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Liachenko S, Sarkar S. In vivo mapping of rat brain partial white matter content using hexachlorophene-induced neurotoxicity model. Brain Res 2024; 1830:148811. [PMID: 38365131 DOI: 10.1016/j.brainres.2024.148811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 01/26/2024] [Accepted: 02/13/2024] [Indexed: 02/18/2024]
Abstract
Segmentation of the white matter in MRI scans of the rat brain presents a significant challenge due to the low contrast. Existing anatomical reference maps of rat brain are usually constructed from fixed tissue, which may suffer from geometrical distortions due to fixation/processing. To significantly increase the in vivo contrast between white and gray matter in the rat brain we used a known neurotoxicant hexachlorophene, which produces selective white matter damage. This model was used to map white matter in the rat brain and estimate the partial white matter content in any given imaging voxel. Hexachlorophene was administered to rats at a dose of 30 mg/kg orally once a day over five consecutive days. A significant white matter changes were observed using quantitative T2 maps, from which the partial white matter content throughout the whole rat brain was derived. Several assumptions were made: hexachlorophene affects T2 relaxation only in the white matter; T2 of gray matter is relatively uniform in the brain; apparent T2 value in a given voxel is a combination of T2s from white and gray matter portions of that voxel, hexachlorophene affects nearly 100 % of white matter. The partial white matter map of the rat brain was constructed with the resolution of 0.2 × 0.2 × 1.0 mm per voxel. This map could be adjusted for segmentation of the brain tissue with preset threshold of the white matter content, or to establish the tissue composition in any region of interest among other applications.
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Affiliation(s)
- Serguei Liachenko
- Division of Neurotoxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, AR, United States.
| | - Sumit Sarkar
- Division of Neurotoxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, AR, United States
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2
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Khodanovich M, Svetlik M, Naumova A, Kamaeva D, Usova A, Kudabaeva M, Anan’ina T, Wasserlauf I, Pashkevich V, Moshkina M, Obukhovskaya V, Kataeva N, Levina A, Tumentceva Y, Yarnykh V. Age-Related Decline in Brain Myelination: Quantitative Macromolecular Proton Fraction Mapping, T2-FLAIR Hyperintensity Volume, and Anti-Myelin Antibodies Seven Years Apart. Biomedicines 2023; 12:61. [PMID: 38255168 PMCID: PMC10812983 DOI: 10.3390/biomedicines12010061] [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: 11/07/2023] [Revised: 12/09/2023] [Accepted: 12/21/2023] [Indexed: 01/24/2024] Open
Abstract
Age-related myelination decrease is considered one of the likely mechanisms of cognitive decline. The present preliminary study is based on the longitudinal assessment of global and regional myelination of the normal adult human brain using fast macromolecular fraction (MPF) mapping. Additional markers were age-related changes in white matter (WM) hyperintensities on FLAIR-MRI and the levels of anti-myelin autoantibodies in serum. Eleven healthy subjects (33-60 years in the first study) were scanned twice, seven years apart. An age-related decrease in MPF was found in global WM, grey matter (GM), and mixed WM-GM, as well as in 48 out of 82 examined WM and GM regions. The greatest decrease in MPF was observed for the frontal WM (2-5%), genu of the corpus callosum (CC) (4.0%), and caudate nucleus (5.9%). The age-related decrease in MPF significantly correlated with an increase in the level of antibodies against myelin basic protein (MBP) in serum (r = 0.69 and r = 0.63 for global WM and mixed WM-GM, correspondingly). The volume of FLAIR hyperintensities increased with age but did not correlate with MPF changes and the levels of anti-myelin antibodies. MPF mapping showed high sensitivity to age-related changes in brain myelination, providing the feasibility of this method in clinics.
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Affiliation(s)
- Marina Khodanovich
- Laboratory of Neurobiology, Research Institute of Biology and Biophysics, Tomsk State University, 36 Lenina Ave., Tomsk 634050, Russia; (M.S.); (A.N.); (M.K.); (T.A.); (I.W.); (N.K.); (A.L.); (Y.T.)
| | - Mikhail Svetlik
- Laboratory of Neurobiology, Research Institute of Biology and Biophysics, Tomsk State University, 36 Lenina Ave., Tomsk 634050, Russia; (M.S.); (A.N.); (M.K.); (T.A.); (I.W.); (N.K.); (A.L.); (Y.T.)
| | - Anna Naumova
- Laboratory of Neurobiology, Research Institute of Biology and Biophysics, Tomsk State University, 36 Lenina Ave., Tomsk 634050, Russia; (M.S.); (A.N.); (M.K.); (T.A.); (I.W.); (N.K.); (A.L.); (Y.T.)
- Department of Radiology, University of Washington, 850 Republican Street, Seattle, WA 98109, USA
| | - Daria Kamaeva
- Laboratory of Molecular Genetics and Biochemistry, Mental Health Research Institute, Tomsk National Research Medical Center of the Russian Academy of Sciences, Tomsk 634014, Russia;
| | - Anna Usova
- Cancer Research Institute, Tomsk National Research Medical Center of the Russian Academy of Sciences, 12/1 Savinykh St., Tomsk 634009, Russia;
| | - Marina Kudabaeva
- Laboratory of Neurobiology, Research Institute of Biology and Biophysics, Tomsk State University, 36 Lenina Ave., Tomsk 634050, Russia; (M.S.); (A.N.); (M.K.); (T.A.); (I.W.); (N.K.); (A.L.); (Y.T.)
| | - Tatyana Anan’ina
- Laboratory of Neurobiology, Research Institute of Biology and Biophysics, Tomsk State University, 36 Lenina Ave., Tomsk 634050, Russia; (M.S.); (A.N.); (M.K.); (T.A.); (I.W.); (N.K.); (A.L.); (Y.T.)
| | - Irina Wasserlauf
- Laboratory of Neurobiology, Research Institute of Biology and Biophysics, Tomsk State University, 36 Lenina Ave., Tomsk 634050, Russia; (M.S.); (A.N.); (M.K.); (T.A.); (I.W.); (N.K.); (A.L.); (Y.T.)
| | - Valentina Pashkevich
- Laboratory of Neurobiology, Research Institute of Biology and Biophysics, Tomsk State University, 36 Lenina Ave., Tomsk 634050, Russia; (M.S.); (A.N.); (M.K.); (T.A.); (I.W.); (N.K.); (A.L.); (Y.T.)
| | - Marina Moshkina
- Laboratory of Neurobiology, Research Institute of Biology and Biophysics, Tomsk State University, 36 Lenina Ave., Tomsk 634050, Russia; (M.S.); (A.N.); (M.K.); (T.A.); (I.W.); (N.K.); (A.L.); (Y.T.)
| | - Victoria Obukhovskaya
- Laboratory of Neurobiology, Research Institute of Biology and Biophysics, Tomsk State University, 36 Lenina Ave., Tomsk 634050, Russia; (M.S.); (A.N.); (M.K.); (T.A.); (I.W.); (N.K.); (A.L.); (Y.T.)
- Department of Fundamental Psychology and Behavioral Medicine, Siberian State Medical University, 2 Moskovskiy Trakt, Tomsk 634050, Russia
| | - Nadezhda Kataeva
- Laboratory of Neurobiology, Research Institute of Biology and Biophysics, Tomsk State University, 36 Lenina Ave., Tomsk 634050, Russia; (M.S.); (A.N.); (M.K.); (T.A.); (I.W.); (N.K.); (A.L.); (Y.T.)
- Department of Neurology and Neurosurgery, Siberian State Medical University, 2 Moskovskiy Trakt, Tomsk 634050, Russia
| | - Anastasia Levina
- Laboratory of Neurobiology, Research Institute of Biology and Biophysics, Tomsk State University, 36 Lenina Ave., Tomsk 634050, Russia; (M.S.); (A.N.); (M.K.); (T.A.); (I.W.); (N.K.); (A.L.); (Y.T.)
