations of prior R 2 $$ {R}_2 $$ and R 2 * $$ {R}_2^{\ast } $$ datasets and on future research.
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Affiliation(s)
- Yuxi Pang
- Department of Radiology, University of Michigan, Ann Arbor, Michigan, USA
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Wang JY, Sonico GJ, Salcedo-Arellano MJ, Hagerman RJ, Martínez-Cerdeño V. A postmortem MRI study of cerebrovascular disease and iron content at end-stage of fragile X-associated tremor/ataxia syndrome. RESEARCH SQUARE 2023:rs.3.rs-2440612. [PMID: 36711694 PMCID: PMC9882645 DOI: 10.21203/rs.3.rs-2440612/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Brain changes at end-stage of fragile X-associated tremor/ataxia syndrome (FXTAS) are largely unknown due to mobility impairment. We conducted a postmortem MRI study of FXTAS to quantify cerebrovascular disease, brain atrophy, and iron content and examined their relationships using principal component analysis (PCA). Intracranial hemorrhage (ICH) was observed in 4/17 FXTAS cases among which one was confirmed by histologic staining. Compared with seven control brains, FXTAS cases showed higher ratings of T2-hyperintensities (indicating cerebral small vessel disease) in the cerebellum, globus pallidus, and frontoparietal white matter and significant atrophy in cerebellar white matter, red nucleus, and dentate nucleus. PCA of FXTAS cases revealed negative associations of T2-hyperintensity ratings with anatomic volumes and iron content in the white matter, hippocampus, and amygdala, that were independent from highly correlated number of regions with ICH and iron content in subcortical nuclei. Post hoc analysis confirmed PCA findings and further revealed increased iron content in the white matter, hippocampus, and amygdala in FXTAS cases than controls after adjusting for T2-hyperintensity ratings. These findings indicate that both ischemic and hemorrhagic brain damage may occur in FXTAS, with the former marked by demyelination/iron depletion and atrophy and the latter, ICH and iron accumulation in basal ganglia.
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5
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Orientation dependence of R 2 relaxation in the newborn brain. Neuroimage 2022; 264:119702. [PMID: 36272671 DOI: 10.1016/j.neuroimage.2022.119702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 09/25/2022] [Accepted: 10/18/2022] [Indexed: 11/09/2022] Open
Abstract
In MRI the transverse relaxation rate, R2 = 1/T2, shows dependence on the orientation of ordered tissue relative to the main magnetic field. In previous studies, orientation effects of R2 relaxation in the mature brain's white matter have been found to be described by a susceptibility-based model of diffusion through local magnetic field inhomogeneities created by the diamagnetic myelin sheaths. Orientation effects in human newborn white matter have not yet been investigated. The newborn brain is known to contain very little myelin and is therefore expected to exhibit a decrease in orientation dependence driven by susceptibility-based effects. We measured R2 orientation dependence in the white matter of human newborns. R2 data were acquired with a 3D Gradient and Spin Echo (GRASE) sequence and fiber orientation was mapped with diffusion tensor imaging (DTI). We found orientation dependence in newborn white matter that is not consistent with the susceptibility-based model and is best described by a model of residual dipolar coupling. In the near absence of myelin in the newborn brain, these findings suggest the presence of residual dipolar coupling between rotationally restricted water molecules. This has important implications for quantitative imaging methods such as myelin water imaging, and suggests orientation dependence of R2 as a potential marker in early brain development.
