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Tal A. The future is 2D: spectral-temporal fitting of dynamic MRS data provides exponential gains in precision over conventional approaches. Magn Reson Med 2023; 89:499-507. [PMID: 36121336 PMCID: PMC10087547 DOI: 10.1002/mrm.29456] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 08/01/2022] [Accepted: 08/23/2022] [Indexed: 12/13/2022]
Abstract
PURPOSE Many MRS paradigms produce 2D spectral-temporal datasets, including diffusion-weighted, functional, and hyperpolarized and enriched (carbon-13, deuterium) experiments. Conventionally, temporal parameters-such as T2 , T1 , or diffusion constants-are assessed by first fitting each spectrum independently and subsequently fitting a temporal model (1D fitting). We investigated whether simultaneously fitting the entire dataset using a single spectral-temporal model (2D fitting) would improve the precision of the relevant temporal parameter. METHODS We derived a Cramer Rao lower bound for the temporal parameters for both 1D and 2D approaches for 2 experiments: a multi-echo experiment designed to estimate metabolite T2 s, and a functional MRS experiment designed to estimate fractional change ( δ $$ \delta $$ ) in metabolite concentrations. We investigated the dependence of the relative standard deviation (SD) of T2 in multi-echo and δ $$ \delta $$ in functional MRS. RESULTS When peaks were spectrally distant, 2D fitting improved precision by approximately 20% relative to 1D fitting, regardless of the experiment and other parameter values. These gains increased exponentially as peaks drew closer. Dependence on temporal model parameters was weak to negligible. CONCLUSION Our results strongly support a 2D approach to MRS fitting where applicable, and particularly in nuclei such as hydrogen and deuterium, which exhibit substantial spectral overlap.
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Affiliation(s)
- Assaf Tal
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
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2
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Roussel T, Le Fur Y, Guye M, Viout P, Ranjeva JP, Callot V. Respiratory-triggered quantitative MR spectroscopy of the human cervical spinal cord at 7 T. Magn Reson Med 2022; 87:2600-2612. [PMID: 35181915 DOI: 10.1002/mrm.29182] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Revised: 01/07/2022] [Accepted: 01/12/2022] [Indexed: 02/06/2023]
Abstract
PURPOSE Ultra-high field 1 H MR spectroscopy (MRS) is of great interest to help characterizing human spinal cord pathologies. However, very few studies have been reported so far in this small size structure at these fields due to challenging experimental difficulties caused by static and radiofrequency field heterogeneities, as well as physiological motion. In this work, in line with the recent developments proposed to strengthen spinal cord MRS feasibility at 7 T, a respiratory-triggered acquisition approach was optimized to compensate for dynamic B 0 field heterogeneities and to provide robust cervical spinal cord MRS data. METHODS A semi-LASER sequence was purposely used, and a dedicated raw data processing algorithm was developed to enhance MR spectral quality by discarding corrupted scans. To legitimate the choices done during the optimization stage, additional tests were carried out to determine the impact of breathing, voluntary motion, body mass index, and fitting algorithm. An in-house quantification tool was concomitantly designed for accurate estimation of the metabolite concentration ratios for choline, N-acetyl-aspartate (NAA), myo-inositol and glutathione. The method was tested on a cohort of 14 healthy volunteers. RESULTS Average water linewidth and NAA signal-to-noise ratio reached 0.04 ppm and 11.01, respectively. The group-average metabolic ratios were in good agreement with previous studies and showed intersession reproducibility variations below 30%. CONCLUSION The developed approach allows a rise of the acquired MRS signal quality and of the quantification robustness as compared to previous studies hence offering strengthened possibilities to probe the metabolism of degenerative and traumatic spinal cord pathologies.
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Affiliation(s)
- Tangi Roussel
- Aix Marseille Univ, CNRS, CRMBM, Marseille, France.,APHM, Hôpital Universitaire Timone, CEMEREM, Marseille, France
| | - Yann Le Fur
- Aix Marseille Univ, CNRS, CRMBM, Marseille, France.,APHM, Hôpital Universitaire Timone, CEMEREM, Marseille, France
| | - Maxime Guye
- Aix Marseille Univ, CNRS, CRMBM, Marseille, France.,APHM, Hôpital Universitaire Timone, CEMEREM, Marseille, France
| | - Patrick Viout
- Aix Marseille Univ, CNRS, CRMBM, Marseille, France.,APHM, Hôpital Universitaire Timone, CEMEREM, Marseille, France
| | - Jean-Philippe Ranjeva
- Aix Marseille Univ, CNRS, CRMBM, Marseille, France.,APHM, Hôpital Universitaire Timone, CEMEREM, Marseille, France
| | - Virginie Callot
- Aix Marseille Univ, CNRS, CRMBM, Marseille, France.,APHM, Hôpital Universitaire Timone, CEMEREM, Marseille, France
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3
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Maudsley AA, Andronesi OC, Barker PB, Bizzi A, Bogner W, Henning A, Nelson SJ, Posse S, Shungu DC, Soher BJ. Advanced magnetic resonance spectroscopic neuroimaging: Experts' consensus recommendations. NMR IN BIOMEDICINE 2021; 34:e4309. [PMID: 32350978 PMCID: PMC7606742 DOI: 10.1002/nbm.4309] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Revised: 02/01/2020] [Accepted: 03/10/2020] [Indexed: 05/04/2023]
Abstract
Magnetic resonance spectroscopic imaging (MRSI) offers considerable promise for monitoring metabolic alterations associated with disease or injury; however, to date, these methods have not had a significant impact on clinical care, and their use remains largely confined to the research community and a limited number of clinical sites. The MRSI methods currently implemented on clinical MRI instruments have remained essentially unchanged for two decades, with only incremental improvements in sequence implementation. During this time, a number of technological developments have taken place that have already greatly benefited the quality of MRSI measurements within the research community and which promise to bring advanced MRSI studies to the point where the technique becomes a true imaging modality, while making the traditional review of individual spectra a secondary requirement. Furthermore, the increasing use of biomedical MR spectroscopy studies has indicated clinical areas where advanced MRSI methods can provide valuable information for clinical care. In light of this rapidly changing technological environment and growing understanding of the value of MRSI studies for biomedical studies, this article presents a consensus from a group of experts in the field that reviews the state-of-the-art for clinical proton MRSI studies of the human brain, recommends minimal standards for further development of vendor-provided MRSI implementations, and identifies areas which need further technical development.
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Affiliation(s)
- Andrew A Maudsley
- Department of Radiology, Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Ovidiu C Andronesi
- Department of Radiology, Massachusetts General Hospital, Athinoula A. Martinos Center for Biomedical Imaging, Harvard Medical School, Boston, Massachusetts
| | - Peter B Barker
- The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, and the Kennedy Krieger Institute, F.M. Kirby Center for Functional Brain Imaging, Baltimore, Maryland
| | - Alberto Bizzi
- Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Wolfgang Bogner
- High Field MR Center, Department of Biomedical Imaging and Image-guided Therapy, Medical University Vienna, Vienna, Austria
| | - Anke Henning
- Max Planck Institute for Biological Cybernetics, Tübingen, Germany
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Sarah J Nelson
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California
| | - Stefan Posse
- Department of Neurology, University of New Mexico, Albuquerque, New Mexico
| | - Dikoma C Shungu
- Department of Neuroradiology, Weill Cornell Medical College, New York, New York
| | - Brian J Soher
- Department of Radiology, Duke University Medical Center, Durham, North Carolina
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4
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Murali‐Manohar S, Borbath T, Wright AM, Soher B, Mekle R, Henning A. T
2
relaxation times of macromolecules and metabolites in the human brain at 9.4 T. Magn Reson Med 2020; 84:542-558. [DOI: 10.1002/mrm.28174] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 12/06/2019] [Accepted: 12/27/2019] [Indexed: 11/10/2022]
Affiliation(s)
- Saipavitra Murali‐Manohar
- High‐Field Magnetic Resonance Max Planck Institute for Biological Cybernetics Tübingen Germany
- Faculty of Science University of Tübingen Tübingen Germany
| | - Tamas Borbath
- High‐Field Magnetic Resonance Max Planck Institute for Biological Cybernetics Tübingen Germany
- Faculty of Science University of Tübingen Tübingen Germany
| | - Andrew Martin Wright
- High‐Field Magnetic Resonance Max Planck Institute for Biological Cybernetics Tübingen Germany
- IMPRS for Cognitive & Systems Neuroscience Tübingen Germany
| | - Brian Soher
- Radiology Duke University Medical Center Durham North Carolina
| | - Ralf Mekle
- Center for Stroke Research Berlin (CSB) Charité ‐ Universitätsmedizin Berlin Berlin Germany
| | - Anke Henning
- High‐Field Magnetic Resonance Max Planck Institute for Biological Cybernetics Tübingen Germany
- Advanced Imaging Research Center UT Southwestern Medical Center Dallas Texas
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5
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Dehghani M, Do KQ, Magistretti P, Xin L. Lactate measurement by neurochemical profiling in the dorsolateral prefrontal cortex at 7T: accuracy, precision, and relaxation times. Magn Reson Med 2019; 83:1895-1908. [PMID: 31729080 DOI: 10.1002/mrm.28066] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Revised: 09/17/2019] [Accepted: 10/14/2019] [Indexed: 12/21/2022]
Abstract
PURPOSE This assesses the potential of measuring lactate in the human brain using three non-editing MRS methods at 7T and compares the accuracy and precision of the methods. METHODS 1 H MRS data were measured in the right dorsolateral prefrontal cortex using a semi-adiabatic spin-echo full-intensity acquired localized sequence with three different protocols: (I) TE = 16 ms, (II) TE = 110 ms, and (III) TE = 16 ms, TI = 300 ms. T1 and T2 relaxation times of lactate were also measured. Simulated spectra were generated for three protocols with known concentrations, using a range of spectral linewidths and SNRs to assess the effect of data quality on the measurement precision and accuracy. RESULTS Lactate was quantified in all three protocols with mean Cramér-Rao lower bound of 8% (I), 13% (II), and 7% (III). The T1 and T2 relaxation times of lactate were 1.9 ± 0.2 s and 94 ± 13 ms, respectively. Simulations predicted a spectral linewidth-associated underestimation of lactate measurement. Simulations, phantom and in vivo results showed that protocol II was most affected by this underestimation. In addition, the estimation error was insensitive to a broad range of spectral linewidth with protocol I. Within-session coefficient of variances of lactate were 6.1 ± 7.9% (I), 22.3 ± 12.3% (II), and 5.1 ± 5.4% (III), respectively. CONCLUSION We conclude that protocols I and III have the potential to measure lactate at 7T with good reproducibility, whereas the measurement accuracy and precision depend on spectral linewidth and SNR, respectively. Moreover, simulation is valuable for the optimization of measurement protocols in future study design and the correction for measurement bias.
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Affiliation(s)
- Masoumeh Dehghani
- Center for Psychiatric Neuroscience (CNP), Department of Psychiatry, Lausanne University Hospital-CHUV, Prilly-Lausanne, Switzerland
| | - Kim Q Do
- Center for Psychiatric Neuroscience (CNP), Department of Psychiatry, Lausanne University Hospital-CHUV, Prilly-Lausanne, Switzerland
| | - Pierre Magistretti
- Center for Psychiatric Neuroscience (CNP), Department of Psychiatry, Lausanne University Hospital-CHUV, Prilly-Lausanne, Switzerland.,BESE Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia.,Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Lijing Xin
- Animal Imaging and Technology Core (AIT), Center for Biomedical Imaging (CIBM), Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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6
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Lenting K, Khurshed M, Peeters TH, van den Heuvel CNAM, van Lith SAM, de Bitter T, Hendriks W, Span PN, Molenaar RJ, Botman D, Verrijp K, Heerschap A, Ter Laan M, Kusters B, van Ewijk A, Huynen MA, van Noorden CJF, Leenders WPJ. Isocitrate dehydrogenase 1-mutated human gliomas depend on lactate and glutamate to alleviate metabolic stress. FASEB J 2018; 33:557-571. [PMID: 30001166 DOI: 10.1096/fj.201800907rr] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Diffuse gliomas often carry point mutations in isocitrate dehydrogenase ( IDH1mut), resulting in metabolic stress. Although IDHmut gliomas are difficult to culture in vitro, they thrive in the brain via diffuse infiltration, suggesting brain-specific tumor-stroma interactions that can compensate for IDH-1 deficits. To elucidate the metabolic adjustments in clinical IDHmut gliomas that contribute to their malignancy, we applied a recently developed method of targeted quantitative RNA next-generation sequencing to 66 clinical gliomas and relevant orthotopic glioma xenografts, with and without the endogenous IDH-1R132H mutation. Datasets were analyzed in R using Manhattan plots to calculate distance between expression profiles, Ward's method to perform unsupervised agglomerative clustering, and the Mann Whitney U test and Fisher's exact tests for supervised group analyses. The significance of transcriptome data was investigated by protein analysis, in situ enzymatic activity mapping, and in vivo magnetic resonance spectroscopy of orthotopic IDH1mut- and IDHwt-glioma xenografts. Gene set enrichment analyses of clinical IDH1mut gliomas strongly suggest a role for catabolism of lactate and the neurotransmitter glutamate, whereas, in IDHwt gliomas, processing of glucose and glutamine are the predominant metabolic pathways. Further evidence of the differential metabolic activity in these cancers comes from in situ enzymatic mapping studies and preclinical in vivo magnetic resonance spectroscopy imaging. Our data support an evolutionary model in which IDHmut glioma cells exist in symbiosis with supportive neuronal cells and astrocytes as suppliers of glutamate and lactate, possibly explaining the diffuse nature of these cancers. The dependency on glutamate and lactate opens the way for novel approaches in the treatment of IDHmut gliomas.-Lenting, K., Khurshed, M., Peeters, T. H., van den Heuvel, C. N. A. M., van Lith, S. A. M., de Bitter, T., Hendriks, W., Span, P. N., Molenaar, R. J., Botman, D., Verrijp, K., Heerschap, A., ter Laan, M., Kusters, B., van Ewijk, A., Huynen, M. A., van Noorden, C. J. F., Leenders, W. P. J. Isocitrate dehydrogenase 1-mutated human gliomas depend on lactate and glutamate to alleviate metabolic stress.