- Medica Diagnostic and Treatment Center, 86 Sovetskaya st., Tomsk 634510, Russia
| | - Yana Tumentceva
- Laboratory of Neurobiology, Research Institute of Biology and Biophysics, Tomsk State University, 36 Lenina Ave., Tomsk 634050, Russia; (M.S.); (A.N.); (M.K.); (T.A.); (I.W.); (N.K.); (A.L.); (Y.T.)
| | - Vasily Yarnykh
- Department of Radiology, University of Washington, 850 Republican Street, Seattle, WA 98109, USA
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Soustelle L, Troalen T, Hertanu A, Ranjeva JP, Guye M, Varma G, Alsop DC, Duhamel G, Girard OM. Quantitative magnetization transfer MRI unbiased by on-resonance saturation and dipolar order contributions. Magn Reson Med 2023. [PMID: 37154400 DOI: 10.1002/mrm.29678] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 03/22/2023] [Accepted: 04/01/2023] [Indexed: 05/10/2023]
Abstract
PURPOSE To demonstrate the bias in quantitative MT (qMT) measures introduced by the presence of dipolar order and on-resonance saturation (ONRS) effects using magnetization transfer (MT) spoiled gradient-recalled (SPGR) acquisitions, and propose changes to the acquisition and analysis strategies to remove these biases. METHODS The proposed framework consists of SPGR sequences prepared with simultaneous dual-offset frequency-saturation pulses to cancel out dipolar order and associated relaxation (T1D ) effects in Z-spectrum acquisitions, and a matched quantitative MT (qMT) mathematical model that includes ONRS effects of readout pulses. Variable flip angle and MT data were fitted jointly to simultaneously estimate qMT parameters (macromolecular proton fraction [MPF], T2,f , T2,b , R, and free pool T1 ). This framework is compared with standard qMT and investigated in terms of reproducibility, and then further developed to follow a joint single-point qMT methodology for combined estimation of MPF and T1 . RESULTS Bland-Altman analyses demonstrated a systematic underestimation of MPF (-2.5% and -1.3%, on average, in white and gray matter, respectively) and overestimation of T1 (47.1 ms and 38.6 ms, on average, in white and gray matter, respectively) if both ONRS and dipolar order effects are ignored. Reproducibility of the proposed framework is excellent (ΔMPF = -0.03% and ΔT1 = -19.0 ms). The single-point methodology yielded consistent MPF and T1 values with respective maximum relative average bias of -0.15% and -3.5 ms found in white matter. CONCLUSION The influence of acquisition strategy and matched mathematical model with regard to ONRS and dipolar order effects in qMT-SPGR frameworks has been investigated. The proposed framework holds promise for improved accuracy with reproducibility.
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Affiliation(s)
- Lucas Soustelle
- Aix Marseille Univ, CNRS, CRMBM, Marseille, France
- APHM, Hôpital Universitaire Timone, CEMEREM, Marseille, France
| | | | - Andreea Hertanu
- Aix Marseille Univ, CNRS, CRMBM, Marseille, France
- APHM, Hôpital Universitaire Timone, CEMEREM, Marseille, France
| | - Jean-Philippe Ranjeva
- Aix Marseille Univ, CNRS, CRMBM, Marseille, France
- APHM, Hôpital Universitaire Timone, CEMEREM, Marseille, France
| | - Maxime Guye
- Aix Marseille Univ, CNRS, CRMBM, Marseille, France
- APHM, Hôpital Universitaire Timone, CEMEREM, Marseille, France
| | - Gopal Varma
- Division of MR Research, Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - David C Alsop
- Division of MR Research, Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Guillaume Duhamel
- Aix Marseille Univ, CNRS, CRMBM, Marseille, France
- APHM, Hôpital Universitaire Timone, CEMEREM, Marseille, France
| | - Olivier M Girard
- Aix Marseille Univ, CNRS, CRMBM, Marseille, France
- APHM, Hôpital Universitaire Timone, CEMEREM, Marseille, France
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Role of Demyelination in the Persistence of Neurological and Mental Impairments after COVID-19. Int J Mol Sci 2022; 23:ijms231911291. [PMID: 36232592 PMCID: PMC9569975 DOI: 10.3390/ijms231911291] [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: 08/22/2022] [Revised: 09/16/2022] [Accepted: 09/21/2022] [Indexed: 11/16/2022] Open
Abstract
Long-term neurological and mental complications of COVID-19, the so-called post-COVID syndrome or long COVID, affect the quality of life. The most persistent manifestations of long COVID include fatigue, anosmia/hyposmia, insomnia, depression/anxiety, and memory/attention deficits. The physiological basis of neurological and psychiatric disorders is still poorly understood. This review summarizes the current knowledge of neurological sequelae in post-COVID patients and discusses brain demyelination as a possible mechanism of these complications with a focus on neuroimaging findings. Numerous reviews, experimental and theoretical studies consider brain demyelination as one of the mechanisms of the central neural system impairment. Several factors might cause demyelination, such as inflammation, direct effect of the virus on oligodendrocytes, and cerebrovascular disorders, inducing myelin damage. There is a contradiction between the solid fundamental basis underlying demyelination as the mechanism of the neurological injuries and relatively little published clinical evidence related to demyelination in COVID-19 patients. The reason for this probably lies in the fact that most clinical studies used conventional MRI techniques, which can detect only large, clearly visible demyelinating lesions. A very limited number of studies use specific methods for myelin quantification detected changes in the white matter tracts 3 and 10 months after the acute phase of COVID-19. Future research applying quantitative MRI assessment of myelin in combination with neurological and psychological studies will help in understanding the mechanisms of post-COVID complications associated with demyelination.
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Khodanovich MY, Anan’ina TV, Krutenkova EP, Akulov AE, Kudabaeva MS, Svetlik MV, Tumentceva YA, Shadrina MM, Naumova AV. Challenges and Practical Solutions to MRI and Histology Matching and Measurements Using Available ImageJ Software Tools. Biomedicines 2022; 10:1556. [PMID: 35884861 PMCID: PMC9313422 DOI: 10.3390/biomedicines10071556] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 06/25/2022] [Accepted: 06/27/2022] [Indexed: 11/29/2022] Open
Abstract
Traditionally histology is the gold standard for the validation of imaging experiments. Matching imaging slices and histological sections and the precise outlining of corresponding tissue structures are difficult. Challenges are based on differences in imaging and histological slice thickness as well as tissue shrinkage and alterations after processing. Here we describe step-by-step instructions that might be used as a universal pathway to overlay MRI and histological images and for a correlation of measurements between imaging modalities. The free available (Fiji is just) ImageJ software tools were used for regions of interest transformation (ROIT) and alignment using a rat brain MRI as an example. The developed ROIT procedure was compared to a manual delineation of rat brain structures. The ROIT plugin was developed for ImageJ to enable an automatization of the image processing and structural analysis of the rodent brain.
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Affiliation(s)
- Marina Y. Khodanovich
- Laboratory of Neurobiology, Research Institute of Biology and Biophysics, Tomsk State University, Russia. 36, Lenina Ave., 634050 Tomsk, Russia; (T.V.A.); len-- (E.P.K.); (M.S.K.); (M.V.S.); (Y.A.T.); (M.M.S.); (A.V.N.)
| | - Tatyana V. Anan’ina
- Laboratory of Neurobiology, Research Institute of Biology and Biophysics, Tomsk State University, Russia. 36, Lenina Ave., 634050 Tomsk, Russia; (T.V.A.); len-- (E.P.K.); (M.S.K.); (M.V.S.); (Y.A.T.); (M.M.S.); (A.V.N.)
| | - Elena P. Krutenkova
- Laboratory of Neurobiology, Research Institute of Biology and Biophysics, Tomsk State University, Russia. 36, Lenina Ave., 634050 Tomsk, Russia; (T.V.A.); len-- (E.P.K.); (M.S.K.); (M.V.S.); (Y.A.T.); (M.M.S.); (A.V.N.)
| | - Andrey E. Akulov
- Institute of Cytology and Genetics, The Siberian Branch of the Russian Academy of Sciences, 10 Lavrentyeva Avenue, 630090 Novosibirsk, Russia;
| | - Marina S. Kudabaeva
- Laboratory of Neurobiology, Research Institute of Biology and Biophysics, Tomsk State University, Russia. 36, Lenina Ave., 634050 Tomsk, Russia; (T.V.A.); len-- (E.P.K.); (M.S.K.); (M.V.S.); (Y.A.T.); (M.M.S.); (A.V.N.)
| | - Mikhail V. Svetlik
- Laboratory of Neurobiology, Research Institute of Biology and Biophysics, Tomsk State University, Russia. 36, Lenina Ave., 634050 Tomsk, Russia; (T.V.A.); len-- (E.P.K.); (M.S.K.); (M.V.S.); (Y.A.T.); (M.M.S.); (A.V.N.)
| | - Yana A. Tumentceva
- Laboratory of Neurobiology, Research Institute of Biology and Biophysics, Tomsk State University, Russia. 36, Lenina Ave., 634050 Tomsk, Russia; (T.V.A.); len-- (E.P.K.); (M.S.K.); (M.V.S.); (Y.A.T.); (M.M.S.); (A.V.N.)
| | - Maria M. Shadrina
- Laboratory of Neurobiology, Research Institute of Biology and Biophysics, Tomsk State University, Russia. 36, Lenina Ave., 634050 Tomsk, Russia; (T.V.A.); len-- (E.P.K.); (M.S.K.); (M.V.S.); (Y.A.T.); (M.M.S.); (A.V.N.)
| | - Anna V. Naumova
- Laboratory of Neurobiology, Research Institute of Biology and Biophysics, Tomsk State University, Russia. 36, Lenina Ave., 634050 Tomsk, Russia; (T.V.A.); len-- (E.P.K.); (M.S.K.); (M.V.S.); (Y.A.T.); (M.M.S.); (A.V.N.)
