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Mandal PK, Guha Roy R, Samkaria A, Maroon JC, Arora Y. In Vivo 13C Magnetic Resonance Spectroscopy for Assessing Brain Biochemistry in Health and Disease. Neurochem Res 2022; 47:1183-1201. [PMID: 35089504 DOI: 10.1007/s11064-022-03538-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 01/15/2022] [Accepted: 01/19/2022] [Indexed: 12/27/2022]
Abstract
Magnetic resonance spectroscopy (MRS) is a non-invasive technique that contributes to the elucidation of brain biochemistry. 13C MRS enables the detection of specific neurochemicals and their neuroenergetic correlation with neuronal function. The synergistic outcome of 13C MRS and the infusion of 13C-labeled substrates provide an understanding of neurometabolism and the role of glutamate/gamma-aminobutyric acid (GABA) neurotransmission in diseases, such as Alzheimer's disease, schizophrenia, and bipolar disorder. Moreover, 13C MRS provides a window into the altered flux rate of different pathways, including the tricarboxylic acid cycle (TCA) and the glutamate/glutamine/GABA cycle, in health and in various diseases. Notably, the metabolic flux rate of the TCA cycle often decreases in neurodegenerative diseases. Additionally, 13C MRS can be used to investigate several psychiatric and neurological disorders as it directly reflects the real-time production and alterations of key brain metabolites. This review aims to highlight the chronology, the technological advancements, and the applications of 13C MRS in various brain diseases.
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Affiliation(s)
- Pravat K Mandal
- Neuroimaging and Neurospectroscopy (NINS) Laboratory, National Brain Research Centre (NBRC), Gurgaon, India.
- Florey Institute of Neuroscience and Mental Health, Melbourne School of Medicine Campus, Melbourne, Australia.
| | - Rimil Guha Roy
- Neuroimaging and Neurospectroscopy (NINS) Laboratory, National Brain Research Centre (NBRC), Gurgaon, India
| | - Avantika Samkaria
- Neuroimaging and Neurospectroscopy (NINS) Laboratory, National Brain Research Centre (NBRC), Gurgaon, India
| | - Joseph C Maroon
- Department of Neurosurgery, University of Pittsburgh Medical School, Pittsburgh, PA, USA
| | - Yashika Arora
- Neuroimaging and Neurospectroscopy (NINS) Laboratory, National Brain Research Centre (NBRC), Gurgaon, India
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2
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Valette J, Tiret B, Boumezbeur F. Experimental strategies for in vivo 13C NMR spectroscopy. Anal Biochem 2016; 529:216-228. [PMID: 27515993 DOI: 10.1016/j.ab.2016.08.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 05/24/2016] [Accepted: 08/04/2016] [Indexed: 11/15/2022]
Abstract
In vivo carbon-13 (13C) MRS opens unique insights into the metabolism of intact organisms, and has led to major advancements in the understanding of cellular metabolism under normal and pathological conditions in various organs such as skeletal muscles, the heart, the liver and the brain. However, the technique comes at the expense of significant experimental difficulties. In this review we focus on the experimental aspects of non-hyperpolarized 13C MRS in vivo. Some of the enrichment strategies which have been proposed so far are described; the various MRS acquisition paradigms to measure 13C labeling are then presented. Finally, practical aspects of 13C spectral quantification are discussed.
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Affiliation(s)
- 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.
| | - Brice Tiret
- 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
| | - Fawzi Boumezbeur
- Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Direction de la Recherche Fondamentale (DRF), Institut d'Imagerie Biomédicale (I2BM), NeuroSpin, F-91190 Gif-sur-Yvette, France
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3
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Yahya A, De Zanche N, Allen PS. A dual-tuned transceive resonator for (13) C{(1) H} MRS: two open coils in one. NMR IN BIOMEDICINE 2013; 26:533-541. [PMID: 23401299 DOI: 10.1002/nbm.2890] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Revised: 10/01/2012] [Accepted: 10/18/2012] [Indexed: 06/01/2023]
Abstract
Proton-decoupled, (13) C nuclear MRS experiments require a RF coil that operates at the Larmor frequencies of both (13) C and (1) H. In this work, we designed, built and tested a single-unit, dual-tuned coil based on a half-birdcage open coil design. It was constructed as a low-pass network with a resonant trap in series with each leg. Traps are tuned in alternate legs such that the two resonant modes arise from currents on alternate legs. The coil performance was compared with that of a dual-tuned coil consisting of two proton surface coils operating in quadrature and a single surface coil for (13) C transmission and reception. The half-birdcage coil was shown to produce a more homogeneous RF field at each frequency and was more sensitive to a (13) C signal arising from regions further from the coil surface. The applicability of the coil in vivo was demonstrated by acquiring a proton decoupled, natural abundance (13) C glycogen signal from the calf of a normal volunteer.