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Chen JJ, Uthayakumar B, Hyder F. Mapping oxidative metabolism in the human brain with calibrated fMRI in health and disease. J Cereb Blood Flow Metab 2022; 42:1139-1162. [PMID: 35296177 PMCID: PMC9207484 DOI: 10.1177/0271678x221077338] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Conventional functional MRI (fMRI) with blood-oxygenation level dependent (BOLD) contrast is an important tool for mapping human brain activity non-invasively. Recent interest in quantitative fMRI has renewed the importance of oxidative neuroenergetics as reflected by cerebral metabolic rate of oxygen consumption (CMRO2) to support brain function. Dynamic CMRO2 mapping by calibrated fMRI require multi-modal measurements of BOLD signal along with cerebral blood flow (CBF) and/or volume (CBV). In human subjects this "calibration" is typically performed using a gas mixture containing small amounts of carbon dioxide and/or oxygen-enriched medical air, which are thought to produce changes in CBF (and CBV) and BOLD signal with minimal or no CMRO2 changes. However non-human studies have demonstrated that the "calibration" can also be achieved without gases, revealing good agreement between CMRO2 changes and underlying neuronal activity (e.g., multi-unit activity and local field potential). Given the simpler set-up of gas-free calibrated fMRI, there is evidence of recent clinical applications for this less intrusive direction. This up-to-date review emphasizes technological advances for such translational gas-free calibrated fMRI experiments, also covering historical progression of the calibrated fMRI field that is impacting neurological and neurodegenerative investigations of the human brain.
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Affiliation(s)
- J Jean Chen
- Medical Biophysics, University of Toronto, Toronto, Canada.,Rotman Research Institute, Baycrest, Toronto, Canada
| | - Biranavan Uthayakumar
- Medical Biophysics, University of Toronto, Toronto, Canada.,Sunnybrook Research Institute, Toronto, Canada
| | - Fahmeed Hyder
- Magnetic Resonance Research Center (MRRC), Yale University, New Haven, Connecticut, USA.,Department of Radiology, Yale University, New Haven, Connecticut, USA.,Quantitative Neuroscience with Magnetic Resonance (QNMR) Research Program, Yale University, New Haven, Connecticut, USA.,Department of Biomedical Engineering, Yale University, New Haven, Connecticut, USA
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Tang S, Zhang G, Liu X, Chen Z, He L. Application of Quantitative Susceptibility Mapping in the Assessment of Iron Content in Brain Regions in Normal Children. Curr Med Imaging 2022; 18:952-961. [PMID: 35339185 DOI: 10.2174/1573405618666220325090655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 12/20/2021] [Accepted: 01/25/2022] [Indexed: 11/22/2022]
Abstract
PURPOSE We evaluated brain iron content in a healthy pediatric population using quantitative susceptibility mapping (QSM). METHODS From June 2018 to December 2019, healthy subjects aged 2-18 years old (200 males, 200 females) with no anatomical abnormalities were assessed. All of the children underwent 3D T1 anatomical MRIs in addition to the sequence scans of enhanced T2 star-weighted angiography (ESWAN). The ESWAN sequence images were obtained with software to attain quantitative susceptibility mapping of the entire brain. The magnetic susceptibility values in the same brain region were compared across different age groups. The magnetic susceptibility values expressed in the same age group were compared across sexes, brain sides, and brain regions. RESULTS The magnetic susceptibility value of each brain region increased with age, and the magnetic susceptibility value expressed by each brain region demonstrated a positive correlation with the children's age (r=0.63, P<0.05). No dramatic difference in magnetic susceptibility was observed between the brain's left side and right side in the children within the age range ≥2-<6; however, among the children within the age range ≥6-<18, the magnetic susceptibility values expressed by the left putamen nucleus, globus pallidus, and substantia nigra were higher than those expressed by the same regions on the right side (P<0.05). CONCLUSION Quantitative susceptibility mapping can be used to evaluate the content of iron in each brain region of normal children. CLINICAL TRIAL REGISTRATION This study protocol was registered at the Chinese clinical trial registry (ChiCTR2000030656).
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Affiliation(s)
- Shilong Tang
- Department of Radiology, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education, Key Laboratory of Child Development and Disorders
| | | | | | - Zhuo Chen
- Chongqing Key Laboratory of Pediatrics
| | - Ling He
- Department of Radiology, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education, Key Laboratory of Child Development and Disorders
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Kan H, Uchida Y, Ueki Y, Arai N, Tsubokura S, Kunitomo H, Kasai H, Aoyama K, Matsukawa N, Shibamoto Y. R2* relaxometry analysis for mapping of white matter alteration in Parkinson's disease with mild cognitive impairment. Neuroimage Clin 2022; 33:102938. [PMID: 34998126 PMCID: PMC8741619 DOI: 10.1016/j.nicl.2022.102938] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 12/22/2021] [Accepted: 01/03/2022] [Indexed: 12/01/2022]
Abstract
R2* relaxometry analysis combined with QSM revealed detail of WM alteration in PD-MCI. R2* relaxometry analysis can detect slight demyelination in PD-MCI. R2* value shows potential for early evaluation of cognitive decline in PD.
