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Koolschijn RS, Clarke WT, Ip IB, Emir UE, Barron HC. Event-related functional magnetic resonance spectroscopy. Neuroimage 2023; 276:120194. [PMID: 37244321 PMCID: PMC7614684 DOI: 10.1016/j.neuroimage.2023.120194] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 05/24/2023] [Indexed: 05/29/2023] Open
Abstract
Proton-Magnetic Resonance Spectroscopy (MRS) is a non-invasive brain imaging technique used to measure the concentration of different neurochemicals. "Single-voxel" MRS data is typically acquired across several minutes, before individual transients are averaged through time to give a measurement of neurochemical concentrations. However, this approach is not sensitive to more rapid temporal dynamics of neurochemicals, including those that reflect functional changes in neural computation relevant to perception, cognition, motor control and ultimately behaviour. In this review we discuss recent advances in functional MRS (fMRS) that now allow us to obtain event-related measures of neurochemicals. Event-related fMRS involves presenting different experimental conditions as a series of trials that are intermixed. Critically, this approach allows spectra to be acquired at a time resolution in the order of seconds. Here we provide a comprehensive user guide for event-related task designs, choice of MRS sequence, analysis pipelines, and appropriate interpretation of event-related fMRS data. We raise various technical considerations by examining protocols used to quantify dynamic changes in GABA, the primary inhibitory neurotransmitter in the brain. Overall, we propose that although more data is needed, event-related fMRS can be used to measure dynamic changes in neurochemicals at a temporal resolution relevant to computations that support human cognition and behaviour.
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Affiliation(s)
- Renée S Koolschijn
- Wellcome Centre for Integrative Neuroimaging, University of Oxford, FMRIB, John Radcliffe Hospital, Oxford, United Kingdom; Donders Institute for Brain, Cognition and Behavior, Radboud University, Nijmegen, The Netherlands.
| | - William T Clarke
- Wellcome Centre for Integrative Neuroimaging, University of Oxford, FMRIB, John Radcliffe Hospital, Oxford, United Kingdom; Medical Research Council Brain Network Dynamics Unit, University of Oxford, Oxford, United Kingdom
| | - I Betina Ip
- Wellcome Centre for Integrative Neuroimaging, University of Oxford, FMRIB, John Radcliffe Hospital, Oxford, United Kingdom
| | - Uzay E Emir
- School of Health Sciences, Purdue University, West Lafayette, United States
| | - Helen C Barron
- Wellcome Centre for Integrative Neuroimaging, University of Oxford, FMRIB, John Radcliffe Hospital, Oxford, United Kingdom; Medical Research Council Brain Network Dynamics Unit, University of Oxford, Oxford, United Kingdom.
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2
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Veeraiah P, Jansen JFA. Multinuclear Magnetic Resonance Spectroscopy at Ultra-High-Field: Assessing Human Cerebral Metabolism in Healthy and Diseased States. Metabolites 2023; 13:metabo13040577. [PMID: 37110235 PMCID: PMC10143499 DOI: 10.3390/metabo13040577] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Revised: 04/06/2023] [Accepted: 04/17/2023] [Indexed: 04/29/2023] Open
Abstract
The brain is a highly energetic organ. Although the brain can consume metabolic substrates, such as lactate, glycogen, and ketone bodies, the energy metabolism in a healthy adult brain mainly relies on glucose provided via blood. The cerebral metabolism of glucose produces energy and a wide variety of intermediate metabolites. Since cerebral metabolic alterations have been repeatedly implicated in several brain disorders, understanding changes in metabolite levels and corresponding cell-specific neurotransmitter fluxes through different substrate utilization may highlight the underlying mechanisms that can be exploited to diagnose or treat various brain disorders. Magnetic resonance spectroscopy (MRS) is a noninvasive tool to measure tissue metabolism in vivo. 1H-MRS is widely applied in research at clinical field strengths (≤3T) to measure mostly high abundant metabolites. In addition, X-nuclei MRS including, 13C, 2H, 17O, and 31P, are also very promising. Exploiting the higher sensitivity at ultra-high-field (>4T; UHF) strengths enables obtaining unique insights into different aspects of the substrate metabolism towards measuring cell-specific metabolic fluxes in vivo. This review provides an overview about the potential role of multinuclear MRS (1H, 13C, 2H, 17O, and 31P) at UHF to assess the cerebral metabolism and the metabolic insights obtained by applying these techniques in both healthy and diseased states.
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Affiliation(s)
- Pandichelvam Veeraiah
- Scannexus (Ultra-High-Field MRI Center), 6229 EV Maastricht, The Netherlands
- Faculty of Health Medicine and Life Sciences, Maastricht University, 6229 ER Maastricht, The Netherlands
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, 6229 HX Maastricht, The Netherlands
| | - Jacobus F A Jansen
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, 6229 HX Maastricht, The Netherlands
- School for Mental Health and Neuroscience, Maastricht University, 6229 ER Maastricht, The Netherlands
- Department of Electrical Engineering, Eindhoven University of Technology, 5612 AZ Eindhoven, The Netherlands
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3
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Genovese G, Diaz-Fernandez B, Lejeune FX, Ronen I, Marjańska M, Yahia-Cherif L, Lehéricy S, Branzoli F, Rosso C. Longitudinal Monitoring of Microstructural Alterations in Cerebral Ischemia with in Vivo Diffusion-weighted MR Spectroscopy. Radiology 2023; 306:e220430. [PMID: 36318030 PMCID: PMC9968771 DOI: 10.1148/radiol.220430] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 08/31/2022] [Accepted: 09/06/2022] [Indexed: 02/22/2023]
Abstract
Background The time course of cellular damage after acute ischemic stroke (IS) is currently not well known, and specific noninvasive markers of microstructural alterations linked to inflammation are lacking, which hinders the monitoring of anti-inflammatory treatment. Purpose To evaluate the temporal pattern of neuronal and glial microstructural changes after stroke using in vivo single-voxel diffusion-weighted MR spectroscopy. Materials and Methods In this prospective longitudinal study, participants with IS and healthy volunteers (HVs) underwent MRI at 3.0 T. In participants with IS, apparent diffusion coefficients (ADCs) and concentrations of total N-acetyl-aspartate (tNAA), total creatine (tCr), and total choline (tCho) were measured in volumes of interest (VOIs), including the lesion VOI (VOIles) and the contralateral VOI (VOIcl) at 2 weeks, 1 month, and 3 months after IS. HVs were examined once, with VOIs located in the same brain regions as participants with IS. Within- and between-group differences and longitudinal changes were examined using linear mixed-effects models. Results Twenty participants with IS (mean age, 61 years ± 13 [SD]; 12 women) and 20 HVs (mean age, 59 years ± 13; 12 women) were evaluated. No differences in ADCs or concentrations were observed in VOIcl between HVs and participants with IS. In participants with IS, the ADC of tCr was higher in VOIles than in VOIcl at 1 month (+14.4%, P = .004) and 3 months after IS (+19.0%, P < .001), while the ADC of tCho was higher only at 1 month (+16.7%, P = .001). No difference in the ADC of tNAA was observed between the two VOIs at any time point. tNAA and tCr concentrations were lower in VOIles than in VOIcl and were stable over time (approximately -50% and -30%, respectively; P < .001). Conclusion High diffusivity of choline-containing compounds and total creatine (tCr) in the ischemic lesion 1 month after ischemic stroke (IS) indicates glial morphologic changes, suggesting that active inflammation is still ongoing at this time point. High tCr diffusivity up to 3 months after IS likely reflects the presence of astrogliosis at the chronic stage of cerebral ischemia. Clinical trial registration no. NCT02833961 © RSNA, 2022 Online supplemental material is available for this article.