- Department of Radiology, University of Washington, 850 Republican Street, Seattle, WA 98109, USA
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6
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Kisel AA, Naumova AV, Yarnykh VL. Macromolecular Proton Fraction as a Myelin Biomarker: Principles, Validation, and Applications. Front Neurosci 2022; 16:819912. [PMID: 35221905 PMCID: PMC8863973 DOI: 10.3389/fnins.2022.819912] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 01/17/2022] [Indexed: 12/16/2022] Open
Abstract
Macromolecular proton fraction (MPF) is a quantitative MRI parameter describing the magnetization transfer (MT) effect and defined as a relative amount of protons bound to biological macromolecules with restricted molecular motion, which participate in magnetic cross-relaxation with water protons. MPF attracted significant interest during past decade as a biomarker of myelin. The purpose of this mini review is to provide a brief but comprehensive summary of MPF mapping methods, histological validation studies, and MPF applications in neuroscience. Technically, MPF maps can be obtained using a variety of quantitative MT methods. Some of them enable clinically reasonable scan time and resolution. Recent studies demonstrated the feasibility of MPF mapping using standard clinical MRI pulse sequences, thus substantially enhancing the method availability. A number of studies in animal models demonstrated strong correlations between MPF and histological markers of myelin with a minor influence of potential confounders. Histological studies validated the capability of MPF to monitor both demyelination and re-myelination. Clinical applications of MPF have been mainly focused on multiple sclerosis where this method provided new insights into both white and gray matter pathology. Besides, several studies used MPF to investigate myelin role in other neurological and psychiatric conditions. Another promising area of MPF applications is the brain development studies. MPF demonstrated the capabilities to quantitatively characterize the earliest stage of myelination during prenatal brain maturation and protracted myelin development in adolescence. In summary, MPF mapping provides a technically mature and comprehensively validated myelin imaging technology for various preclinical and clinical neuroscience applications.
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Affiliation(s)
- Alena A. Kisel
- Department of Radiology, University of Washington, Seattle, WA, United States
- Laboratory of Neurobiology, Tomsk State University, Tomsk, Russia
| | - Anna V. Naumova
- Department of Radiology, University of Washington, Seattle, WA, United States
| | - Vasily L. Yarnykh
- Department of Radiology, University of Washington, Seattle, WA, United States
- Laboratory of Neurobiology, Tomsk State University, Tomsk, Russia
- *Correspondence: Vasily L. Yarnykh,
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Extended Ischemic Recovery After Implantation of Human Mesenchymal Stem Cell Aggregates Indicated by Sodium MRI at 21.1 T. Transl Stroke Res 2022; 13:543-555. [DOI: 10.1007/s12975-021-00976-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 11/17/2021] [Accepted: 12/12/2021] [Indexed: 12/19/2022]
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8
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Yarnykh VL, Korostyshevskaya AM, Savelov AA, Isaeva YO, Gornostaeva AM, Tulupov AA, Sagdeev RZ. Macromolecular proton fraction mapping in magnetic resonance imaging: physicochemical principles and biomedical applications. Russ Chem Bull 2022. [DOI: 10.1007/s11172-021-3343-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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9
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Yarnykh VL. Data-Driven Retrospective Correction of B 1 Field Inhomogeneity in Fast Macromolecular Proton Fraction and R 1 Mapping. IEEE TRANSACTIONS ON MEDICAL IMAGING 2021; 40:3473-3484. [PMID: 34110989 PMCID: PMC8711232 DOI: 10.1109/tmi.2021.3088258] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Correction of B1 field non-uniformity is critical for many quantitative MRI methods including variable flip angle (VFA) T1 mapping and single-point macromolecular proton fraction (MPF) mapping. The latter method showed promising results as a fast and robust quantitative myelin imaging approach and involves VFA-based R1=1/T1 map reconstruction as an intermediate processing step. The need for B1 correction restricts applications of the above methods, since B1 mapping sequences increase the examination time and are not commonly available in clinics. A new algorithm was developed to enable retrospective data-driven simultaneous B1 correction in VFA R1 and single-point MPF mapping. The principle of the algorithm is based on different mathematical dependences of B1 -related errors in R1 and MPF allowing extraction of a surrogate B1 field map from uncorrected R1 and MPF maps. To validate the method, whole-brain R1 and MPF maps with isotropic 1.25 mm3 resolution were obtained on a 3 T MRI scanner from 11 volunteers. Mean parameter values in segmented brain tissues were compared between three reconstruction options including the absence of correction, actual B1 correction, and surrogate B1 correction. Surrogate B1 maps closely reproduced actual patterns of B1 inhomogeneity. Without correction, B1 non-uniformity caused highly significant biases in R1 and MPF ( ). Surrogate B1 field correction reduced the biases in both R1 and MPF to a non-significant level ( 0.1 ≤ P ≤ 0.8 ). The described algorithm obviates the use of dedicated B1 mapping sequences in fast single-point MPF mapping and provides an alternative solution for correction of B1 non-uniformities in VFA R1 mapping.
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10
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Khodanovich MY, Gubskiy IL, Kudabaeva MS, Namestnikova DD, Kisel AA, Anan’ina TV, Tumentceva YA, Mustafina LR, Yarnykh VL. Long-term monitoring of chronic demyelination and remyelination in a rat ischemic stroke model using macromolecular proton fraction mapping. J Cereb Blood Flow Metab 2021; 41:2856-2869. [PMID: 34107787 PMCID: PMC8756474 DOI: 10.1177/0271678x211020860] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 04/24/2021] [Accepted: 04/26/2021] [Indexed: 12/23/2022]
Abstract
Remyelination is a key process enabling post-stroke brain tissue recovery and plasticity. This study aimed to explore the feasibility of demyelination and remyelination monitoring in experimental stroke from the acute to chronic stage using an emerging myelin imaging biomarker, macromolecular proton fraction (MPF). After stroke induction by transient middle cerebral artery occlusion, rats underwent repeated MRI examinations during 85 days after surgery with histological endpoints for the animal subgroups on the 7th, 21st, 56th, and 85th days. MPF maps revealed two sub-regions within the infarct characterized by distinct temporal profiles exhibiting either a persistent decrease by 30%-40% or a transient decrease followed by return to nearly normal values after one month of observation. Myelin histology confirmed that these sub-regions had nearly similar extent of demyelination in the sub-acute phase and then demonstrated either chronic demyelination or remyelination. The remyelination zones also exhibited active axonal regrowth, reconstitution of compact fiber bundles, and proliferation of neuronal and oligodendroglial precursors. The demyelination zones showed more extensive astrogliosis from the 21st day endpoint. Both sub-regions had substantially depleted neuronal population over all endpoints. These results histologically validate MPF mapping as a novel approach for quantitative assessment of myelin damage and repair in ischemic stroke.
