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Ligneul C, Najac C, Döring A, Beaulieu C, Branzoli F, Clarke WT, Cudalbu C, Genovese G, Jbabdi S, Jelescu I, Karampinos D, Kreis R, Lundell H, Marjańska M, Möller HE, Mosso J, Mougel E, Posse S, Ruschke S, Simsek K, Szczepankiewicz F, Tal A, Tax C, Oeltzschner G, Palombo M, Ronen I, Valette J. Diffusion-weighted MR spectroscopy: Consensus, recommendations, and resources from acquisition to modeling. Magn Reson Med 2024; 91:860-885. [PMID: 37946584 DOI: 10.1002/mrm.29877] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 07/18/2023] [Accepted: 09/08/2023] [Indexed: 11/12/2023]
Abstract
Brain cell structure and function reflect neurodevelopment, plasticity, and aging; and changes can help flag pathological processes such as neurodegeneration and neuroinflammation. Accurate and quantitative methods to noninvasively disentangle cellular structural features are needed and are a substantial focus of brain research. Diffusion-weighted MRS (dMRS) gives access to diffusion properties of endogenous intracellular brain metabolites that are preferentially located inside specific brain cell populations. Despite its great potential, dMRS remains a challenging technique on all levels: from the data acquisition to the analysis, quantification, modeling, and interpretation of results. These challenges were the motivation behind the organization of the Lorentz Center workshop on "Best Practices & Tools for Diffusion MR Spectroscopy" held in Leiden, the Netherlands, in September 2021. During the workshop, the dMRS community established a set of recommendations to execute robust dMRS studies. This paper provides a description of the steps needed for acquiring, processing, fitting, and modeling dMRS data, and provides links to useful resources.
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Affiliation(s)
- Clémence Ligneul
- Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Chloé Najac
- C.J. Gorter MRI Center, Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - André Döring
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Cardiff, UK
- CIBM Center for Biomedical Imaging, Lausanne, Switzerland
| | - Christian Beaulieu
- Departments of Biomedical Engineering and Radiology, University of Alberta, Alberta, Edmonton, Canada
| | - Francesca Branzoli
- Paris Brain Institute-ICM, Sorbonne University, UMR S 1127, Inserm U 1127, CNRS UMR 7225, Paris, France
| | - William T Clarke
- Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Cristina Cudalbu
- CIBM Center for Biomedical Imaging, Lausanne, Switzerland
- Animal Imaging and Technology, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Guglielmo Genovese
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minnesota, Minneapolis, USA
| | - Saad Jbabdi
- Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Ileana Jelescu
- Department of Radiology, Lausanne University Hospital, Lausanne, Switzerland
- Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Dimitrios Karampinos
- Department of Diagnostic and Interventional Radiology, Technical University of Munich, Munich, Germany
| | - Roland Kreis
- MR Methodology, Department for Diagnostic and Interventional Neuroradiology, University of Bern, Bern, Switzerland
- Translational Imaging Center (TIC), Swiss Institute for Translational and Entrepreneurial Medicine, Bern, Switzerland
| | - Henrik Lundell
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital-Amager anf Hvidovre, Hvidovre, Denmark
- Department of Health Technology, Technical University of Denmark, Lyngby, Denmark
| | - Małgorzata Marjańska
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minnesota, Minneapolis, USA
| | - Harald E Möller
- NMR Methods & Development Group, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Jessie Mosso
- CIBM Center for Biomedical Imaging, Lausanne, Switzerland
- Animal Imaging and Technology, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
- LIFMET, EPFL, Lausanne, Switzerland
| | - Eloïse Mougel
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoires des Maladies Neurodégénératives, Fontenay-aux-Roses, France
| | - Stefan Posse
- Department of Neurology, University of New Mexico School of Medicine, New Mexico, Albuquerque, USA
- Department of Physics and Astronomy, University of New Mexico School of Medicine, New Mexico, Albuquerque, USA
| | - Stefan Ruschke
- Department of Diagnostic and Interventional Radiology, Technical University of Munich, Munich, Germany
| | - Kadir Simsek
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Cardiff, UK
- School of Computer Science and Informatics, Cardiff University, Cardiff, UK
| | | | - Assaf Tal
- Department of Chemical and Biological Physics, The Weizmann Institute of Science, Rehovot, Israel
| | - Chantal Tax
- University Medical Center Utrecht, Utrecht, The Netherlands
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Physics and Astronomy, Cardiff University, Cardiff, United Kingdom
| | - Georg Oeltzschner
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Maryland, Baltimore, USA
- F. M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Maryland, Baltimore, USA
| | - Marco Palombo
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Cardiff, UK
- School of Computer Science and Informatics, Cardiff University, Cardiff, UK
| | - Itamar Ronen
- Clinical Imaging Sciences Centre, Brighton and Sussex Medical School, Brighton, UK
| | - Julien Valette
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoires des Maladies Neurodégénératives, Fontenay-aux-Roses, France
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Tkáč I, Xie T, Shah N, Larson S, Dubinsky JM, Gomez-Pastor R, McLoughlin HS, Orr HT, Eberly LE, Öz G. Regional sex differences in neurochemical profiles of healthy mice measured by magnetic resonance spectroscopy at 9.4 tesla. Front Neurosci 2023; 17:1278828. [PMID: 37954878 PMCID: PMC10634209 DOI: 10.3389/fnins.2023.1278828] [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: 08/16/2023] [Accepted: 10/03/2023] [Indexed: 11/14/2023] Open
Abstract
Objective To determine sex differences in the neurochemical concentrations measured by in vivo proton magnetic resonance spectroscopy (1H MRS) of healthy mice on a genetic background commonly used for neurodegenerative disease models. Methods 1H MRS data collected from wild type mice with C57BL/6 or related genetic backgrounds in seven prior studies were used in this retrospective analysis. To be included, data had to be collected at 9.4 tesla magnetic field using advanced 1H MRS protocols, with isoflurane anesthesia and similar animal handling protocols, and a similar number of datasets from male and female mice had to be available for the brain regions analyzed. Overall, 155 spectra from female mice and 166 spectra from male mice (321 in total), collected from six brain regions (brainstem, cerebellum, cortex, hippocampus, hypothalamus, and striatum) at various ages were included. Results Concentrations of taurine, total creatine (creatine + phosphocreatine), ascorbate, glucose and glutamate were consistently higher in male vs. female mice in most brain regions. Striatum was an exception with similar total creatine in male and female mice. The sex difference pattern in the hypothalamus was notably different from other regions. Interaction between sex and age was significant for total creatine and taurine in the cerebellum and hippocampus. Conclusion Sex differences in regional neurochemical levels are small but significant and age-dependent, with consistent male-female differences across most brain regions. The neuroendocrine region hypothalamus displays a different pattern of sex differences in neurochemical levels. Differences in energy metabolism and cellular density may underlie the differences, with higher metabolic rates in females and higher osmoregulatory and antioxidant capacity in males.
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Affiliation(s)
- Ivan Tkáč
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, MN, United States
| | - Tiankai Xie
- Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis, MN, United States
| | - Nitya Shah
- Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis, MN, United States
| | - Sarah Larson
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, MN, United States
| | - Janet M. Dubinsky
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, United States
| | - Rocio Gomez-Pastor
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, United States
| | | | - Harry T. Orr
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN, United States
| | - Lynn E. Eberly
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, MN, United States
- Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis, MN, United States
| | - Gülin Öz
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, MN, United States
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Peng SL, Huang SM, Chu LWL, Chiu SC. Anesthetic modulation of water diffusion: Insights from a diffusion tensor imaging study. Med Eng Phys 2023; 118:104015. [PMID: 37536836 DOI: 10.1016/j.medengphy.2023.104015] [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: 11/25/2022] [Revised: 06/15/2023] [Accepted: 06/24/2023] [Indexed: 08/05/2023]
Abstract
Diffusion tensor imaging (DTI) in animal models are essential for translational neuroscience studies. A critical step in animal studies is the use of anesthetics. Understanding the influence of specific anesthesia regimes on DTI-derived parameters, such as fractional anisotropy (FA) and mean diffusivity (MD), is imperative when comparing results between animal studies using different anesthetics. Here, the quantification of FA and MD under different anesthetic regimes, alpha-chloralose and isoflurane, is discussed. We also used a range of b-values to determine whether the anesthetic effect was b-value dependent. The first group of rats (n = 6) was anesthetized with alpha-chloralose (80 mg/kg), whereas the second group of rats (n = 7) was anesthetized with isoflurane (1.5%). DTI was performed with b-values of 500, 1500, and 1500s/mm2, and the MD and FA were assessed individually. Anesthesia-specific differences in MD were apparent, as manifested by the higher estimated MD under isoflurane anesthesia than that under alpha-chloralose anesthesia (P < 0.001). MD values increased with decreasing b-value in all regions studied, and the degree of increase when rats were anesthetized with isoflurane was more pronounced than that associated with alpha-chloralose (P < 0.05). FA quantitation was also influenced by anesthesia regimens to varying extents, depending on the brain regions and b-values. In conclusion, both scanning parameters and the anesthesia regimens significantly impacted the quantification of DTI indices.