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Affiliation(s)
| | | | - François-Xavier Lejeune
- From the Paris Brain Institute (Institut du Cerveau–ICM),
Center for Neuroimaging Research–CENIR, Hôpital
Pitié-Salpêtrière, 47 Boulevard de l’Hôpital,
CS 21414, 75646 Paris Cedex 13, France (G.G., L.Y.C., S.L., F.B.); Hopital
Pitié-Salpêtrière, ICM, Sorbonne Université, Inserm
U 1127, CNRS UMR 7225, Paris, France (G.G., F.X.L., L.Y.C., S.L., F.B., C.R.);
APHP-Urgences Cérébro-Vasculaires, Hôpital
Pitié-Salpêtrière, Paris, France (B.D.F., C.R.); Center for
Magnetic Resonance Research, Department of Radiology, University of Minnesota,
Minneapolis, Minn (G.G., M.M.); Paris Brain Institute’s Data Analysis
Core, Paris, France (F.X.L.); Clinical Imaging Sciences Centre, Brighton and
Sussex Medical School, Falmer, United Kingdom (I.R.); and STARE Team, iCRIN,
Institut du Cerveau et de la Moelle Épinière, ICM, Paris, France
(C.R.)
| | - Itamar Ronen
- From the Paris Brain Institute (Institut du Cerveau–ICM),
Center for Neuroimaging Research–CENIR, Hôpital
Pitié-Salpêtrière, 47 Boulevard de l’Hôpital,
CS 21414, 75646 Paris Cedex 13, France (G.G., L.Y.C., S.L., F.B.); Hopital
Pitié-Salpêtrière, ICM, Sorbonne Université, Inserm
U 1127, CNRS UMR 7225, Paris, France (G.G., F.X.L., L.Y.C., S.L., F.B., C.R.);
APHP-Urgences Cérébro-Vasculaires, Hôpital
Pitié-Salpêtrière, Paris, France (B.D.F., C.R.); Center for
Magnetic Resonance Research, Department of Radiology, University of Minnesota,
Minneapolis, Minn (G.G., M.M.); Paris Brain Institute’s Data Analysis
Core, Paris, France (F.X.L.); Clinical Imaging Sciences Centre, Brighton and
Sussex Medical School, Falmer, United Kingdom (I.R.); and STARE Team, iCRIN,
Institut du Cerveau et de la Moelle Épinière, ICM, Paris, France
(C.R.)
| | - Małgorzata Marjańska
- From the Paris Brain Institute (Institut du Cerveau–ICM),
Center for Neuroimaging Research–CENIR, Hôpital
Pitié-Salpêtrière, 47 Boulevard de l’Hôpital,
CS 21414, 75646 Paris Cedex 13, France (G.G., L.Y.C., S.L., F.B.); Hopital
Pitié-Salpêtrière, ICM, Sorbonne Université, Inserm
U 1127, CNRS UMR 7225, Paris, France (G.G., F.X.L., L.Y.C., S.L., F.B., C.R.);
APHP-Urgences Cérébro-Vasculaires, Hôpital
Pitié-Salpêtrière, Paris, France (B.D.F., C.R.); Center for
Magnetic Resonance Research, Department of Radiology, University of Minnesota,
Minneapolis, Minn (G.G., M.M.); Paris Brain Institute’s Data Analysis
Core, Paris, France (F.X.L.); Clinical Imaging Sciences Centre, Brighton and
Sussex Medical School, Falmer, United Kingdom (I.R.); and STARE Team, iCRIN,
Institut du Cerveau et de la Moelle Épinière, ICM, Paris, France
(C.R.)
| | - Lydia Yahia-Cherif
- From the Paris Brain Institute (Institut du Cerveau–ICM),
Center for Neuroimaging Research–CENIR, Hôpital
Pitié-Salpêtrière, 47 Boulevard de l’Hôpital,
CS 21414, 75646 Paris Cedex 13, France (G.G., L.Y.C., S.L., F.B.); Hopital
Pitié-Salpêtrière, ICM, Sorbonne Université, Inserm
U 1127, CNRS UMR 7225, Paris, France (G.G., F.X.L., L.Y.C., S.L., F.B., C.R.);
APHP-Urgences Cérébro-Vasculaires, Hôpital
Pitié-Salpêtrière, Paris, France (B.D.F., C.R.); Center for
Magnetic Resonance Research, Department of Radiology, University of Minnesota,
Minneapolis, Minn (G.G., M.M.); Paris Brain Institute’s Data Analysis
Core, Paris, France (F.X.L.); Clinical Imaging Sciences Centre, Brighton and
Sussex Medical School, Falmer, United Kingdom (I.R.); and STARE Team, iCRIN,
Institut du Cerveau et de la Moelle Épinière, ICM, Paris, France
(C.R.)
| | - Stéphane Lehéricy
- From the Paris Brain Institute (Institut du Cerveau–ICM),
Center for Neuroimaging Research–CENIR, Hôpital
Pitié-Salpêtrière, 47 Boulevard de l’Hôpital,
CS 21414, 75646 Paris Cedex 13, France (G.G., L.Y.C., S.L., F.B.); Hopital
Pitié-Salpêtrière, ICM, Sorbonne Université, Inserm
U 1127, CNRS UMR 7225, Paris, France (G.G., F.X.L., L.Y.C., S.L., F.B., C.R.);
APHP-Urgences Cérébro-Vasculaires, Hôpital
Pitié-Salpêtrière, Paris, France (B.D.F., C.R.); Center for
Magnetic Resonance Research, Department of Radiology, University of Minnesota,
Minneapolis, Minn (G.G., M.M.); Paris Brain Institute’s Data Analysis
Core, Paris, France (F.X.L.); Clinical Imaging Sciences Centre, Brighton and
Sussex Medical School, Falmer, United Kingdom (I.R.); and STARE Team, iCRIN,
Institut du Cerveau et de la Moelle Épinière, ICM, Paris, France
(C.R.)