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Affiliation(s)
| | - Ilya L Gubskiy
- Research Institute of Cerebrovascular Pathology and Stroke, Pirogov Russian Medical University, Moscow, Russian Federation
| | - Marina S Kudabaeva
- Laboratory of Neurobiology, Tomsk State University, Tomsk, Russian Federation
| | - Darya D Namestnikova
- Research Institute of Cerebrovascular Pathology and Stroke, Pirogov Russian Medical University, Moscow, Russian Federation
| | - Alena A Kisel
- Laboratory of Neurobiology, Tomsk State University, Tomsk, Russian Federation
- Department of Radiology, University of Washington, Seattle, USA
| | - Tatyana V Anan’ina
- Laboratory of Neurobiology, Tomsk State University, Tomsk, Russian Federation
| | - Yana A Tumentceva
- Laboratory of Neurobiology, Tomsk State University, Tomsk, Russian Federation
| | - Lilia R Mustafina
- Department of histology, embriology, and cytology, Siberian State Medical University, Tomsk, Russian Federation
| | - Vasily L Yarnykh
- Laboratory of Neurobiology, Tomsk State University, Tomsk, Russian Federation
- Department of Radiology, University of Washington, Seattle, USA
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11
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Global hypomyelination of the brain white and gray matter in schizophrenia: quantitative imaging using macromolecular proton fraction. Transl Psychiatry 2021; 11:365. [PMID: 34226491 PMCID: PMC8257619 DOI: 10.1038/s41398-021-01475-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 05/08/2021] [Accepted: 05/17/2021] [Indexed: 02/06/2023] Open
Abstract
Myelin deficiency is commonly recognized as an important pathological feature of brain tissues in schizophrenia (SZ). In this pilot study, global myelin content abnormalities in white matter (WM) and gray matter (GM) of SZ patients were non-invasively investigated using a novel clinically-targeted quantitative myelin imaging technique, fast macromolecular proton fraction (MPF) mapping. MPF maps were obtained from 23 healthy subjects and 31 SZ patients using a clinical 1.5T magnetic resonance imaging (MRI) scanner. Mean MPF in WM and GM was compared between the healthy control subjects and SZ patients with positive and negative leading symptoms using the multivariate analysis of covariance. The SZ patients had significantly reduced MPF in GM (p < 0.001) and WM (p = 0.02) with the corresponding relative decrease of 5% and 3%, respectively. The effect sizes for the myelin content loss in SZ relative to the control group were 1.0 and 1.5 for WM and GM, respectively. The SZ patients with leading negative symptoms had significantly lower MPF in GM (p < 0.001) and WM (p = 0.003) as compared to the controls and showed a significant MPF decrease in WM (p = 0.03) relative to the patients with leading positive symptoms. MPF in WM significantly negatively correlated with the disease duration in SZ patients (Pearson's r = -0.51; p = 0.004). This study demonstrates that chronic SZ is characterized by global microscopic brain hypomyelination of both WM and GM, which is associated with the disease duration and negative symptoms. Myelin deficiency in SZ can be detected and quantified by the fast MPF mapping method.
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Soustelle L, Antal MC, Lamy J, Harsan LA, Loureiro de Sousa P. Determination of optimal parameters for 3D single-point macromolecular proton fraction mapping at 7T in healthy and demyelinated mouse brain. Magn Reson Med 2020; 85:369-379. [PMID: 32767495 DOI: 10.1002/mrm.28397] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 06/05/2020] [Accepted: 06/05/2020] [Indexed: 12/19/2022]
Abstract
PURPOSE To determine optimal constrained tissue parameters and off-resonance sequence parameters for single-point macromolecular proton fraction (SP-MPF) mapping based on a comprehensive quantitative magnetization transfer (qMT) protocol in healthy and demyelinated living mice at 7T. METHODS Using 3D spoiled gradient echo-based sequences, a comprehensive qMT protocol is performed by sampling the Z-spectrum of mice brains, in vivo. Provided additional T1 , B 1 + and B0 maps allow for the estimation of qMT tissue parameters, among which three will be constrained, namely the longitudinal and transverse relaxation characteristics of the free pool (R1,f T2,f ), the cross-relaxation rate (R) and the bound pool transverse relaxation time (T2,r ). Different sets of constrained parameters are investigated to reduce the bias between the SP-MPF and its reference based on the comprehensive protocol. RESULTS Based on a whole-brain histogram analysis about the constrained parameters, the optimal experimental parameters that minimize the global bias between reference and SP-MPF maps consist of a 600° and 6 kHz off-resonance irradiation pulse. Following a Bland-Altman analysis over regions of interest, optimal constrained parameters were R1,f T2,f = 0.0129, R = 26.5 s-1 , and T2,r = 9.1 µs, yielding an overall MPF bias of 10-4 (limits of agreement [-0.0068;0.0070]) and a relative variation of 0.64% ± 5.95% between the reference and the optimal single-point method across all mice. CONCLUSION The necessity of estimating animal model- and field-dependent constrained parameters was demonstrated. The single-point MPF method can be reliably applied at 7T, as part of routine preclinical in vivo imaging protocol in mice.
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Affiliation(s)
- Lucas Soustelle
- ICube, Université de Strasbourg, CNRS, Strasbourg, France.,Aix Marseille University, CNRS, CRMBM, Marseille, France
| | | | - Julien Lamy
- ICube, Université de Strasbourg, CNRS, Strasbourg, France
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13
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Anisimov NV, Pavlova OS, Pirogov YA, Yarnykh VL. Three-dimensional fast single-point macromolecular proton fraction mapping of the human brain at 0.5 Tesla. Quant Imaging Med Surg 2020; 10:1441-1449. [PMID: 32676363 DOI: 10.21037/qims-19-1057] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Fast single-point macromolecular proton fraction (MPF) mapping is a recent magnetic resonance imaging (MRI) method enabling quantitative assessment of myelin content in neural tissues. To date, the reported technical implementations of MPF mapping utilized high-field MRI equipment (1.5 T or higher), while low-field applications might pose challenges due to signal-to-noise ratio (SNR) limitations and short T1 . This study aimed to evaluate the feasibility of MPF mapping of the human brain at 0.5 T. The three-dimensional MPF mapping protocol was implemented according to the single-point synthetic-reference method, which includes three spoiled gradient-echo sequences providing proton density, T1 , and magnetization transfer contrast weightings. Whole-brain MPF maps were obtained from three healthy volunteers with spatial resolution of 1.5×1.5×2 mm3 and the total scan time of 19 minutes. MPF values were measured in a series of white and gray matter structures and compared with literature data for 3 T magnetic field. MPF maps enabled high contrast between white and gray matter with notable insensitivity to paramagnetic effects in iron-rich structures, such as globus pallidus, substantia nigra, and dentate nucleus. MPF values at 0.5 T appeared in close agreement with those at 3 T. This study demonstrates the feasibility of fast MPF mapping with low-field MRI equipment and the independence of brain MPF values of magnetic field. The presented results confirm the utility of MPF as an absolute scale for MRI-based myelin content measurements across a wide range of magnetic field strengths and extend the applicability of fast MPF mapping to inexpensive low-field MRI hardware.
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Affiliation(s)
- Nikolay V Anisimov
- Faculty of Fundamental Medicine, Lomonosov Moscow State University, 117192, Moscow, Lomonosovsky Prospekt, 31-5, Russian Federation
| | - Olga S Pavlova
- Faculty of Fundamental Medicine, Lomonosov Moscow State University, 117192, Moscow, Lomonosovsky Prospekt, 31-5, Russian Federation.,Faculty of Physics, Lomonosov Moscow State University, 119991, Moscow, GSP-1, Leninskie Gory, 1-2, Russian Federation
| | - Yury A Pirogov
- Faculty of Physics, Lomonosov Moscow State University, 119991, Moscow, GSP-1, Leninskie Gory, 1-2, Russian Federation.,Institute for Physical and Chemical Fundamentals of Artificial Intelligence, Lomonosov Moscow State University, 119991, Moscow, GSP-1, Leninskie Gory, 1-11, Russian Federation
| | - Vasily L Yarnykh
- Department of Radiology, University of Washington, Seattle, WA 98109, USA.,Research Institute of Biology and Biophysics, Tomsk State University, 634050, Tomsk, Russian Federation
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14
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Khodanovich M, Pishchelko A, Glazacheva V, Pan E, Akulov A, Svetlik M, Tyumentseva Y, Anan'ina T, Yarnykh V. Quantitative Imaging of White and Gray Matter Remyelination in the Cuprizone Demyelination Model Using the Macromolecular Proton Fraction. Cells 2019; 8:cells8101204. [PMID: 31590363 PMCID: PMC6830095 DOI: 10.3390/cells8101204] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 10/01/2019] [Accepted: 10/01/2019] [Indexed: 02/07/2023] Open
Abstract
Macromolecular proton fraction (MPF) has been established as a quantitative clinically-targeted MRI myelin biomarker based on recent demyelination studies. This study aimed to assess the capability of MPF to quantify remyelination using the murine cuprizone-induced reversible demyelination model. MPF was measured in vivo using the fast single-point method in three animal groups (control, cuprizone-induced demyelination, and remyelination after cuprizone withdrawal) and compared to quantitative immunohistochemistry for myelin basic protein (MBP), myelinating oligodendrocytes (CNP-positive cells), and oligodendrocyte precursor cells (OPC, NG2-positive cells) in the corpus callosum, caudate putamen, hippocampus, and cortex. In the demyelination group, MPF, MBP-stained area, and oligodendrocyte count were significantly reduced, while OPC count was significantly increased as compared to both control and remyelination groups in all anatomic structures (p < 0.05). All variables were similar in the control and remyelination groups. MPF and MBP-stained area strongly correlated in each anatomic structure (Pearson’s correlation coefficients, r = 0.80–0.90, p < 0.001). MPF and MBP correlated positively with oligodendrocyte count (r = 0.70–0.84, p < 0.01 for MPF; r = 0.81–0.92, p < 0.001 for MBP) and negatively with OPC count (r = −0.69–−0.77, p < 0.01 for MPF; r = −0.72–−0.89, p < 0.01 for MBP). This study provides immunohistological validation of fast MPF mapping as a non-invasive tool for quantitative assessment of de- and remyelination in white and gray matter and indicates the feasibility of using MPF as a surrogate marker of reparative processes in demyelinating diseases.