Background R2* relaxometry analysis combined with quantitative susceptibility mapping (QSM), which has high sensitivity to iron deposition, can distinguish microstructural changes of the white matter (WM) and iron deposition, thereby providing a sensitive and biologically specific measure of the WM owing to the changes in myelin and its surrounding environment. This study aimed to explore the microstructural WM alterations associated with cognitive impairment in patients with Parkinson’s disease (PD) using R2* relaxometry analysis combined with QSM. Materials and methods We enrolled 24 patients with PD and mild cognitive impairment (PD-MCI), 22 patients with PD and normal cognition (PD-CN), and 19 age- and sex-matched healthy controls (HC). All participants underwent Montreal Cognitive Assessment (MoCA) and brain magnetic resonance imaging, including structural three-dimensional T1-weighted images and multiple spoiled gradient echo sequence (mGRE). The R2* and susceptibility maps were estimated from the multiple magnitude images of mGRE. The susceptibility maps were used for verifying iron deposition in the WM. The voxel-based R2* of the entire WM and its correlation with cognitive performance were analyzed. Results In the voxel-based group comparisons, the R2* in the PD-MCI group was lower in some WM regions, including the corpus callosum, than R2* in the PD-CN and HC groups. The mean susceptibility values in almost all brain regions were negative and close-to-zero values, indicating no detectable paramagnetic iron deposition in the WM of all subjects. There was a significant positive correlation between R2* and MoCA in some regions of the WM, mainly the corpus callosum and left hemisphere. Conclusion R2* relaxometry analysis for WM microstructural changes provided further biologic insights on demyelination and changes in the surrounding environment, supported by the QSM results demonstrating no iron existence. This analysis highlighted the potential for the early evaluation of cognitive decline in patients with PD.
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Affiliation(s)
- Hirohito Kan
- Department of Integrated Health Sciences, Nagoya University Graduate School of Medicine, Japan; Department of Radiology, Nagoya City University, Graduate School of Medical Sciences, Japan.
| | - Yuto Uchida
- Department of Neurology, Nagoya City University, Graduate School of Medical Sciences, Japan; Department of Neurology, Toyokawa City Hospital, Japan.
| | - Yoshino Ueki
- Department of Rehabilitation Medicine, Nagoya City University, Graduate School of Medical Sciences, Japan.
| | - Nobuyuki Arai
- Department of Radiology, Suzuka University of Medical Science, Japan.
| | | | - Hiroshi Kunitomo
- Department of Radiology, Nagoya City University Hospital, Japan.
| | - Harumasa Kasai
- Department of Radiology, Nagoya City University Hospital, Japan
| | - Kiminori Aoyama
- Department of Rehabilitation Medicine, Nagoya City University, Graduate School of Medical Sciences, Japan
| | - Noriyuki Matsukawa
- Department of Neurology, Nagoya City University, Graduate School of Medical Sciences, Japan.
| | - Yuta Shibamoto
- Department of Radiology, Nagoya City University, Graduate School of Medical Sciences, Japan.
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Miniello VL, Verga MC, Miniello A, Di Mauro C, Diaferio L, Francavilla R. Complementary Feeding and Iron Status: " The Unbearable Lightness of Being" Infants. Nutrients 2021; 13:4201. [PMID: 34959753 PMCID: PMC8707490 DOI: 10.3390/nu13124201] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 10/23/2021] [Accepted: 11/09/2021] [Indexed: 12/15/2022] Open
Abstract
The complementary feeding (CF) period that takes place between 6 and 24 months of age is of key importance for nutritional and developmental reasons during the transition from exclusively feeding on milk to family meals. In 2021, a multidisciplinary panel of experts from four Italian scientific pediatric societies elaborated a consensus document on CF, focusing in particular on healthy term infants. The aim was to provide healthcare providers with useful guidelines for clinical practice. Complementary feeding is also the time window when iron deficiency (ID) and iron deficiency anemia (IDA) are most prevalent. Thus, it is appropriate to address the problem of iron deficiency through nutritional interventions. Adequate iron intake during the first two years is critical since rapid growth in that period increases iron requirements per kilogram more than at any other developmental stage. Complementary foods should be introduced at around six months of age, taking into account infant iron status.