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Hanstock C, Beaulieu C. Rapid acquisition diffusion MR spectroscopy of metabolites in human brain. NMR IN BIOMEDICINE 2021; 34:e4270. [PMID: 32045958 DOI: 10.1002/nbm.4270] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 01/18/2020] [Accepted: 01/20/2020] [Indexed: 06/10/2023]
Abstract
Few studies have focused on metabolite diffusion in the human brain using 1 H-MRS due to significant technical challenges. Moreover, such studies have required lengthy acquisition times and are therefore impractical to implement clinically. By first characterizing and then minimizing the effects of linear and oscillating eddy currents, which arise from the diffusion gradients, and by implementing phase-cycle and slice-order strategies, as well as introducing a new phase-alignment methodology, we report a method that allows data acquisition requiring 20 seconds per spectrum. This remained feasible, even for b-values >8000 s/mm2 , with a rapid acquisition diffusion MRS methodology. It has allowed the nonlinear characterization of signal intensity with multiple b-values, and has improved the measurement of rotationally invariant diffusion parameters via six-direction, six b-value diffusion tensor spectroscopy (DTS) in 12 minutes at 4.7 T. The shorter DTS acquisition will enable its application to white matter regions not aligned with the gradients and permit clinical studies in a feasible time.
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Affiliation(s)
- Chris Hanstock
- Department of Biomedical Engineering, University of Alberta, Alberta, Canada
| | - Christian Beaulieu
- Department of Biomedical Engineering, University of Alberta, Alberta, Canada
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5
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Just N. Proton functional magnetic resonance spectroscopy in rodents. NMR IN BIOMEDICINE 2021; 34:e4254. [PMID: 31967711 DOI: 10.1002/nbm.4254] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 12/04/2019] [Accepted: 12/16/2019] [Indexed: 06/10/2023]
Abstract
Proton functional magnetic resonance spectroscopy (1 H-fMRS) in the human brain is able to assess and quantify the metabolic response due to localized brain activity. Currently, 1 H-fMRS of the human brain is complementary to functional magnetic resonance imaging (fMRI) and a recommended technique at high field strengths (>7 T) for the investigation of neurometabolic couplings, thereby providing insight into the mechanisms underlying brain activity and brain connectivity. Understanding typical healthy brain metabolism during a task is expected to provide a baseline from which to detect and characterize neurochemical alterations associated with various neurological or psychiatric disorders and diseases. It is of paramount importance to resolve fundamental questions related to the regulation of neurometabolic processes. New techniques such as optogenetics may be coupled to fMRI and fMRS to bring more specificity to investigations of brain cell populations during cerebral activation thus enabling a higher link to molecular changes and therapeutic advances. These rather novel techniques are mainly available for rodent applications and trigger renewed interest in animal fMRS. However, rodent fMRS remains fairly confidential due to its inherent low signal-to-noise ratio and its dependence on anesthesia. For instance, the accurate determination of metabolic concentration changes during stimulation requires robust knowledge of the physiological environment of the measured region of interest linked to anesthesia in most cases. These factors may also have a strong influence on B0 homogeneity. Therefore, a degree of calibration of the stimulus strength and duration may be needed for increased knowledge of the underpinnings of cerebral activity. Here, we propose an early review of the current status of 1 H-fMRS in rodents and summarize current difficulties and future perspectives.
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Affiliation(s)
- Nathalie Just
- Department of Clinical Radiology, University Hospital Münster, Germany
- INRAE, Centre, Tours Val de Loire, France
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6
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Temporal Dynamics of GABA and Glx in the Visual Cortex. eNeuro 2020; 7:ENEURO.0082-20.2020. [PMID: 32571964 PMCID: PMC7429906 DOI: 10.1523/eneuro.0082-20.2020] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 05/19/2020] [Accepted: 06/01/2020] [Indexed: 01/24/2023] Open
Abstract
Magnetic resonance spectroscopy (MRS) can be used in vivo to quantify neurometabolite concentration and provide evidence for the involvement of different neurotransmitter systems (e.g., inhibitory and excitatory) in sensory and cognitive processes. The relatively low signal-to-noise ratio of MRS measurements has shaped the types of questions that it has been used to address. In particular, temporal resolution is often sacrificed in MRS studies to achieve a signal sufficient to produce a reliable estimate of neurometabolite concentration. Here we apply novel analyses with large datasets from human participants (both sexes) to reveal the dynamics of GABA+ and Glx in visual cortex while participants are at rest (with eyes closed) and compare this with changes in posterior cingulate cortex from a previously collected dataset (under different conditions). We find that the dynamic concentration of GABA+ and Glx in visual cortex drifts in opposite directions; that is, GABA+ decreases while Glx increases over time. Further, we find that in visual, but not posterior cingulate cortex, the concentration of GABA+ predicts that of Glx 120 s later, such that a change in GABA+ is correlated with a subsequent opposite change in Glx. Together, these results expose novel temporal trends and interdependencies of primary neurotransmitters in visual cortex. More broadly, we demonstrate the feasibility of using MRS to investigate in vivo dynamic changes of neurometabolites.