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Affiliation(s)
- Krissie Lenting
- Department of Biochemistry, Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands.,Department of Pathology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Mohammed Khurshed
- Department of Medical Biology, Cancer Center Amsterdam, Academic Medical Centre, Amsterdam, The Netherlands
| | - Tom H Peeters
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Corina N A M van den Heuvel
- Department of Biochemistry, Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands.,Department of Pathology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Sanne A M van Lith
- Department of Pathology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Tessa de Bitter
- Department of Pathology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Wiljan Hendriks
- Department of Cell Biology, Radboud Institute of Molecular Life Sciences, Nijmegen, The Netherlands
| | - Paul N Span
- Radiotherapy and Oncoimmunology Laboratory, Department of Radiation Oncology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Remco J Molenaar
- Department of Medical Biology, Cancer Center Amsterdam, Academic Medical Centre, Amsterdam, The Netherlands
| | - Dennis Botman
- Department of Medical Biology, Cancer Center Amsterdam, Academic Medical Centre, Amsterdam, The Netherlands
| | - Kiek Verrijp
- Department of Pathology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Arend Heerschap
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Mark Ter Laan
- Department of Neurosurgery, Radboud University Medical Center, Nijmegen, The Netherlands; and
| | - Benno Kusters
- Department of Pathology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Anne van Ewijk
- Department of Biochemistry, Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands
| | - Martijn A Huynen
- Center for Molecular and Biomolecular Informatics, Radboud Institute of Molecular Life Sciences, Nijmegen, The Netherlands
| | - Cornelis J F van Noorden
- Department of Medical Biology, Cancer Center Amsterdam, Academic Medical Centre, Amsterdam, The Netherlands
| | - William P J Leenders
- Department of Biochemistry, Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands.,Department of Pathology, Radboud University Medical Center, Nijmegen, The Netherlands
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7
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Carlin D, Babourina-Brooks B, Davies NP, Wilson M, Peet AC. Variation of T 2 relaxation times in pediatric brain tumors and their effect on metabolite quantification. J Magn Reson Imaging 2018; 49:195-203. [PMID: 29697883 PMCID: PMC6492201 DOI: 10.1002/jmri.26054] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 03/29/2018] [Accepted: 03/29/2018] [Indexed: 12/24/2022] Open
Abstract
Background Metabolite concentrations are fundamental biomarkers of disease and prognosis. Magnetic resonance spectroscopy (MRS) is a noninvasive method for measuring metabolite concentrations; however, quantitation is affected by T2 relaxation. Purpose To estimate T2 relaxation times in pediatric brain tumors and assess how variation in T2 relaxation affects metabolite quantification. Study Type Retrospective. Population Twenty‐seven pediatric brain tumor patients (n = 17 pilocytic astrocytoma and n = 10 medulloblastoma) and 24 age‐matched normal controls. Field Strength/Sequence Short‐ (30 msec) and long‐echo (135 msec) single‐voxel MRS acquired at 1.5T. Assessment T2 relaxation times were estimated by fitting signal amplitudes at two echo times to a monoexponential decay function and were used to correct metabolite concentration estimates for relaxation effects. Statistical Tests One‐way analysis of variance (ANOVA) on ranks were used to analyze the mean T2 relaxation times and metabolite concentrations for each tissue group and paired Mann–Whitney U‐tests were performed. Results The mean T2 relaxation of water was measured as 181 msec, 123 msec, 90 msec, and 86 msec in pilocytic astrocytomas, medulloblastomas, basal ganglia, and white matter, respectively. The T2 of water was significantly longer in both tumor groups than normal brain (P < 0.001) and in pilocytic astrocytomas compared with medulloblastomas (P < 0.01). The choline T2 relaxation time was significantly longer in medulloblastomas compared with pilocytic astrocytomas (P < 0.05), while the T2 relaxation time of NAA was significantly shorter in pilocytic astrocytomas compared with normal brain (P < 0.001). Overall, the metabolite concentrations were underestimated by ∼22% when default T2 values were used compared with case‐specific T2 values at short echo time. The difference was reduced to 4% when individually measured water T2s were used. Data Conclusion Differences exist in water and metabolite T2 relaxation times for pediatric brain tumors, which lead to significant underestimation of metabolite concentrations when using default water T2 relaxation times. Level of Evidence: 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:195–203.
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Affiliation(s)
- Dominic Carlin
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, West Midlands, UK.,Birmingham Children's Hospital NHS Foundation Trust, Birmingham, West Midlands, UK
| | - Ben Babourina-Brooks
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, West Midlands, UK.,Birmingham Children's Hospital NHS Foundation Trust, Birmingham, West Midlands, UK
| | - Nigel P Davies
- Birmingham Children's Hospital NHS Foundation Trust, Birmingham, West Midlands, UK.,Imaging and Medical Physics, University Hospitals Birmingham NHS Foundation Trust, Birmingham, West Midlands, UK
| | - Martin Wilson
- Birmingham Children's Hospital NHS Foundation Trust, Birmingham, West Midlands, UK.,Birmingham University Imaging Centre (BUIC), School of Psychology, University of Birmingham, West Midlands, UK
| | - Andrew C Peet
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, West Midlands, UK.,Birmingham Children's Hospital NHS Foundation Trust, Birmingham, West Midlands, UK
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8
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Lizarbe B, Lei H, Duarte JM, Lanz B, Cherix A, Gruetter R. Feasibility of in vivo measurement of glucose metabolism in the mouse hypothalamus by1H-[13C] MRS at 14.1T. Magn Reson Med 2018; 80:874-884. [DOI: 10.1002/mrm.27129] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 01/22/2018] [Accepted: 01/22/2018] [Indexed: 12/24/2022]
Affiliation(s)
- Blanca Lizarbe
- Laboratory of Functional and Metabolic Imaging (LIFMET), École Polytechnique Fédérale de Lausanne; Lausanne Switzerland
| | - Hongxia Lei
- Department of Radiology; University of Geneva, Geneva, Switzerland and Center for Biomedical Imaging (CIBM); Lausanne Switzerland
| | - Joao M.N. Duarte
- Laboratory of Functional and Metabolic Imaging (LIFMET), École Polytechnique Fédérale de Lausanne; Lausanne Switzerland
| | - Bernard Lanz
- Laboratory of Functional and Metabolic Imaging (LIFMET), École Polytechnique Fédérale de Lausanne; Lausanne Switzerland
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham; Nottingham United Kingdom
| | - Antoine Cherix
- Laboratory of Functional and Metabolic Imaging (LIFMET), École Polytechnique Fédérale de Lausanne; Lausanne Switzerland
| | - Rolf Gruetter
- Laboratory of Functional and Metabolic Imaging (LIFMET), École Polytechnique Fédérale de Lausanne; Lausanne Switzerland
- Department of Radiology; University of Geneva, Geneva, Switzerland and Center for Biomedical Imaging (CIBM); Lausanne Switzerland
- Department of Radiology; University of Lausanne; Lausanne Switzerland
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9
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Dobberthien BJ, Tessier AG, Yahya A. Improved resolution of glutamate, glutamine and γ-aminobutyric acid with optimized point-resolved spectroscopy sequence timings for their simultaneous quantification at 9.4 T. NMR IN BIOMEDICINE 2018; 31:e3851. [PMID: 29105187 DOI: 10.1002/nbm.3851] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 09/15/2017] [Accepted: 09/25/2017] [Indexed: 06/07/2023]
Abstract
Glutamine (Gln), glutamate (Glu) and γ-aminobutyric acid (GABA) are relevant brain metabolites that can be measured with magnetic resonance spectroscopy (MRS). This work optimizes the point-resolved spectroscopy (PRESS) sequence echo times, TE1 and TE2 , for improved simultaneous quantification of the three metabolites at 9.4 T. Quantification was based on the proton resonances of Gln, Glu and GABA at ≈2.45, ≈2.35 and ≈2.28 ppm, respectively. Glu exhibits overlap with both Gln and GABA; in addition, the Gln peak is contaminated by signal from the strongly coupled protons of N-acetylaspartate (NAA), which resonate at about 2.49 ppm. J-coupling evolution of the protons was characterized numerically and verified experimentally. A {TE1 , TE2 } combination of {106 ms, 16 ms} minimized the NAA signal in the Gln spectral region, whilst retaining Gln, Glu and GABA peaks. The efficacy of the technique was verified on phantom solutions and on rat brain in vivo. LCModel was employed to analyze the in vivo spectra. The average T2 -corrected Gln, Glu and GABA concentrations were found to be 3.39, 11.43 and 2.20 mM, respectively, assuming a total creatine concentration of 8.5 mM. LCModel Cramér-Rao lower bounds (CRLBs) for Gln, Glu and GABA were in the ranges 14-17%, 4-6% and 16-19%, respectively. The optimal TE resulted in concentrations for Gln and GABA that agreed more closely with literature concentrations compared with concentrations obtained from short-TE spectra acquired with a {TE1 , TE2 } combination of {12 ms, 9 ms}. LCModel estimations were also evaluated with short-TE PRESS and with the optimized long TE of {106 ms, 16 ms}, using phantom solutions of known metabolite concentrations. It was shown that concentrations estimated with LCModel can be inaccurate when combined with short-TE PRESS, where there is peak overlap, even when low (<20%) CRLBs are reported.
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Affiliation(s)
| | - Anthony G Tessier
- Department of Oncology, University of Alberta, Edmonton, AB, Canada
- Department of Medical Physics, Cross Cancer Institute, Edmonton, AB, Canada
| | - Atiyah Yahya
- Department of Oncology, University of Alberta, Edmonton, AB, Canada
- Department of Medical Physics, Cross Cancer Institute, Edmonton, AB, Canada
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10
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Quantum-mechanical simulations for in vivo MR spectroscopy: Principles and possibilities demonstrated with the program NMRScopeB. Anal Biochem 2017; 529:79-97. [DOI: 10.1016/j.ab.2016.10.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 08/24/2016] [Accepted: 10/07/2016] [Indexed: 11/19/2022]
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11
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van der Kemp WJ, Stehouwer BL, Boer VO, Luijten PR, Klomp DW, Wijnen JP. Proton and phosphorus magnetic resonance spectroscopy of the healthy human breast at 7 T. NMR IN BIOMEDICINE 2017; 30:e3684. [PMID: 28032377 PMCID: PMC5248643 DOI: 10.1002/nbm.3684] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Revised: 11/14/2016] [Accepted: 11/17/2016] [Indexed: 05/18/2023]
Abstract
In vivo water- and fat-suppressed 1 H magnetic resonance spectroscopy (MRS) and 31 P magnetic resonance adiabatic multi-echo spectroscopic imaging were performed at 7 T in duplicate in healthy fibroglandular breast tissue of a group of eight volunteers. The transverse relaxation times of 31 P metabolites were determined, and the reproducibility of 1 H and 31 P MRS was investigated. The transverse relaxation times for phosphoethanolamine (PE) and phosphocholine (PC) were fitted bi-exponentially, with an added short T2 component of 20 ms for adenosine monophosphate, resulting in values of 199 ± 8 and 239 ± 14 ms, respectively. The transverse relaxation time for glycerophosphocholine (GPC) was also fitted bi-exponentially, with an added short T2 component of 20 ms for glycerophosphatidylethanolamine, which resonates at a similar frequency, resulting in a value of 177 ± 6 ms. Transverse relaxation times for inorganic phosphate, γ-ATP and glycerophosphatidylcholine mobile phospholipid were fitted mono-exponentially, resulting in values of 180 ± 4, 19 ± 3 and 20 ± 4 ms, respectively. Coefficients of variation for the duplicate determinations of 1 H total choline (tChol) and the 31 P metabolites were calculated for the group of volunteers. The reproducibility of inorganic phosphate, the sum of phosphomonoesters and the sum of phosphodiesters with 31 P MRS imaging was superior to the reproducibility of 1 H MRS for tChol. 1 H and 31 P data were combined to calculate estimates of the absolute concentrations of PC, GPC and PE in healthy fibroglandular tissue, resulting in upper limits of 0.1, 0.1 and 0.2 mmol/kg of tissue, respectively.