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Affiliation(s)
- Atiyah Yahya
- Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada.
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Pan JW, Avdievich N, Hetherington HP. J-refocused coherence transfer spectroscopic imaging at 7 T in human brain. Magn Reson Med 2011; 64:1237-46. [PMID: 20648684 DOI: 10.1002/mrm.22534] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Short echo spectroscopy is commonly used to minimize signal modulation due to J-evolution of the cerebral amino acids. However, short echo acquisitions suffer from high sensitivity to macromolecules which make accurate baseline determination difficult. In this report, we describe implementation at 7 T of a double echo J-refocused coherence transfer sequence at echo time (TE) of 34 msec to minimize J-modulation of amino acids while also decreasing interfering macromolecule signals. Simulation of the pulse sequence at 7 T shows excellent resolution of glutamate, glutamine, and N-acetyl aspartate. B(1) sufficiency at 7 T for the double echo acquisition is achieved using a transceiver array with radiofrequency (RF) shimming. Using an alternate RF distribution to minimize receiver phase cancellation in the transceiver, accurate phase determination for the coherence transfer is achieved with rapid single scan calibration. This method is demonstrated in spectroscopic imaging mode with n = 5 healthy volunteers resulting in metabolite values consistent with literature and in a patient with epilepsy.
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Affiliation(s)
- J W Pan
- Department of Neurosurgery, Yale University School of Medicine, New Haven, Connecticut 06520-0882, USA.
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Henry PG, Marjanska M, Walls JD, Valette J, Gruetter R, Ugurbil K. Proton-observed carbon-edited NMR spectroscopy in strongly coupled second-order spin systems. Magn Reson Med 2006; 55:250-7. [PMID: 16402370 DOI: 10.1002/mrm.20764] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Proton-observed carbon-edited (POCE) NMR spectroscopy is commonly used to measure 13C labeling with higher sensitivity compared to direct 13C NMR spectroscopy, at the expense of spectral resolution. For weakly coupled first-order spin systems, the multiplet signal at a specific proton chemical shift in POCE spectra directly reflects 13C enrichment of the carbon attached to this proton. The present study demonstrates that this is not necessarily the case for strongly coupled second-order spin systems. In such cases NMR signals can be detected in the POCE spectra even at chemical shifts corresponding to protons bound to 12C. This effect is demonstrated theoretically with density matrix calculations and simulations, and experimentally with measured POCE spectra of [3-13C]glutamate.
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Affiliation(s)
- Pierre-Gilles Henry
- Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota Medical School, Minneapolis, Minnesota, USA.
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Srinivasan R, Cunningham C, Chen A, Vigneron D, Hurd R, Nelson S, Pelletier D. TE-Averaged two-dimensional proton spectroscopic imaging of glutamate at 3 T. Neuroimage 2006; 30:1171-8. [PMID: 16431138 DOI: 10.1016/j.neuroimage.2005.10.048] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2005] [Revised: 10/26/2005] [Accepted: 10/31/2005] [Indexed: 12/01/2022] Open
Abstract
Glutamate and glutamine are important neurochemicals in the central nervous system and the neurotoxic properties of excess glutamate have been associated with several neurodegenerative diseases. The TE-Averaged PRESS technique has been shown by our group to detect an unobstructed glutamate signal at 3 T that is resolved from glutamine and NAA at 2.35 ppm. TE-Averaged PRESS therefore provides an unambiguous measurement of glutamate as well as other metabolites such as NAA, choline, creatine, and myo-inositol. In this study, we extend the single voxel TE-Averaged PRESS technique for two-dimensional (2D) spectroscopic imaging (TE-Averaged MRSI) to generate 2D glutamate maps. To facilitate TE-Averaged MRSI within a reasonable time, a fast encoding trajectory was used. This enabled rapid acquisition of TE-Averaged spectral arrays with good spectral bandwidth (977 Hz) and resolution (approximately 2 Hz). MRSI data arrays of 10 x 16 were acquired with 1.8 cm3 spatial resolution over a approximately 110 cm3 volume in a scan time of approximately 21 min. Two-dimensional metabolite maps were obtained with good SNR and clear differentiation in glutamate levels was observed between gray and white matter with significantly higher glutamate in gray matter relative to white matter as anticipated.