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7
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Fernandes CC, Lanz B, Chen C, Morris PG. Measurement of brain lactate during visual stimulation using a long TE semi-LASER sequence at 7 T. NMR IN BIOMEDICINE 2020; 33:e4223. [PMID: 31995265 PMCID: PMC7079106 DOI: 10.1002/nbm.4223] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 10/21/2019] [Accepted: 10/22/2019] [Indexed: 05/14/2023]
Abstract
Estimation of metabolic changes during neuronal activation represents a challenge for in vivo MRS, especially for metabolites with low concentration and signal overlap, such as lactate. In this work, we aimed to evaluate the feasibility of detecting lactate during brain activation using a long TE (144 ms) semi-LASER sequence at 7 T. 1H spectra were acquired on healthy volunteers ( N=6 ) during a paradigm with 15 min of visual stimulation. Outer-volume signals were further attenuated by the use of saturation slabs, and macromolecular signals in the vicinity of the inverted lactate peak were individually fitted with simulated Lorentzian peaks. All spectra were free of artefacts and highly reproducible across subjects. Lactate was accurately quantified with an average Cramér-Rao lower bound of 8%. Statistically significant ( P<0.05 , one-tailed t -test) increases in lactate ( ∼ 10%) and glutamate ( ∼ 3%) levels during stimulation were detected in the visual cortex. Lactate and glutamate changes were consistent with previous measurements. We demonstrated that quantification of a clear and non-contaminated lactate peak obtained with a long TE sequence has the potential of improving the accuracy of functional MRS studies targeting non-oxidative reaction pathways.
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Affiliation(s)
- Carolina C. Fernandes
- Sir Peter Mansfield Imaging CentreUniversity of NottinghamNottingham, NG7 2RDNottinghamshireUnited Kingdom
| | - Bernard Lanz
- Sir Peter Mansfield Imaging CentreUniversity of NottinghamNottingham, NG7 2RDNottinghamshireUnited Kingdom
| | - Chen Chen
- Sir Peter Mansfield Imaging CentreUniversity of NottinghamNottingham, NG7 2RDNottinghamshireUnited Kingdom
| | - Peter G. Morris
- Sir Peter Mansfield Imaging CentreUniversity of NottinghamNottingham, NG7 2RDNottinghamshireUnited Kingdom
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Rideaux R, Goncalves NR, Welchman AE. Mixed-polarity random-dot stereograms alter GABA and Glx concentration in the early visual cortex. J Neurophysiol 2019; 122:888-896. [PMID: 31291136 PMCID: PMC6734395 DOI: 10.1152/jn.00208.2019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The offset between images projected onto the left and right retina (binocular disparity) provides a powerful cue to the three-dimensional structure of the environment. It was previously shown that depth judgements are better when images comprise both light and dark features, rather than only light or only dark elements. Since Harris and Parker (Nature 374: 808-811, 1995) discovered the "mixed-polarity benefit," there has been limited evidence supporting their hypothesis that the benefit is due to separate bright and dark channels. Goncalves and Welchman (Curr Biol 27: 1403-1412, 2017) observed that single- and mixed-polarity stereograms evoke different levels of positive and negative activity in a deep neural network trained on natural images to make depth judgements, which also showed the mixed-polarity benefit. Motivated by this discovery, we seek to test the potential for changes in the balance of excitation and inhibition that are produced by viewing these stimuli. In particular, we use magnetic resonance spectroscopy to measure Glx and GABA concentrations in the early visual cortex of adult humans during viewing of single- and mixed-polarity random-dot stereograms (RDS). We find that participants' Glx concentration is significantly higher, whereas GABA concentration is significantly lower, when mixed-polarity RDS are viewed than when single-polarity RDS are viewed. These results indicate that excitation and inhibition facilitate processing of single- and mixed-polarity stereograms in the early visual cortex to different extents, consistent with recent theoretical work (Goncalves NR, Welchman AE. Curr Biol 27: 1403-1412, 2017).NEW & NOTEWORTHY Depth judgements are better when images comprise both light and dark features, rather than only light or only dark elements. Using magnetic resonance spectroscopy, we show that adult human participants' Glx concentration is significantly higher whereas GABA concentration is significantly lower in the early visual cortex when participants view mixed-polarity random-dot stereograms (RDS) compared with single-polarity RDS. These results indicate that excitation and inhibition facilitate processing of single- and mixed-polarity stereograms in the early visual cortex to different extents.
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Affiliation(s)
- Reuben Rideaux
- Department of Psychology, University of Cambridge, Cambridge, United Kingdom
| | - Nuno R Goncalves
- Department of Psychology, University of Cambridge, Cambridge, United Kingdom
| | - Andrew E Welchman
- Department of Psychology, University of Cambridge, Cambridge, United Kingdom
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Jones DK, Alexander DC, Bowtell R, Cercignani M, Dell'Acqua F, McHugh DJ, Miller KL, Palombo M, Parker GJM, Rudrapatna US, Tax CMW. Microstructural imaging of the human brain with a 'super-scanner': 10 key advantages of ultra-strong gradients for diffusion MRI. Neuroimage 2018; 182:8-38. [PMID: 29793061 DOI: 10.1016/j.neuroimage.2018.05.047] [Citation(s) in RCA: 105] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Revised: 05/17/2018] [Accepted: 05/18/2018] [Indexed: 12/13/2022] Open
Abstract
The key component of a microstructural diffusion MRI 'super-scanner' is a dedicated high-strength gradient system that enables stronger diffusion weightings per unit time compared to conventional gradient designs. This can, in turn, drastically shorten the time needed for diffusion encoding, increase the signal-to-noise ratio, and facilitate measurements at shorter diffusion times. This review, written from the perspective of the UK National Facility for In Vivo MR Imaging of Human Tissue Microstructure, an initiative to establish a shared 300 mT/m-gradient facility amongst the microstructural imaging community, describes ten advantages of ultra-strong gradients for microstructural imaging. Specifically, we will discuss how the increase of the accessible measurement space compared to a lower-gradient systems (in terms of Δ, b-value, and TE) can accelerate developments in the areas of 1) axon diameter distribution mapping; 2) microstructural parameter estimation; 3) mapping micro-vs macroscopic anisotropy features with gradient waveforms beyond a single pair of pulsed-gradients; 4) multi-contrast experiments, e.g. diffusion-relaxometry; 5) tractography and high-resolution imaging in vivo and 6) post mortem; 7) diffusion-weighted spectroscopy of metabolites other than water; 8) tumour characterisation; 9) functional diffusion MRI; and 10) quality enhancement of images acquired on lower-gradient systems. We finally discuss practical barriers in the use of ultra-strong gradients, and provide an outlook on the next generation of 'super-scanners'.