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Affiliation(s)
- Shin-Lei Peng
- Department of Biomedical Imaging and Radiological Science, China Medical University, Taichung, Taiwan; Neuroscience and Brain Disease Center, China Medical University, Taichung, Taiwan.
| | - Sheng-Min Huang
- Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, Miaoli, Taiwan
| | - Lok Wang Lauren Chu
- Department of Biomedical Imaging and Radiological Science, China Medical University, Taichung, Taiwan
| | - Shao-Chieh Chiu
- Center for Advanced Molecular Imaging and Translation, Chang Gung Memorial Hospital, Taoyuan, Taiwan
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Şimşek K, Döring A, Pampel A, Möller HE, Kreis R. Macromolecular background signal and non-Gaussian metabolite diffusion determined in human brain using ultra-high diffusion weighting. Magn Reson Med 2022; 88:1962-1977. [PMID: 35803740 PMCID: PMC9545875 DOI: 10.1002/mrm.29367] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 05/08/2022] [Accepted: 05/31/2022] [Indexed: 12/14/2022]
Abstract
Purpose Definition of a macromolecular MR spectrum based on diffusion properties rather than relaxation time differences and characterization of non‐Gaussian diffusion of brain metabolites with strongly diffusion‐weighted MR spectroscopy. Methods Short echo time MRS with strong diffusion‐weighting with b‐values up to 25 ms/μm2 at two diffusion times was implemented on a Connectom system and applied in combination with simultaneous spectral and diffusion decay modeling. Motion‐compensation was performed with a combined method based on the simultaneously acquired water and a macromolecular signal. Results The motion compensation scheme prevented spurious signal decay reflected in very small apparent diffusion constants for macromolecular signal. Macromolecular background signal patterns were determined using multiple fit strategies. Signal decay corresponding to non‐Gaussian metabolite diffusion was represented by biexponential fit models yielding parameter estimates for human gray matter that are in line with published rodent data. The optimal fit strategies used constraints for the signal decay of metabolites with limited signal contributions to the overall spectrum. Conclusion The determined macromolecular spectrum based on diffusion properties deviates from the conventional one derived from longitudinal relaxation time differences calling for further investigation before use as experimental basis spectrum when fitting clinical MR spectra. The biexponential characterization of metabolite signal decay is the basis for investigations into pathologic alterations of microstructure. Click here for author‐reader discussions
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Affiliation(s)
- Kadir Şimşek
- Magnetic Resonance MethodologyInstitute of Diagnostic and Interventional Neuroradiology, University of BernBernSwitzerland
- Graduate School for Cellular and Biomedical SciencesUniversity of BernBernSwitzerland
- Translational Imaging Center (TIC)Swiss Institute for Translational and Entrepreneurial MedicineBernSwitzerland
| | - André Döring
- Cardiff University Brain Research Imaging Centre (CUBRIC)School of Psychology, Cardiff UniversityCardiffUK
| | - André Pampel
- Max Planck Institute for Human Cognitive and Brain SciencesLeipzigGermany
| | - Harald E. Möller
- Max Planck Institute for Human Cognitive and Brain SciencesLeipzigGermany
| | - Roland Kreis
- Magnetic Resonance MethodologyInstitute of Diagnostic and Interventional Neuroradiology, University of BernBernSwitzerland
- Translational Imaging Center (TIC)Swiss Institute for Translational and Entrepreneurial MedicineBernSwitzerland
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Spees WM, Sukstanskii AL, Bretthorst GL, Neil JJ, Ackerman JJH. Rat Brain Global Ischemia-Induced Diffusion Changes Revisited: Biophysical Modeling of the Water and NAA MR "Diffusion Signal". Magn Reson Med 2022; 88:1333-1346. [PMID: 35452137 DOI: 10.1002/mrm.29262] [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: 10/12/2021] [Revised: 03/18/2022] [Accepted: 03/20/2022] [Indexed: 11/06/2022]
Abstract
PURPOSE To assess changes in intracellular diffusion as a mechanism for the reduction in water ADC that accompanies brain injury. Using NAA as a marker of neuronal cytoplasmic diffusion, NAA diffusion was measured before and after global ischemia (immediately postmortem) in the female Sprague-Dawley rat. METHODS Diffusion-weighted PRESS spectra, with diffusion encoding in a single direction, were acquired from large voxels of rat brain gray matter in vivo and postischemia employing either pairs of pulsed half-sine-shaped gradients (in vivo and postischemia, bmax = 19 ms/μm2 ) or sinusoidal oscillating gradients (in vivo only) with frequencies of 99.2-250 Hz. A 2D randomly oriented cylinder (neurite) model gave estimates of longitudinal and transverse diffusivities (DL and DT , respectively). In this model, DL represents the "free" diffusivity of NAA, whereas DT reflects highly restricted diffusion. Using oscillating gradients, the frequency dependence of DT [DT (ω)] gave estimates of the cylinder (axon/dendrite) radius. RESULTS A 10% decrease in DL,NAA followed global ischemia, dropping from 0.391 ± 0.012 μm2 /ms to 0.350 ± 0.009 μm2 /ms. Modeling DT,NAA (ω) provided an estimate of the neurite radius of 1.0 ± 0.6 μm. CONCLUSION Whereas the increase in apparent intraneuronal viscosity suggested by changes in DL,NAA may contribute to the overall reduction in water ADC associated with brain injury, it is not sufficient to be the sole explanation. Estimates of neurite radius based on DT (ω) were consistent with literature values.
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Affiliation(s)
- William M Spees
- Biomedical MR Laboratory, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri
| | - Alex L Sukstanskii
- Biomedical MR Laboratory, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri
| | - G Larry Bretthorst
- Biomedical MR Laboratory, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri
| | - Jeffrey J Neil
- Biomedical MR Laboratory, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri.,Department of Neurology, Washington University School of Medicine, St. Louis, Missouri.,Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri
| | - Joseph J H Ackerman
- Biomedical MR Laboratory, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri.,Department of Chemistry, Washington University, St. Louis, Missouri.,Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri.,Alvin J Siteman Cancer Center, Washington University School of Medicine, St. Louis, Missouri
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6
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Ianus A, Alexander DC, Zhang H, Palombo M. Mapping complex cell morphology in the grey matter with double diffusion encoding MR: A simulation study. Neuroimage 2021; 241:118424. [PMID: 34311067 PMCID: PMC8961003 DOI: 10.1016/j.neuroimage.2021.118424] [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: 01/08/2021] [Revised: 07/13/2021] [Accepted: 07/21/2021] [Indexed: 01/18/2023] Open
Abstract
This paper investigates the impact of cell body (namely soma) size and branching of cellular projections on diffusion MR imaging (dMRI) and spectroscopy (dMRS) signals for both standard single diffusion encoding (SDE) and more advanced double diffusion encoding (DDE) measurements using numerical simulations. The aim is to investigate the ability of dMRI/dMRS to characterize the complex morphology of brain cells focusing on these two distinctive features of brain grey matter. To this end, we employ a recently developed computational framework to create three dimensional meshes of neuron-like structures for Monte Carlo simulations, using diffusion coefficients typical of water and brain metabolites. Modelling the cellular structure as realistically connected spherical soma and cylindrical cellular projections, we cover a wide range of combinations of sphere radii and branching order of cellular projections, characteristic of various grey matter cells. We assess the impact of spherical soma size and branching order on the b-value dependence of the SDE signal as well as the time dependence of the mean diffusivity (MD) and mean kurtosis (MK). Moreover, we also assess the impact of spherical soma size and branching order on the angular modulation of DDE signal at different mixing times, together with the mixing time dependence of the apparent microscopic anisotropy (μA), a promising contrast derived from DDE measurements. The SDE results show that spherical soma size has a measurable impact on both the b-value dependence of the SDE signal and the MD and MK diffusion time dependence for both water and metabolites. On the other hand, we show that branching order has little impact on either, especially for water. In contrast, the DDE results show that spherical soma size has a measurable impact on the DDE signal's angular modulation at short mixing times and the branching order of cellular projections significantly impacts the mixing time dependence of the DDE signal's angular modulation as well as of the derived μA, for both water and metabolites. Our results confirm that SDE based techniques may be sensitive to spherical soma size, and most importantly, show for the first time that DDE measurements may be more sensitive to the dendritic tree complexity (as parametrized by the branching order of cellular projections), paving the way for new ways of characterizing grey matter morphology, non-invasively using dMRS and potentially dMRI.
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Affiliation(s)
- A Ianus
- Centre for Medical Image Computing and Department of Computer Science, University College London, London, United Kingdom; Champalimaud Research, Champalimaud Centre for the Unknown, Lisbon, Portugal
| | - D C Alexander
- Centre for Medical Image Computing and Department of Computer Science, University College London, London, United Kingdom
| | - H Zhang
- Centre for Medical Image Computing and Department of Computer Science, University College London, London, United Kingdom
| | - M Palombo
- Centre for Medical Image Computing and Department of Computer Science, University College London, London, United Kingdom.