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Affiliation(s)
- Marina Khodanovich
- Laboratory of Neurobiology, Research Institute of Biology and Biophysics, Tomsk State University, Tomsk 634050, Russia.
| | - Anna Pishchelko
- Laboratory of Neurobiology, Research Institute of Biology and Biophysics, Tomsk State University, Tomsk 634050, Russia.
| | - Valentina Glazacheva
- Laboratory of Neurobiology, Research Institute of Biology and Biophysics, Tomsk State University, Tomsk 634050, Russia.
| | - Edgar Pan
- Laboratory of Neurobiology, Research Institute of Biology and Biophysics, Tomsk State University, Tomsk 634050, Russia.
| | - Andrey Akulov
- Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk 630090, Russia.
| | - Mikhail Svetlik
- Laboratory of Neurobiology, Research Institute of Biology and Biophysics, Tomsk State University, Tomsk 634050, Russia.
| | - Yana Tyumentseva
- Laboratory of Neurobiology, Research Institute of Biology and Biophysics, Tomsk State University, Tomsk 634050, Russia.
| | - Tatyana Anan'ina
- Laboratory of Neurobiology, Research Institute of Biology and Biophysics, Tomsk State University, Tomsk 634050, Russia.
| | - Vasily Yarnykh
- Laboratory of Neurobiology, Research Institute of Biology and Biophysics, Tomsk State University, Tomsk 634050, Russia.
- Department of Radiology, University of Washington, Seattle, WA 98109, USA.
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15
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Soustelle L, Antal MC, Lamy J, Rousseau F, Armspach JP, Loureiro de Sousa P. Correlations of quantitative MRI metrics with myelin basic protein (MBP) staining in a murine model of demyelination. NMR IN BIOMEDICINE 2019; 32:e4116. [PMID: 31225675 DOI: 10.1002/nbm.4116] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 04/17/2019] [Accepted: 04/21/2019] [Indexed: 06/09/2023]
Abstract
Myelin imaging in the central nervous system is essential for monitoring pathologies involving white matter alterations. Various quantitative MRI protocols relying on the modeling of the interactions of water protons with myelinated tissues have shown sensitivities in case of myelin disruption. Some extracted model parameters are more sensitive to demyelination, such as the bound pool fraction (f) in quantitative magnetization transfer imaging (qMTI), the radial diffusivity in diffusion tensor imaging (DTI), and the myelin water fraction (MWF) in myelin water imaging (MWI). A 3D ultrashort echo time (UTE) sequence within an appropriate water suppression condition (Diff-UTE) is also considered for the direct visualization of the myelin semi-solid matrix (Diff-UTE normalized signal; rSPF). In this paper, we aimed at assessing the sensitivities and correlations of the parameters mentioned above to an immuno-histological study of the myelin basic protein (MBP) in a murine model of demyelination at 7 T. We demonstrated a high sensitivity of the MRI metrics to demyelination, and strong Spearman correlations in the corpus callosum between histology, macromolecular proton fraction (ρ>0.87) and Diff-UTE signal (ρ>0.76), but moderate ones with radial diffusivity and MWF (|ρ|<0.70).
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Affiliation(s)
- Lucas Soustelle
- Université de Strasbourg, CNRS, ICube, FMTS, Strasbourg, France
| | - Maria C Antal
- Université de Strasbourg, CNRS, ICube, FMTS, Strasbourg, France
| | - Julien Lamy
- Université de Strasbourg, CNRS, ICube, FMTS, Strasbourg, France
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16
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Duhamel G, Prevost VH, Cayre M, Hertanu A, Mchinda S, Carvalho VN, Varma G, Durbec P, Alsop DC, Girard OM. Validating the sensitivity of inhomogeneous magnetization transfer (ihMT) MRI to myelin with fluorescence microscopy. Neuroimage 2019; 199:289-303. [PMID: 31141736 DOI: 10.1016/j.neuroimage.2019.05.061] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 05/22/2019] [Accepted: 05/23/2019] [Indexed: 11/30/2022] Open
Abstract
Inhomogeneous Magnetization Transfer (ihMT) is a development from the MT MRI technique. IhMT can be considered as a dipolar order relaxation time (T1D) weighted imaging modality whose signal has shown an enhanced selectivity for myelin-rich structures. However, a formal validation of the ihMT sensitivity relative to a gold standard myelin density measurement has not yet been reported. To address this need, we compared ihMT MRI with green fluorescence protein (GFP) microscopy, in a study performed on genetically-modified plp-GFP mice, considered as a reference technique for myelin-content assessment. Various ihMT protocols consisting of variable T1D-filtering and radiofrequency power temporal distributions, were used for comparison with fluorescence microscopy. Strong and significant linear relationships (r2 (0.87-0.96), p < 0.0001) were found between GFP and ihMT ratio signals across brain regions for all tested protocol variants. Conventional MT ratios showed weaker correlations (r2 (0.24-0.78), p ≤ 0.02) and a much larger signal fraction unrelated to myelin, hence corresponding to a much lower specificity for myelin. T1D-filtering reduced the ihMT signal fraction not attributed to myelin by almost twofold relative to zero filtering suggesting that at least half of the unrelated signal has a substantially shorter T1D than myelin. Overall, these results strongly support the sensitivity of ihMT to myelin content.
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Affiliation(s)
- G Duhamel
- Aix Marseille Univ, CNRS, CRMBM - UMR 7339, Marseille, France.
| | - V H Prevost
- Aix Marseille Univ, CNRS, CRMBM - UMR 7339, Marseille, France
| | - M Cayre
- Aix Marseille Univ, CNRS, IBDM - UMR 7288, Marseille, France
| | - A Hertanu
- Aix Marseille Univ, CNRS, CRMBM - UMR 7339, Marseille, France
| | - S Mchinda
- Aix Marseille Univ, CNRS, CRMBM - UMR 7339, Marseille, France
| | - V N Carvalho
- Aix Marseille Univ, CNRS, CRMBM - UMR 7339, Marseille, France
| | - G Varma
- Department of Radiology, Division of MR Research, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, 02215, USA
| | - P Durbec
- Aix Marseille Univ, CNRS, IBDM - UMR 7288, Marseille, France
| | - D C Alsop
- Department of Radiology, Division of MR Research, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, 02215, USA
| | - O M Girard
- Aix Marseille Univ, CNRS, CRMBM - UMR 7339, Marseille, France
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17
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Spadoni AD, Huang M, Simmons AN. Emerging Approaches to Neurocircuits in PTSD and TBI: Imaging the Interplay of Neural and Emotional Trauma. Curr Top Behav Neurosci 2019; 38:163-192. [PMID: 29285732 PMCID: PMC8896198 DOI: 10.1007/7854_2017_35] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Posttraumatic stress disorder (PTSD) and traumatic brain injury (TBI) commonly co-occur in general and military populations and have a number of overlapping symptoms. While research suggests that TBI is risk factor for PTSD and that PTSD may mediate TBI-related outcomes, the mechanisms of these relationships are not well understood. Neuroimaging may help elucidate patterns of neurocircuitry both specific and common to PTSD and TBI and thus help define the nature of their interaction, refine diagnostic classification, and may potentially yield opportunities for targeted treatments. In this review, we provide a summary of some of the most common and the most innovative neuroimaging approaches used to characterize the neural circuits associated with PTSD, TBI, and their comorbidity. We summarize the state of the science for each disorder and describe the few studies that have explicitly attempted to characterize the neural substrates of their shared and dissociable influence. While some promising targets in the medial frontal lobes exist, there is not currently a comprehensive understanding of the neurocircuitry mediating the interaction of PTSD and TBI. Future studies should exploit innovative neuroimaging approaches and longitudinal designs to specifically target the neural mechanisms driving PTSD-TBI-related outcomes.