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Affiliation(s)
| | | | - Vincent O. Boer
- Department of RadiologyUniversity Medical Center UtrechtUtrechtthe Netherlands
| | - Peter R. Luijten
- Department of RadiologyUniversity Medical Center UtrechtUtrechtthe Netherlands
| | - Dennis W.J. Klomp
- Department of RadiologyUniversity Medical Center UtrechtUtrechtthe Netherlands
| | - Jannie P. Wijnen
- Department of RadiologyUniversity Medical Center UtrechtUtrechtthe Netherlands
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12
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Lee HH, Kim H. Parameterization of spectral baseline directly from short echo time full spectra in 1
H-MRS. Magn Reson Med 2016; 78:836-847. [DOI: 10.1002/mrm.26502] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 08/11/2016] [Accepted: 09/18/2016] [Indexed: 12/24/2022]
Affiliation(s)
- Hyeong Hun Lee
- Department of Biomedical Sciences; Seoul National University; Seoul Korea
| | - Hyeonjin Kim
- Department of Biomedical Sciences; Seoul National University; Seoul Korea
- Department of Radiology; Seoul National University Hospital; Seoul Korea
- Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology; Seoul National University; Suwon Korea
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13
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Fisher ME, Dobberthien BJ, Tessier AG, Yahya A. Characterization of the response of taurine protons to PRESS at 9.4 T for Resolving choline and Determining taurine T2. NMR IN BIOMEDICINE 2016; 29:1427-1435. [PMID: 27496562 DOI: 10.1002/nbm.3588] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 06/13/2016] [Accepted: 06/24/2016] [Indexed: 06/06/2023]
Abstract
Point-resolved spectroscopy (PRESS), characterized by two TEs (TE1 and TE2 ), can be employed to perform animal magnetic resonance spectroscopy (MRS) studies at 9.4 T. Taurine (Tau) and choline (Cho) are relevant metabolites that can be measured by MRS. In this work, the response of the J-coupled protons of Tau as a function of PRESS TE1 and TE2 was characterized at 9.4 T to achieve two objectives. The first was to determine two TE1 and TE2 combinations that could be used to obtain T2 -corrected measures of Tau (3.42 ppm) that were minimally influenced by J coupling. The second was to exploit the Tau J coupling to find a timing combination that minimized the 3.25-ppm Tau signal to enable the Cho (3.22 ppm) resonance to be resolved from the overlapping Tau signal. The response of Tau protons was investigated both numerically and experimentally. It was numerically determined that the timings {TE1 , TE2 } = {17 ms, 10 ms} and {TE1 , TE2 } = {80 ms, 70 ms} yielded similar 3.42-ppm Tau resonance areas (5% difference), rendering them suitable for Tau T2 determination. {TE1 , TE2 } = {25 ms, 50 ms} was found to yield minimal 3.25-ppm Tau signal, reducing its interference with Cho. The efficacy of the timings was demonstrated on phantom solutions and in vivo in four Sprague Dawley rats. LCModel was employed to analyse the in vivo spectra and Tau T2 values were estimated by fitting the Tau peak areas obtained with {TE1 , TE2 } = {17 ms, 10 ms} and {TE1 , TE2 } = {80 ms, 70 ms} to a monoexponentially decaying function. An average Tau T2 of 106 ms (standard deviation, 12 ms) was obtained. LCModel analysis of rat spectra obtained with {TE1 , TE2 } = {25 ms, 50 ms} demonstrated negligible levels of Tau signal, compared with that obtained with short TE.
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Affiliation(s)
- Marissa E Fisher
- Department of Oncology, University of Alberta, Edmonton, AB, Canada
| | | | - Anthony G Tessier
- Department of Oncology, University of Alberta, Edmonton, AB, Canada
- Department of Medical Physics, Cross Cancer Institute, Edmonton, AB, Canada
| | - Atiyah Yahya
- Department of Oncology, University of Alberta, Edmonton, AB, Canada.
- Department of Medical Physics, Cross Cancer Institute, Edmonton, AB, Canada.
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Koob M, Viola A, Le Fur Y, Viout P, Ratiney H, Confort-Gouny S, Cozzone PJ, Girard N. Creatine, Glutamine plus Glutamate, and Macromolecules Are Decreased in the Central White Matter of Premature Neonates around Term. PLoS One 2016; 11:e0160990. [PMID: 27547969 PMCID: PMC4993494 DOI: 10.1371/journal.pone.0160990] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 07/28/2016] [Indexed: 11/18/2022] Open
Abstract
Preterm birth represents a high risk of neurodevelopmental disabilities when associated with white-matter damage. Recent studies have reported cognitive deficits in children born preterm without brain injury on MRI at term-equivalent age. Understanding the microstructural and metabolic underpinnings of these deficits is essential for their early detection. Here, we used diffusion-weighted imaging and single-voxel 1H magnetic resonance spectroscopy (MRS) to compare brain maturation at term-equivalent age in premature neonates with no evidence of white matter injury on conventional MRI except diffuse excessive high-signal intensity, and normal term neonates. Thirty-two infants, 16 term neonates (mean post-conceptional age at scan: 39.8±1 weeks) and 16 premature neonates (mean gestational age at birth: 29.1±2 weeks, mean post-conceptional age at scan: 39.2±1 weeks) were investigated. The MRI/MRS protocol performed at 1.5T involved diffusion-weighted MRI and localized 1H-MRS with the Point RESolved Spectroscopy (PRESS) sequence. Preterm neonates showed significantly higher ADC values in the temporal white matter (P<0.05), the occipital white matter (P<0.005) and the thalamus (P<0.05). The proton spectrum of the centrum semiovale was characterized by significantly lower taurine/H2O and macromolecules/H2O ratios (P<0.05) at a TE of 30 ms, and reduced (creatine+phosphocreatine)/H2O and (glutamine+glutamate)/H2O ratios (P<0.05) at a TE of 135 ms in the preterm neonates than in full-term neonates. Our findings indicate that premature neonates with normal conventional MRI present a delay in brain maturation affecting the white matter and the thalamus. Their brain metabolic profile is characterized by lower levels of creatine, glutamine plus glutamate, and macromolecules in the centrum semiovale, a finding suggesting altered energy metabolism and protein synthesis.
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Affiliation(s)
- Meriam Koob
- Service de Neuroradiologie, AP-HM Timone, Aix-Marseille Université, Marseille, France
- Service de Radiopédiatrie-Imagerie 2, CHU de Strasbourg, Hôpital de Hautepierre, Strasbourg, France
- Laboratoire ICube, UMR 7357, FMTS, Université de Strasbourg-CNRS, Strasbourg, France
| | - Angèle Viola
- Aix-Marseille Université, CNRS, Centre de Résonance Magnétique Biologique et Médicale, UMR 7339, Faculté de Médecine la Timone, Marseille, France
- * E-mail: (NG); (AV)
| | - Yann Le Fur
- Aix-Marseille Université, CNRS, Centre de Résonance Magnétique Biologique et Médicale, UMR 7339, Faculté de Médecine la Timone, Marseille, France
| | - Patrick Viout
- Aix-Marseille Université, CNRS, Centre de Résonance Magnétique Biologique et Médicale, UMR 7339, Faculté de Médecine la Timone, Marseille, France
| | - Hélène Ratiney
- Laboratoire CREATIS, CNRS UMR 5220, Inserm U1044, Université Claude Bernard Lyon I, INSA-Lyon, Lyon, France
| | - Sylviane Confort-Gouny
- Aix-Marseille Université, CNRS, Centre de Résonance Magnétique Biologique et Médicale, UMR 7339, Faculté de Médecine la Timone, Marseille, France
| | - Patrick J. Cozzone
- Aix-Marseille Université, CNRS, Centre de Résonance Magnétique Biologique et Médicale, UMR 7339, Faculté de Médecine la Timone, Marseille, France
| | - Nadine Girard
- Service de Neuroradiologie, AP-HM Timone, Aix-Marseille Université, Marseille, France
- Aix-Marseille Université, CNRS, Centre de Résonance Magnétique Biologique et Médicale, UMR 7339, Faculté de Médecine la Timone, Marseille, France
- * E-mail: (NG); (AV)
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15
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Rosenberg JT, Shemesh N, Muniz JA, Dumez JN, Frydman L, Grant SC. Transverse relaxation of selectively excited metabolites in stroke at 21.1 T. Magn Reson Med 2016; 77:520-528. [PMID: 26834031 DOI: 10.1002/mrm.26132] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 12/11/2015] [Accepted: 12/27/2015] [Indexed: 12/21/2022]
Abstract
PURPOSE This study seeks to evaluate in vivo T2 relaxation times of selectively excited stroke-relevant metabolites via 1 H relaxation-enhanced magnetic resonance spectroscopy (RE-MRS) at 21.1 T (900 MHz). METHODS A quadrature surface coil was designed and optimized for investigations of rodents at 21.1 T. With voxel localization, a RE-MRS pulse sequence incorporating the excitation of selected metabolites was modified to include a variable echo delay for T2 measurements. A middle cerebral artery occlusion (MCAO) animal model for stroke was examined with spectra taken 24 h post occlusion. Fourteen echo times were acquired, with each measurement completed in less than 2 min. RESULTS The RE-MRS approach produced high-quality spectra of the selectively excited metabolites in the stroked and contralateral regions. T2 measurements reveal differential results between these regions, with significance achieved for lactic acid. CONCLUSION Using the RE-MRS technique at ultra-high magnetic field and an optimized quadrature surface coil design, full metabolic T2 quantifications in a localized voxel is now possible in less than 27 min. Magn Reson Med 77:520-528, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Jens T Rosenberg
- The National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida, USA
| | - Noam Shemesh
- Champalimaud Neuroscience Programme, Champalimaud Centre for the Unknown, Lisbon, Portugal
| | - Jose A Muniz
- The National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida, USA.,Department of Chemical & Biomedical Engineering, FAMU-FSU College of Engineering, Florida State University, Tallahassee, Florida, USA
| | - Jean-Nicolas Dumez
- French National Centre for Scientific Research, Institute de Chime des Substances Naturelles, Gif-sur-Yvette, France
| | - Lucio Frydman
- The National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida, USA.,Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Samuel C Grant
- The National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida, USA.,Department of Chemical & Biomedical Engineering, FAMU-FSU College of Engineering, Florida State University, Tallahassee, Florida, USA
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Abstract
PURPOSE An enhanced version of the ProFit fitting tool was developed and validated to improve the quantification of two-dimensional JRPESS spectroscopic data. METHODS The proposed enhancements were achieved by flexible organization of prior knowledge, configurations for different situations, the inclusion of measured macromolecular baseline contribution, additional baseline splines and a model-free lineshape based on self-deconvolution. The new software was tested and tuned on simulated data and subsequently applied to in vivo intrasubject and intersubject data. RESULTS Fit results of simulated and acquired spectra show good overall quality suggesting the potential reliable detection of up to 18 metabolites on a 3T system yielding Cramer-Lower-Bounds below 20%. CONCLUSION The proposed enhanced version of ProFit together with two-dimensional J-resolved spectroscopy offers the opportunity to reliably detect a wide selection of important brain metabolites on 3T.