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Affiliation(s)
- D K Jones
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Maindy Road, Cardiff, CF24 4HQ, UK; School of Psychology, Faculty of Health Sciences, Australian Catholic University, Melbourne, Victoria, 3065, Australia.
| | - D C Alexander
- Centre for Medical Image Computing (CMIC), Department of Computer Science, UCL (University College London), Gower Street, London, UK; Clinical Imaging Research Centre, National University of Singapore, Singapore
| | - R Bowtell
- Sir Peter Mansfield Magnetic Resonance Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham, UK
| | - M Cercignani
- Department of Psychiatry, Brighton and Sussex Medical School, Brighton, UK
| | - F Dell'Acqua
- Natbrainlab, Department of Neuroimaging, King's College London, London, UK
| | - D J McHugh
- Division of Informatics, Imaging and Data Sciences, The University of Manchester, Manchester, UK; CRUK and EPSRC Cancer Imaging Centre in Cambridge and Manchester, Cambridge and Manchester, UK
| | - K L Miller
- Oxford Centre for Functional MRI of the Brain, University of Oxford, Oxford, UK
| | - M Palombo
- Centre for Medical Image Computing (CMIC), Department of Computer Science, UCL (University College London), Gower Street, London, UK
| | - G J M Parker
- Division of Informatics, Imaging and Data Sciences, The University of Manchester, Manchester, UK; CRUK and EPSRC Cancer Imaging Centre in Cambridge and Manchester, Cambridge and Manchester, UK; Bioxydyn Ltd., Manchester, UK
| | - U S Rudrapatna
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Maindy Road, Cardiff, CF24 4HQ, UK
| | - C M W Tax
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Maindy Road, Cardiff, CF24 4HQ, UK
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Palombo M, Shemesh N, Ronen I, Valette J. Insights into brain microstructure from in vivo DW-MRS. Neuroimage 2018; 182:97-116. [DOI: 10.1016/j.neuroimage.2017.11.028] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2017] [Revised: 10/09/2017] [Accepted: 11/15/2017] [Indexed: 12/27/2022] Open
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11
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Budinger TF, Bird MD. MRI and MRS of the human brain at magnetic fields of 14 T to 20 T: Technical feasibility, safety, and neuroscience horizons. Neuroimage 2018; 168:509-531. [DOI: 10.1016/j.neuroimage.2017.01.067] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 01/23/2017] [Accepted: 01/27/2017] [Indexed: 11/16/2022] Open
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Abstract
Since the original observation by Zeeman, that spectral lines can be affected by magnetic fields, 'magnetic spectroscopy' has evolved into the broad arsenal of techniques known as 'magnetic resonance'. This review focuses on nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR), and muon spin resonance (μSR): methods which have provided unparalleled insight into the structures, reactivity and dynamics of molecules, and thereby contributed to a detailed understanding of important aspects of chemistry, and the materials, biomedical, and environmental sciences. Magnetic resonance imaging (MRI), in vivo magnetic resonance spectroscopy (MRS) and functional magnetic resonance spectroscopy (fMRS) are also described. EPR is outlined as a principal method for investigating free radicals, along with biomedical applications, and mention is given to the more recent innovation of pulsed EPR techniques. In the final section of the article, the various methods known as μSR are collected under the heading 'muon spin resonance', in order to emphasise their complementarity with the more familiar NMR and EPR.
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Bodini B, Branzoli F, Poirion E, García-Lorenzo D, Didier M, Maillart E, Socha J, Bera G, Lubetzki C, Ronen I, Lehericy S, Stankoff B. Dysregulation of energy metabolism in multiple sclerosis measured in vivo with diffusion-weighted spectroscopy. Mult Scler 2017; 24:313-321. [DOI: 10.1177/1352458517698249] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Objective: We employed diffusion-weighted magnetic resonance spectroscopy (DW-MRS), which allows to measure in vivo the diffusion properties of metabolites, to explore the functional neuro-axonal damage and the ongoing energetic dysregulation in multiple sclerosis (MS). Methods: Twenty-five patients with MS and 18 healthy controls (HC) underwent conventional magnetic resonance imaging (MRI) and DW-MRS. The apparent diffusion coefficient (ADC) of total N-acetyl-aspartate (tNAA) and creatine–phosphocreatine (tCr) were measured in the parietal normal-appearing white matter (NAWM) and in the thalamic grey matter (TGM). Multiple regressions were used to compare metabolite ADCs between groups and to explore clinical correlations. Results: In patients compared with HCs, we found a reduction in ADC(tNAA) in the TGM, reflecting functional and structural neuro-axonal damage, and in ADC(tCr) in both NAWM and TGM, possibly reflecting a reduction in energy supply in neurons and glial cells. Metabolite ADCs did not correlate with tissue atrophy, lesional volume or metabolite concentrations, while in TGM metabolite ADCs correlated with clinical scores. Conclusion: DW-MRS showed a reduction in tCr diffusivity in the normal-appearing brain of patients with MS, which might reflect a state of ongoing energy dysregulation affecting neurons and/or glial cells. Reversing this energy dysregulation before neuro-axonal degeneration arises may become a key objective in future neuroprotective strategies.