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Affiliation(s)
- Radhika Srinivasan
- Center for Molecular and Functional Imaging, University of California San Francisco, 185 Berry Street, Suite #350, San Francisco, CA 94107-1739, USA.
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7
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Abstract
Localized 13C nuclear magnetic resonance (NMR) spectroscopy provides a unique window for studying cerebral carbohydrate metabolism through, e.g. the completely non-invasive measurement of cerebral glucose and glycogen metabolism. In addition, label incorporation into amino acid neurotransmitters such as glutamate (Glu), GABA and aspartate can be measured providing information on Krebs cycle flux and oxidative metabolism. Given the compartmentation of key enzymes such as pyruvate carboxylase and glutamine synthetase, the detection of label incorporation into glutamine indicated that neuronal and glial metabolism can be measured in vivo. The purpose of this paper is to provide a critical overview of these recent advances into measuring compartmentation of brain energy metabolism using localized in vivo 13C NMR spectroscopy. The studies reviewed herein showed that anaplerosis is significant in brain, as is oxidative ATP generation in glia and the rate of glial glutamine synthesis attributed to the replenishment of the neuronal Glu pool and that brain glycogen metabolism is slow under resting conditions. This new modality promises to provide a new investigative tool to study aspects of normal and diseased brain hitherto unaccessible, such as the interplay between glutamatergic action, glucose and glycogen metabolism during brain activation, and the derangements thereof in patients with hepatic encephalopathy, neurodegenerative diseases and diabetes.
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Affiliation(s)
- Rolf Gruetter
- Department of Radiology, Center for MR Research, University of Minnesota, 2021 6th Street SE, Minneapolis, MN 55455, USA.
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Blüml S, Moreno A, Hwang JH, Ross BD. 1-(13)C glucose magnetic resonance spectroscopy of pediatric and adult brain disorders. NMR IN BIOMEDICINE 2001; 14:19-32. [PMID: 11252037 DOI: 10.1002/nbm.679] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
With protocols designed for use in a clinical environment we investigated the feasibility and diagnostic potential of (13)C MRS after 1-(13)C labeled glucose infusion. (13)C MRS brain examinations were performed in 27 subjects (17 children and pediatric patients, six adult patients, and four adult controls), using a standard 1.5 T clinical MR scanner. 1-(13)C glucose, 99% enriched (20% w/v) was administered intravenously (690 or 210 mg/kg body weight) or orally (730 mg/kg). Cerebral (13)C-enrichment patterns and time courses were compared. 1-(13)C glucose appeared in brain spectra within 2.5-15 min, with ensuing enrichment of its metabolites. No complications were encountered. When data obtained in patients were compared with controls, striking abnormalities in hepatic encephalopathy and in premature brain were observed, consistent with reduced cerebral glucose metabolism. Abnormalities in the (13)C enrichment pattern were also observed in pediatric patients with leukodystrophies and mitochondrial disorders. In this preliminary survey, we conclude that (13)C MRS in combination with glucose infusion is safe and efficient and provides new insights into the pathophysiology of brain disorders.
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Affiliation(s)
- S Blüml
- Huntington Medical Research Institutes, 660 South Fair Oaks Blvd., Pasadena, CA 91105, USA
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Pan JW, Stein DT, Telang F, Lee JH, Shen J, Brown P, Cline G, Mason GF, Shulman GI, Rothman DL, Hetherington HP. Spectroscopic imaging of glutamate C4 turnover in human brain. Magn Reson Med 2000; 44:673-9. [PMID: 11064400 DOI: 10.1002/1522-2594(200011)44:5<673::aid-mrm3>3.0.co;2-l] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
One-dimensional spectroscopic imaging of (13)C-4-glutamate turnover is performed in the human brain with a 6 cc nominal voxel resolution at 4T. Data were acquired with an indirect detection approach using a short spin echo single quantum (1)H-(13)C heteronuclear editing method and a 7 cm surface coil with quadrature (13)C decoupling coils. To analyze the data as a function of tissue type, T(1)-based image segmentation through the surface coil was performed to determine the gray and white matter contributions to each voxel. The tricarboxylic acid (TCA) cycle rate in gray and white matter was then determined using a two-compartment model with the tissue fractionation derived from the image segmentation. The mean values for the TCA cycle rate for occipital gray and white matter from three volunteers was 0.88 +/- 0.12 and 0.28 +/- 0.13 respectively, in agreement with literature data.