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Measuring Glycolytic Activity with Hyperpolarized [ 2H 7, U- 13C 6] D-Glucose in the Naive Mouse Brain under Different Anesthetic Conditions. Metabolites 2021; 11:metabo11070413. [PMID: 34201777 PMCID: PMC8303162 DOI: 10.3390/metabo11070413] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 06/01/2021] [Accepted: 06/19/2021] [Indexed: 12/30/2022] Open
Abstract
Glucose is the primary fuel for the brain; its metabolism is linked with cerebral function. Different magnetic resonance spectroscopy (MRS) techniques are available to assess glucose metabolism, providing complementary information. Our first aim was to investigate the difference between hyperpolarized 13C-glucose MRS and non-hyperpolarized 2H-glucose MRS to interrogate cerebral glycolysis. Isoflurane anesthesia is commonly employed in preclinical MRS, but it affects cerebral hemodynamics and functional connectivity. A combination of low doses of isoflurane and medetomidine is routinely used in rodent functional magnetic resonance imaging (fMRI) and shows similar functional connectivity, as in awake animals. As glucose metabolism is tightly linked to neuronal activity, our second aim was to assess the impact of these two anesthetic conditions on the cerebral metabolism of glucose. Brain metabolism of hyperpolarized 13C-glucose and non-hyperpolaized 2H-glucose was monitored in two groups of mice in a 9.4 T MRI system. We found that the very different duration and temporal resolution of the two techniques enable highlighting the different aspects in glucose metabolism. We demonstrate (by numerical simulations) that hyperpolarized 13C-glucose reports on de novo lactate synthesis and is sensitive to cerebral metabolic rate of glucose (CMRGlc). We show that variations in cerebral glucose metabolism, under different anesthesia, are reflected differently in hyperpolarized and non-hyperpolarized X-nuclei glucose MRS.
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Merisaari H, Laakso H, Liljenbäck H, Virtanen H, Aronen HJ, Minn H, Poutanen M, Roivainen A, Liimatainen T, Jambor I. Statistical Evaluation of Different Mathematical Models for Diffusion Weighted Imaging of Prostate Cancer Xenografts in Mice. Front Oncol 2021; 11:583921. [PMID: 34123770 PMCID: PMC8188898 DOI: 10.3389/fonc.2021.583921] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 03/23/2021] [Indexed: 01/28/2023] Open
Abstract
Purpose To evaluate fitting quality and repeatability of four mathematical models for diffusion weighted imaging (DWI) during tumor progression in mouse xenograft model of prostate cancer. Methods Human prostate cancer cells (PC-3) were implanted subcutaneously in right hind limbs of 11 immunodeficient mice. Tumor growth was followed by weekly DWI examinations using a 7T MR scanner. Additional DWI examination was performed after repositioning following the fourth DWI examination to evaluate short term repeatability. DWI was performed using 15 and 12 b-values in the ranges of 0-500 and 0-2000 s/mm2, respectively. Corrected Akaike information criteria and F-ratio were used to evaluate fitting quality of each model (mono-exponential, stretched exponential, kurtosis, and bi-exponential). Results Significant changes were observed in DWI data during the tumor growth, indicated by ADCm, ADCs, and ADCk. Similar results were obtained using low as well as high b-values. No marked changes in model preference were present between the weeks 1−4. The parameters of the mono-exponential, stretched exponential, and kurtosis models had smaller confidence interval and coefficient of repeatability values than the parameters of the bi-exponential model. Conclusion Stretched exponential and kurtosis models showed better fit to DWI data than the mono-exponential model and presented with good repeatability.
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Affiliation(s)
- Harri Merisaari
- Department of Radiology, University of Turku, Turku, Finland.,Turku Brain and Mind Center, University of Turku, Turku, Finland
| | - Hanne Laakso
- Department of Biotechnology and Molecular Medicine, A.I. Virtanen Institute for Molecular Sciences, Kuopio, Finland
| | - Heidi Liljenbäck
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland
| | - Helena Virtanen
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland.,Turku Center for Disease Modeling, University of Turku, Turku, Finland
| | - Hannu J Aronen
- Department of Radiology, University of Turku, Turku, Finland.,Medical Imaging Centre of Southwest Finland, Turku University Hospital, Turku, Finland
| | - Heikki Minn
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland.,Department of Oncology and Radiotherapy, Turku University Hospital, Turku, Finland
| | - Matti Poutanen
- Turku Center for Disease Modeling, University of Turku, Turku, Finland
| | - Anne Roivainen
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland.,Turku Center for Disease Modeling, University of Turku, Turku, Finland
| | - Timo Liimatainen
- Department of Biotechnology and Molecular Medicine, A.I. Virtanen Institute for Molecular Sciences, Kuopio, Finland.,Research Unit of Medical Imaging, Physics and Technology, University of Oulu, Oulu, Finland.,Department of Clinical Radiology, Oulu University Hospital, Oulu, Finland.,Department of Radiology, University of Oulu, Oulu, Finland
| | - Ivan Jambor
- Department of Radiology, University of Turku, Turku, Finland.,Medical Imaging Centre of Southwest Finland, Turku University Hospital, Turku, Finland
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Magnetic resonance spectroscopy extended by oscillating diffusion gradients: Cell-specific anomalous diffusion as a probe for tissue microstructure in human brain. Neuroimage 2019; 202:116075. [DOI: 10.1016/j.neuroimage.2019.116075] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 08/01/2019] [Accepted: 08/04/2019] [Indexed: 11/23/2022] Open
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10
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Chen X, Tamang SM, Du F, Ongur D. Glutamate diffusion in the rat brain in vivo under light and deep anesthesia conditions. Magn Reson Med 2019; 82:84-94. [PMID: 30860289 DOI: 10.1002/mrm.27722] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 01/08/2019] [Accepted: 02/11/2019] [Indexed: 11/08/2022]
Abstract
PURPOSE Glutamate (Glu) is the most abundant neurotransmitter in the human central nervous system and glutamatergic neurotransmission has been implicated in many common and severe neuropsychiatric disorders. In vivo MRS techniques have been developed to measure brain Glu concentration to investigate the pathophysiology of various brain disorders. However, it is difficult to interpret Glu signal changes because Glu plays multiple roles in the brain and is found in multiple microenvironments including cytosolic, vesicular, and extracellular. METHODS In vivo diffusion-weighted MRS (DW-MRS) with low to very high b-values was performed on the rat prefrontal cortex at 9.4T under both light and deep anesthetic conditions to examine Glu diffusion properties. RESULTS Significant alterations in Glu diffusion as well as reduced Glu concentration were observed under deep anesthesia compared with superficial anesthesia in the absence of similar changes in NAA or creatine. CONCLUSION The modifications in Glu diffusion under deep anesthesia might reflect changes in Glu microenvironment. The present work shows that Glu DW-MRS could be an important tool to explore Glu physiology with changing levels of neuronal activity and synaptic function.
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Affiliation(s)
- Xi Chen
- McLean Imaging Center, McLean Hospital, Harvard Medical School, Belmont, Massachusetts.,Psychotic Disorders Division, McLean Hospital, Harvard Medical School, Belmont, Massachusetts
| | - Siddartha M Tamang
- Psychotic Disorders Division, McLean Hospital, Harvard Medical School, Belmont, Massachusetts
| | - Fei Du
- McLean Imaging Center, McLean Hospital, Harvard Medical School, Belmont, Massachusetts.,Psychotic Disorders Division, McLean Hospital, Harvard Medical School, Belmont, Massachusetts
| | - Dost Ongur
- Psychotic Disorders Division, McLean Hospital, Harvard Medical School, Belmont, Massachusetts
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11
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Marjańska M, Shestov AA, Deelchand DK, Kittelson E, Henry PG. Brain metabolism under different anesthetic conditions using hyperpolarized [1- 13 C]pyruvate and [2- 13 C]pyruvate. NMR IN BIOMEDICINE 2018; 31:e4012. [PMID: 30276897 PMCID: PMC6449100 DOI: 10.1002/nbm.4012] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 07/25/2018] [Accepted: 08/13/2018] [Indexed: 05/12/2023]
Abstract
Carbon-13 NMR spectroscopy (13 C MRS) offers the unique capability to measure brain metabolic rates in vivo. Hyperpolarized 13 C reduces the time required to assess brain metabolism from hours to minutes when compared with conventional 13 C MRS. This study investigates metabolism of hyperpolarized [1-13 C]pyruvate and [2-13 C]pyruvate in the rat brain in vivo under various anesthetics: pentobarbital, isoflurane, α-chloralose, and morphine. The apparent metabolic rate from pyruvate to lactate modeled using time courses obtained after injection of hyperpolarized [1-13 C]pyruvate was significantly greater for isoflurane than for all other anesthetic conditions, and significantly greater for morphine than for α-chloralose. The apparent metabolic rate from pyruvate to bicarbonate was significantly greater for morphine than for all other anesthetic conditions, and significantly lower for pentobarbital than for α-chloralose. Results show that relative TCA cycle rates determined from hyperpolarized 13 C data are consistent with rates previously measured using conventional 13 C MRS under similar anesthetic conditions, and that using morphine for sedation greatly improves detection of downstream metabolic products compared with other anesthetics.