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Affiliation(s)
- Benedetta Bodini
- Institut du Cerveau et de la Moelle épinière (ICM), CNRS UMR 7225, INSERM, Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, Hôpital de la Pitié Salpêtrière, Paris, France/AP-HP, Hôpital de la Pitié Salpêtrière, Paris, France/AP-HP, Hôpital Saint-Antoine, Paris, France
| | - Francesca Branzoli
- Institut du Cerveau et de la Moelle épinière (ICM), CNRS UMR 7225, INSERM, Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, Hôpital de la Pitié Salpêtrière, Paris, France/Centre de NeuroImagerie de Recherche – Institut du Cerveau et de la Moelle épinière (ICM), Paris, France
| | - Emilie Poirion
- Institut du Cerveau et de la Moelle épinière (ICM), CNRS UMR 7225, INSERM, Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, Hôpital de la Pitié Salpêtrière, Paris, France
| | - Daniel García-Lorenzo
- Institut du Cerveau et de la Moelle épinière (ICM), CNRS UMR 7225, INSERM, Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, Hôpital de la Pitié Salpêtrière, Paris, France
| | - Mélanie Didier
- Institut du Cerveau et de la Moelle épinière (ICM), CNRS UMR 7225, INSERM, Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, Hôpital de la Pitié Salpêtrière, Paris, France/Centre de NeuroImagerie de Recherche – Institut du Cerveau et de la Moelle épinière (ICM), Paris, France
| | | | - Julie Socha
- AP-HP, Hôpital de la Pitié Salpêtrière, Paris, France
| | - Geraldine Bera
- Institut du Cerveau et de la Moelle épinière (ICM), CNRS UMR 7225, INSERM, Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, Hôpital de la Pitié Salpêtrière, Paris, France
| | - Catherine Lubetzki
- Institut du Cerveau et de la Moelle épinière (ICM), CNRS UMR 7225, INSERM, Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, Hôpital de la Pitié Salpêtrière, Paris, France/AP-HP, Hôpital de la Pitié Salpêtrière, Paris, France
| | - Itamar Ronen
- Department of Radiology, Leiden University Medical Centre, Leiden, The Netherlands
| | - Stephane Lehericy
- Institut du Cerveau et de la Moelle épinière (ICM), CNRS UMR 7225, INSERM, Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, Hôpital de la Pitié Salpêtrière, Paris, France/Centre de NeuroImagerie de Recherche – Institut du Cerveau et de la Moelle épinière (ICM), Paris, France/AP-HP, Hôpital de la Pitié Salpêtrière, Paris, France
| | - Bruno Stankoff
- Institut du Cerveau et de la Moelle épinière (ICM), CNRS UMR 7225, INSERM, Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, Hôpital de la Pitié Salpêtrière, Paris, France/AP-HP, Hôpital Saint-Antoine, Paris, France
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14
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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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15
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Ligneul C, Valette J. Probing metabolite diffusion at ultra-short time scales in the mouse brain using optimized oscillating gradients and "short"-echo-time diffusion-weighted MRS. NMR IN BIOMEDICINE 2017; 30:10.1002/nbm.3671. [PMID: 27891691 PMCID: PMC5164933 DOI: 10.1002/nbm.3671] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 10/13/2016] [Accepted: 10/18/2016] [Indexed: 05/29/2023]
Abstract
Measuring diffusion at ultra-short time scales may yield information about short-range intracellular structure and cytosol viscosity. However, reaching such time scales usually requires oscillating gradients, which in turn imply long echo times TE . Here we propose a new kind of stretched oscillating gradient that allows us to increase diffusion-weighting b while preserving spectral and temporal properties of the gradient modulation. We used these optimized gradients to measure metabolite diffusion in the mouse brain down to effective diffusion times of 1 ms while keeping TE relatively short (60 ms). At such TE , a significant macromolecule signal could still be observed and used as an internal reference of approximately null diffusivity, which proved critical to discard datasets corrupted by some motion artifact. The methods introduced here may be useful to improve the accuracy and precision of metabolite apparent diffusion coefficient measurements with oscillating gradients.
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Affiliation(s)
- Clémence Ligneul
- Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA), Direction de la Recherche Fondamentale (DRF), Institut d’Imagerie Biomédicale (I2BM), MIRCen, F-92260 Fontenay-aux-Roses, France
- Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud, Université Paris-Saclay, UMR 9199, Neurodegenerative Diseases Laboratory, F-92260 Fontenay-aux-Roses, France
| | - Julien Valette
- Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA), Direction de la Recherche Fondamentale (DRF), Institut d’Imagerie Biomédicale (I2BM), MIRCen, F-92260 Fontenay-aux-Roses, France
- Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud, Université Paris-Saclay, UMR 9199, Neurodegenerative Diseases Laboratory, F-92260 Fontenay-aux-Roses, France
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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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Branzoli F, Ercan E, Valabrègue R, Wood ET, Buijs M, Webb A, Ronen I. Differentiating between axonal damage and demyelination in healthy aging by combining diffusion-tensor imaging and diffusion-weighted spectroscopy in the human corpus callosum at 7 T. Neurobiol Aging 2016; 47:210-217. [PMID: 27616673 DOI: 10.1016/j.neurobiolaging.2016.07.022] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 07/28/2016] [Accepted: 07/30/2016] [Indexed: 11/30/2022]
Abstract
Diffusion-tensor imaging and single voxel diffusion-weighted magnetic resonance spectroscopy were used at 7T to explore in vivo age-related microstructural changes in the corpus callosum. Sixteen healthy elderly (age range 60-71 years) and 13 healthy younger controls (age range 23-32 years) were included in the study. In healthy elderly, we found lower water fractional anisotropy and higher water mean diffusivity and radial diffusivity in the corpus callosum, indicating the onset of demyelination processes with healthy aging. These changes were not associated with a concomitant significant difference in the cytosolic diffusivity of the intra-axonal metabolite N-acetylaspartate (p = 0.12), the latter representing a pure measure of intra-axonal integrity. It was concluded that the possible intra-axonal changes associated with normal aging processes are below the detection level of diffusion-weighted magnetic resonance spectroscopy in our experiment (e.g., smaller than 10%) in the age range investigated. Lower axial diffusivity of total creatine was observed in the elderly group (p = 0.058), possibly linked to a dysfunction in the energy metabolism associated with a deficit in myelin synthesis.
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Affiliation(s)
- Francesca Branzoli
- Centre de NeuroImagerie de Recherche - CENIR, Institut du Cerveau et de la Moelle épinière - ICM, Paris, France; Sorbonne Universités, UPMC Paris 06, Inserm UMR S 1127, CNRS UMR 7225, Paris, France.
| | - Ece Ercan
- C. J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, Netherlands
| | - Romain Valabrègue
- Centre de NeuroImagerie de Recherche - CENIR, Institut du Cerveau et de la Moelle épinière - ICM, Paris, France; Sorbonne Universités, UPMC Paris 06, Inserm UMR S 1127, CNRS UMR 7225, Paris, France
| | - Emily T Wood
- NeuroImmunology Branch (NINDS), National Institutes of Health, Bethesda, MD, USA
| | - Mathijs Buijs
- C. J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, Netherlands
| | - Andrew Webb
- C. J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, Netherlands
| | - Itamar Ronen
- C. J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, Netherlands
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18
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Transportation in the Interstitial Space of the Brain Can Be Regulated by Neuronal Excitation. Sci Rep 2015; 5:17673. [PMID: 26631412 PMCID: PMC4668547 DOI: 10.1038/srep17673] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 10/30/2015] [Indexed: 01/03/2023] Open
Abstract
The transportation of substances in the interstitial space (ISS) is crucial for the maintenance of brain homeostasis, however its link to neuronal activity remains unclear. Here, we report a marked reduction in substance transportation in the ISS after neuronal excitation. Using a tracer-based method, water molecules in the interstitial fluid (ISF) could be specifically visualized in magnetic resonance (MR) imaging. We first observed the flow of ISF in the thalamus and caudate nucleus of a rat. The ISF flow was then modulated using a painful stimulation model. We demonstrated that the flow of ISF slowed significantly following neuronal activity in the thalamus. This reduction in ISF flow continued for hours and was not accompanied by slow diffusion into the ISS. This observation suggests that the transportation of substances into the ISS can be regulated with a selective external stimulation.