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Affiliation(s)
- Andrea D Spadoni
- Research Service, VA San Diego Healthcare System, San Diego, CA, USA.
- Department of Psychiatry, University of California, San Diego, La Jolla, CA, USA.
| | - Mingxiong Huang
- Radiology and Research Services, VA San Diego Healthcare System, San Diego, CA, USA
- Department of Radiology, University of California, San Diego, La Jolla, CA, USA
| | - Alan N Simmons
- Research Service, VA San Diego Healthcare System, San Diego, CA, USA
- Department of Psychiatry, University of California, San Diego, La Jolla, CA, USA
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18
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Goussakov I, Synowiec S, Yarnykh V, Drobyshevsky A. Immediate and delayed decrease of long term potentiation and memory deficits after neonatal intermittent hypoxia. Int J Dev Neurosci 2019; 74:27-37. [PMID: 30858028 PMCID: PMC6461389 DOI: 10.1016/j.ijdevneu.2019.03.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 03/07/2019] [Accepted: 03/07/2019] [Indexed: 11/25/2022] Open
Abstract
Apnea of prematurity is a common clinical condition that occurs in premature infants and results in intermittent hypoxia (IH) to brain and other organs. While short episodes of apnea are considered of no clinical significance, prolonged apnea with bradycardia and large oxygen desaturation is associated with adverse neurological and cognitive outcome. The mechanisms of cognitive deficits in IH are poorly understood. We hypothesized that brief but multiple episodes of severe oxygen desaturation accompanied by bradycardia may affect early and late synaptic plasticity and produce long-term cognitive deficits. C57BL/6 mouse pups were exposed to IH paradigm consisting of alternating cycles of 5% oxygen for 2.5 min and room air for 5-10 min, 2 h a day from P3 to P7. Long term potentiation (LTP) of synaptic strength in response to high frequency stimulation in hippocampal slices were examined 3 days and 6 weeks after IH. LTP was decreased in IH group relative to controls at both time points. That decrease was associated with deficits in spatial memory on Morris water maze and context fear conditioning test. Hypomyelination was observed in multiple gray and white matter areas on in vivo MRI using micromolecule proton fraction and ex vivo diffusion tensor imaging. No difference in caspase labeling was found between control and IH groups. We conclude that early changes in synaptic plasticity occurring during severe episodes of neonatal IH and persisting to adulthood may represent functional and structural substrate for long term cognitive deficits.
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Affiliation(s)
- Ivan Goussakov
- Department of Pediatrics, NorthShore University HealthSystem Research Institute, 2650 Ridge Ave 60201, Evanston, IL, USA
| | - Sylvia Synowiec
- Department of Pediatrics, NorthShore University HealthSystem Research Institute, 2650 Ridge Ave 60201, Evanston, IL, USA
| | - Vasily Yarnykh
- Department of Radiology, University of Washington, 850 Republican St., Room 255 Seattle, WA, USA
| | - Alexander Drobyshevsky
- Department of Pediatrics, NorthShore University HealthSystem Research Institute, 2650 Ridge Ave 60201, Evanston, IL, USA.
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19
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Lu J, Synowiec S, Lu L, Yu Y, Bretherick T, Takada S, Yarnykh V, Caplan J, Caplan M, Claud EC, Drobyshevsky A. Microbiota influence the development of the brain and behaviors in C57BL/6J mice. PLoS One 2018; 13:e0201829. [PMID: 30075011 PMCID: PMC6075787 DOI: 10.1371/journal.pone.0201829] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 07/23/2018] [Indexed: 12/22/2022] Open
Abstract
We investigated the contributions of commensal bacteria to brain structural maturation by magnetic resonance imaging and behavioral tests in four and 12 weeks old C57BL/6J specific pathogen free (SPF) and germ free (GF) mice. SPF mice had increased volumes and fractional anisotropy in major gray and white matter areas and higher levels of myelination in total brain, major white and grey matter structures at either four or 12 weeks of age, demonstrating better brain maturation and organization. In open field test, SPF mice had better mobility and were less anxious than GF at four weeks. In Morris water maze, SPF mice demonstrated better spatial and learning memory than GF mice at 12 weeks. In fear conditioning, SPF mice had better contextual memory than GF mice at 12 weeks. In three chamber social test, SPF mice demonstrated better social novelty than GF mice at 12 weeks. Our data demonstrate numerous significant differences in morphological brain organization and behaviors between SPF and GF mice. This suggests that commensal bacteria are necessary for normal morphological development and maturation in the grey and white matter of the brain regions with implications for behavioral outcomes such as locomotion and cognitive functions.
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Affiliation(s)
- Jing Lu
- Department of Pediatrics, Neonatology, Pritzker School of Medicine, the University of Chicago, Chicago, Illinois, United States of America
| | - Sylvia Synowiec
- Department of Pediatrics, NorthShore University HealthSystem Research Institute, Evanston, Illinois, United States of America
| | - Lei Lu
- Department of Pediatrics, Neonatology, Pritzker School of Medicine, the University of Chicago, Chicago, Illinois, United States of America
| | - Yueyue Yu
- Department of Pediatrics, Neonatology, Pritzker School of Medicine, the University of Chicago, Chicago, Illinois, United States of America
| | - Talitha Bretherick
- Laboratório de Neurogenética, Federal University of São Paulo, São Paulo, Brazil
| | - Silvia Takada
- Laboratório de Neurogenética, Federal University of São Paulo, São Paulo, Brazil
| | - Vasily Yarnykh
- Department of Radiology, University of Washington, Seattle, Washington, United States of America
- Research Institute of Biology and Biophysics, Tomsk State University, Tomsk, Russian Federation
| | - Jack Caplan
- Department of Chemical Engineering, University of Illinois at Urbana-Champaign, Urbana-Champaign, Illinois, United States of America
| | - Michael Caplan
- Department of Pediatrics, NorthShore University HealthSystem Research Institute, Evanston, Illinois, United States of America
| | - Erika C. Claud
- Department of Pediatrics, Neonatology, Pritzker School of Medicine, the University of Chicago, Chicago, Illinois, United States of America
- * E-mail: (AD); (ECC)
| | - Alexander Drobyshevsky
- Department of Pediatrics, NorthShore University HealthSystem Research Institute, Evanston, Illinois, United States of America
- * E-mail: (AD); (ECC)
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20
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Fan SJ, Ma Y, Zhu Y, Searleman A, Szeverenyi NM, Bydder GM, Du J. Yet more evidence that myelin protons can be directly imaged with UTE sequences on a clinical 3T scanner: Bicomponent T2* analysis of native and deuterated ovine brain specimens. Magn Reson Med 2018; 80:538-547. [PMID: 29271083 PMCID: PMC5910230 DOI: 10.1002/mrm.27052] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 11/05/2017] [Accepted: 11/29/2017] [Indexed: 01/15/2023]
Abstract
PURPOSE UTE sequences with a minimal nominal TE of 8 µs have shown promise for direct imaging of myelin protons (T2 , < 1 ms). However, there is still debate about the efficiency of 2D slice-selective UTE sequences in exciting myelin protons because the half excitation pulses used in these sequences have a relatively long duration (e.g., 0.3-0.6 ms). Here, we compared UTE and inversion-recovery (IR) UTE sequences used with either hard or half excitation pulses (durations 32 µs or 472 µs, respectively) for imaging myelin in native and deuterated ovine brain at 3T. METHODS Freshly frozen ovine brains were dissected into ∼2 mm-thick pure white matter and ∼3 to 8 mm-thick cerebral hemisphere specimens, which were imaged before and/or after different immersion time in deuterium oxide. RESULTS Bicomponent T2* analysis of UTE signals obtained with hard excitation pulses detected an ultrashort T2 component (STC) fraction (fS ) of 0% to 10% in native specimens, and up to ∼86% in heavily deuterated specimens. fS values were significantly affected by the TIs used in IR-UTE sequences with either hard or half excitation pulses in native specimens but not in heavily deuterated specimens. The STC T2* was in the range of 150 to 400 µs in all UTE and IR-UTE measurements obtained with either hard or half excitation pulses. CONCLUSION Our results further support myelin protons as the major source of the ultrashort T2* signals seen on IR-UTE images and demonstrate the potential of IR-UTE sequences with half excitation pulses for directly imaging myelin using clinical scanners. Magn Reson Med 80:538-547, 2017. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Shu-Juan Fan