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Affiliation(s)
- J W Pan
- Department of Medicine, Brookhaven National Laboratory, Upton, New York 11973-5000, USA.
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Pan JW, Rothman TL, Behar KL, Stein DT, Hetherington HP. Human brain beta-hydroxybutyrate and lactate increase in fasting-induced ketosis. J Cereb Blood Flow Metab 2000; 20:1502-7. [PMID: 11043913 DOI: 10.1097/00004647-200010000-00012] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Ketones are known to constitute an important fraction of fuel for consumption by the brain, with brain ketone content generally thought to be low. However, the recent observation of 1-mmol/L levels of brain beta-hydroxybutyrate (BHB) in children on the ketogenic diet suggests otherwise. The authors report the measurement of brain BHB and lactate in the occipital lobe of healthy adults using high field (4-T) magnetic resonance spectroscopy, measured in the nonfasted state and after 2- and 3-day fasting-induced ketosis. A 9-mL voxel located in the calcarine fissure was studied, detecting the BHB and lactate upfield resonances using a 1H homonuclear editing sequence. Plasma BHB levels also were measured. The mean brain BHB concentration increased from a nonfasted level of 0.05 +/- 0.05 to 0.60 +/- 0.26 mmol/L (after second day of fasting), increasing further to 0.98 +/- 0.16 mmol/L (after the third day of fasting). The mean nonfasted brain lactate was 0.69 +/- 0.17 mmol/L, increasing to 1.47 +/- 0.22 mmol/L after the third day. The plasma and brain BHB levels correlated well (r = 0.86) with a brain-plasma slope of 0.26. These data show that brain BHB rises significantly with 2- and 3-day fasting-induced ketosis. The lactate increase likely results from ketones displacing lactate oxidation without altering glucose phosphorylation and glycolysis.
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Affiliation(s)
- J W Pan
- Department of Medicine, Brookhaven National Laboratory, Upton, New York 11973, USA
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11
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Abstract
A new scheme is proposed to edit separately glutamate C(3) and C(4) resonances of (1)H bound to (13)C, in order to resolve these two signals which overlap at intermediate magnetic fields (1.5 T-3 T), commonly available for human brain studies. The two edited spectra are obtained by combining the individual acquisitions from a four-scan measurement in two different ways. The four acquisitions correspond to the two steps of the classical POCE scheme combined with another two-scan module, where the relative phases of the C(3) and C(4) (1)H resonances are manipulated using zero quantum and double quantum coherence pathways. This new technique exhibits the same sensitivity as POCE and allows the (13)C labeling of C(3) and C(4) glutamate from [1-(13)C]glucose to be monitored separately in the rat brain at 3 T.
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Affiliation(s)
- P G Henry
- CEA, Service Hospitalier Frédéric Joliot, Département de Recherche Médicale, Orsay, France
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12
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Blüml S, Hwang JH, Moreno A, Ross BD. Novel peak assignments of in vivo (13)C MRS in human brain at 1.5 T. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2000; 143:292-298. [PMID: 10729255 DOI: 10.1006/jmre.1999.2001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
(13)C MRS studies at natural abundance and after intravenous 1-(13)C glucose infusion were performed on a 1.5-T clinical scanner in four subjects. Localization to the occipital cortex was achieved by a surface coil. In natural abundance spectra glucose C(3beta,5beta), myo-inositol, glutamate C(1,2,5), glutamine C(1,2,5), N-acetyl-aspartate C(1-4,C=O), creatine CH(2), CH(3), and C(C=N), taurine C(2,3), bicarbonate HCO(-)(3) were identified. After glucose infusion (13)C enrichment of glucose C(1alpha,1beta), glutamate C(1-4), glutamine C(1-4), aspartate C(2,3), N-acetyl-aspartate C(2,3), lactate C(3), alanine C(3), and HCO(-)(3) were observed. The observation of (13)C enrichment of resonances resonating at >150 ppm is an extension of previously published studies and will provide a more precise determination of metabolic rates and substrate decarboxylation in human brain.