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Affiliation(s)
- Vito Leonardo Miniello
- Nutrition Unit, Department of Pediatrics, “Giovanni XXIII” Children Hospital, “Aldo Moro” University of Bari, 70126 Bari, Italy
| | | | - Andrea Miniello
- Department of Allergology and Immunology, “Aldo Moro” University of Bari, 70124 Bari, Italy;
| | - Cristina Di Mauro
- Regional Centre of Pharmacovigilance Campania, Department of Experimental Medicine, University “Luigi Vanvitelli”, 80138 Naples, Italy;
| | | | - Ruggiero Francavilla
- Gastroenterology Unit, Department of Pediatrics, “Giovanni XXIII” Children Hospital, “Aldo Moro” University of Bari, 70126 Bari, Italy;
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In vivo assessment of anisotropy of apparent magnetic susceptibility in white matter from a single orientation acquisition. Neuroimage 2021; 241:118442. [PMID: 34339831 DOI: 10.1016/j.neuroimage.2021.118442] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 06/02/2021] [Accepted: 07/29/2021] [Indexed: 11/20/2022] Open
Abstract
Multiple studies have reported a significant dependence of the effective transverse relaxation rate constant (R2*) and the phase of gradient-echo based (GRE) signal on the orientation of white matter fibres in the human brain. It has also been hypothesized that magnetic susceptibility, as obtained by single-orientation quantitative susceptibility mapping (QSM), exhibits such a dependence. In this study, we investigated this hypothesized relationship in a cohort of healthy volunteers. We show that R2* follows the predicted orientation dependence consistently across white matter regions, whereas the apparent magnetic susceptibility is related differently to fibre orientation across the brain and often in a complex non-monotonic manner. In addition, we explored the effect of fractional anisotropy measured by diffusion-weighted MRI on the strength of the orientation dependence and observed only a limited influence in many regions. However, with careful consideration of such an impact and the limitations imposed by the ill-posed nature of the dipole inversion process, it is possible to study magnetic susceptibility anisotropy in specific brain regions with a single orientation acquisition.
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11
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Khattar N, Triebswetter C, Kiely M, Ferrucci L, Resnick SM, Spencer RG, Bouhrara M. Investigation of the association between cerebral iron content and myelin content in normative aging using quantitative magnetic resonance neuroimaging. Neuroimage 2021; 239:118267. [PMID: 34139358 PMCID: PMC8370037 DOI: 10.1016/j.neuroimage.2021.118267] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 06/10/2021] [Accepted: 06/11/2021] [Indexed: 12/24/2022] Open
Abstract
Myelin loss and iron accumulation are cardinal features of aging and various neurodegenerative diseases. Oligodendrocytes incorporate iron as a metabolic substrate for myelin synthesis and maintenance. An emerging hypothesis in Alzheimer’s disease research suggests that myelin breakdown releases substantial stores of iron that may accumulate, leading to further myelin breakdown and neurodegeneration. We assessed associations between iron content and myelin content in critical brain regions using quantitative magnetic resonance imaging (MRI) on a cohort of cognitively unimpaired adults ranging in age from 21 to 94 years. We measured whole-brain myelin water fraction (MWF), a surrogate of myelin content, using multicomponent relaxometry, and whole-brain iron content using susceptibility weighted imaging in all individuals. MWF was negatively associated with iron content in most brain regions evaluated indicating that lower myelin content corresponds to higher iron content. Moreover, iron content was significantly higher with advanced age in most structures, with men exhibiting a trend towards higher iron content as compared to women. Finally, relationship between MWF and age, in all brain regions investigated, suggests that brain myelination continues until middle age, followed by degeneration at older ages. This work establishes a foundation for further investigations of the etiology and sequelae of myelin breakdown and iron accumulation in neurodegeneration and may lead to new imaging markers for disease progression and treatment.
