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Faulkner ME, Gong Z, Guo A, Laporte JP, Bae J, Bouhrara M. Harnessing myelin water fraction as an imaging biomarker of human cerebral aging, neurodegenerative diseases, and risk factors influencing myelination: A review. J Neurochem 2024. [PMID: 38973579 DOI: 10.1111/jnc.16170] [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: 04/19/2024] [Revised: 06/12/2024] [Accepted: 06/19/2024] [Indexed: 07/09/2024]
Abstract
Myelin water fraction (MWF) imaging has emerged as a promising magnetic resonance imaging (MRI) biomarker for investigating brain function and composition. This comprehensive review synthesizes the current state of knowledge on MWF as a biomarker of human cerebral aging, neurodegenerative diseases, and risk factors influencing myelination. The databases used include Web of Science, Scopus, Science Direct, and PubMed. We begin with a brief discussion of the theoretical foundations of MWF imaging, including its basis in MR physics and the mathematical modeling underlying its calculation, with an overview of the most adopted MRI methods of MWF imaging. Next, we delve into the clinical and research applications that have been explored to date, highlighting its advantages and limitations. Finally, we explore the potential of MWF to serve as a predictive biomarker for neurological disorders and identify future research directions for optimizing MWF imaging protocols and interpreting MWF in various contexts. By harnessing the power of MWF imaging, we may gain new insights into brain health and disease across the human lifespan, ultimately informing novel diagnostic and therapeutic strategies.
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Affiliation(s)
- Mary E Faulkner
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Zhaoyuan Gong
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Alex Guo
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - John P Laporte
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Jonghyun Bae
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Mustapha Bouhrara
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
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Bi C, Ou MY, Bouhrara M, Spencer RG. Span of regularization for solution of inverse problems with application to magnetic resonance relaxometry of the brain. Sci Rep 2022; 12:20194. [PMID: 36418516 PMCID: PMC9684479 DOI: 10.1038/s41598-022-22739-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 10/19/2022] [Indexed: 11/25/2022] Open
Abstract
We present a new regularization method for the solution of the Fredholm integral equation (FIE) of the first kind, in which we incorporate solutions corresponding to a range of Tikhonov regularizers into the end result. This method identifies solutions within a much larger function space, spanned by this set of regularized solutions, than is available to conventional regularization methods. An additional key development is the use of dictionary functions derived from noise-corrupted inversion of the discretized FIE. In effect, we combine the stability of solutions with greater degrees of regularization with the resolution of those that are less regularized. The span of regularizations (SpanReg) method may be widely applicable throughout the field of inverse problems.
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Affiliation(s)
- Chuan Bi
- grid.411024.20000 0001 2175 4264Department of Psychiatry, University of Maryland, Baltimore, Baltimore, MD 21201 USA
| | - M. Yvonne Ou
- grid.33489.350000 0001 0454 4791Department of Mathematical Sciences, University of Delaware, Newark, DE 19716 USA
| | - Mustapha Bouhrara
- grid.94365.3d0000 0001 2297 5165National Institute on Aging, National Institutes of Health, Baltimore, MD 21224 USA
| | - Richard G. Spencer
- grid.94365.3d0000 0001 2297 5165National Institute on Aging, National Institutes of Health, Baltimore, MD 21224 USA
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Stabilization of parameter estimates from multiexponential decay through extension into higher dimensions. Sci Rep 2022; 12:5773. [PMID: 35388008 PMCID: PMC8986819 DOI: 10.1038/s41598-022-08638-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 03/07/2022] [Indexed: 11/23/2022] Open
Abstract
Analysis of multiexponential decay has remained a topic of active research for over 200 years. This attests to the widespread importance of this problem and to the profound difficulties in characterizing the underlying monoexponential decays. Here, we demonstrate the fundamental improvement in stability and conditioning of this classic problem through extension to a second dimension; we present statistical analysis, Monte-Carlo simulations, and experimental magnetic resonance relaxometry data to support this remarkable fact. Our results are readily generalizable to higher dimensions and provide a potential means of circumventing conventional limits on multiexponential parameter estimation.
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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: 30] [Impact Index Per Article: 10.0] [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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Nuixe M, Traoré AS, Blystone S, Bonny JM, Falcimagne R, Pagès G, Picon-Cochard C. Circadian Variation of Root Water Status in Three Herbaceous Species Assessed by Portable NMR. PLANTS (BASEL, SWITZERLAND) 2021; 10:782. [PMID: 33923406 PMCID: PMC8073897 DOI: 10.3390/plants10040782] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 04/14/2021] [Accepted: 04/14/2021] [Indexed: 11/17/2022]
Abstract
Roots are at the core of plant water dynamics. Nonetheless, root morphology and functioning are not easily assessable without destructive approaches. Nuclear Magnetic Resonance (NMR), and particularly low-field NMR (LF-NMR), is an interesting noninvasive method to study water in plants, as measurements can be performed outdoors and independent of sample size. However, as far as we know, there are no reported studies dealing with the water dynamics in plant roots using LF-NMR. Thus, the aim of this study is to assess the feasibility of using LF-NMR to characterize root water status and water dynamics non-invasively. To achieve this goal, a proof-of-concept study was designed using well-controlled environmental conditions. NMR and ecophysiological measurements were performed continuously over one week on three herbaceous species grown in rhizotrons. The NMR parameters measured were either the total signal or the transverse relaxation time T2. We observed circadian variations of the total NMR signal in roots and in soil and of the root slow relaxing T2 value. These results were consistent with ecophysiological measurements, especially with the variation of fluxes between daytime and nighttime. This study assessed the feasibility of using LF-NMR to evaluate root water status in herbaceous species.
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Affiliation(s)
- Magali Nuixe
- INRAE, UR QuaPA, F-63122 Saint-Genès Champanelle, France; (M.N.); (S.B.); (J.-M.B.); (G.P.)
- INRAE, ISC AgroResonance, F-63122 Saint-Genès-Champanelle, France
- Université Clermont Auvergne, INRAE, VetAgro Sup, UREP, F-63000 Clermont-Ferrand, France;
| | - Amidou Sissou Traoré
- INRAE, UR QuaPA, F-63122 Saint-Genès Champanelle, France; (M.N.); (S.B.); (J.-M.B.); (G.P.)
- INRAE, ISC AgroResonance, F-63122 Saint-Genès-Champanelle, France
| | - Shannan Blystone
- INRAE, UR QuaPA, F-63122 Saint-Genès Champanelle, France; (M.N.); (S.B.); (J.-M.B.); (G.P.)
- INRAE, ISC AgroResonance, F-63122 Saint-Genès-Champanelle, France
- Université Clermont Auvergne, INRAE, VetAgro Sup, UREP, F-63000 Clermont-Ferrand, France;
| | - Jean-Marie Bonny
- INRAE, UR QuaPA, F-63122 Saint-Genès Champanelle, France; (M.N.); (S.B.); (J.-M.B.); (G.P.)
- INRAE, ISC AgroResonance, F-63122 Saint-Genès-Champanelle, France
| | - Robert Falcimagne
- Université Clermont Auvergne, INRAE, VetAgro Sup, UREP, F-63000 Clermont-Ferrand, France;
| | - Guilhem Pagès
- INRAE, UR QuaPA, F-63122 Saint-Genès Champanelle, France; (M.N.); (S.B.); (J.-M.B.); (G.P.)
- INRAE, ISC AgroResonance, F-63122 Saint-Genès-Champanelle, France
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