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Affiliation(s)
- Alexander Fuchs
- Department of Information Technology and Electrical Engineering, Institute for Biomedical Engineering, ETH & University Zurich, Switzerland
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Lin Y, Lin L, Wei Z, Zhong J, Chen Z. Localized one-dimensional single voxel magnetic resonance spectroscopy without J coupling modulations. Magn Reson Med 2015; 76:1661-1667. [PMID: 26667321 DOI: 10.1002/mrm.26066] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Revised: 10/26/2015] [Accepted: 10/31/2015] [Indexed: 11/12/2022]
Abstract
PURPOSE To acquire single voxel localized one-dimensional 1 H magnetic resonance spectroscopy (MRS) without J coupling modulations, free from amplitude and phase distortions. METHODS A pulse sequence, named PRESSIR, is developed for volume localized MRS without J modulations at arbitrary echo time (TE). The J coupling evolution is suppressed by the J-refocused module that uses a 90° pulse at the midpoint of a double spin echo. RESULTS The localization performance of the PRESSIR sequence was tested with a two-compartment phantom. The proposed sequence shows similar voxel localization accuracy as PRESS. Both PRESSIR and PRESS sequences were performed on MRS brain phantom and pig brain tissue. PRESS spectra suffer from amplitude and phase distortions due to J modulations, especially under moderate and long TEs, while PRESSIR spectra are almost free from distortions. CONCLUSION The PRESSIR sequence proposed herein enables the acquisition of single voxel in-phase MRS within a single scan. It allows an enhanced signal intensity of J coupling metabolites and reducing undesired broad resonances with short T2s while suppressing J modulations. Moreover, it provides an approach for direct measurement of nonoverlapping J coupling peaks and of transverse relaxation times T2s. Magn Reson Med 76:1661-1667, 2016. © 2015 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Yanqin Lin
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen, China
| | - Liangjie Lin
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen, China
| | - Zhiliang Wei
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen, China
| | - Jianhui Zhong
- Department of Imaging Sciences, University of Rochester, Rochester, New York, USA.,Department of Biomedical Engineering and State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Zhejiang University, Hangzhou, China
| | - Zhong Chen
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen, China
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18
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Cui MH, Jayalakshmi K, Liu L, Guha C, Branch CA. In vivo (1)H MRS and (31)P MRSI of the response to cyclocreatine in transgenic mouse liver expressing creatine kinase. NMR IN BIOMEDICINE 2015; 28:1634-1644. [PMID: 26451872 DOI: 10.1002/nbm.3391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Revised: 08/05/2015] [Accepted: 08/11/2015] [Indexed: 06/05/2023]
Abstract
Hepatocyte transplantation has been explored as a therapeutic alternative to liver transplantation, but a means to monitor the success of the procedure is lacking. Published findings support the use of in vivo (31)P MRSI of creatine kinase (CK)-expressing hepatocytes to monitor proliferation of implanted hepatocytes. Phosphocreatine tissue level depends upon creatine (Cr) input to the CK enzyme reaction, but Cr measurement by (1)H MRS suffers from low signal-to-noise ratio (SNR). We examine the possibility of using the Cr analog cyclocreatine (CCr, a substrate for CK), which is quickly phosphorylated to phosphocyclocreatine (PCCr), as a higher SNR alternative to Cr. (1)H MRS and (31)P MRSI were employed to measure the effect of incremental supplementation of CCr upon PCCr, γ-ATP, pH and Pi /ATP in the liver of transgenic mice expressing the BB isoform of CK (CKBB) in hepatocytes. Water supplementation with 0.1% CCr led to a peak total PCCr level of 17.15 ± 1.07 mmol/kg wet weight by 6 weeks, while adding 1.0% CCr led to a stable PCCr liver level of 18.12 ± 3.91 mmol/kg by the fourth day of feeding. PCCr was positively correlated with CCr, and ATP concentration and pH declined with increasing PCCr. Feeding with 1% CCr in water induced an apparent saturated level of PCCr, suggesting that CCr quantization may not be necessary for quantifying expression of CK in mice. These findings support the possibility of using (31)P MRS to noninvasively monitor hepatocyte transplant success with CK-expressing hepatocytes.
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Affiliation(s)
- Min-Hui Cui
- Gruss Magnetic Resonance Research Center, Albert Einstein College of Medicine, Bronx, NY, USA
- Department of Radiology, Albert Einstein College of Medicine, Bronx, NY, USA
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Kamaiah Jayalakshmi
- Gruss Magnetic Resonance Research Center, Albert Einstein College of Medicine, Bronx, NY, USA
- Department of Radiation Oncology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Laibin Liu
- Department of Radiation Oncology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Chandan Guha
- Department of Radiation Oncology, Albert Einstein College of Medicine, Bronx, NY, USA
- Department of Pathology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Craig A Branch
- Gruss Magnetic Resonance Research Center, Albert Einstein College of Medicine, Bronx, NY, USA
- Department of Radiology, Albert Einstein College of Medicine, Bronx, NY, USA
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, NY, USA
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Janik R, Thomason LAM, Stanisz AM, Forsythe P, Bienenstock J, Stanisz GJ. Magnetic resonance spectroscopy reveals oral Lactobacillus promotion of increases in brain GABA, N-acetyl aspartate and glutamate. Neuroimage 2015; 125:988-995. [PMID: 26577887 DOI: 10.1016/j.neuroimage.2015.11.018] [Citation(s) in RCA: 180] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 10/25/2015] [Accepted: 11/08/2015] [Indexed: 01/09/2023] Open
Abstract
The gut microbiome has been shown to regulate the development and functions of the enteric and central nervous systems. Its involvement in the regulation of behavior has attracted particular attention because of its potential translational importance in clinical disorders, however little is known about the pathways involved. We previously have demonstrated that administration of Lactobacillus rhamnosus (JB-1) to healthy male BALB/c mice, promotes consistent changes in GABA-A and -B receptor sub-types in specific brain regions, accompanied by reductions in anxiety and depression-related behaviors. In the present study, using magnetic resonance spectroscopy (MRS), we quantitatively assessed two clinically validated biomarkers of brain activity and function, glutamate+glutamine (Glx) and total N-acetyl aspartate+N-acetyl aspartyl glutamic acid (tNAA), as well as GABA, the chief brain inhibitory neurotransmitter. Mice received 1×10(9) cfu of JB-1 per day for 4weeks and were subjected to MRS weekly and again 4weeks after cessation of treatment to ascertain temporal changes in these neurometabolites. Baseline concentrations for Glx, tNAA and GABA were equal to 10.4±0.3mM, 8.7±0.1mM, and 1.2±0.1mM, respectively. Delayed increases were first seen for Glx (~10%) and NAA (~37%) at 2weeks which persisted only to the end of treatment. However, Glx was still elevated 4weeks after treatment had ceased. Significantly elevated GABA (~25%) was only seen at 4weeks. These results suggest specific metabolic pathways in our pursuit of mechanisms of action of psychoactive bacteria. They also offer through application of standard clinical neurodiagnostic techniques, translational opportunities to assess biomarkers accompanying behavioral changes induced by alterations in the gut microbiome.
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Affiliation(s)
- Rafal Janik
- Department of Medical Biophysics, University of Toronto, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada
| | - Lynsie A M Thomason
- Physical Sciences, Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada
| | - Andrew M Stanisz
- McMaster Brain-Body Institute at St. Joseph's Healthcare Hamilton, T3304, Juravinski Tower, 50 Charlton Avenue East, Hamilton, ON L8N 4A6, Canada
| | - Paul Forsythe
- Department of Medicine, McMaster University, St. Joseph's Healthcare Hamilton, T3302, 50 Charlton Avenue East, Hamilton, ON L8N 4A6, Canada; McMaster Brain-Body Institute at St. Joseph's Healthcare Hamilton, T3304, Juravinski Tower, 50 Charlton Avenue East, Hamilton, ON L8N 4A6, Canada
| | - John Bienenstock
- Department of Pathology, McMaster University, St. Joseph's Healthcare Hamilton,, Juravinski Tower, 50 Charlton Avenue East, Hamilton, ON L8N 4A6, Canada; McMaster Brain-Body Institute at St. Joseph's Healthcare Hamilton, T3304, Juravinski Tower, 50 Charlton Avenue East, Hamilton, ON L8N 4A6, Canada
| | - Greg J Stanisz
- Department of Medical Biophysics, University of Toronto, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada; Physical Sciences, Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada; Department of Neurosurgery and Pediatrics Neurosurgery, Medical University of Lublin, Aleje Raclawickie 1, 20-059 Lublin, Poland.
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Považan M, Hangel G, Strasser B, Gruber S, Chmelik M, Trattnig S, Bogner W. Mapping of brain macromolecules and their use for spectral processing of 1 H-MRSI data with an ultra-short acquisition delay at 7 T. Neuroimage 2015. [DOI: 10.1016/j.neuroimage.2015.07.042] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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21
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Martel D, Tse Ve Koon K, Le Fur Y, Ratiney H. Localized 2D COSY sequences: Method and experimental evaluation for a whole metabolite quantification approach. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2015; 260:98-108. [PMID: 26432399 DOI: 10.1016/j.jmr.2015.09.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2014] [Revised: 09/03/2015] [Accepted: 09/04/2015] [Indexed: 05/08/2023]
Abstract
Two-dimensional spectroscopy offers the possibility to unambiguously distinguish metabolites by spreading out the multiplet structure of J-coupled spin systems into a second dimension. Quantification methods that perform parametric fitting of the 2D MRS signal have recently been proposed for resolved PRESS (JPRESS) but not explicitly for Localized Correlation Spectroscopy (LCOSY). Here, through a whole metabolite quantification approach, correlation spectroscopy quantification performances are studied. The ability to quantify metabolite relaxation constant times is studied for three localized 2D MRS sequences (LCOSY, LCTCOSY and the JPRESS) in vitro on preclinical MR systems. The issues encountered during implementation and quantification strategies are discussed with the help of the Fisher matrix formalism. The described parameterized models enable the computation of the lower bound for error variance--generally known as the Cramér Rao bounds (CRBs), a standard of precision--on the parameters estimated from these 2D MRS signal fittings. LCOSY has a theoretical net signal loss of two per unit of acquisition time compared to JPRESS. A rapid analysis could point that the relative CRBs of LCOSY compared to JPRESS (expressed as a percentage of the concentration values) should be doubled but we show that this is not necessarily true. Finally, the LCOSY quantification procedure has been applied on data acquired in vivo on a mouse brain.
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Affiliation(s)
- Dimitri Martel
- Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Claude Bernard Lyon 1, France
| | - K Tse Ve Koon
- Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Claude Bernard Lyon 1, France
| | - Yann Le Fur
- Aix-Marseille Université, CRMBM, CNRS UMR, 7339 Marseille, France
| | - Hélène Ratiney
- Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Claude Bernard Lyon 1, France.
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22
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Breitkreutz DY, Fallone BG, Yahya A. Effect of J coupling on 1.3-ppm lipid methylene signal acquired with localised proton MRS at 3 T. NMR IN BIOMEDICINE 2015; 28:1324-1331. [PMID: 26314546 DOI: 10.1002/nbm.3387] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Revised: 07/10/2015] [Accepted: 07/30/2015] [Indexed: 06/04/2023]
Abstract
The purpose of this work was to investigate the effect of J-coupling interactions on the quantification and T2 determination of 1.3-ppm lipid methylene protons at 3 T. The response of the 1.3-ppm protons of hexanoic, heptanoic, octanoic, linoleic and oleic acid was measured as a function of point-resolved spectroscopy (PRESS) and stimulated echo acquisition mode (STEAM) TE. In addition, a narrow-bandwidth refocusing PRESS sequence designed to rewind J-coupling evolution of the 1.3-ppm protons was applied to the five fatty acids, to corn oil and to tibial bone marrow of six healthy volunteers. Peak areas were plotted as a function of TE, and data were fitted to monoexponentially decaying functions to determine Mo (the extrapolated area for TE = 0 ms) and T2 values. In phantoms, rewinding J-coupling evolution resulted in 198%, 64%, 44%, 20% and 15% higher T2 values for heptanoic, octanoic, linoleic and oleic acid, and corn oil, respectively, compared with those obtained with standard PRESS. The narrow-bandwidth PRESS sequence also resulted in significant changes in Mo , namely -77%, -22%, 28%, 23% and 28% for heptanoic, octanoic, linoleic and oleic acid, and corn oil, respectively. T2 values obtained with STEAM were closer to the values measured with narrow-bandwidth PRESS. On average, in tibial bone marrow (six volunteers) rewinding J-coupling evolution resulted in 21% ± 3% and 9 % ± 1% higher Mo and T2 values, respectively. This work demonstrates that the consequence of neglecting to consider scalar coupling effects on the quantification of 1.3-ppm lipid methylene protons and their T2 values is not negligible. The linoleic and oleic acid T2 results indicate that T2 measures of lipids with standard MRS techniques are dependent on lipid composition.