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Affiliation(s)
- Nikkita Khattar
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, 21224 MD, United States
| | - Curtis Triebswetter
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, 21224 MD, United States
| | - Matthew Kiely
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, 21224 MD, United States
| | - Luigi Ferrucci
- Translational Gerontology Branch, National Institute on Aging, National Institutes of Health, Baltimore, 21224 MD, United States
| | - Susan M Resnick
- Laboratory of Behavioral Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, 21224 MD, United States
| | - Richard G Spencer
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, 21224 MD, United States
| | - Mustapha Bouhrara
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, 21224 MD, United States.
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12
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Lenz C, Berger C, Bauer M, Scheurer E, Birkl C. Sensitivity of fiber orientation dependent R 2 ∗ to temperature and post mortem interval. Magn Reson Med 2021; 86:2703-2715. [PMID: 34086354 DOI: 10.1002/mrm.28874] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 04/23/2021] [Accepted: 05/10/2021] [Indexed: 12/21/2022]
Abstract
PURPOSE R 2 ∗ imaging of brain white matter is well known for being sensitive to the orientation of nerve fibers with respect to the B0 field of the MRI scanner. The goal of this study was to evaluate whether and to which extent fiber orientation dependent R 2 ∗ differs between in vivo and post mortem in situ examinations, and to investigate the influence of varying temperatures and post mortem intervals (PMI). METHODS Post mortem in situ and in vivo MRI scans were conducted at 3T. R 2 ∗ was acquired with a multi-echo gradient-echo sequence, and the orientation of white matter fibers was computed using diffusion tensor imaging (DTI). Fitting of the measured fiber orientation dependent R 2 ∗ was performed using three different formulations of a previously proposed model. RESULTS R 2 ∗ increased with increasing fiber angle for in vivo and post mortem in situ examinations, whereby the orientation dependency was lower post mortem. The different formulations of the fiber orientation model resulted in an identical fit, but showed large variations of the estimated parameters. The higher order orientation dependent R 2 ∗ components significantly decreased with decreasing temperature, while the orientation independent R 2 ∗ components showed no significant correlation with either temperature or PMI. CONCLUSION Although the mean diffusivity is strongly reduced post mortem, we could successfully estimate the fiber angle using DTI. Due to the strong correlation of the higher order orientation dependent R 2 ∗ components with temperature, the decreased R 2 ∗ fiber orientation dependency post mortem in situ might primarily be attributed to the lower brain temperature.
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Affiliation(s)
- Claudia Lenz
- Institute of Forensic Medicine, Department of Biomedical Engineering, University of Basel, Basel, Switzerland.,Institute of Forensic Medicine, Health Department Basel-Stadt, Basel, Switzerland
| | - Celine Berger
- Institute of Forensic Medicine, Department of Biomedical Engineering, University of Basel, Basel, Switzerland.,Institute of Forensic Medicine, Health Department Basel-Stadt, Basel, Switzerland
| | - Melanie Bauer
- Institute of Forensic Medicine, Department of Biomedical Engineering, University of Basel, Basel, Switzerland.,Institute of Forensic Medicine, Health Department Basel-Stadt, Basel, Switzerland
| | - Eva Scheurer
- Institute of Forensic Medicine, Department of Biomedical Engineering, University of Basel, Basel, Switzerland.,Institute of Forensic Medicine, Health Department Basel-Stadt, Basel, Switzerland
| | - Christoph Birkl
- Department of Neuroradiology, Medical University of Innsbruck, Innsbruck, Austria
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Biel D, Steiger TK, Bunzeck N. Age-related iron accumulation and demyelination in the basal ganglia are closely related to verbal memory and executive functioning. Sci Rep 2021; 11:9438. [PMID: 33941809 PMCID: PMC8093241 DOI: 10.1038/s41598-021-88840-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 04/13/2021] [Indexed: 02/02/2023] Open
Abstract
Age-related cognitive decline has been linked to alterations of the dopaminergic system and its subcortical trajectories. Recent work suggests a critical role of iron accumulation within the basal ganglia (BG) in verbal memory performance, and increased iron levels have been related to demyelination. However, the specificity of age-related iron increases with respect to cognitive functions remains unclear. Therefore, we investigated the interplay of age, cognitive performance, and structural integrity of the BG. In total, 79 healthy older participants underwent a broad cognitive assessment (fluid and crystallized intelligence, verbal and numeric memory, processing speed, executive functions) and structural MRI. As expected, performance in most cognitive tests had a negative relationship with age. Moreover, BG grey matter volume and magnetization transfer (MT, indicative of myelin) decreased, and R2* (indicative of iron) increased with age. Importantly, R2* and demyelination negatively correlated with verbal memory and executive functions. Within the SN/VTA, age correlated negatively with MT, but there was no clear evidence in favor of a relationship between behavior and R2* or MT. Our results suggest that age-related increases in iron and demyelination within the BG, which are part of a fronto-striatal network, not only impact on verbal memory but also executive functions.