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19
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Wood ET, Ercan AE, Branzoli F, Webb A, Sati P, Reich DS, Ronen I. Reproducibility and optimization of in vivo human diffusion-weighted MRS of the corpus callosum at 3 T and 7 T. NMR IN BIOMEDICINE 2015; 28:976-987. [PMID: 26084563 PMCID: PMC5082280 DOI: 10.1002/nbm.3340] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 04/10/2015] [Accepted: 05/14/2015] [Indexed: 05/12/2023]
Abstract
Diffusion-weighted MRS (DWS) of brain metabolites enables the study of cell-specific alterations in tissue microstructure by probing the diffusion of intracellular metabolites. In particular, the diffusion properties of neuronal N-acetylaspartate (NAA), typically co-measured with N-acetylaspartyl glutamate (NAAG) (NAA + NAAG = tNAA), have been shown to be sensitive to intraneuronal/axonal damage in pathologies such as stroke and multiple sclerosis. Lacking, so far, are empirical assessments of the reproducibility of DWS measures across time and subjects, as well as a systematic investigation of the optimal acquisition parameters for DWS experiments, both of which are sorely needed for clinical applications of the method. In this study, we acquired comprehensive single-volume DWS datasets of the human corpus callosum at 3 T and 7 T. We investigated the inter- and intra-subject variability of empirical and modeled diffusion properties of tNAA [D(avg) (tNAA) and D(model) (tNAA), respectively]. Subsequently, we used a jackknife-like resampling approach to explore the variance of these properties in partial data subsets reflecting different total scan durations. The coefficients of variation (C(V)) and repeatability coefficients (C(R)) for D(avg) (tNAA) and D(model) (tNAA) were calculated for both 3 T and 7 T, with overall lower variability in the 7 T results. Although this work is limited to the estimation of the diffusion properties in the corpus callosum, we show that a careful choice of diffusion-weighting conditions at both field strengths allows the accurate measurement of tNAA diffusion properties in clinically relevant experimental time. Based on the resampling results, we suggest optimized acquisition schemes of 13-min duration at 3T and 10-min duration at 7 T, whilst retaining low variability (C(V) ≈ 8%) for the tNAA diffusion measures. Power calculations for the estimation of D(model )(tNAA) and D(avg) (tNAA) based on the suggested schemes show that less than 21 subjects per group are sufficient for the detection of a 10% effect between two groups in case-control studies.
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Affiliation(s)
- Emily T. Wood
- Translational Neuroradiology Unit (NINDS), National Institutes of Health, Bethesda, MD, USA
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Ayse Ece Ercan
- C. J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Francesca Branzoli
- Institut du Cerveau et de la Moelle épinière - ICM, Centre for NeuroImaging Research – CENIR, Paris, France
- Sorbonne Universités, UPMC Paris 06, Inserm UMR S 1127, CNRS UMR 7225, Paris, France
| | - Andrew Webb
- C. J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Pascal Sati
- Translational Neuroradiology Unit (NINDS), National Institutes of Health, Bethesda, MD, USA
| | - Daniel S. Reich
- Translational Neuroradiology Unit (NINDS), National Institutes of Health, Bethesda, MD, USA
| | - Itamar Ronen
- C. J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands
- Correspondence to: I. Ronen, C. J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Albinusdreef 2, Leiden 2333ZA, the Netherlands.
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Brain intracellular metabolites are freely diffusing along cell fibers in grey and white matter, as measured by diffusion-weighted MR spectroscopy in the human brain at 7 T. Brain Struct Funct 2014; 221:1245-54. [PMID: 25520054 DOI: 10.1007/s00429-014-0968-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 12/11/2014] [Indexed: 01/13/2023]
Abstract
Due to the specific compartmentation of brain metabolites, diffusion-weighted magnetic resonance spectroscopy opens unique insight into neuronal and astrocytic microstructures. The apparent diffusion coefficient (ADC) of brain metabolites depends on various intracellular parameters including cytosol viscosity and molecular crowding. When diffusion time (t d) is long enough, the size and geometry of the compartment in which the metabolites diffuse strongly influence metabolites ADC. In a previous study, performed in the macaque brain, we measured neuronal and astrocytic metabolites ADC at long t d (from 86 to 1,011 ms) in a large voxel enclosing an equal proportion of white and grey matter. We showed that metabolites apparently diffuse freely along the axis of dendrites, axons and astrocytic processes. To assess potential differences between these two tissue types, here we measured for the first time in the Human brain the t d-dependency of metabolites trace/3 ADC at 7 teslas using a localized diffusion-weighted STEAM sequence, in parietal and occipital voxels, respectively, containing mainly white and grey matter. We show that, in both tissues and over the observed timescale (t d varying from 92 to 712 ms) metabolite ADC reaches a non-zero plateau, suggesting that metabolites are not confined inside subcellular regions such as cell bodies, or inside subcellular compartments such as organelles, but are rather free to diffuse in the whole fiber-like structure of neurons and astrocytes. Beyond the fundamental insights into intracellular compartmentation of metabolites, this work also provides a new framework for interpreting results of neuroimaging techniques based on molecular diffusion, such as diffusion-weighted magnetic resonance spectroscopy and imaging.