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Affiliation(s)
| | - B Gino Fallone
- Department of Oncology, University of Alberta, Edmonton, AB, Canada
- Department of Medical Physics, Cross Cancer Institute, Edmonton, AB, Canada
| | - Atiyah Yahya
- Department of Oncology, University of Alberta, Edmonton, AB, Canada
- Department of Medical Physics, Cross Cancer Institute, Edmonton, AB, Canada
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Baker EH, Levin SW, Zhang Z, Mukherjee AB. Evaluation of disease progression in INCL by MR spectroscopy. Ann Clin Transl Neurol 2015; 2:797-809. [PMID: 26339674 PMCID: PMC4554441 DOI: 10.1002/acn3.222] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 05/13/2015] [Indexed: 11/06/2022] Open
Abstract
OBJECTIVE Infantile neuronal ceroid lipofuscinosis (INCL) is a devastating neurodegenerative storage disease caused by palmitoyl-protein thioesterase-1 deficiency, which impairs degradation of palmitoylated proteins (constituents of ceroid) by lysosomal hydrolases. Consequent lysosomal ceroid accumulation leads to neuronal injury. As part of a pilot study to evaluate treatment benefits of cysteamine bitartrate and N-acetylcysteine, we quantitatively measured brain metabolite levels using magnetic resonance spectroscopy (MRS). METHODS A subset of two patients from a larger treatment and follow-up study underwent serial quantitative single-voxel MRS examinations of five anatomical sites. Three echo times were acquired in order to estimate metabolite T2. Measured metabolite levels included correction for partial volume of cerebrospinal fluid. Comparison of INCL patients was made to a reference group composed of asymptomatic and minimally symptomatic Niemann-Pick disease type C patients. RESULTS In INCL patients, N-acetylaspartate (NAA) was abnormally low at all locations upon initial measurement, and further declined throughout the follow-up period. In the cerebrum (affected early in the disease course), choline and myo-inositol were initially elevated and fell during the follow-up period, whereas in the cerebellum and brainstem (affected later), choline and myo-inositol were initially normal and rose subsequently. INTERPRETATION Choline and myo-inositol levels in our patients are consistent with patterns of neuroinflammation observed in two INCL mouse models. Low, persistently declining NAA was expected based on the progressive, irreversible nature of the disease. Progression of metabolite levels in INCL has not been previously quantified; therefore the results of this study serve as a reference for quantitative evaluation of future therapeutic interventions.
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Affiliation(s)
- Eva H Baker
- Department of Radiology and Imaging Sciences, Clinical Center, National Institutes of Health Bethesda, Maryland, USA, 20892
| | - Sondra W Levin
- Program on Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH Bethesda, Maryland, USA, 20892 ; Department of Pediatrics, Walter Reed National Military Medical Center Bethesda, Maryland, USA, 20889-5600
| | - Zhongjian Zhang
- Program on Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH Bethesda, Maryland, USA, 20892
| | - Anil B Mukherjee
- Program on Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH Bethesda, Maryland, USA, 20892
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Monin A, Baumann PS, Griffa A, Xin L, Mekle R, Fournier M, Butticaz C, Klaey M, Cabungcal JH, Steullet P, Ferrari C, Cuenod M, Gruetter R, Thiran JP, Hagmann P, Conus P, Do KQ. Glutathione deficit impairs myelin maturation: relevance for white matter integrity in schizophrenia patients. Mol Psychiatry 2015; 20:827-38. [PMID: 25155877 DOI: 10.1038/mp.2014.88] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Revised: 04/30/2014] [Accepted: 06/23/2014] [Indexed: 12/18/2022]
Abstract
Schizophrenia pathophysiology implies both abnormal redox control and dysconnectivity of the prefrontal cortex, partly related to oligodendrocyte and myelin impairments. As oligodendrocytes are highly vulnerable to altered redox state, we investigated the interplay between glutathione and myelin. In control subjects, multimodal brain imaging revealed a positive association between medial prefrontal glutathione levels and both white matter integrity and resting-state functional connectivity along the cingulum bundle. In early psychosis patients, only white matter integrity was correlated with glutathione levels. On the other side, in the prefrontal cortex of peripubertal mice with genetically impaired glutathione synthesis, mature oligodendrocyte numbers, as well as myelin markers, were decreased. At the molecular levels, under glutathione-deficit conditions induced by short hairpin RNA targeting the key glutathione synthesis enzyme, oligodendrocyte progenitors showed a decreased proliferation mediated by an upregulation of Fyn kinase activity, reversed by either the antioxidant N-acetylcysteine or Fyn kinase inhibitors. In addition, oligodendrocyte maturation was impaired. Interestingly, the regulation of Fyn mRNA and protein expression was also impaired in fibroblasts of patients deficient in glutathione synthesis. Thus, glutathione and redox regulation have a critical role in myelination processes and white matter maturation in the prefrontal cortex of rodent and human, a mechanism potentially disrupted in schizophrenia.
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Affiliation(s)
- A Monin
- 1] Center for Psychiatric Neuroscience, Centre Hospitalier Universitaire Vaudois and University of Lausanne (CHUV-UNIL), Prilly-Lausanne, Switzerland [2] Department of Psychiatry, Centre Hospitalier Universitaire Vaudois and University of Lausanne (CHUV-UNIL), Prilly-Lausanne, Switzerland
| | - P S Baumann
- 1] Center for Psychiatric Neuroscience, Centre Hospitalier Universitaire Vaudois and University of Lausanne (CHUV-UNIL), Prilly-Lausanne, Switzerland [2] Department of Psychiatry, Centre Hospitalier Universitaire Vaudois and University of Lausanne (CHUV-UNIL), Prilly-Lausanne, Switzerland [3] Service of General Psychiatry, Centre Hospitalier Universitaire Vaudois and University of Lausanne (CHUV-UNIL), Prilly-Lausanne, Switzerland
| | - A Griffa
- 1] Signal Processing Laboratory, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland [2] Department of Radiology, Centre Hospitalier Universitaire Vaudois and University of Lausanne (CHUV-UNIL), Lausanne, Switzerland
| | - L Xin
- Laboratory for Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - R Mekle
- Physikalisch-Technische Bundesanstalt, Berlin, Germany
| | - M Fournier
- 1] Center for Psychiatric Neuroscience, Centre Hospitalier Universitaire Vaudois and University of Lausanne (CHUV-UNIL), Prilly-Lausanne, Switzerland [2] Department of Psychiatry, Centre Hospitalier Universitaire Vaudois and University of Lausanne (CHUV-UNIL), Prilly-Lausanne, Switzerland
| | - C Butticaz
- 1] Center for Psychiatric Neuroscience, Centre Hospitalier Universitaire Vaudois and University of Lausanne (CHUV-UNIL), Prilly-Lausanne, Switzerland [2] Department of Psychiatry, Centre Hospitalier Universitaire Vaudois and University of Lausanne (CHUV-UNIL), Prilly-Lausanne, Switzerland
| | - M Klaey
- 1] Center for Psychiatric Neuroscience, Centre Hospitalier Universitaire Vaudois and University of Lausanne (CHUV-UNIL), Prilly-Lausanne, Switzerland [2] Department of Psychiatry, Centre Hospitalier Universitaire Vaudois and University of Lausanne (CHUV-UNIL), Prilly-Lausanne, Switzerland
| | - J H Cabungcal
- 1] Center for Psychiatric Neuroscience, Centre Hospitalier Universitaire Vaudois and University of Lausanne (CHUV-UNIL), Prilly-Lausanne, Switzerland [2] Department of Psychiatry, Centre Hospitalier Universitaire Vaudois and University of Lausanne (CHUV-UNIL), Prilly-Lausanne, Switzerland
| | - P Steullet
- 1] Center for Psychiatric Neuroscience, Centre Hospitalier Universitaire Vaudois and University of Lausanne (CHUV-UNIL), Prilly-Lausanne, Switzerland [2] Department of Psychiatry, Centre Hospitalier Universitaire Vaudois and University of Lausanne (CHUV-UNIL), Prilly-Lausanne, Switzerland
| | - C Ferrari
- 1] Center for Psychiatric Neuroscience, Centre Hospitalier Universitaire Vaudois and University of Lausanne (CHUV-UNIL), Prilly-Lausanne, Switzerland [2] Department of Psychiatry, Centre Hospitalier Universitaire Vaudois and University of Lausanne (CHUV-UNIL), Prilly-Lausanne, Switzerland
| | - M Cuenod
- 1] Center for Psychiatric Neuroscience, Centre Hospitalier Universitaire Vaudois and University of Lausanne (CHUV-UNIL), Prilly-Lausanne, Switzerland [2] Department of Psychiatry, Centre Hospitalier Universitaire Vaudois and University of Lausanne (CHUV-UNIL), Prilly-Lausanne, Switzerland
| | - R Gruetter
- 1] Department of Radiology, Centre Hospitalier Universitaire Vaudois and University of Lausanne (CHUV-UNIL), Lausanne, Switzerland [2] Laboratory for Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - J P Thiran
- 1] Signal Processing Laboratory, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland [2] Department of Radiology, Centre Hospitalier Universitaire Vaudois and University of Lausanne (CHUV-UNIL), Lausanne, Switzerland
| | - P Hagmann
- 1] Signal Processing Laboratory, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland [2] Department of Radiology, Centre Hospitalier Universitaire Vaudois and University of Lausanne (CHUV-UNIL), Lausanne, Switzerland
| | - P Conus
- 1] Department of Psychiatry, Centre Hospitalier Universitaire Vaudois and University of Lausanne (CHUV-UNIL), Prilly-Lausanne, Switzerland [2] Service of General Psychiatry, Centre Hospitalier Universitaire Vaudois and University of Lausanne (CHUV-UNIL), Prilly-Lausanne, Switzerland
| | - K Q Do
- 1] Center for Psychiatric Neuroscience, Centre Hospitalier Universitaire Vaudois and University of Lausanne (CHUV-UNIL), Prilly-Lausanne, Switzerland [2] Department of Psychiatry, Centre Hospitalier Universitaire Vaudois and University of Lausanne (CHUV-UNIL), Prilly-Lausanne, Switzerland
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Xin L, Lanz B, Lei H, Gruetter R. Assessment of metabolic fluxes in the mouse brain in vivo using 1H-[13C] NMR spectroscopy at 14.1 Tesla. J Cereb Blood Flow Metab 2015; 35:759-65. [PMID: 25605294 PMCID: PMC4420852 DOI: 10.1038/jcbfm.2014.251] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 11/27/2014] [Accepted: 12/15/2014] [Indexed: 01/13/2023]
Abstract
(13)C magnetic resonance spectroscopy (MRS) combined with the administration of (13)C labeled substrates uniquely allows to measure metabolic fluxes in vivo in the brain of humans and rats. The extension to mouse models may provide exclusive prospect for the investigation of models of human diseases. In the present study, the short-echo-time (TE) full-sensitivity (1)H-[(13)C] MRS sequence combined with high magnetic field (14.1 T) and infusion of [U-(13)C6] glucose was used to enhance the experimental sensitivity in vivo in the mouse brain and the (13)C turnover curves of glutamate C4, glutamine C4, glutamate+glutamine C3, aspartate C2, lactate C3, alanine C3, γ-aminobutyric acid C2, C3 and C4 were obtained. A one-compartment model was used to fit (13)C turnover curves and resulted in values of metabolic fluxes including the tricarboxylic acid (TCA) cycle flux VTCA (1.05 ± 0.04 μmol/g per minute), the exchange flux between 2-oxoglutarate and glutamate Vx (0.48 ± 0.02 μmol/g per minute), the glutamate-glutamine exchange rate V(gln) (0.20 ± 0.02 μmol/g per minute), the pyruvate dilution factor K(dil) (0.82 ± 0.01), and the ratio for the lactate conversion rate and the alanine conversion rate V(Lac)/V(Ala) (10 ± 2). This study opens the prospect of studying transgenic mouse models of brain pathologies.
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Affiliation(s)
- Lijing Xin
- Laboratory of Functional and Metabolic Imaging (LIFMET), Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
- Unit for Research in Schizophrenia, Department of Psychiatry, Center for Psychiatric Neuroscience, Lausanne University Hospital (CHUV), Lausanne, Switzerland
| | - Bernard Lanz
- Laboratory of Functional and Metabolic Imaging (LIFMET), Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Hongxia Lei
- Department of Radiology, University of Geneva, Geneva, Switzerland
- Animal Imaging and Technology Core (AIT), Center for Biomedical Imaging (CIBM), Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Rolf Gruetter
- Laboratory of Functional and Metabolic Imaging (LIFMET), Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
- Department of Radiology, University of Geneva, Geneva, Switzerland
- Department of Radiology, University of Lausanne, Lausanne, Switzerland
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26
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Lopez‐Kolkovsky AL, Mériaux S, Boumezbeur F. Metabolite and macromolecule T
1
and T
2
relaxation times in the rat brain in vivo at 17.2T. Magn Reson Med 2015; 75:503-14. [DOI: 10.1002/mrm.25602] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Revised: 11/27/2014] [Accepted: 12/15/2014] [Indexed: 12/12/2022]
Affiliation(s)
| | - Sebastien Mériaux
- NeuroSpin, I2BM, Commissariat à l'Energie AtomiqueGif‐sur‐Yvette France
| | - Fawzi Boumezbeur
- NeuroSpin, I2BM, Commissariat à l'Energie AtomiqueGif‐sur‐Yvette France
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27
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Ganji SK, Maher EA, Choi C. In vivo (1)H MRSI of glycine in brain tumors at 3T. Magn Reson Med 2015; 75:52-62. [PMID: 25651788 DOI: 10.1002/mrm.25588] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 11/06/2014] [Accepted: 11/28/2014] [Indexed: 01/10/2023]
Abstract
PURPOSE MR spectroscopic imaging (SI) of glycine (Gly) in the human brain is challenging due to the interference of the abundant neighboring J-coupled resonances. Our aim is to accomplish reliable imaging of Gly in healthy brain and brain tumors using an optimized MR sequence scheme at 3 tesla. METHODS Two-dimensional (1)H SI was performed with a point-resolved spectroscopy scheme. An echo time of 160 ms was used for separation between Gly and myo-inositol signals. Data were collected from eight healthy volunteers and 14 subjects with gliomas. Spectra were analyzed with the linear combination model using numerically calculated basis spectra. Metabolite concentrations were estimated with reference to creatine in white matter (WM) regions at 6.4 molar concentrations (mM). RESULTS From a linear regression analysis with respect to the fractional gray matter (GM) content, the Gly concentrations in pure GM and WM in healthy brains were estimated to be 1.1 and 0.3 mM, respectively. Gly was significantly elevated in tumors. The tumor-to-contralateral Gly concentration ratio was more extensive with higher grades, showing ∼ 10-fold elevation of Gly in glioblastomas. CONCLUSION The Gly level is significantly different between GM and WM in healthy brains. Our data indicate that SI of Gly may provide a biomarker of brain tumor malignancy.