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Affiliation(s)
- S Blüml
- Huntington Medical Research Institutes, Pasadena, California 91105, USA
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Mason GF, Pan JW, Chu WJ, Newcomer BR, Zhang Y, Orr R, Hetherington HP. Measurement of the tricarboxylic acid cycle rate in human grey and white matter in vivo by 1H-[13C] magnetic resonance spectroscopy at 4.1T. J Cereb Blood Flow Metab 1999; 19:1179-88. [PMID: 10566964 DOI: 10.1097/00004647-199911000-00002] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
13C isotopic labeling data were obtained by 1H-observed/13C-edited magnetic resonance spectroscopy in the human brain in vivo and analyzed using a mathematical model to determine metabolic rates in human grey matter and white matter. 22.5-cc and 56-cc voxels were examined for grey matter and white matter, respectively. When partial volume effects were ignored, the measured tricarboxylic acid cycle rate was 0.72+/-0.22 (mean +/- SD) and 0.29+/-0.09 micromol min(-1) g(-1) (mean +/- SD) in voxels of approximately 70% grey and approximately 70% white matter, respectively. After correction for partial volume effects using a model with two tissue compartments, the tricarboxylic acid cycle rate in pure grey matter was higher (0.80+/-0.10 mol min(-1) g(-1); mean +/- SD) and in white matter was significantly lower (0.17+/-0.01 micromol min(-1) g(-1); mean +/- SD). In 1H-observed/13C-edited magnetic resonance spectroscopy labeling studies, the larger concentrations of labeled metabolites and faster metabolic rates in grey matter biased the measurements heavily toward grey matter, with labeling time courses in 70% grey matter appearing nearly identical to labeling in pure grey matter.
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Affiliation(s)
- G F Mason
- Department of Psychiatry, Yale University, New Haven, Connecticut, USA
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Henry PG, van de Moortele PF, Giacomini E, Nauerth A, Bloch G. Field-frequency locked in vivo proton MRS on a whole-body spectrometer. Magn Reson Med 1999; 42:636-42. [PMID: 10502751 DOI: 10.1002/(sici)1522-2594(199910)42:4<636::aid-mrm4>3.0.co;2-i] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The stability of the main magnetic field is critical for prolonged in vivo magnetic resonance spectroscopy (MRS) acquisitions, especially for difference spectroscopy. This study was focused on the implementation and optimization of a field-frequency lock (FFL) on a whole body spectrometer, to correct the main field drift during localized proton MRS of the human brain. The FFL was achieved through a negative feed-back applied in real time on the Z0 shim coil current, after calculation of the frequency shift from a reference signal. This signal was obtained from the whole head with a small flip angle acquisition interleaved with the PRESS acquisition of interest. To avoid propagation of the important short-term time-correlated fluctuations of the head water frequency (mainly due to respiratory motion) onto Z0 correction, the sampling rate of the reference frequency and the smoothing window for the Z0 correction were carefully optimized. Thus, an effective FFL was demonstrated in vivo with no significant increase of the short-term variance of the water frequency. Magn Reson Med 1999 42:636-642, 1999.
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Affiliation(s)
- P G Henry
- CEA, Service Hospitalier Frédéric Joliot, Département de Recherche Médicale, Orsay, France
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Kanamori K, Ross BD. In vivo detection of (15)N-coupled protons in rat brain by ISIS localization and multiple-quantum editing. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 1999; 139:240-249. [PMID: 10423361 DOI: 10.1006/jmre.1999.1764] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Three-dimensional image-selected in vivo spectroscopy (ISIS) was combined with phase-cycled (1)H-(15)N heteronuclear multiple-quantum coherence (HMQC) transfer NMR for localized selective observation of protons J-coupled to (15)N in phantoms and in vivo. The ISIS-HMQC sequence, supplemented by jump-return water suppression, permitted localized selective observation of 2-5 micromol of [(15)N(indole)]tryptophan, a precursor of the neurotransmitter serotonin, through the (15)N-coupled proton in 20-40 min of acquisition in vitro at 4.7 T. In vivo, the amide proton of [5-(15)N]glutamine was selectively observed in the brain of spontaneously breathing (15)NH(4)(+)-infused rats, using a volume probe with homogeneous (1)H and (15)N fields. Signal recovery after three-dimensional localization was 72-82% in phantoms and 59 +/- 4% in vivo. The result demonstrates that localized selective observation of (15)N-coupled protons, with complete cancellation of all other protons except water, can be achieved in spontaneously breathing animals by the ISIS-HMQC sequence. This sequence performs both volume selection and heteronuclear editing through an addition/subtraction scheme and predicts the highest intrinsic sensitivity for detection of (15)N-coupled protons in the selected volume. The advantages and limitations of this method for in vivo application are compared to those of other localized editing techniques currently in use for non-exchanging protons.