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Affiliation(s)
- Małgorzata Marjańska
- Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota, 2021 6 ST SE, Minneapolis, Minnesota 55455, United States
| | - Alexander A. Shestov
- Department of Radiology, University of Pennsylvania, 423 Guardian Drive, Philadelphia, PA 19104, United States
| | - Dinesh K. Deelchand
- Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota, 2021 6 ST SE, Minneapolis, Minnesota 55455, United States
| | - Emily Kittelson
- Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota, 2021 6 ST SE, Minneapolis, Minnesota 55455, United States
| | - Pierre-Gilles Henry
- Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota, 2021 6 ST SE, Minneapolis, Minnesota 55455, United States
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12
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Studying neurons and glia non-invasively via anomalous subdiffusion of intracellular metabolites. Brain Struct Funct 2018; 223:3841-3854. [DOI: 10.1007/s00429-018-1719-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Accepted: 07/12/2018] [Indexed: 12/31/2022]
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13
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Söbbeler FJ, Carrera I, Pasloske K, Ranasinghe MG, Kircher P, Kästner SBR. Effects of isoflurane, sevoflurane, propofol and alfaxalone on brain metabolism in dogs assessed by proton magnetic resonance spectroscopy ( 1H MRS). BMC Vet Res 2018; 14:69. [PMID: 29506576 PMCID: PMC5839062 DOI: 10.1186/s12917-018-1396-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2017] [Accepted: 02/27/2018] [Indexed: 01/18/2023] Open
Abstract
Background The purpose of this study was to determine the effects of isoflurane, sevoflurane, propofol and alfaxalone on the canine brain metabolite bioprofile, measured with single voxel short echo time proton magnetic resonance spectroscopy at 3 Tesla. Ten adult healthy Beagle dogs were assigned to receive isoflurane, sevoflurane, propofol and alfaxalone at 3 different dose rates each in a randomized cross-over study design. Doses for isoflurane, sevoflurane, propofol and alfaxalone were FE’Iso 1.7 vol%, 2.1 vol%, 2.8 vol%, FE’Sevo 2.8 vol%, 3.5 vol% and 4.7 vol%, 30, 45 and 60 mg kg− 1 h− 1 and 10, 15 and 20 mg kg− 1 h− 1 respectively. A single voxel Point Resolved Spectroscopy Sequence was performed on a 3 T MRI scanner in three brain regions (basal ganglia, parietal and occipital lobes). Spectral data were analyzed with LCModel. Concentration of total N-acetylaspartate (tNAA), choline, creatine, inositol and glutamine and glutamate complex (Glx) relative to water content was obtained. Plasma concentration of lactate, glucose, triglycerides, propofol and alfaxalone were determined. Statistics were performed using repeated measures ANOVA or Wilcoxon Sign Rank test with alpha = 5%. Results Plasma glucose increased with isoflurane, sevoflurane and alfaxalone but decreased with propofol. Plasma lactate increased with all anesthetics (isoflurane > sevoflurane > propofol > alfaxalone). Cerebral lactate could not be detected. Only minor changes in cerebral metabolite concentrations of tNAA, choline, inositol, creatine and Glx occurred with anesthetic dose changes. Conclusion The metabolomic profile detected with proton magnetic resonance spectroscopy at 3 Tesla of canine brain showed only minor differences between doses and anesthetics related to tNAA, choline, creatine, inositol and Glx.
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Affiliation(s)
- Franz Josef Söbbeler
- Small Animal Clinic (Söbbeler, Kästner), University of Veterinary Medicine Hanover Foundation, Bünteweg 9, 30559, Hannover, Germany.
| | - Inés Carrera
- Clinic of Diagnostic Imaging (Carrera, Kircher), Vetsuisse Faculty, University of Zurich, Winterthurestrasse 258c, 8057, Zurich, Switzerland
| | - Kirby Pasloske
- Jurox Pty Ltd. (Pasloske, Ranasinghe), 85 Gardiner St, Rutherford, NSW, 2320, Australia
| | | | - Patrick Kircher
- Clinic of Diagnostic Imaging (Carrera, Kircher), Vetsuisse Faculty, University of Zurich, Winterthurestrasse 258c, 8057, Zurich, Switzerland
| | - Sabine Beate Rita Kästner
- Small Animal Clinic (Söbbeler, Kästner), University of Veterinary Medicine Hanover Foundation, Bünteweg 9, 30559, Hannover, Germany
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14
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Abad N, Rosenberg JT, Roussel T, Grice DC, Harrington MG, Grant SC. Metabolic assessment of a migraine model using relaxation-enhanced 1 H spectroscopy at ultrahigh field. Magn Reson Med 2018; 79:1266-1275. [PMID: 28921630 PMCID: PMC5775911 DOI: 10.1002/mrm.26811] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 04/10/2017] [Accepted: 06/02/2017] [Indexed: 01/08/2023]
Abstract
PURPOSE This study evaluates biochemical imbalances in a rat model that reflects dysfunctional pathways in migraine. The high sensitivity and spectral dispersion available to 1 H MRS at 21.1 T expands metabolic profiling in this migraine model to include lactate (Lac), taurine (Tau), aspartate, and Gly-a mixture of glycine, glutamine, and glutamate. METHODS Sprague-Dawley male rats were administered in situ an intraperitoneal injection of nitroglycerin (NTG) to induce the migraine analogue or saline as a control. A selective relaxation-enhanced MR spectroscopy sequence was used to target upfield metabolites from a 4-mm3 voxel for 2.5 h after injection. RESULTS Significant increases were evident for Lac as early as 10 min after NTG injection, peaking over 50% compared with baseline and control (normalized Lac/N-acetyl aspartate with NTG = 1.54 ± 0.65 versus with saline = 0.99 ± 0.08). Tau decreased progressively in controls over 2 h after injection, but remained elevated with NTG, peaking at 105 min after injection (normalized Tau/N-acetyl aspartate with NTG = 1.10 ± 0.18 versus with saline = 0.85 ± 0.14). Total creatine under NTG showed significant decreases with time and compared with saline; Gly demonstrated temporal increases for NTG. CONCLUSIONS These changes indicate an altered metabolic profile in the migraine analogue consistent with early changes in neural activity and/or vasodilation consistent with progressively enhanced neuroprotection and osmoregulation. Magn Reson Med 79:1266-1275, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Nastaren Abad
- Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Tallahassee, Florida, USA
- The National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida, USA
| | - Jens T Rosenberg
- The National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida, USA
| | - Tangi Roussel
- Department of Chemical Physics, Weizmann Institute Science, Rehovot, Israel
| | - Dillon C Grice
- Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Tallahassee, Florida, USA
| | - Michael G Harrington
- Molecular Neurology Program, Huntington Medical Research Institutes, Pasadena, California, USA
| | - Samuel C Grant
- Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Tallahassee, Florida, USA
- The National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida, USA
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15
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Cao P, Wu EX. In vivo diffusion MRS investigation of non-water molecules in biological tissues. NMR IN BIOMEDICINE 2017; 30:e3481. [PMID: 26797798 DOI: 10.1002/nbm.3481] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Revised: 11/19/2015] [Accepted: 12/04/2015] [Indexed: 06/05/2023]
Abstract
Diffusion MRS of non-water molecules offers great potential in directly revealing various tissue microstructures and physiology at both cellular and subcellular levels. In brain, 1 H diffusion MRS has been demonstrated as a new tool for probing normal tissue microstructures and their pathological changes. In skeletal muscle, 1 H diffusion MRS could characterize slow and restricted intramyocellular lipid diffusion, providing a sensitive marker for metabolic alterations, while 31 P diffusion MRS can measure ATP and PCr diffusion, which may reflect the capacity of cellular energy transport, complementing the information from frequently used 31 P MRS in muscle. In intervertebral disk, 1 H diffusion MRS can directly monitor extracellular matrix integrity by quantifying the mobility of macromolecules such as proteoglycans and collagens. In tumor tissue, 13 C diffusion MRS could probe intracellular glycolytic metabolism, while 1 H diffusion MRS may separate the spectrally overlapped lactate and lipid resonances. In this review, recent diffusion MRS studies of these biologically relevant non-water molecules under normal and diseased conditions will be presented. Technical considerations for diffusion MRS experiments will be discussed. With advances in MRI hardware and diffusion methodology, diffusion MRS of non-water molecules is expected to provide increasingly valuable and biologically specific information on tissue microstructures and physiology, complementing the traditional diffusion MRI of small and ubiquitous water molecules. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Peng Cao
- Department of Radiology and Biomedical Imaging, University of California at San Francisco, San Francisco, CA, USA
| | - Ed X Wu
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong, China
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong, China
- State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, Hong Kong, China
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16
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Landheer K, Schulte R, Geraghty B, Hanstock C, Chen AP, Cunningham CH, Graham SJ. Diffusion-weighted J-resolved spectroscopy. Magn Reson Med 2016; 78:1235-1245. [PMID: 27797114 DOI: 10.1002/mrm.26514] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 09/26/2016] [Accepted: 09/26/2016] [Indexed: 12/19/2022]
Abstract
PURPOSE To develop a novel diffusion-weighted magnetic resonance spectroscopy (DW-MRS) technique in conjunction with J-resolved spatially localized spectroscopy (JPRESS) to measure the apparent diffusion coefficients (ADCs) of brain metabolites beyond N-acetylaspartic acid (NAA), creatine (Cr), and choline (Cho) at 3T. This technique will be useful to probe tissue microstructures in vivo, as the various metabolites have different physiological characteristics. METHODS Two JPRESS spectra were collected (high b-value and low b-value), and the ADCs of 16 different metabolites were estimated. Two analysis pipelines were developed: 1) a 2D pipeline that uses ProFit software to extract ADCs from metabolites not typically accessible at 3T and 2) a 1D pipeline that uses TARQUIN software to extract the metabolite concentrations from each line in the 2D dataset, allowing for scaling as well as validation. RESULTS The ADCs of 16 different metabolites were estimated from within six subjects in parietal white matter. There was excellent agreement between the results obtained from the 1D and 2D pipelines for NAA, Cr, and Cho. CONCLUSION The proposed technique provided consistent estimates for the ADCs of NAA, Cr, Cho, glutamate + glutamine, and myo-inositol in all subjects and additionally glutathione and scyllo-inositol in all but one subject. Magn Reson Med 78:1235-1245, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Karl Landheer