- Department of Radiology, University of California, San Diego
| | - Yajun Ma
- Department of Radiology, University of California, San Diego
| | - Yanchun Zhu
- Department of Radiology, University of California, San Diego
| | - Adam Searleman
- Department of Radiology, University of California, San Diego
| | | | | | - Jiang Du
- Department of Radiology, University of California, San Diego
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21
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Cohen O, Huang S, McMahon MT, Rosen MS, Farrar CT. Rapid and quantitative chemical exchange saturation transfer (CEST) imaging with magnetic resonance fingerprinting (MRF). Magn Reson Med 2018; 80:2449-2463. [PMID: 29756286 DOI: 10.1002/mrm.27221] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Revised: 03/19/2018] [Accepted: 03/25/2018] [Indexed: 01/19/2023]
Abstract
PURPOSE To develop a fast magnetic resonance fingerprinting (MRF) method for quantitative chemical exchange saturation transfer (CEST) imaging. METHODS We implemented a CEST-MRF method to quantify the chemical exchange rate and volume fraction of the Nα -amine protons of L-arginine (L-Arg) phantoms and the amide and semi-solid exchangeable protons of in vivo rat brain tissue. L-Arg phantoms were made with different concentrations (25-100 mM) and pH (pH 4-6). The MRF acquisition schedule varied the saturation power randomly for 30 iterations (phantom: 0-6 μT; in vivo: 0-4 μT) with a total acquisition time of ≤2 min. The signal trajectories were pattern-matched to a large dictionary of signal trajectories simulated using the Bloch-McConnell equations for different combinations of exchange rate, exchangeable proton volume fraction, and water T1 and T2 relaxation times. RESULTS The chemical exchange rates of the Nα -amine protons of L-Arg were significantly (P < 0.0001) correlated with the rates measured with the quantitation of exchange using saturation power method. Similarly, the L-Arg concentrations determined using MRF were significantly (P < 0.0001) correlated with the known concentrations. The pH dependence of the exchange rate was well fit (R2 = 0.9186) by a base catalyzed exchange model. The amide proton exchange rate measured in rat brain cortex (34.8 ± 11.7 Hz) was in good agreement with that measured previously with the water exchange spectroscopy method (28.6 ± 7.4 Hz). The semi-solid proton volume fraction was elevated in white (12.2 ± 1.7%) compared to gray (8.1 ± 1.1%) matter brain regions in agreement with previous magnetization transfer studies. CONCLUSION CEST-MRF provides a method for fast, quantitative CEST imaging.
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Affiliation(s)
- Ouri Cohen
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts
| | - Shuning Huang
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts
| | - Michael T McMahon
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland.,Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Matthew S Rosen
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts.,Department of Physics, Harvard University, Cambridge, Massachusetts
| | - Christian T Farrar
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts
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22
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Yarnykh VL, Prihod'ko IY, Savelov AA, Korostyshevskaya AM. Quantitative Assessment of Normal Fetal Brain Myelination Using Fast Macromolecular Proton Fraction Mapping. AJNR Am J Neuroradiol 2018; 39:1341-1348. [PMID: 29748201 DOI: 10.3174/ajnr.a5668] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 03/23/2018] [Indexed: 01/08/2023]
Abstract
BACKGROUND AND PURPOSE Fast macromolecular proton fraction mapping is a recently emerged MRI method for quantitative myelin imaging. Our aim was to develop a clinically targeted technique for macromolecular proton fraction mapping of the fetal brain and test its capability to characterize normal prenatal myelination. MATERIALS AND METHODS This prospective study included 41 pregnant women (gestational age range, 18-38 weeks) without abnormal findings on fetal brain MR imaging performed for clinical indications. A fast fetal brain macromolecular proton fraction mapping protocol was implemented on a clinical 1.5T MR imaging scanner without software modifications and was performed after a clinical examination with an additional scan time of <5 minutes. 3D macromolecular proton fraction maps were reconstructed from magnetization transfer-weighted, T1-weighted, and proton density-weighted images by the single-point method. Mean macromolecular proton fraction in the brain stem, cerebellum, and thalamus and frontal, temporal, and occipital WM was compared between structures and pregnancy trimesters using analysis of variance. Gestational age dependence of the macromolecular proton fraction was assessed using the Pearson correlation coefficient (r). RESULTS The mean macromolecular proton fraction in the fetal brain structures varied between 2.3% and 4.3%, being 5-fold lower than macromolecular proton fraction in adult WM. The macromolecular proton fraction in the third trimester was higher compared with the second trimester in the brain stem, cerebellum, and thalamus. The highest macromolecular proton fraction was observed in the brain stem, followed by the thalamus, cerebellum, and cerebral WM. The macromolecular proton fraction in the brain stem, cerebellum, and thalamus strongly correlated with gestational age (r = 0.88, 0.80, and 0.73; P < .001). No significant correlations were found for cerebral WM regions. CONCLUSIONS Myelin is the main factor determining macromolecular proton fraction in brain tissues. Macromolecular proton fraction mapping is sensitive to the earliest stages of the fetal brain myelination and can be implemented in a clinical setting.
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Affiliation(s)
- V L Yarnykh
- From the Department of Radiology (V.L.Y.), University of Washington, Seattle, Washington .,Research Institute of Biology and Biophysics (V.L.Y.), Tomsk State University, Tomsk, Russian Federation
| | - I Y Prihod'ko
- Institute "International Tomography Center" of the Siberian Branch of the Russian Academy of Sciences (I.Y.P., A.A.S., A.M.K.), Novosibirsk, Russian Federation
| | - A A Savelov
- Institute "International Tomography Center" of the Siberian Branch of the Russian Academy of Sciences (I.Y.P., A.A.S., A.M.K.), Novosibirsk, Russian Federation
| | - A M Korostyshevskaya
- Institute "International Tomography Center" of the Siberian Branch of the Russian Academy of Sciences (I.Y.P., A.A.S., A.M.K.), Novosibirsk, Russian Federation
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23
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Khodanovich MY, Kisel AA, Akulov AE, Atochin DN, Kudabaeva MS, Glazacheva VY, Svetlik MV, Medvednikova YA, Mustafina LR, Yarnykh VL. Quantitative assessment of demyelination in ischemic stroke in vivo using macromolecular proton fraction mapping. J Cereb Blood Flow Metab 2018; 38:919-931. [PMID: 29372644 PMCID: PMC5987939 DOI: 10.1177/0271678x18755203] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A recent MRI method, fast macromolecular proton fraction (MPF) mapping, was used to quantify demyelination in the transient middle cerebral artery occlusion (MCAO) rat stroke model. MPF and other quantitative MRI parameters (T1, T2, proton density, and apparent diffusion coefficient) were compared with histological and immunohistochemical markers of demyelination (Luxol Fast Blue stain, (LFB)), neuronal loss (NeuN immunofluorescence), axonal loss (Bielschowsky stain), and inflammation (Iba1 immunofluorescence) in three animal groups ( n = 5 per group) on the 1st, 3rd, and 10th day after MCAO. MPF and LFB optical density (OD) were significantly reduced in the ischemic lesion on all days after MCAO relative to the symmetrical regions of the contralateral hemisphere. Percentage changes in MPF and LFB OD in the ischemic lesion relative to the contralateral hemisphere significantly differed on the first day only. Percentage changes in LFB OD and MPF were strongly correlated (R = 0.81, P < 0.001) and did not correlate with other MRI parameters. MPF also did not correlate with other histological variables. Addition of T2 into multivariate regression further improved agreement between MPF and LFB OD (R = 0.89, P < 0.001) due to correction of the edema effect. This study provides histological validation of MPF as an imaging biomarker of demyelination in ischemic stroke.