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Affiliation(s)
- Sandeep K Ganji
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Elizabeth A Maher
- Harold C. Simmons Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Annette Strauss Center for Neuro-Oncology, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Changho Choi
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Harold C. Simmons Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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28
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Bogner W, Gagoski B, Hess AT, Bhat H, Tisdall MD, van der Kouwe AJW, Strasser B, Marjańska M, Trattnig S, Grant E, Rosen B, Andronesi OC. 3D GABA imaging with real-time motion correction, shim update and reacquisition of adiabatic spiral MRSI. Neuroimage 2014; 103:290-302. [PMID: 25255945 PMCID: PMC4312209 DOI: 10.1016/j.neuroimage.2014.09.032] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Revised: 09/04/2014] [Accepted: 09/15/2014] [Indexed: 12/12/2022] Open
Abstract
Gamma-aminobutyric acid (GABA) and glutamate (Glu) are the major neurotransmitters in the brain. They are crucial for the functioning of healthy brain and their alteration is a major mechanism in the pathophysiology of many neuro-psychiatric disorders. Magnetic resonance spectroscopy (MRS) is the only way to measure GABA and Glu non-invasively in vivo. GABA detection is particularly challenging and requires special MRS techniques. The most popular is MEscher-GArwood (MEGA) difference editing with single-voxel Point RESolved Spectroscopy (PRESS) localization. This technique has three major limitations: a) MEGA editing is a subtraction technique, hence is very sensitive to scanner instabilities and motion artifacts. b) PRESS is prone to localization errors at high fields (≥3T) that compromise accurate quantification. c) Single-voxel spectroscopy can (similar to a biopsy) only probe steady GABA and Glu levels in a single location at a time. To mitigate these problems, we implemented a 3D MEGA-editing MRS imaging sequence with the following three features: a) Real-time motion correction, dynamic shim updates, and selective reacquisition to eliminate subtraction artifacts due to scanner instabilities and subject motion. b) Localization by Adiabatic SElective Refocusing (LASER) to improve the localization accuracy and signal-to-noise ratio. c) K-space encoding via a weighted stack of spirals provides 3D metabolic mapping with flexible scan times. Simulations, phantom and in vivo experiments prove that our MEGA-LASER sequence enables 3D mapping of GABA+ and Glx (Glutamate+Gluatmine), by providing 1.66 times larger signal for the 3.02ppm multiplet of GABA+ compared to MEGA-PRESS, leading to clinically feasible scan times for 3D brain imaging. Hence, our sequence allows accurate and robust 3D-mapping of brain GABA+ and Glx levels to be performed at clinical 3T MR scanners for use in neuroscience and clinical applications.
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Affiliation(s)
- Wolfgang Bogner
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; MRCE, Department of Biomedical Imaging and Image-guided Therapy, Medical University Vienna, Vienna, Austria
| | - Borjan Gagoski
- Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Aaron T Hess
- Department of Cardiovascular Medicine, John Radcliffe Hospital, University of Oxford Centre for Clinical Magnetic Resonance Research, Oxford, UK
| | | | - M Dylan Tisdall
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Andre J W van der Kouwe
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Bernhard Strasser
- MRCE, Department of Biomedical Imaging and Image-guided Therapy, Medical University Vienna, Vienna, Austria
| | - Małgorzata Marjańska
- Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota, Minneapolis, MN, USA
| | - Siegfried Trattnig
- MRCE, Department of Biomedical Imaging and Image-guided Therapy, Medical University Vienna, Vienna, Austria
| | - Ellen Grant
- Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Bruce Rosen
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Ovidiu C Andronesi
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
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Craveiro M, Cudalbu C, Mlynárik V, Gruetter R. Optimized MEGA-SPECIAL for in vivo glutamine detection in the rat brain at 14.1 T. NMR IN BIOMEDICINE 2014; 27:1151-1158. [PMID: 25070114 DOI: 10.1002/nbm.3168] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Revised: 04/04/2014] [Accepted: 06/22/2014] [Indexed: 06/03/2023]
Abstract
Glutamine has multiple roles in brain metabolism and its concentration can be altered in various pathological conditions. An accurate knowledge of its concentration is therefore highly desirable to monitor and study several brain disorders in vivo. However, in recent years, several MRS studies have reported conflicting glutamine concentrations in the human brain. A recent hypothesis for explaining these discrepancies is that a short T2 component of the glutamine signal may impact on its quantification at long echo times. The present study therefore aimed to investigate the impact of acquisition parameters on the quantified glutamine concentration using two different acquisition techniques, SPECIAL at ultra-short echo time and MEGA-SPECIAL at moderate echo time. For this purpose, MEGA-SPECIAL was optimized for the first time for glutamine detection. Based on the very good agreement of the glutamine concentration obtained between the two measurements, it was concluded that no impact of a short T2 component of the glutamine signal was detected.
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Affiliation(s)
- Mélanie Craveiro
- Laboratory for Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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30
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Deelchand DK, Adanyeguh IM, Emir UE, Nguyen TM, Valabregue R, Henry PG, Mochel F, Öz G. Two-site reproducibility of cerebellar and brainstem neurochemical profiles with short-echo, single-voxel MRS at 3T. Magn Reson Med 2014; 73:1718-25. [PMID: 24948590 DOI: 10.1002/mrm.25295] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 04/08/2014] [Accepted: 04/25/2014] [Indexed: 12/25/2022]
Abstract
PURPOSE To determine whether neurochemical concentrations obtained at two MRI sites using clinical 3T scanners can be pooled when a highly optimized, nonvendor short-echo, single-voxel proton MRS pulse sequence is used in conjunction with identical calibration and quantification procedures. METHODS A modified semi-LASER sequence (TE = 28 ms) was used to acquire spectra from two brain regions (cerebellar vermis and pons) on two Siemens 3T scanners using the same B0 and B1 calibration protocols from two different cohorts of healthy volunteers (N = 24-33 per site) matched for age and body mass index. Spectra were quantified with LCModel using water scaling. RESULTS The spectral quality was very consistent between the two sites and allowed reliable quantification of at least 13 metabolites in the vermis and pons compared with 3-5 metabolites in prior multisite magnetic resonance spectroscopy trials using vendor-provided sequences. The neurochemical profiles were nearly identical at the two sites and showed the feasibility to detect interindividual differences in the healthy brain. CONCLUSION Highly reproducible neurochemical profiles can be obtained on different clinical 3T scanners at different sites, provided that the same, optimized acquisition and analysis techniques are used. This will allow pooling of multisite data in clinical studies, which is particularly critical for rare neurological diseases.
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Affiliation(s)
- Dinesh K Deelchand
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, Minnesota, USA
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31
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Reynaud O, Gallichan D, Schaller B, Gruetter R. Fast low-specific absorption rate B0
-mapping along projections at high field using two-dimensional radiofrequency pulses. Magn Reson Med 2014; 73:901-8. [DOI: 10.1002/mrm.25217] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Revised: 02/13/2014] [Accepted: 02/13/2014] [Indexed: 12/24/2022]
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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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33
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Deelchand DK, Henry PG, Marjańska M. Effect of Carr-Purcell refocusing pulse trains on transverse relaxation times of metabolites in rat brain at 9.4 Tesla. Magn Reson Med 2014; 73:13-20. [PMID: 24436256 DOI: 10.1002/mrm.25088] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 11/08/2013] [Accepted: 11/27/2013] [Indexed: 01/29/2023]
Abstract
PURPOSE To investigate the effect of Carr-Purcell (CP) pulse trains on transverse relaxation times, T2, of tissue water and metabolites (both noncoupled and J-coupled spins) in the rat brain at 9.4 Tesla (T) using LASER, CP-LASER, and T2ρ-LASER sequences. METHODS Proton NMR spectra were measured in rat brain in vivo at 9.4T. Spectra were acquired at multiple echo times ranging from 18 to 402 ms. All spectra were analyzed using LCModel with simulated basis sets. Signals of metabolites as a function of echo time were fitted using a mono-exponential function to determine their T2 relaxation times. RESULTS Measured T2 s for tissue water and all metabolites were significantly longer with CP-LASER and T2ρ-LASER compared with LASER. The T2 increased by a factor of ∼ 1.3 for noncoupled and weakly coupled spins (e.g., N-acetylaspartate and total creatine) and by a factor of ∼ 2 (e.g., glutamine and taurine) to ∼ 4 (e.g., glutamate and myo-inositol) for strongly coupled spins. CONCLUSION Application of a CP pulse train results in a larger increase in T2 relaxation times for strongly coupled spins than for noncoupled (singlet) and weakly coupled spins. This needs to be taken into account when correcting for T2 relaxation in CP-like sequences such as LASER.
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Affiliation(s)
- Dinesh Kumar Deelchand
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota Medical School, Minneapolis, Minnesota, USA
| | - Pierre-Gilles Henry
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota Medical School, Minneapolis, Minnesota, USA
| | - Małgorzata Marjańska
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota Medical School, Minneapolis, Minnesota, USA
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Schaller B, Xin L, Gruetter R. Is the macromolecule signal tissue-specific in healthy human brain? A (1)H MRS study at 7 Tesla in the occipital lobe. Magn Reson Med 2013; 72:934-40. [PMID: 24407736 DOI: 10.1002/mrm.24995] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Revised: 08/23/2013] [Accepted: 09/18/2013] [Indexed: 12/24/2022]
Abstract
PURPOSE The macromolecule signal plays a key role in the precision and the accuracy of the metabolite quantification in short-TE (1) H MR spectroscopy. Macromolecules have been reported at 1.5 Tesla (T) to depend on the cerebral studied region and to be age specific. As metabolite concentrations vary locally, information about the profile of the macromolecule signal in different tissues may be of crucial importance. METHODS The aim of this study was to investigate, at 7T for healthy subjects, the neurochemical profile differences provided by macromolecule signal measured in two different tissues in the occipital lobe, predominantly composed of white matter tissue or of grey matter tissue. RESULTS White matter-rich macromolecule signal was relatively lower than the gray matter-rich macromolecule signal from 1.5 to 1.8 ppm and from 2.3 to 2.5 ppm with mean difference over these regions of 7% and 12% (relative to the reference peak at 0.9 ppm), respectively. The neurochemical profiles, when using either of the two macromolecule signals, were similar for 11 reliably quantified metabolites (CRLB < 20%) with relatively small concentration differences (< 0.3 μmol/g), except Glu (± 0.8 μmol/g). CONCLUSION Given the small quantification differences, we conclude that a general macromolecule baseline provides a sufficiently accurate neurochemical profile in occipital lobe at 7T in healthy human brain.