- Department of Medical Biophysics, University of Toronto, Ontario, Canada.,Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | | | - Ben Geraghty
- Department of Medical Biophysics, University of Toronto, Ontario, Canada.,Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Christopher Hanstock
- Department of Biomedical Engineering, University of Alberta, Edmonton, Alberta, Canada
| | | | - Charles H Cunningham
- Department of Medical Biophysics, University of Toronto, Ontario, Canada.,Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Simon J Graham
- Department of Medical Biophysics, University of Toronto, Ontario, Canada.,Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
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17
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Puhl MD, Mintzopoulos D, Jensen JE, Gillis TE, Konopaske GT, Kaufman MJ, Coyle JT. In vivo magnetic resonance studies reveal neuroanatomical and neurochemical abnormalities in the serine racemase knockout mouse model of schizophrenia. Neurobiol Dis 2015; 73:269-74. [PMID: 25461193 PMCID: PMC4408217 DOI: 10.1016/j.nbd.2014.10.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 09/26/2014] [Accepted: 10/12/2014] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Decreased availability of the N-methyl-D-aspartate receptor (NMDAR) co-agonist D-serine is thought to promote NMDAR hypofunction and contribute to the pathophysiology of schizophrenia, including neuroanatomical abnormalities, such as cortical atrophy and ventricular enlargement, and neurochemical abnormalities, such as aberrant glutamate and γ-aminobutyric acid (GABA) signaling. It is thought that these abnormalities directly relate to the negative symptoms and cognitive impairments that are hallmarks of the disorder. Because of the genetic complexity of schizophrenia, animal models of the disorder are extremely valuable for the study of genetically predisposing factors. Our laboratory developed a transgenic mouse model lacking serine racemase (SR), the synthetic enzyme of d-serine, polymorphisms of which are associated with schizophrenia. Null mutants (SR-/-) exhibit NMDAR hypofunction and cognitive impairments. We used 9.4 T magnetic resonance imaging (MRI) and proton spectroscopy (MRS) to compare in vivo brain structure and neurochemistry in wildtype (WT) and SR-/- mice. METHODS Mice were anesthetized with isoflurane for MRI and MRS scans. RESULTS Compared to WT controls, SR-/- mice exhibited 23% larger ventricular volumes (p<0.05). Additionally, in a medial frontal cortex voxel (15 μl), SR-/- mice exhibited significantly higher glutamate/water (12%, t=1.83, p<0.05) and GABA/water (72%, t=4.10, p<0.001) ratios. CONCLUSIONS Collectively, these data demonstrate in vivo neuroanatomical and neurochemical abnormalities in the SR-/- mouse comparable to those previously reported in humans with schizophrenia.
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Affiliation(s)
- Matthew D Puhl
- Harvard Medical School, Department of Psychiatry, McLean Hospital, Boston, MA 02115, USA; Laboratory for Psychiatric and Molecular Neuroscience, Belmont, MA 02478, USA
| | - Dionyssios Mintzopoulos
- Harvard Medical School, Department of Psychiatry, McLean Hospital, Boston, MA 02115, USA; McLean Imaging Center, Belmont, MA 02478, USA
| | - J Eric Jensen
- Harvard Medical School, Department of Psychiatry, McLean Hospital, Boston, MA 02115, USA; McLean Imaging Center, Belmont, MA 02478, USA
| | - Timothy E Gillis
- Harvard Medical School, Department of Psychiatry, McLean Hospital, Boston, MA 02115, USA; McLean Imaging Center, Belmont, MA 02478, USA
| | - Glenn T Konopaske
- Harvard Medical School, Department of Psychiatry, McLean Hospital, Boston, MA 02115, USA; Laboratory for Psychiatric and Molecular Neuroscience, Belmont, MA 02478, USA
| | - Marc J Kaufman
- Harvard Medical School, Department of Psychiatry, McLean Hospital, Boston, MA 02115, USA; McLean Imaging Center, Belmont, MA 02478, USA
| | - Joseph T Coyle
- Harvard Medical School, Department of Psychiatry, McLean Hospital, Boston, MA 02115, USA; Harvard Medical School, Department of Psychiatry, McLean Hospital, Boston, MA 02115, USA.
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18
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Abstract
A plethora of magnetic resonance (MR) techniques developed in the last two decades provide unique and noninvasive measurement capabilities for studies of basic brain function and brain diseases in humans. Animal model experiments have been an indispensible part of this development. MR imaging and spectroscopy measurements have been employed in animal models, either by themselves or in combination with complementary and often invasive techniques, to enlighten us about the information content of such MR methods and/or verify observations made in the human brain. They have also been employed, with or independently of human efforts, to examine mechanisms underlying pathological developments in the brain, exploiting the wealth of animal models available for such studies. In this endeavor, the desire to push for ever-higher spatial and/or spectral resolution, better signal-to-noise ratio, and unique image contrast has inevitably led to the introduction of increasingly higher magnetic fields. As a result, today, animal model studies are starting to be conducted at magnetic fields ranging from ~ 11 to 17 Tesla, significantly enhancing the armamentarium of tools available for the probing brain function and brain pathologies.
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Affiliation(s)
- Gülin Öz
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, USA
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19
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Branzoli F, Ercan E, Webb A, Ronen I. The interaction between apparent diffusion coefficients and transverse relaxation rates of human brain metabolites and water studied by diffusion-weighted spectroscopy at 7 T. NMR IN BIOMEDICINE 2014; 27:495-506. [PMID: 24706330 DOI: 10.1002/nbm.3085] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 01/07/2014] [Accepted: 01/08/2014] [Indexed: 06/03/2023]
Abstract
The dependence of apparent diffusion coefficients (ADCs) of molecules in biological tissues on an acquisition-specific timescale is a powerful mechanism for studying tissue microstructure. Unlike water, metabolites are confined mainly to intracellular compartments, thus providing higher specificity to tissue microstructure. Compartment-specific structural and chemical properties may also affect molecule transverse relaxation times (T₂). Here, we investigated the correlation between diffusion and relaxation for N-acetylaspartate, creatine and choline compounds in human brain white matter in vivo at 7 T, and compared them with those of water under the same experimental conditions. Data were acquired in a volume of interest in parietal white matter at two different diffusion times, Δ = 44 and 246 ms, using a matrix of three echo times (T(E)) and five diffusion weighting values (up to 4575 s/mm²). Significant differences in the dependence of the ADCs on T(E) were found between water and metabolites, as well as among the different metabolites. A significant decrease in water ADC as a function of TE was observed only at the longest diffusion time (p < 0.001), supporting the hypothesis that at least part of the restricted water pool can be associated with longer T₂, as suggested by previous studies in vitro. Metabolite data showed an increase of creatine (p < 0.05) and N-acetylaspartate (p < 0.05) ADCs with TE at Δ = 44 ms, and a decrease of creatine (p < 0.05) and N-acetylaspartate (p = 0.1) ADCs with TE at Δ = 246 ms. No dependence of choline ADC on TE was observed. The metabolite results suggest that diffusion and relaxation properties are dictated not only by metabolite distribution in different cell types, but also by other mechanisms, such as interactions with membranes, exchange between "free" and "bound" states or interactions with microsusceptibility gradients.
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Affiliation(s)
- Francesca Branzoli
- C. J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, Netherlands
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20
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Najac C, Marchadour C, Guillermier M, Houitte D, Slavov V, Brouillet E, Hantraye P, Lebon V, Valette J. Intracellular metabolites in the primate brain are primarily localized in long fibers rather than in cell bodies, as shown by diffusion-weighted magnetic resonance spectroscopy. Neuroimage 2014; 90:374-80. [DOI: 10.1016/j.neuroimage.2013.12.045] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 11/21/2013] [Accepted: 12/15/2013] [Indexed: 10/25/2022] Open
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21
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Faster metabolite (1)H transverse relaxation in the elder human brain. PLoS One 2013; 8:e77572. [PMID: 24098589 PMCID: PMC3788805 DOI: 10.1371/journal.pone.0077572] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Accepted: 09/03/2013] [Indexed: 11/21/2022] Open
Abstract
1H magnetic resonance spectroscopy (MRS) is unique among imaging modalities because signals from several metabolites are measured during a single examination period. Each metabolite reflects a distinct intracellular process. Furthermore transverse (T2) relaxation times probe the viability of the cell microenvironment, e.g., the viscosity of the cellular fluids, the microscopic susceptibility distribution within the cells, and the iron content. In this study, T2s of brain metabolites were measured in the occipital lobe of eighteen young and fourteen elderly subjects at a field strength of 4 tesla. The T2s of N-acetylaspartate, total creatine, and total choline were 23%, 16% and 10% shorter in elderly than in young subjects. The findings of this study suggest that noninvasive detection of T2 provides useful biological information on changes in the cellular microenvironment that take place during aging.