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Affiliation(s)
- Davina Biel
- grid.4562.50000 0001 0057 2672Department of Psychology, University of Lübeck, 23562 Lübeck, Germany ,grid.5252.00000 0004 1936 973XInstitute for Stroke and Dementia Research (ISD), University Hospital, LMU Munich, 81377 Munich, Germany
| | - Tineke K. Steiger
- grid.4562.50000 0001 0057 2672Department of Psychology, University of Lübeck, 23562 Lübeck, Germany
| | - Nico Bunzeck
- grid.4562.50000 0001 0057 2672Department of Psychology, University of Lübeck, 23562 Lübeck, Germany ,grid.4562.50000 0001 0057 2672Center of Brain, Behavior and Metabolism (CBBM), University of Lübeck, Ratzeburger Allee 160, 23562 Lübeck, Germany
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14
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Tang S, Xu Y, Liu X, Chen Z, Zhou Y, Nie L, He L. Quantitative susceptibility mapping shows lower brain iron content in children with autism. Eur Radiol 2020; 31:2073-2083. [PMID: 32945969 DOI: 10.1007/s00330-020-07267-w] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 07/23/2020] [Accepted: 09/08/2020] [Indexed: 11/29/2022]
Abstract
OBJECTIVE To explore the application of quantitative susceptibility mapping (QSM) of brain iron content in children with autism. METHODS For the control group, 40 normal children aged 2-3, 3-4, 4-5, and 5-6 years were prospectively selected from June 2018 to December 2018, with equal numbers of males and females in each age group. For the study group, 40 children with autism aged 2-3, 3-4, 4-5, and 5-6 years were prospectively selected from January 2019 to October 2019; once again, there were equal numbers of males and females in each age group. All children received routine head MRI scans and enhanced T2*-weighted angiography (ESWAN) sequence scans, and the ESWAN sequence images were processed by software to obtain magnetic susceptibility maps. The regions of interest (ROIs) of the frontal white matter, frontal gray matter, thalamus, red nucleus, substantia nigra, dentate nucleus, globus pallidus, putamen nucleus, caudate nucleus, pons, and splenium of the corpus callosum were selected, and the magnetic susceptibility values were measured. The differences in magnetic susceptibility between the two groups were compared in children at the same age. RESULTS For the children aged 2-3 years, the magnetic susceptibility values in the caudate nucleus, dentate nucleus, and splenium of the corpus callosum in the study group were lower than those in the control group (p < 0.05). For the children aged 3-4, 4-5, and 5-6 years, the magnetic susceptibility values in the frontal white matter, caudate nucleus, red nucleus, substantia nigra, dentate nucleus, and splenium of the corpus callosum in the study group were lower than those in the control group (p < 0.05). CONCLUSION The brain iron content of children with autism is lower than that of normal children. TRIAL REGISTRATION This study protocol was registered at the Chinese clinical trial registry (registration number: ChiCTR2000029699; http://www.chictr.org.cn/searchprojen.aspx ). KEY POINTS • In this study, the brain iron content of normal children and children with autism was compared to identify the differences, which provided a new objective basis for the early diagnosis of children with autism. • This study examined the iron content values in various brain regions of normal children aged 2-6 years in this region and established a reference range for iron content in various brain regions of normal children in one geographical area, providing a reliable and objective standard for the diagnosis and treatment of some brain diseases in children. • The results of this study indicate that the brain iron content of preschool children with autism is lower than that of normal preschool children.