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Affiliation(s)
- Benoît Schaller
- Laboratory of Functional and Metabolic Imaging, Ecole Polytechnique Fédèrale de Lausanne, Lausanne, Switzerland
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35
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Emir UE, Brent Clark H, Vollmers ML, Eberly LE, Öz G. Non-invasive detection of neurochemical changes prior to overt pathology in a mouse model of spinocerebellar ataxia type 1. J Neurochem 2013; 127:660-8. [PMID: 24032423 DOI: 10.1111/jnc.12435] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 08/19/2013] [Accepted: 08/23/2013] [Indexed: 01/09/2023]
Abstract
Spinocerebellar ataxia type 1 (SCA1) is a hereditary, progressive and fatal movement disorder that primarily affects the cerebellum. Non-invasive imaging markers to detect early disease in SCA1 will facilitate testing and implementation of potential therapies. We have previously demonstrated the sensitivity of neurochemical levels measured by (1) H magnetic resonance spectroscopy (MRS) to progressive neurodegeneration using a transgenic mouse model of SCA1. In order to investigate very early neurochemical changes related to neurodegeneration, here we utilized a knock-in mouse model, the Sca1(154Q/2Q) line, which displays milder cerebellar pathology than the transgenic model. We measured cerebellar neurochemical profiles of Sca1(154Q/2Q) mice and wild-type littermates using 9.4T MRS at ages 6, 12, 24, and 39 weeks and assessed the cerebellar pathology of a subset of the mice at each time point. The Sca1(154Q/2Q) mice displayed very mild cerebellar pathology even at 39 weeks, however, were distinguished from wild types by MRS starting at 6 weeks. Taurine and total choline levels were significantly lower at all ages and glutamine and total creatine levels were higher starting at 12 weeks in Sca1(154Q/2Q) mice than controls, demonstrating the sensitivity of neurochemical levels to neurodegeneration related changes in the absence of overt pathology. We measured cerebellar neurochemical alterations in a knock-in mouse model of spinocerebellar ataxia type 1, a hereditary movement disorder, using ultra-high field magnetic resonance spectroscopy (MRS). Very early neurochemical alterations were detectable prior to overt pathology in the volume-of-interest for MRS. Alterations were indicative of osmolytic changes and of disturbances in membrane phospholipid and energy metabolism.
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Affiliation(s)
- Uzay E Emir
- Department of Radiology, Medical School, Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, USA
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Morgan JJ, Kleven GA, Tulbert CD, Olson J, Horita DA, Ronca AE. Longitudinal 1H MRS of rat forebrain from infancy to adulthood reveals adolescence as a distinctive phase of neurometabolite development. NMR IN BIOMEDICINE 2013; 26:683-691. [PMID: 23322706 PMCID: PMC3634877 DOI: 10.1002/nbm.2913] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2012] [Revised: 12/04/2012] [Accepted: 12/05/2012] [Indexed: 06/01/2023]
Abstract
This study represents the first longitudinal, within-subject (1) H MRS investigation of the developing rat brain spanning infancy, adolescence and early adulthood. We obtained neurometabolite profiles from a voxel located in a central location of the forebrain, centered on the striatum, with smaller contributions for the cortex, thalamus and hypothalamus, on postnatal days 7, 35 and 60. Water-scaled metabolite signals were corrected for T1 effects and quantified using the automated processing software LCModel, yielding molal concentrations. Our findings indicate age-related concentration changes in N-acetylaspartate + N-acetylaspartylglutamate, myo-inositol, glutamate + glutamine, taurine, creatine + phosphocreatine and glycerophosphocholine + phosphocholine. Using a repeated measures design and analysis, we identified significant neurodevelopment changes across all three developmental ages and identified adolescence as a distinctive phase in normative neurometabolic brain development. Between postnatal days 35 and 60, changes were observed in the concentrations of N-acetylaspartate + N-acetylaspartylglutamate, glutamate + glutamine and glycerophosphocholine + phosphocholine. Our data replicate past studies of early neurometabolite development and, for the first time, link maturational profiles in the same subjects across infancy, adolescence and adulthood.
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Affiliation(s)
- Jonathan J. Morgan
- Program in Neuroscience, Wake Forest University School of Medicine, Winston Salem, NC, USA
| | - Gale A. Kleven
- Department of Psychology, Wright State University, Dayton, OH USA
| | - Christina D. Tulbert
- Department of Obstetrics and Gynecology, Wake Forest University School of Medicine, Winston Salem, NC, USA
| | - John Olson
- Center for Biomolecular Imaging, Wake Forest University School of Medicine, Winston Salem, NC, USA
| | - David A. Horita
- Department of Biochemistry, Wake Forest University School of Medicine, Winston Salem, NC, USA
| | - April E. Ronca
- Program in Neuroscience, Wake Forest University School of Medicine, Winston Salem, NC, USA
- Department of Obstetrics and Gynecology, Wake Forest University School of Medicine, Winston Salem, NC, USA
- Center for Biomolecular Imaging, Wake Forest University School of Medicine, Winston Salem, NC, USA
- Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, Winston Salem, NC, USA
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Schaller B, Xin L, Cudalbu C, Gruetter R. Quantification of the neurochemical profile using simulated macromolecule resonances at 3 T. NMR IN BIOMEDICINE 2013; 26:593-599. [PMID: 23413241 DOI: 10.1002/nbm.2896] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Revised: 10/30/2012] [Accepted: 11/01/2012] [Indexed: 06/01/2023]
Abstract
The broad resonances underlying the entire (1) H NMR spectrum of the brain, ascribed to macromolecules, can influence metabolite quantification. At the intermediate field strength of 3 T, distinct approaches for the determination of the macromolecule signal, previously used at either 1.5 or 7 T and higher, may become equivalent. The aim of this study was to evaluate, at 3 T for healthy subjects using LCModel, the impact on the metabolite quantification of two different macromolecule approaches: (i) experimentally measured macromolecules; and (ii) mathematically estimated macromolecules. Although small, but significant, differences in metabolite quantification (up to 23% for glutamate) were noted for some metabolites, 10 metabolites were quantified reproducibly with both approaches with a Cramer-Rao lower bound below 20%, and the neurochemical profiles were therefore similar. We conclude that the mathematical approximation can provide sufficiently accurate and reproducible estimation of the macromolecule contribution to the (1) H spectrum at 3 T.
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Affiliation(s)
- Benoît Schaller
- Laboratory of Functional and Metabolic Imaging, Ecole Polytechnique Federale de Lausanne, Lausanne, Switzerland
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Xin L, Gambarota G, Cudalbu C, Mlynárik V, Gruetter R. Single spin-echo T2 relaxation times of cerebral metabolites at 14.1 T in the in vivo rat brain. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2013; 26:549-54. [PMID: 23604579 DOI: 10.1007/s10334-013-0378-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Revised: 04/02/2013] [Accepted: 04/03/2013] [Indexed: 01/08/2023]
Abstract
OBJECT To determine the single spin-echo T2 relaxation times of uncoupled and J-coupled metabolites in rat brain in vivo at 14.1 T and to compare these results with those previously obtained at 9.4 T. MATERIALS AND METHODS Measurements were performed on five rats at 14.1 T using the SPECIAL sequence and TE-specific basis-sets for LCModel analysis. RESULTS AND CONCLUSION The T2 of singlets ranged from 98 to 148 ms and T2 of J-coupled metabolites ranged from 72 ms (glutamate) to 97 ms (myo-inositol). When comparing the T2s of the metabolites measured at 14.1 T with those previously measured at 9.4 T, a decreasing trend was found (p<0.0001). We conclude that the modest shortening of T2 at 14.1 T has a negligible impact on the sensitivity of the 1H MRS when performed at TE shorter than 10 ms.
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Affiliation(s)
- Lijing Xin
- Departments of Radiology, University of Lausanne, Lausanne, Switzerland,
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Steinberg JD, Velan SS. Measuring glucose concentrations in the rat brain using echo-time-averaged point resolved spectroscopy at 7 tesla. Magn Reson Med 2012; 70:301-8. [PMID: 22987321 DOI: 10.1002/mrm.24493] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Revised: 07/19/2012] [Accepted: 08/20/2012] [Indexed: 12/15/2022]
Abstract
Glucose has multiple functions in the brain, and there is interest in estimating in vivo concentrations rather than merely the uptake determined by nuclear medicine. Glucose can be estimated using magnetic resonance spectroscopy, but measurement is difficult due to its multiple J-coupled proton signals overlapping with other metabolite signals. To minimize the effect of interfering signals, echo time (TE) values between 60 and 95 ms were averaged, and the loss in signal due to the T2 effect was corrected in both the estimation of glucose concentration and in creation of the basis files for fitting. The effectiveness of the TE-averaging method was evaluated by measuring the glucose concentration in fasted rats before and after feeding. The brain glucose in all rats increased after feeding with fasted and fed glucose-to-creatine ratios of 0.15 ± 0.03 and 0.24 ± 0.04, respectively. Data at a short TE of 13 ms measured ratios of 0.30 ± 0.16 and 0.36 ± 0.24 for the fasted and fed rats, respectively, demonstrating the difficulty in obtaining reliable glucose measurements at short TE. Overall, TE averaging minimizes the influence of macromolecular signals and nearby peaks to give precise, consistent estimates of glucose.
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Affiliation(s)
- Jeffrey D Steinberg
- Laboratory of Molecular Imaging, Singapore Bioimaging Consortium, Agency for Science, Technology and Research, Singapore, Singapore.
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Liu M, Yue Q, Isobe T, Matsumura A, Li J, Yang Z, Quan H, Xing H, Gong Q. Proton MR spectroscopy of central neurocytoma using short and long echo time: new proofs for the existence of glycine and glutamate. Acad Radiol 2012; 19:779-84. [PMID: 22503892 DOI: 10.1016/j.acra.2012.02.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2011] [Revised: 02/12/2012] [Accepted: 02/13/2012] [Indexed: 12/28/2022]
Abstract
RATIONALE AND OBJECTIVES Central neurocytomas (CNCs) are rare benign tumors typically located in the lateral ventricle of the central nervous system. The authors report five patients with CNCs and review 16 previously published studies that included 52 patients with CNCs to explore the magnetic resonance spectroscopic features of CNCs. MATERIALS AND METHODS Five patients with CNCs were retrospectively reviewed. They were examined using point-resolved spectroscopic series with short and/or long echo times. The integrals of choline, creatine, and the 3.55-ppm peak were determined using Magnetic Resonance User Interface software, and the metabolite ratios relative to creatine were obtained. In two cases, T2 relaxation times of choline and the metabolite resonance at 3.55 ppm were calculated using data points acquired with different echo times and an exponential decay model. RESULTS Consistent with previously published studies, all five patients showed highly increased choline and reduced N-acetylaspartate and creatine. Four patients in the present study and 35 in published data demonstrated prominent peaks at 3.55 ppm, which were assigned to glycine because of its relaxation pattern and long T2 relaxation time. In addition, increased in vivo glutamate and glutamine was also confirmed in three patients examined with short echo times. Alanine and lactate peaks were observed in three and two patients, respectively. CONCLUSIONS The present study shows that the 3.55-ppm peak characteristic of CNC should be assigned to glycine according to its T2 relaxation time. Besides increased glycine and choline, the presence of glutamate or glutamine, which appears on series with short echo times, may further confirm the diagnosis of CNC.
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Banerjee A, Ganji S, Hulsey K, Dimitrov I, Maher E, Ghose S, Tamminga C, Choi C. Measurement of glycine in gray and white matter in the human brain in vivo by 1H MRS at 7.0 T. Magn Reson Med 2012; 68:325-31. [PMID: 22693073 DOI: 10.1002/mrm.24368] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 05/14/2012] [Accepted: 05/16/2012] [Indexed: 01/07/2023]
Abstract
The concentration of glycine (Gly) was measured in gray matter (GM) and white matter (WM) in the human brain using single-voxel localized (1)H MRS at 7 T. A point-resolved spectroscopy sequence with echo time = 150 ms was used for measuring Gly levels in various regions of the frontal and occipital lobes in 11 healthy volunteers and one subject with a glioblastoma. The point-resolved spectroscopy spectra were analyzed with LCModel using basis functions generated from density matrix simulations that included the effects of volume localized radio-frequency and gradient pulses. The fraction of GM and white matter within the voxels was obtained from T(1)-weighted image segmentation. The metabolite concentrations within the voxels, estimated with respect to the GM + WM water concentrations, were fitted to a linear function of fractional GM content. The Gly concentrations in pure GM and white matter were estimated to be 1.1 and 0.1 mM, with 95% confidence intervals 1.0-1.2 and 0.0-0.2, respectively.