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21
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Wang AM, Cao P, Yee A, Chan D, Wu EX. Detection of extracellular matrix degradation in intervertebral disc degeneration by diffusion magnetic resonance spectroscopy. Magn Reson Med 2014; 73:1703-12. [PMID: 24817583 DOI: 10.1002/mrm.25289] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 04/16/2014] [Accepted: 04/22/2014] [Indexed: 01/07/2023]
Abstract
PURPOSE To investigate whether diffusion magnetic resonance spectroscopy (MRS) can detect the extracellular matrix (ECM) degradation during intervertebral disc degeneration (IVDD) by the increased mobility of ECM macromolecules such as proteoglycans and collagens. METHODS Fresh bovine intervertebral discs were injected with papain solution to induce ECM degradation. The apparent diffusion coefficients (ADCs), T2 values, and contents of ECM macromolecules and water resonances were measured longitudinally in the nucleus pulposus. RESULTS The macromolecule ADCs increased drastically at day 1 after papain injection, and continued increasing for 5 days. In contrast, the proteoglycan content exhibited a small and slow decrease after injection while the macromolecule T2 values, water T2, ADC, and content showed slight increase or no change. The protein gel electrophoresis analysis confirmed the gradually increased ECM fragmentation in accordance with the observed macromolecule ADC increases. CONCLUSION Diffusion MRS provides a new method to characterize the ECM degradation processes directly and sensitively. Macromolecule ADCs offer a potentially more sensitive and earlier marker for ECM degradation than the proteoglycan content and T2, and water MR properties during early IVDD. Such diffusion approach offers the possibility to directly monitor ECM integrity and degradation processes in vivo at molecular and microstructural levels in both preclinical and clinical settings.
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Affiliation(s)
- Anna M Wang
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR, China; Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
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22
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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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23
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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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Schaller B, Xin L, O'Brien K, Magill AW, Gruetter R. Are glutamate and lactate increases ubiquitous to physiological activation? A (1)H functional MR spectroscopy study during motor activation in human brain at 7Tesla. Neuroimage 2014; 93 Pt 1:138-45. [PMID: 24555953 DOI: 10.1016/j.neuroimage.2014.02.016] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 01/28/2014] [Accepted: 02/10/2014] [Indexed: 11/19/2022] Open
Abstract
Recent studies at high field (7Tesla) have reported small metabolite changes, in particular lactate and glutamate (below 0.3μmol/g) during visual stimulation. These studies have been limited to the visual cortex because of its high energy metabolism and good magnetic resonance spectroscopy (MRS) sensitivity using surface coil. The aim of this study was to extend functional MRS (fMRS) to investigate for the first time the metabolite changes during motor activation at 7T. Small but sustained increases in lactate (0.17μmol/g±0.05μmol/g, p<0.001) and glutamate (0.17μmol/g±0.09μmol/g, p<0.005) were detected during motor activation followed by a return to the baseline after the end of activation. The present study demonstrates that increases in lactate and glutamate during motor stimulation are small, but similar to those observed during visual stimulation. From the observed glutamate and lactate increase, we inferred that these metabolite changes may be a general manifestation of the increased neuronal activity. In addition, we propose that the measured metabolite concentration increases imply an increase in ΔCMRO2 that is transiently below that of ΔCMRGlc during the first 1 to 2min of the stimulation.
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Affiliation(s)
- Benoît Schaller
- Laboratory of Functional and Metabolic Imaging, Ecole Polytechnique Federale de Lausanne, Station 6, 1015 Lausanne, Switzerland.
| | - Lijing Xin
- Department of Radiology, University Hospitals of Lausanne Rue du Bugnon 21, 1011 Lausanne, Switzerland.
| | - Kieran O'Brien
- Centre d'Imagerie BioMédicale, University of Geneva, Geneva 14, Geneva, Switzerland.
| | - Arthur W Magill
- Laboratory of Functional and Metabolic Imaging, Ecole Polytechnique Federale de Lausanne, Station 6, 1015 Lausanne, Switzerland; Department of Radiology, University Hospitals of Lausanne Rue du Bugnon 21, 1011 Lausanne, Switzerland.
| | - Rolf Gruetter
- Laboratory of Functional and Metabolic Imaging, Ecole Polytechnique Federale de Lausanne, Station 6, 1015 Lausanne, Switzerland; Department of Radiology, University Hospitals of Lausanne Rue du Bugnon 21, 1011 Lausanne, Switzerland; Department of Radiology, University Hospitals of Geneva, Rue Gabrielle-Perret-Gentil 4, 1211 Geneva 14, Switzerland.
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Mandl RCW, Schnack HG, Zwiers MP, Kahn RS, Hulshoff Pol HE. Functional diffusion tensor imaging at 3 Tesla. Front Hum Neurosci 2013; 7:817. [PMID: 24409133 PMCID: PMC3847896 DOI: 10.3389/fnhum.2013.00817] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Accepted: 11/11/2013] [Indexed: 11/13/2022] Open
Abstract
In a previous study we reported on a non-invasive functional diffusion tensor imaging (fDTI) method to measure neuronal signals directly from subtle changes in fractional anisotropy along white matter tracts. We hypothesized that these fractional anisotropy changes relate to morphological changes of glial cells induced by axonal activity. In the present study we set out to replicate the results of the previous study with an improved fDTI scan acquisition scheme. A group of twelve healthy human participants were scanned on a 3 Tesla MRI scanner. Activation was revealed in the contralateral thalamo-cortical tract and optic radiations during tactile and visual stimulation, respectively. Mean percent signal change in FA was 3.47% for the tactile task and 3.79% for the visual task, while for the MD the mean percent signal change was only -0.10 and -0.09%. The results support the notion of different response functions for tactile and visual stimuli. With this study we successfully replicated our previous findings using the same types of stimuli but on a different group of healthy participants and at different field-strength. The successful replication of our first fDTI results suggests that the non-invasive fDTI method is robust enough to study the functional neural networks in the human brain within a practically feasible time period.
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Affiliation(s)
- René C W Mandl
- 1Department of Psychiatry, Brain Center Rudolf Magnus, University Medical Center Utrecht Utrecht, Netherlands
| | - Hugo G Schnack
- 1Department of Psychiatry, Brain Center Rudolf Magnus, University Medical Center Utrecht Utrecht, Netherlands
| | - Marcel P Zwiers
- 2Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour Centre for Cognitive Neuroimaging Nijmegen, Netherlands
| | - René S Kahn
- 1Department of Psychiatry, Brain Center Rudolf Magnus, University Medical Center Utrecht Utrecht, Netherlands
| | - Hilleke E Hulshoff Pol
- 1Department of Psychiatry, Brain Center Rudolf Magnus, University Medical Center Utrecht Utrecht, Netherlands
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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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