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Affiliation(s)
- Shilong Tang
- Department of Radiology, Children's Hospital of Chongqing Medical University, Chongqing, 400014, China
| | - Ye Xu
- Ministry of Education Key Laboratory of Child Development and Disorders, Children's Hospital of Chongqing Medical University, Chongqing, China
| | - Xianfan Liu
- National Clinical Research Center for Child Health and Disorders, Children's Hospital of Chongqing Medical University, Chongqing, China
| | - Zhuo Chen
- China International Science and Technology Cooperation Base of Child Development and Critical Disorders, Children's Hospital of Chongqing Medical University, Chongqing, China
| | - Yu Zhou
- Chongqing Key Laboratory of Pediatrics, Children's Hospital of Chongqing Medical University, Chongqing, China
| | - Lisha Nie
- GE Healthcare, MR Research China, Beijing, China
| | - Ling He
- Department of Radiology, Children's Hospital of Chongqing Medical University, Chongqing, 400014, China.
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15
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Thapaliya K, Vegh V, Bollmann S, Barth M. Influence of 7T GRE-MRI Signal Compartment Model Choice on Tissue Parameters. Front Neurosci 2020; 14:271. [PMID: 32457565 PMCID: PMC7206227 DOI: 10.3389/fnins.2020.00271] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Accepted: 03/10/2020] [Indexed: 12/16/2022] Open
Abstract
Quantitative assessment of tissue microstructure is important in studying human brain diseases and disorders. Ultra-high field magnetic resonance imaging (MRI) data obtained using a multi-echo gradient echo sequence have been shown to contain information on myelin, axonal, and extracellular compartments in tissue. Quantitative assessment of water fraction, relaxation time (T2*), and frequency shift using multi-compartment models has been shown to be useful in studying white matter properties via specific tissue parameters. It remains unclear how tissue parameters vary with model selection based on 7T multiple echo time gradient-recalled echo (GRE) MRI data. We applied existing signal compartment models to the corpus callosum and investigated whether a three-compartment model can be reduced to two compartments and still resolve white matter parameters [i.e., myelin water fraction (MWF) and g-ratio]. We show that MWF should be computed using a three-compartment model in the corpus callosum, and the g-ratios obtained using three compartment models are consistent with previous reports. We provide results for other parameters, such as signal compartment frequency shifts.
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Affiliation(s)
- Kiran Thapaliya
- Centre for Advanced Imaging, The University of Queensland, Brisbane, QLD, Australia
| | - Viktor Vegh
- Centre for Advanced Imaging, The University of Queensland, Brisbane, QLD, Australia.,ARC Centre for Innovation in Biomedical Imaging Technology, Brisbane, QLD, Australia
| | - Steffen Bollmann
- Centre for Advanced Imaging, The University of Queensland, Brisbane, QLD, Australia.,ARC Centre for Innovation in Biomedical Imaging Technology, Brisbane, QLD, Australia
| | - Markus Barth
- Centre for Advanced Imaging, The University of Queensland, Brisbane, QLD, Australia.,ARC Centre for Innovation in Biomedical Imaging Technology, Brisbane, QLD, Australia.,School of Information Technology and Electrical Engineering, The University of Queensland, Brisbane, QLD, Australia
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Hu XY, Rajendran L, Lapointe E, Tam R, Li D, Traboulsee A, Rauscher A. Three-dimensional MRI sequences in MS diagnosis and research. Mult Scler 2019; 25:1700-1709. [DOI: 10.1177/1352458519848100] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The most recent guidelines for magnetic resonance imaging (MRI) in multiple sclerosis (MS) recommend three-dimensional (3D) MRI sequences over their two-dimensional (2D) counterparts. This development has been made possible by advances in MRI scanner hardware and software. In this article, we review the 3D versions of conventional sequences, including T1-weighted, T2-weighted and fluid-attenuated inversion recovery (FLAIR), as well as more advanced scans, including double inversion recovery (DIR), FLAIR2, FLAIR*, phase-sensitive inversion recovery, and susceptibility weighted imaging (SWI).