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22
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Du F, Cooper AJ, Thida T, Shinn AK, Cohen BM, Öngür D. Myelin and axon abnormalities in schizophrenia measured with magnetic resonance imaging techniques. Biol Psychiatry 2013; 74:451-7. [PMID: 23571010 PMCID: PMC3720707 DOI: 10.1016/j.biopsych.2013.03.003] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Revised: 02/13/2013] [Accepted: 03/04/2013] [Indexed: 02/04/2023]
Abstract
BACKGROUND In schizophrenia (SZ), disturbances in integration of activity among brain regions seem to be as important as abnormal activity of any single region. Brain regions are connected through white matter (WM) tracts, and diffusion tensor imaging has provided compelling evidence for WM abnormalities in SZ. However, diffusion tensor imaging alone cannot currently pinpoint the biological basis of these abnormalities. METHODS In this study, we combined a myelin-specific and an axon-specific magnetic resonance imaging approach to examine potentially distinct abnormalities of WM components in SZ. Magnetization transfer ratio (MTR) provides information on myelin content, whereas diffusion tensor spectroscopy provides information on metabolite diffusion within axons. We collected data from a 1 × 3 × 3 cm voxel within the right prefrontal cortex WM at 4 Tesla and studied 23 patients with SZ and 22 age- and sex-matched healthy control participants. RESULTS The MTR was significantly reduced in SZ, suggesting reduced myelin content. By contrast, the apparent diffusion coefficient of N-acetylaspartate (NAA) was significantly elevated, suggesting intra-axonal abnormalities. Greater abnormality of both MTR and the apparent diffusion coefficient of NAA correlated with more adverse outcomes in the patient group. CONCLUSIONS The results suggest that WM abnormalities in SZ include both abnormal myelination and abnormal NAA diffusion within axons. These processes might be associated with abnormal signal transduction and abnormal information processing in SZ.
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Affiliation(s)
- Fei Du
- McLean Hospital, Belmont, MA,Harvard Medical School, Boston, MA
| | | | | | - Ann K. Shinn
- McLean Hospital, Belmont, MA,Harvard Medical School, Boston, MA
| | - Bruce M. Cohen
- McLean Hospital, Belmont, MA,Harvard Medical School, Boston, MA
| | - Dost Öngür
- McLean Hospital, Belmont, MA,Harvard Medical School, Boston, MA
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23
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Ronen I, Budde M, Ercan E, Annese J, Techawiboonwong A, Webb A. Microstructural organization of axons in the human corpus callosum quantified by diffusion-weighted magnetic resonance spectroscopy of N-acetylaspartate and post-mortem histology. Brain Struct Funct 2013; 219:1773-85. [PMID: 23794120 DOI: 10.1007/s00429-013-0600-0] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Accepted: 06/12/2013] [Indexed: 10/26/2022]
Abstract
Diffusion-weighted magnetic resonance spectroscopy of brain metabolites offers unique access to compartment-specific microstructural information on neural tissue. Here, we investigated in detail the diffusion characteristics of the neuronal/axonal markers N-acetylaspartate + N-acetyl aspartyl glutamate (tNAA) in a small region of the human corpus callosum at 7 T. The diffusion-weighted spectroscopy data were analyzed by fitting to a model in which information about cross-callosal tract orientation within the spectroscopy volume, obtained from diffusion tensor imaging data, was incorporated. We estimated the microscopic misalignment of axons (σ φ = 18.6° ± 3.0°) in excellent agreement with independent histological results (σ φ = 18.1° ± 4.6°) obtained from microscopic analysis of axonal orientations in the body of the corpus callosum from post-mortem human brain slices. We also robustly quantified the diffusion coefficient of tNAA (0.51 ± 0.06 × 10(-3) mm(2)/s) in axonal cytoplasm, unbiased by the tract curvature. This work supports the notion that microscopic axonal misalignment is a dominant microstructural property in white matter tracts and has a strong impact on the evaluation of tissue microstructure using diffusion information, and should therefore be taken into consideration in the evaluation of white matter microstructure. Additionally, this study enabled robust and unbiased assessment of the cytosolic diffusion coefficient of tNAA, a potential biomarker for axonopathy and neuronal degeneration.
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Affiliation(s)
- Itamar Ronen
- C.J. Gorter Center for High Field MRI Research, Department of Radiology, Leiden University Medical Center, Albinusdreef 2, Leiden, 2333, ZA, The Netherlands,
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24
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Boretius S, Tammer R, Michaelis T, Brockmöller J, Frahm J. Halogenated volatile anesthetics alter brain metabolism as revealed by proton magnetic resonance spectroscopy of mice in vivo. Neuroimage 2013; 69:244-55. [DOI: 10.1016/j.neuroimage.2012.12.020] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2012] [Revised: 12/02/2012] [Accepted: 12/11/2012] [Indexed: 11/17/2022] Open
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25
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Ronen I, Ercan E, Webb A. Axonal and glial microstructural information obtained with diffusion-weighted magnetic resonance spectroscopy at 7T. Front Integr Neurosci 2013; 7:13. [PMID: 23493316 PMCID: PMC3595513 DOI: 10.3389/fnint.2013.00013] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Accepted: 02/27/2013] [Indexed: 11/23/2022] Open
Abstract
Diffusion-weighted magnetic resonance spectroscopy (DWS) offers unique access to compartment-specific microstructural information on tissue, and potentially sensitive detection of compartment-specific changes in disease. The specificity of DWS is, however, offset by its relative low sensitivity, intrinsic to all MRS-based methods, and further exacerbated by the signal loss due to the diffusion weighting and long echo times. In this work we first provide an experimental example for the type of compartment-specific information that can be obtained with DWS from a small volume of interest (VOI) in brain white matter. We then propose and discuss a strategy for the analysis of DWS data, which includes the use of models of diffusion in compartments with simple geometries. We conclude with a broader discussion of the potential role of DWS in the characterization of tissue microstructure and the complementarity of DWS with less-specific but more sensitive microstructural tools such as diffusion tensor imaging.
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Affiliation(s)
- Itamar Ronen
- C.J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical CenterLeiden, Netherlands
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26
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Anomalous diffusion of brain metabolites evidenced by diffusion-weighted magnetic resonance spectroscopy in vivo. J Cereb Blood Flow Metab 2012; 32:2153-60. [PMID: 22929443 PMCID: PMC3519410 DOI: 10.1038/jcbfm.2012.119] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Translational displacement of molecules within cells is a key process in cellular biology. Molecular motion potentially depends on many factors, including active transport, cytosol viscosity and molecular crowding, tortuosity resulting from cytoskeleton and organelles, and restriction barriers. However, the relative contribution of these factors to molecular motion in the cytoplasm remains poorly understood. In this work, we designed an original diffusion-weighted magnetic resonance spectroscopy strategy to probe molecular motion at subcellular scales in vivo. This led to the first observation of anomalous diffusion, that is, dependence of the apparent diffusion coefficient (ADC) on the diffusion time, for endogenous intracellular metabolites in the brain. The observed increase of the ADC at short diffusion time yields evidence that metabolite motion is characteristic of hindered random diffusion rather than active transport, for time scales up to the dozen milliseconds. Armed with this knowledge, data modeling based on geometrically constrained diffusion was performed. Results suggest that metabolite diffusion occurs in a low-viscosity cytosol hindered by ∼2-μm structures, which is consistent with known intracellular organization.
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Functional diffusion-weighted magnetic resonance spectroscopy of the human primary visual cortex at 7 T. Magn Reson Med 2012; 69:303-9. [DOI: 10.1002/mrm.24542] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Revised: 10/05/2012] [Accepted: 10/05/2012] [Indexed: 11/07/2022]
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Kan HE, Techawiboonwong A, van Osch MJP, Versluis MJ, Deelchand DK, Henry PG, Marjańska M, van Buchem MA, Webb AG, Ronen I. Differences in apparent diffusion coefficients of brain metabolites between grey and white matter in the human brain measured at 7 T. Magn Reson Med 2012; 67:1203-9. [PMID: 22083562 DOI: 10.1002/mrm.23129] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2011] [Revised: 06/10/2011] [Accepted: 07/11/2011] [Indexed: 01/27/2023]
Abstract
Diffusion weighted spectroscopy can provide microstructural information that is specific to compartmental geometry. So far, in human brain, apparent diffusion coefficients (ADCs) of only the metabolites N-acetyl aspartate, creatine (tCr) and choline (tCho) have been assessed. High field MR at 7 T allows the collection and analysis of diffusion weighted spectroscopy data of additional metabolites of interest such as glutamate (Glu), N-acetyl aspartyl glutamate, and glutamine (Gln), which are of interest due to their different compartmentalization and role in brain physiology. In this study, we performed (1)H diffusion weighted spectroscopy at 7 T using a diffusion-weighted PRESS sequence in parietal white matter (n = 6) and occipital grey matter (n = 7). Data were analyzed using the LCmodel. ADCs could reliably be obtained of N-acetyl aspartate, tCr, tCho, Glu, Gln in grey and white matter, and N-acetyl aspartyl glutamate in white matter. Significant differences in ADC values were observed between grey and white matter for all metabolites. ADCs in grey matter were consistently lower than in white matter. These differences can probably be attributed to different compartmentalization as well as to the differential impact of diffusion time on ADC of different molecules under conditions of restricted diffusion.