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Affiliation(s)
| | - Alena A Kisel
- 1 Laboratory of Neurobiology, Tomsk State University, Tomsk, Russian Federation
| | - Andrey E Akulov
- 1 Laboratory of Neurobiology, Tomsk State University, Tomsk, Russian Federation.,2 Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russian Federation
| | - Dmitriy N Atochin
- 1 Laboratory of Neurobiology, Tomsk State University, Tomsk, Russian Federation.,3 Cardiovascular Research Center, Harvard Medical School, Massachusetts General Hospital, Boston, MA, USA.,4 RASA Center in Tomsk, Tomsk Polytechnic University, Tomsk, Russian Federation
| | - Marina S Kudabaeva
- 1 Laboratory of Neurobiology, Tomsk State University, Tomsk, Russian Federation
| | | | - Michael V Svetlik
- 1 Laboratory of Neurobiology, Tomsk State University, Tomsk, Russian Federation
| | - Yana A Medvednikova
- 1 Laboratory of Neurobiology, Tomsk State University, Tomsk, Russian Federation
| | - Lilia R Mustafina
- 5 Department of Histology, Embryology and Cytology, Siberian State Medical University, Tomsk, Russian Federation
| | - Vasily L Yarnykh
- 1 Laboratory of Neurobiology, Tomsk State University, Tomsk, Russian Federation.,6 Department of Radiology, University of Washington, Seattle, WA, USA
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24
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Yarnykh V, Korostyshevskaya A. Implementation of fast macromolecular proton fraction mapping on 1.5 and 3 Tesla clinical MRI scanners: preliminary experience. ACTA ACUST UNITED AC 2017. [DOI: 10.1088/1742-6596/886/1/012010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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25
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Prevost VH, Girard OM, Mchinda S, Varma G, Alsop DC, Duhamel G. Optimization of inhomogeneous magnetization transfer (ihMT) MRI contrast for preclinical studies using dipolar relaxation time (T 1D ) filtering. NMR IN BIOMEDICINE 2017; 30:e3706. [PMID: 28195663 DOI: 10.1002/nbm.3706] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 01/10/2017] [Accepted: 01/11/2017] [Indexed: 06/06/2023]
Abstract
A pulsed inhomogeneous magnetization transfer (ihMT)-prepared fast imaging sequence was implemented at 11.75 T for preclinical studies on mouse central nervous system. A strategy based on filtering the ihMT signal originating from short dipolar relaxation time (T1D ) components is proposed. It involves increasing the repetition time of consecutive radiofrequency (RF) pulses of the dual saturation and allows improved signal specificity for long T1D myelinated structures. Furthermore, frequency offset, power and timing saturation parameters were adjusted to optimize the ihMT sensitivity. The optimization of the ihMT sensitivity, whilst preserving the strong specificity for the long T1D component of myelinated tissues, allowed measurements of ihMT ratios on the order of 4-5% in white matter (WM), 2.5% in gray matter (GM) and 1-1.3% in muscle. This led to high relative ihMT contrasts between myelinated tissues and others (~3-4 between WM and muscle, and ≥2 between GM and muscle). Conversely, higher ihMT ratios (~6-7% in WM) could be obtained using minimal T1D filtering achieved with short saturation pulse repetition time or cosine-modulated pulses for the dual-frequency saturation. This study represents a first stage in the process of validating ihMT as a myelin biomarker by providing optimized ihMT preclinical sequences, directly transposable and applicable to other preclinical magnetic fields and scanners. Finally, ihMT ratios measured in various central nervous system areas are provided for future reference.
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Affiliation(s)
- V H Prevost
- Aix Marseille Université, CNRS, Marseille, France
| | - O M Girard
- Aix Marseille Université, CNRS, Marseille, France
| | - S Mchinda
- Aix Marseille Université, CNRS, Marseille, France
| | - G Varma
- Department of Radiology, Division of MR Research, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - D C Alsop
- Department of Radiology, Division of MR Research, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - G Duhamel
- Aix Marseille Université, CNRS, Marseille, France
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26
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Khodanovich MY, Sorokina IV, Glazacheva VY, Akulov AE, Nemirovich-Danchenko NM, Romashchenko AV, Tolstikova TG, Mustafina LR, Yarnykh VL. Histological validation of fast macromolecular proton fraction mapping as a quantitative myelin imaging method in the cuprizone demyelination model. Sci Rep 2017; 7:46686. [PMID: 28436460 PMCID: PMC5402392 DOI: 10.1038/srep46686] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 03/24/2017] [Indexed: 12/18/2022] Open
Abstract
Cuprizone-induced demyelination in mice is a frequently used model in preclinical multiple sclerosis research. A recent quantitative clinically-targeted MRI method, fast macromolecular proton fraction (MPF) mapping demonstrated a promise as a myelin biomarker in human and animal studies with a particular advantage of sensitivity to both white matter (WM) and gray matter (GM) demyelination. This study aimed to histologically validate the capability of MPF mapping to quantify myelin loss in brain tissues using the cuprizone demyelination model. Whole-brain MPF maps were obtained in vivo on an 11.7T animal MRI scanner from 7 cuprizone-treated and 7 control С57BL/6 mice using the fast single-point synthetic-reference method. Brain sections were histologically stained with Luxol Fast Blue (LFB) for myelin quantification. Significant (p < 0.05) demyelination in cuprizone-treated animals was found according to both LFB staining and MPF in all anatomical structures (corpus callosum, anterior commissure, internal capsule, thalamus, caudoputamen, and cortex). MPF strongly correlated with quantitative histology in all animals (r = 0.95, p < 0.001) as well as in treatment and control groups taken separately (r = 0.96, p = 0.002 and r = 0.93, p = 0.007, respectively). Close agreement between histological myelin staining and MPF suggests that fast MPF mapping enables robust and accurate quantitative assessment of demyelination in both WM and GM.
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Affiliation(s)
- Marina Yu Khodanovich
- Research Institute of Biology and Biophysics, Tomsk State University, Tomsk, Russian Federation
| | - Irina V. Sorokina
- Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russian Federation
| | - Valentina Yu Glazacheva
- Research Institute of Biology and Biophysics, Tomsk State University, Tomsk, Russian Federation
| | - Andrey E. Akulov
- Research Institute of Biology and Biophysics, Tomsk State University, Tomsk, Russian Federation
- Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russian Federation
| | | | - Alexander V. Romashchenko
- Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russian Federation
| | - Tatyana G. Tolstikova
- Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russian Federation
| | | | - Vasily L. Yarnykh
- Research Institute of Biology and Biophysics, Tomsk State University, Tomsk, Russian Federation
- Department of Radiology, University of Washington, Seattle, WA, United States
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27
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Naumova AV, Akulov AE, Khodanovich MY, Yarnykh VL. High-resolution three-dimensional quantitative map of the macromolecular proton fraction distribution in the normal rat brain. Data Brief 2016; 10:381-384. [PMID: 28018953 PMCID: PMC5176127 DOI: 10.1016/j.dib.2016.11.066] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 10/12/2016] [Accepted: 11/17/2016] [Indexed: 11/30/2022] Open
Abstract
The presented dataset provides a normative high-resolution three-dimensional (3D) macromolecular proton fraction (MPF) map of the healthy rat brain in vivo and source images used for its reconstruction. The images were acquired using the protocol described elsewhere (Naumova, et al. High-resolution three-dimensional macromolecular proton fraction mapping for quantitative neuroanatomical imaging of the rodent brain in ultra-high magnetic fields. Neuroimage (2016) doi: 10.1016/j.neuroimage.2016.09.036). The map was reconstructed from three source images with different contrast weightings (proton density, T1, and magnetization transfer) using the single-point algorithm with a synthetic reference image. Source images were acquired from a living animal on an 11.7 T small animal MRI scanner with isotropic spatial resolution of 170 µm3 and total acquisition time about 1.5 h. The 3D dataset can be used for multiple purposes including interactive viewing of rat brain anatomy, measurements of reference MPF values in various brain structures, and development of image processing techniques for the rodent brain segmentation. It also can serve as a gold standard image for implementation and optimization of rodent brain MRI protocols.
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Affiliation(s)
- Anna V Naumova
- University of Washington, Department of Radiology, 850 Republican St., Seattle, WA, USA; National Research Tomsk State University, Research Institute of Biology and Biophysics, 36 Lenina Ave, Tomsk, Russia
| | - Andrey E Akulov
- Institute of Cytology and Genetics, The Siberian Branch of the Russian Academy of Sciences, Prospekt Lavrentyeva 10, Novosibirsk, Russia
| | - Marina Yu Khodanovich
- National Research Tomsk State University, Research Institute of Biology and Biophysics, 36 Lenina Ave, Tomsk, Russia
| | - Vasily L Yarnykh
- University of Washington, Department of Radiology, 850 Republican St., Seattle, WA, USA; National Research Tomsk State University, Research Institute of Biology and Biophysics, 36 Lenina Ave, Tomsk, Russia
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