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Affiliation(s)
- Abhishek Banerjee
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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42
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The neurochemical profile quantified by in vivo 1H NMR spectroscopy. Neuroimage 2012; 61:342-62. [DOI: 10.1016/j.neuroimage.2011.12.038] [Citation(s) in RCA: 168] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Accepted: 12/15/2011] [Indexed: 12/13/2022] Open
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Bogner W, Gruber S, Trattnig S, Chmelik M. High-resolution mapping of human brain metabolites by free induction decay (1)H MRSI at 7 T. NMR IN BIOMEDICINE 2012; 25:873-82. [PMID: 22190245 DOI: 10.1002/nbm.1805] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Revised: 05/26/2011] [Accepted: 09/27/2011] [Indexed: 05/06/2023]
Abstract
This work describes a new approach for high-spatial-resolution (1)H MRSI of the human brain at 7 T. (1)H MRSI at 7 T using conventional approaches, such as point-resolved spectroscopy and stimulated echo acquisition mode with volume head coils, is limited by technical difficulties, including chemical shift displacement errors, B(0)/B(1) inhomogeneities, a high specific absorption rate and decreased T(2) relaxation times. The method presented here is based on free induction decay acquisition with an ultrashort acquisition delay (TE*) of 1.3 ms. This allows full signal detection with negligible T(2) decay or J-modulation. Chemical shift displacement errors were reduced to below 5% per part per million in the in-slice direction and were eliminated in-plane. The B(1) sensitivity was reduced significantly and further corrected using flip angle maps. Specific absorption rate requirements were well below the limit (~20 % = 0.7 W/kg). The suppression of subcutaneous lipid signals was achieved by substantially improving the point-spread function. High-quality metabolic mapping of five important brain metabolites was achieved with high in-plane resolution (64 × 64 matrix with a 3.4 × 3.4 × 12 mm(3) nominal voxel size) in four healthy subjects. The ultrashort TE* increased the signal-to-noise ratio of J-coupled resonances, such as glutamate and myo-inositol, several-fold to enable the mapping of even these metabolites with high resolution. Four measurement repetitions in one healthy volunteer provided proof of the good reproducibility of this method. The high spatial resolution allowed the visualization of several anatomical structures on metabolic maps. Free induction decay MRSI is insensitive to T(2) decay, J-modulation, B(1) inhomogeneities and chemical shift displacement errors, and overcomes specific absorption rate restrictions at ultrahigh magnetic fields. This makes it a promising method for high-resolution (1)H MRSI at 7 T and above.
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Affiliation(s)
- W Bogner
- Department of Radiology, MR Center of Excellence, Medical University Vienna, Vienna, Austria
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44
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Xin L, Schaller B, Mlynarik V, Lu H, Gruetter R. Proton T
1
relaxation times of metabolites in human occipital white and gray matter at 7 T. Magn Reson Med 2012; 69:931-6. [DOI: 10.1002/mrm.24352] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Revised: 05/02/2012] [Accepted: 05/04/2012] [Indexed: 12/24/2022]
Affiliation(s)
- Lijing Xin
- Department of Radiology; University of Lausanne; Lausanne Switzerland
| | - Benoît Schaller
- Laboratory of Functional and Metabolic Imaging; Ecole Polytechnique Fédérale de Lausanne; Lausanne Switzerland
| | - Vladimir Mlynarik
- Laboratory of Functional and Metabolic Imaging; Ecole Polytechnique Fédérale de Lausanne; Lausanne Switzerland
| | - Huanxiang Lu
- Institute of Surgical Technologies and Biomechanics; University of Bern; Bern Switzerland
| | - Rolf Gruetter
- Department of Radiology; University of Lausanne; Lausanne Switzerland
- Laboratory of Functional and Metabolic Imaging; Ecole Polytechnique Fédérale de Lausanne; Lausanne Switzerland
- Department of Radiology; University of Geneva; Geneva Switzerland
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Ganji SK, Banerjee A, Patel AM, Zhao YD, Dimitrov IE, Browning JD, Brown ES, Maher EA, Choi C. T2 measurement of J-coupled metabolites in the human brain at 3T. NMR IN BIOMEDICINE 2012; 25:523-9. [PMID: 21845738 PMCID: PMC3852663 DOI: 10.1002/nbm.1767] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2010] [Revised: 04/06/2011] [Accepted: 05/20/2011] [Indexed: 05/12/2023]
Abstract
Proton T(2) relaxation times of metabolites in the human brain were measured using point resolved spectroscopy at 3T in vivo. Four echo times (54, 112, 246 and 374 ms) were selected from numerical and phantom analyses for effective detection of the glutamate multiplet at ~ 2.35 ppm. In vivo data were obtained from medial and left occipital cortices of five healthy volunteers. The cortices contained predominantly gray and white matter, respectively. Spectra were analyzed with LCModel software using volume-localized calculated spectra of brain metabolites. The estimate of the signal strength vs. TE was fitted to a monoexponential function for estimation of apparent T(2) (T(2)(†)). T(2)(†) was estimated to be similar between the brain regions for creatine, choline, glutamate and myo-inositol, but significantly different for N-acetylaspartate singlet and multiplet. T(2)(†)s of glutamate and myo-inositol were measured as 181 ± 16 and 197 ± 14 ms (mean ± SD, N = 5) for medial occipital cortices, and 180 ± 12 and 196 ± 17 ms for left occipital cortices, respectively.
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Affiliation(s)
- Sandeep K. Ganji
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Abhishek Banerjee
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Aditya M. Patel
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Yan D. Zhao
- Department of Clinical Sciences, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Harold C. Simmons Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Ivan E. Dimitrov
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Philips Medical Systems, Cleveland, Ohio, USA
| | - Jeffrey D. Browning
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - E. Sherwood Brown
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Elizabeth A. Maher
- Departments of Internal Medicine and Neurology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Changho Choi
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Correspondence to: Changho Choi, Ph.D, Phone: 214-645-2805, FAX: 214-645-2885,
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Marjańska M, Auerbach EJ, Valabrègue R, Van de Moortele PF, Adriany G, Garwood M. Localized 1H NMR spectroscopy in different regions of human brain in vivo at 7 T: T2 relaxation times and concentrations of cerebral metabolites. NMR IN BIOMEDICINE 2012; 25:332-9. [PMID: 21796710 PMCID: PMC3357544 DOI: 10.1002/nbm.1754] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Revised: 05/03/2011] [Accepted: 05/05/2011] [Indexed: 05/22/2023]
Abstract
At the high field strength of 7 T, in vivo spectra of the human brain with exceptional spectral quality sufficient to quantify 16 metabolites have been obtained previously only in the occipital lobe. However, neurochemical abnormalities associated with many brain disorders are expected to occur in brain structures other than the occipital lobe. The purpose of the present study was to obtain high-quality spectra from various brain regions at 7 T and to quantify the concentrations of different metabolites. To obtain concentrations of metabolites within four different regions of the brain, such as the occipital lobe, motor cortex, basal ganglia and cerebellum, the T(2) relaxation times of the singlets and J-coupled metabolites in these regions were measured for the first time at 7 T. Our results demonstrate that high-quality, quantifiable spectra can be obtained in regions other than the occipital lobe at 7 T utilizing a 16-channel transceiver coil and B(1)(+) shimming.
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Affiliation(s)
- Małgorzata Marjańska
- Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota, Minneapolis, MN 55455, USA.
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Edden RAE, Intrapiromkul J, Zhu H, Cheng Y, Barker PB. Measuring T2 in vivo with J-difference editing: application to GABA at 3 Tesla. J Magn Reson Imaging 2011; 35:229-34. [PMID: 22045601 DOI: 10.1002/jmri.22865] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Accepted: 09/29/2011] [Indexed: 12/25/2022] Open
Abstract
PURPOSE To develop an experimental approach for determining in vivo transverse relaxation rates (T(2)) of metabolites that are detected by spectral editing without using simulations, and to demonstrate this approach to measure the T(2) of γ-aminobutyric acid (GABA). MATERIALS AND METHODS The proposed method first determines the TE-dependence of the edited signals using measurements in a pure phantom solution (10 mM γ-aminobutyric acid; GABA); the phantom T(2) is also determined. Once the editing echo time (TE)-modulation pattern is known, it can then be used to determine T(2) in vivo. The method was applied to measure GABA T(2) in the occipital lobe of five healthy adult subjects at 3T, using a J-difference editing method. Unwanted macromolecular contributions to the GABA signal were also measured. RESULTS The in vivo T(2) of edited GABA signal was 88 ± 12 ms; this preliminary result is somewhat shorter than other metabolite T(2) values in the literature at this field strength. CONCLUSION Spectral editing methods are now widely used to detect low concentration metabolites, such as GABA, but to date no edited acquisition methods have been proposed for the measurement of transverse relaxation times (T(2)). The method described has been successfully applied to measuring the T(2) of GABA.
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Affiliation(s)
- Richard A E Edden
- Division of Neuroradiology, Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA.
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Chadzynski GL, Bender B, Groeger A, Erb M, Klose U. Tissue specific resonance frequencies of water and metabolites within the human brain. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2011; 212:55-63. [PMID: 21752679 DOI: 10.1016/j.jmr.2011.06.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2011] [Revised: 06/10/2011] [Accepted: 06/11/2011] [Indexed: 05/31/2023]
Abstract
Chemical shift imaging (CSI) without water suppression was used to examine tissue-specific resonance frequencies of water and metabolites within the human brain. The aim was to verify if there are any regional differences in those frequencies and to determine the influence of chemical shift displacement in slice-selection direction. Unsuppressed spectra were acquired at 3T from nine subjects. Resonance frequencies of water and after water signal removal of total choline, total creatine and NAA were estimated. Furthermore, frequency distances between the water and those resonances were calculated. Results were corrected for chemical shift displacement. Frequency distances between water and metabolites were consistent and greater for GM than for WM. The highest value of WM to GM difference (14ppb) was observed for water to NAA frequency distance. This study demonstrates that there are tissue-specific differences between frequency distances of water and metabolites. Moreover, the influence of chemical shift displacement in slice-selection direction is showed to be negligible.
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Affiliation(s)
- Grzegorz L Chadzynski
- MR Research Group, Department of Diagnostic and Interventional Neuroradiology, University Hospital Tuebingen, Hoppe-Seyler strasse 3, 72076 Tuebingen, Germany.
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Deelchand DK, Henry PG, Uǧurbil K, Marjańska M. Measurement of transverse relaxation times of J-coupled metabolites in the human visual cortex at 4 T. Magn Reson Med 2011; 67:891-7. [PMID: 21748799 DOI: 10.1002/mrm.23080] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Revised: 06/08/2011] [Accepted: 06/12/2011] [Indexed: 12/24/2022]
Abstract
Accurate quantification of (1) H NMR spectra often requires knowledge of the relaxation times to correct for signal losses due to relaxation and saturation. In human brain, T(2) values for singlets such as N-acetylaspartate, creatine, and choline have been reported, but few T(2) values are available for J-coupled spin systems. The purpose of this study was to measure the T(2) relaxation times of J-coupled metabolites in the human occipital lobe using the LASER sequence. Spectra were acquired at multiple echo times and were analyzed with an LCModel using basis sets simulated at each echo time. Separate basis spectra were used for resonances of protons belonging to the same molecule but having very different T(2) values (e.g., two separate basis spectra were used for the singlet and multiplet signal in N-acetylaspartate). The T(2) values for the N-acetylaspartate multiplet (149 ± 12 ms), glutamate (125 ± 10 ms), myo-inositol (139 ± 20 ms), and taurine (196 ± 28 ms) were successfully measured in the human visual cortex at 4 T. These measured T(2) relaxation times have enabled the accurate and absolute quantification of cerebral metabolites at longer echo times.
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Affiliation(s)
- Dinesh Kumar Deelchand
- Department of Radiology, University of Minnesota Medical School, Minneapolis, MN 55455, USA.
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50
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Emir UE, Deelchand D, Henry PG, Terpstra M. Noninvasive quantification of T2 and concentrations of ascorbate and glutathione in the human brain from the same double-edited spectra. NMR IN BIOMEDICINE 2011; 24:263-9. [PMID: 20925125 PMCID: PMC3092362 DOI: 10.1002/nbm.1583] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2009] [Revised: 04/26/2010] [Accepted: 05/31/2010] [Indexed: 05/22/2023]
Abstract
The transverse relaxation times (T(2)) and concentrations of Ascorbate (Asc) and glutathione (GSH) were measured from a single dataset of double-edited spectra that were acquired at several TEs at 4 T in the human brain. Six TEs between 102 and 152 ms were utilized to calculate T(2) for the group of 12 subjects scanned five times each. Spectra measured at all six TEs were summed to quantify the concentration in each individual scan. LCModel fitting was optimized for the quantification of the Asc and GSH double-edited spectra. When the fitted baseline was constrained to be flat, T(2) was found to be 67 ms (95% confidence interval, 50-83 ms) for GSH and ≤115 ms for Asc using the sum of spectra measured over 60 scans. The Asc and GSH concentrations quantified in each of the 60 scans were 0.62 ± 0.08 and 0.81 ± 0.11 µmol/g [mean ± standard deviation (SD), n = 60], respectively, using 10 µmol/g N-acetylaspartate as an internal reference and assuming a constant influence of N-acetylaspartate and antioxidant T(2) relaxation in the reference solution and in vivo. The T(2) value of GSH was measured for the first time in the human brain. The data are consistent with short T(2) for both antioxidants. These T(2) values are essential for the absolute quantification of Asc and GSH concentrations measured at long TE, and provide a critical step towards addressing assumptions about T(2), and therefore towards the quantification of concentrations without the possibility of systematic bias.
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Affiliation(s)
- Uzay E Emir
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, MN, USA.
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