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Affiliation(s)
- Hermien E Kan
- CJ Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands.
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Zheng DD, Liu ZH, Fang J, Wang XY, Zhang J. The effect of age and cerebral ischemia on diffusion-weighted proton MR spectroscopy of the human brain. AJNR Am J Neuroradiol 2012; 33:563-8. [PMID: 22081680 PMCID: PMC7966455 DOI: 10.3174/ajnr.a2793] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2011] [Accepted: 06/16/2011] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE DW-MRS is a promising tool for the noninvasive identification of the cellular response to cerebral ischemia. To date, the potential confounding effects of aging and the stage of ischemia are unknown. We, therefore, examined the cross-sectional effects of age and different stages of cerebral ischemia on the diffusion of brain metabolites. MATERIALS AND METHODS The ADCs of 3 major metabolites, including Cho, Cr, and NAA were measured by DW-MRS in healthy younger (n = 26, 24 ± 2.2 years of age) and older (n = 17, 63 ± 7.0 years of age) adults, as well as in patients with acute (n = 7, 57 ± 4.0 years of age) and subacute (n = 12, 62 ± 7.8 years of age) cerebral ischemia. RESULTS Compared with younger adults, healthy older adults presented with significantly reduced ADC values of NAA (P = .000052), Cr (P = .000018), and Cho (P = .00075). Meanwhile, the ADC values of NAA (F(2,36) = 6.057, P = .006), Cr (F(2,36) = 5.634, P = .008), and Cho (F(2,36) = 8.167, P = .001) were significantly different among the acute cerebral ischemia group, subacute cerebral ischemia group, and healthy older controls. These metabolites decreased in the acute stage of cerebral ischemia but increased in the subacute stage, compared with age-matched controls. CONCLUSIONS The effect of age should be considered when analyzing diffusion of cerebral metabolites with DW-MRS. Our observations also suggest that metabolite diffusion data may be used to reveal changes in the intracellular environment, depending on the pathologic status of ischemia.
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Affiliation(s)
- D D Zheng
- Academy of Advanced Interdisciplinary Studies, Peking University, Beijing, China, People's Republic of China
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Valette J, Giraudeau C, Marchadour C, Djemai B, Geffroy F, Ghaly MA, Le Bihan D, Hantraye P, Lebon V, Lethimonnier F. A new sequence for single-shot diffusion-weighted NMR spectroscopy by the trace of the diffusion tensor. Magn Reson Med 2012; 68:1705-12. [DOI: 10.1002/mrm.24193] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 01/04/2012] [Accepted: 01/07/2012] [Indexed: 12/24/2022]
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Makaryus R, Lee H, Yu M, Zhang S, Smith SD, Rebecchi M, Glass PS, Benveniste H. The metabolomic profile during isoflurane anesthesia differs from propofol anesthesia in the live rodent brain. J Cereb Blood Flow Metab 2011; 31:1432-42. [PMID: 21266982 PMCID: PMC3130322 DOI: 10.1038/jcbfm.2011.1] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Development of noninvasive techniques to discover new biomarkers in the live brain is important to further understand the underlying metabolic pathways of significance for processes such as anesthesia-induced apoptosis and cognitive dysfunction observed in the undeveloped brain. We used in vivo proton magnetic resonance spectroscopy and two different signal processing approaches to test the hypothesis that volatile (isoflurane) and intravenous (propofol) anesthetics at equipotent doses produce distinct metabolomic profiles in the hippocampus and parietal cortex of the live rodent. For both brain regions, prolonged isoflurane anesthesia was characterized by higher levels of lactate (Lac) and glutamate compared with long-lasting propofol. In contrast, propofol anesthesia was characterized by very low concentrations of Lac ([lac]) as well as glucose. Quantitative analysis revealed that the [lac] was fivefold higher with isoflurane compared with propofol anesthesia and independent of [lac] in blood. The metabolomic profiling further demonstrated that for both brain regions, Lac was the most important metabolite for the observed differences, suggesting activation of distinct metabolic pathways that may impact mechanisms of action, background cellular functions, and possible agent-specific neurotoxicity.
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Affiliation(s)
- Rany Makaryus
- Department of Anesthesiology, Health Sciences Center, Stony Brook University, Stony Brook, New York 11794, USA
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Ellegood J, Hanstock CC, Beaulieu C. Considerations for measuring the fractional anisotropy of metabolites with diffusion tensor spectroscopy. NMR IN BIOMEDICINE 2011; 24:270-280. [PMID: 20925126 DOI: 10.1002/nbm.1586] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2009] [Revised: 04/05/2010] [Accepted: 06/12/2010] [Indexed: 05/30/2023]
Abstract
Diffusion tensor spectroscopy of metabolites in brain is challenging because of their lower diffusivity (i.e. less signal attenuation for a given b value) and much poorer signal-to-noise ratio relative to water. Although diffusion tensor acquisition protocols have been studied in detail for water, they have not been evaluated systematically for the measurement of the fractional anisotropy of metabolites such as N-acetylaspartate, creatine and choline in the white and gray matter of human brain. Diffusion tensor spectroscopy was performed in vivo with variable maximal b values (1815 or 5018 s/mm(2)). Experiments were also performed on simulated spectra and isotropic alcohol phantoms of various diffusivities, ranging from approximately 0.54 × 10(-3) to 0.13 × 10(-3) mm(2)/s, to assess the sensitivity of diffusion tensor spectroscopic parameters to low diffusivity, noise and b value. The low maximum b value of 1815 s/mm(2) yielded elevated fractional anisotropy (0.53-0.60) of N-acetylaspartate in cortical gray matter relative to the more isotropic value (0.25-0.30) obtained with a higher b value of 5018 s/mm(2); in contrast, the fractional anisotropy of white matter was consistently anisotropic with the different maximal b values (i.e. 0.43-0.54 for b = 1815 s/mm(2) and 0.47-0.51 for b = 5018 s/mm(2)). Simulations, phantoms and in vivo data indicate that greater signal attenuation, to a degree, is desirable for the accurate quantification of diffusion-weighted spectra for slowly diffusing metabolites.
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Affiliation(s)
- Jacob Ellegood
- Department of Biomedical Engineering, University of Alberta, Edmonton, AB, Canada
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Noninvasive detection of presymptomatic and progressive neurodegeneration in a mouse model of spinocerebellar ataxia type 1. J Neurosci 2010; 30:3831-8. [PMID: 20220018 DOI: 10.1523/jneurosci.5612-09.2010] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Recent studies with a conditional mouse model of spinocerebellar ataxia type 1 (SCA1) suggest that neuronal dysfunction is reversible and neurodegeneration preventable with early interventions. Success of such interventions will depend on early detection of neuronal and glial abnormalities before cell loss and availability of objective methods to monitor progressive neurodegeneration. Cerebellar concentrations of N-acetylaspartate (NAA), myo-inositol, and glutamate as measured by magnetic resonance spectroscopy (MRS) correlate with ataxia scores of patients with SCA1, indicating their potential as reliable biomarkers of neurodegeneration. Here we investigated whether neurochemical levels are altered by early, presymptomatic disease and whether they gauge disease progression in a mouse model of SCA1. Cerebellar neurochemical profiles of transgenic mice that overexpress the mutant human ataxin-1 (the SCA1[82Q] line) were measured longitudinally up to 1 year by MRS at 9.4 T and compared to those of transgenic mice that overexpress the normal human ataxin-1 (the SCA1[30Q] line) and wild-type controls. Multiple neurochemicals distinguished the SCA1[82Q] mice from controls with no overlap at all ages. Six neurochemicals were significantly different in SCA1[82Q] mice at 6 weeks, before major pathological and neurological changes. Alterations in NAA, myo-inositol, and glutamate progressively worsened and were significantly correlated (p < 0.0001) with disease progression as assessed by histology (molecular layer thickness and an overall severity score). Therefore, the neurochemicals that correlate with clinical status in patients reflected progressive pathology in the mouse model. These data demonstrate that presymptomatic and progressive neurodegeneration in SCA1 can be noninvasively monitored using MRS.