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Affiliation(s)
- Xun Yang Hu
- Faculty of Medicine, The University of British Columbia, Vancouver, BC, Canada
| | - Luckshi Rajendran
- Faculty of Medicine, The University of British Columbia, Vancouver, BC, Canada
| | - Emmanuelle Lapointe
- Department of Medicine, Division of Neurology, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Roger Tam
- Department of Radiology, School of Biomedical Engineering, The University of British Columbia, Vancouver, BC, Canada
| | - David Li
- Department of Radiology, UBC Hospital, Vancouver, BC, Canada
| | - Anthony Traboulsee
- Division of Neurology, Faculty of Medicine, The University of British Columbia, Vancouver, BC, Canada
| | - Alexander Rauscher
- Department of Radiology, The University of British Columbia, Vancouver, BC, Canada
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Birkl C, Birkl-Toeglhofer AM, Endmayr V, Höftberger R, Kasprian G, Krebs C, Haybaeck J, Rauscher A. The influence of brain iron on myelin water imaging. Neuroimage 2019; 199:545-552. [PMID: 31108214 DOI: 10.1016/j.neuroimage.2019.05.042] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 05/15/2019] [Accepted: 05/16/2019] [Indexed: 12/19/2022] Open
Abstract
With myelin playing a vital role in normal brain integrity and function and thus in various neurological disorders, myelin sensitive magnetic resonance imaging (MRI) techniques are of great importance. In particular, multi-exponential T2 relaxation was shown to be highly sensitive to myelin. The myelin water imaging (MWI) technique allows to separate the T2 decay into short components, specific to myelin water, and long components reflecting the intra- and extracellular water. The myelin water fraction (MWF) is the ratio of the short components to all components. In the brain's white matter (WM), myelin and iron are closely linked via the presence of iron in the myelin generating oligodendrocytes. Iron is known to decrease T2 relaxation times and may therefore mimic myelin. In this study, we investigated if variations in WM iron content can lead to apparent MWF changes. We performed MWI in post mortem human brain tissue prior and after chemical iron extraction. Histology for iron and myelin confirmed a decrease in iron content and no change in myelin content after iron extraction. In MRI, iron extraction lead to a decrease in MWF by 26%-28% in WM. Thus, a change in MWF does not necessarily reflect a change in myelin content. This observation has important implications for the interpretation of MWI findings in previously published studies and future research.
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Affiliation(s)
- Christoph Birkl
- UBC MRI Research Centre, University of British Columbia, Vancouver, BC, Canada; Department of Neurology, Medical University of Graz, Austria.
| | - Anna Maria Birkl-Toeglhofer
- Department of Pathology, Neuropathology and Molecular Pathology, Medical University of Innsbruck, Austria; Diagnostic and Research Institute of Pathology, Medical University of Graz, Austria
| | - Verena Endmayr
- Institute of Neurology, Medical University of Vienna, Austria
| | | | - Gregor Kasprian
- Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Austria
| | - Claudia Krebs
- Department of Cellular & Physiological Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Johannes Haybaeck
- Department of Pathology, Neuropathology and Molecular Pathology, Medical University of Innsbruck, Austria; Diagnostic and Research Institute of Pathology, Medical University of Graz, Austria; Department of Pathology, Medical Faculty, Otto-von-Guerecke University Magdeburg, Germany
| | - Alexander Rauscher
- UBC MRI Research Centre, University of British Columbia, Vancouver, BC, Canada; Department of Physics & Astronomy, University of British Columbia, Vancouver, BC, Canada; Department of Pediatrics (Division of Neurology), University of British Columbia, Vancouver, BC, Canada
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