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Affiliation(s)
- K Kanamori
- Magnetic Resonance Spectroscopy Laboratory, Huntington Medical Research Institutes, 660 South Fair Oaks Avenue, Pasadena, California 91105, USA.
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16
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Pfeuffer J, Tkác I, Choi IY, Merkle H, Ugurbil K, Garwood M, Gruetter R. Localized in vivo 1H NMR detection of neurotransmitter labeling in rat brain during infusion of [1-13C] D-glucose. Magn Reson Med 1999; 41:1077-83. [PMID: 10371437 DOI: 10.1002/(sici)1522-2594(199906)41:6<1077::aid-mrm1>3.0.co;2-#] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Resolved localized nuclear magnetic resonance (NMR) signals of 1H bound to 13C label in the carbon positions of glutamate C4, C3 and glutamine C4, C3, as well as in aspartate C3, lactate C3, alanine C3, gamma-aminobutyric acid C3, and glucose C1 were simultaneously observed in spectra obtained from rat brain in vivo. Time-resolved label incorporation was measured with a new adiabatic carbon editing and decoupling (ACED) single-voxel stimulated echo acquisition mode (STEAM) sequence. Adiabatic carbon broadband decoupling of 12 kHz bandwidth was achieved in vivo, which decoupled the entire 13C spectrum at 9.4 T. Resonances from N-acetyl-aspartate and creatine were also detected, consistent with natural-abundance 13C levels. These results emphasize the potential of 1H NMR for following complex biochemical pathways in localized areas of resting rat brain as well as during focal activation using infusions of 13C-labeled glucose.
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Affiliation(s)
- J Pfeuffer
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota Medical School, Minneapolis 55455, USA
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Abstract
Relaxation time measurements at 3.0 T are reported for both gray and white matter in normal human brain. Measurements were made using a 3.0 T Bruker Biospec magnetic resonance imaging (MRI) scanner in normal adults with no clinical evidence of neurological disease. Nineteen subjects, 8 female and 11 male, were studied for T1 and T2 measurements, and 7 males were studied for T2. Measurements were made using a saturation recovery method for T1, a multiple spin-echo experiment for T2, and a fast low-angle shot (FLASH) sequence with 14 different echo times for T2. Results of the measurements are summarized as follows. Average T1 values measured for gray matter and white matter were 1331 and 832 msec, respectively. Average T2 values measured for gray matter and white matter were 80 and 110 msec, respectively. The average T2 values for occipital and frontal gray matter were 41.6 and 51.8 msec, respectively. Average T2 values for occipital and frontal white matter were 48.4 and 44.7 msec, respectively. ANOVA tests of the measurements revealed that for both gray and white matter there were no significant differences in T1 from one location in the brain to another. T2 in occipital gray matter was significantly higher (0.0001 < P < .0375) than the rest of the gray matter, while T2 in frontal white matter was significantly lower (P < 0.0001). Statistical analysis of cerebral hemispheric differences in relaxation time measurements showed no significant differences in T1 values from the left hemisphere compared with the right, except in insular gray matter, where this difference was significant at P = 0.0320. No significant difference in T2 values existed between the left and right cerebral hemispheres. Significant differences were apparent between male and female relaxation time measurements in brain.
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Affiliation(s)
- J P Wansapura
- Department of Physics, University of Cincinnati, Ohio 45229, USA
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Abstract
The advantages of performing spectroscopic studies at higher field strengths include increased SNR, improved spectral resolution for J-coupled resonances, and improvements in the selectivity of spectral editing schemes. By using pulse sequences that minimize the required echo time, refocus J-evolution, employ low peak B1 requiring pulses and take advantage of spectroscopic imaging methods, these advantages can also be utilized in clinical applications of spectroscopy at high field. In addition to the static measurements measurements of N-acetyl aspartate (NAA), creatine (CR) and choline (CH) which can be performed at 1.5 T, high resolution measurements of glutamate, glutamine, GABA and the incorporation of 13C labeled glucose into glutamate are possible with improved spatial and spectral resolution. These methods have been utilized in patients with seizure disorders and multiple sclerosis to identify, characterize and map the metabolic changes associated with these diseases and their treatment.
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Affiliation(s)
- H P Hetherington
- Department of Medicine, University of Alabama at Birmingham, AL 35294-4470, USA
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