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Iltis I, Koski DM, Eberly LE, Nelson CD, Deelchand DK, Valette J, Ugurbil K, Lim KO, Henry PG. Neurochemical changes in the rat prefrontal cortex following acute phencyclidine treatment: an in vivo localized (1)H MRS study. NMR IN BIOMEDICINE 2009; 22:737-44. [PMID: 19338025 PMCID: PMC2732191 DOI: 10.1002/nbm.1385] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Acute phencyclidine (PCP) administration mimics some aspects of schizophrenia in rats, such as behavioral alterations, increased dopaminergic activity and prefrontal cortex dysfunction. In this study, we used single-voxel (1)H-MRS to investigate neurochemical changes in rat prefrontal cortex in vivo before and after an acute injection of PCP. A short-echo time sequence (STEAM) was used to acquire spectra in a 32-microL voxel positioned in the prefrontal cortex area of 12 rats anesthetized with isoflurane. Data were acquired for 30 min before and for 140 min after a bolus of PCP (10 mg/kg, n = 6) or saline (n = 6). Metabolites were quantified with the LCModel. Time courses for 14 metabolites were obtained with a temporal resolution of 10 min. The glutamine/glutamate ratio was significantly increased after PCP injection (p < 0.0001, pre- vs. post-injection), while the total concentration of these two metabolites remained constant. Glucose was transiently increased (+70%) while lactate decreased after the injection (both p < 0.0001). Lactate, but not glucose and glutamine, returned to baseline levels after 140 min. These results show that an acute injection of PCP leads to changes in glutamate and glutamine concentrations, similar to what has been observed in schizophrenic patients, and after ketamine administration in humans. MRS studies of this pharmacological rat model may be useful for assessing the effects of potential anti-psychotic drugs in vivo.
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Affiliation(s)
- Isabelle Iltis
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, 55455, USA.
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Gybina AA, Tkac I, Prohaska JR. Copper deficiency alters the neurochemical profile of developing rat brain. Nutr Neurosci 2009; 12:114-22. [PMID: 19356314 DOI: 10.1179/147683009x423265] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Copper deficiency is associated with impaired brain development and mitochondrial dysfunction. Perinatal copper deficiency was produced in Holtzman rats. In vivo proton NMR spectroscopy was used to quantify 18 cerebellar and hippocampal metabolites on postnatal day 21 (P21). Copper status was evaluated in male copper-adequate (CuA) and copper-deficient (CuD) brothers at P19 and at P23, 2 days following NMR experiments, by metal and in vitro metabolite data. Compared to CuA pups, CuD pups had lower ascorbate concentration in both brain regions, confirming prior HPLC data. Both regions of CuD rats also had lower N-acetylaspartate levels consistent with delayed development or impaired mitochondrial function similar to prior work demonstrating elevated lactate and citrate. For other metabolites, the P21 neurochemical profile of CuD rats was remarkably similar to CuA rats but uniquely different from iron-deficient or chronic hypoxia models. Further research is needed to determine the neurochemical consequences of copper deficiency.
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Affiliation(s)
- Anna A Gybina
- Department of Biochemistry and Molecular Biology, University of Minnesota Medical School, Duluth, Minnesota 55812, USA
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Posse S, Otazo R, Tsai SY, Yoshimoto AE, Lin FH. Single-shot magnetic resonance spectroscopic imaging with partial parallel imaging. Magn Reson Med 2009; 61:541-7. [PMID: 19097245 PMCID: PMC2827332 DOI: 10.1002/mrm.21855] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2008] [Accepted: 09/18/2008] [Indexed: 11/11/2022]
Abstract
A magnetic resonance spectroscopic imaging (MRSI) pulse sequence based on proton-echo-planar-spectroscopic-imaging (PEPSI) is introduced that measures two-dimensional metabolite maps in a single excitation. Echo-planar spatial-spectral encoding was combined with interleaved phase encoding and parallel imaging using SENSE to reconstruct absorption mode spectra. The symmetrical k-space trajectory compensates phase errors due to convolution of spatial and spectral encoding. Single-shot MRSI at short TE was evaluated in phantoms and in vivo on a 3-T whole-body scanner equipped with a 12-channel array coil. Four-step interleaved phase encoding and fourfold SENSE acceleration were used to encode a 16 x 16 spatial matrix with a 390-Hz spectral width. Comparison with conventional PEPSI and PEPSI with fourfold SENSE acceleration demonstrated comparable sensitivity per unit time when taking into account g-factor-related noise increases and differences in sampling efficiency. LCModel fitting enabled quantification of inositol, choline, creatine, and N-acetyl-aspartate (NAA) in vivo with concentration values in the ranges measured with conventional PEPSI and SENSE-accelerated PEPSI. Cramer-Rao lower bounds were comparable to those obtained with conventional SENSE-accelerated PEPSI at the same voxel size and measurement time. This single-shot MRSI method is therefore suitable for applications that require high temporal resolution to monitor temporal dynamics or to reduce sensitivity to tissue movement.
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Affiliation(s)
- Stefan Posse
- Department of Neurology, University of New Mexico School of Medicine, Albuquerque, New Mexico 87131, USA.
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Deelchand DK, Nelson C, Shestov AA, Uğurbil K, Henry PG. Simultaneous measurement of neuronal and glial metabolism in rat brain in vivo using co-infusion of [1,6-13C2]glucose and [1,2-13C2]acetate. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2009; 196:157-63. [PMID: 19027334 PMCID: PMC2722028 DOI: 10.1016/j.jmr.2008.11.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2008] [Revised: 09/18/2008] [Accepted: 11/03/2008] [Indexed: 05/21/2023]
Abstract
In this work the feasibility of measuring neuronal-glial metabolism in rat brain in vivo using co-infusion of [1,6-(13)C(2)]glucose and [1,2-(13)C(2)]acetate was investigated. Time courses of (13)C spectra were measured in vivo while infusing both (13)C-labeled substrates simultaneously. Individual (13)C isotopomers (singlets and multiplets observed in (13)C spectra) were quantified automatically using LCModel. The distinct (13)C spectral pattern observed in glutamate and glutamine directly reflected the fact that glucose was metabolized primarily in the neuronal compartment and acetate in the glial compartment. Time courses of concentration of singly and multiply-labeled isotopomers of glutamate and glutamine were obtained with a temporal resolution of 11 min. Although dynamic metabolic modeling of these (13)C isotopomer data will require further work and is not reported here, we expect that these new data will allow more precise determination of metabolic rates as is currently possible when using either glucose or acetate as the sole (13)C-labeled substrate.
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Affiliation(s)
- Dinesh K Deelchand
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota Medical School, 2021 6th St SE, Minneapolis, MN 55455, USA.
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Valette J, Chaumeil M, Guillermier M, Bloch G, Hantraye P, Lebon V. Diffusion-weighted NMR spectroscopy allows probing of 13C labeling of glutamate inside distinct metabolic compartments in the brain. Magn Reson Med 2008; 60:306-11. [PMID: 18666130 DOI: 10.1002/mrm.21661] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
In the present work, diffusion-weighted (DW)-NMR spectroscopy of glutamate was performed during a (13)C-labeled glucose infusion in monkey brain (six experiments). It is shown that glutamate (13)C labeling occurs significantly faster at higher diffusion weightings-slightly for glutamate in position C4, and more markedly for glutamate in position C3. This demonstrates the existence of different diffusion compartments for glutamate, associated with different metabolic rates. Metabolic modeling of (13)C enrichment time-courses suggests that these compartments might be gray and white matter, each having a specific oxidative metabolism rate possibly paralleled by a specific glutamate diffusion coefficient.
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Ellegood J, McKay RT, Hanstock CC, Beaulieu C. Anisotropic diffusion of metabolites in peripheral nerve using diffusion weighted magnetic resonance spectroscopy at ultra-high field. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2007; 184:20-8. [PMID: 17027305 DOI: 10.1016/j.jmr.2006.09.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2006] [Revised: 08/25/2006] [Accepted: 09/15/2006] [Indexed: 05/12/2023]
Abstract
Although the diffusivity and anisotropy of water has been investigated thoroughly in ordered axonal systems (i.e., nervous tissue), there have been very few studies on the directional dependence of diffusion of metabolites. In this study, the mean apparent diffusion coefficient (Trace/3 ADC) and fractional anisotropy (FA) values of the intracellular metabolites N-acetyl aspartate (NAA), creatine and phosphocreatine (tCr), choline (Cho), taurine (Tau), and glutamate and glutamine (Glx) were measured parallel and perpendicular to the length of excised frog sciatic nerve using a water suppressed, diffusion-weighted, spin-echo pulse sequence at 18.8T. The degree of anisotropy (FA) of NAA (0.41+/-0.09) was determined to be less than tCr (0.59+/-0.07) and Cho (0.61+/-0.11), which is consistent with previously reported human studies of white matter. In contrast, Glx diffusion was found to be almost isotropic with an FA value of 0.20+/-0.06. The differences of FA between the metabolites is most likely due to their differing micro-environments and could be beneficial as an indicator of compartment specific changes with disease, information not readily available with water diffusion.
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Affiliation(s)
- Jacob Ellegood
- Department of Biomedical Engineering, University of Alberta, 1098 Research Transition Facility, Edmonton, Alta., Canada T6G 2V2
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