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Bogner W, Otazo R, Henning A. Accelerated MR spectroscopic imaging-a review of current and emerging techniques. NMR IN BIOMEDICINE 2021; 34:e4314. [PMID: 32399974 PMCID: PMC8244067 DOI: 10.1002/nbm.4314] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 03/24/2020] [Accepted: 03/30/2020] [Indexed: 05/14/2023]
Abstract
Over more than 30 years in vivo MR spectroscopic imaging (MRSI) has undergone an enormous evolution from theoretical concepts in the early 1980s to the robust imaging technique that it is today. The development of both fast and efficient sampling and reconstruction techniques has played a fundamental role in this process. State-of-the-art MRSI has grown from a slow purely phase-encoded acquisition technique to a method that today combines the benefits of different acceleration techniques. These include shortening of repetition times, spatial-spectral encoding, undersampling of k-space and time domain, and use of spatial-spectral prior knowledge in the reconstruction. In this way in vivo MRSI has considerably advanced in terms of spatial coverage, spatial resolution, acquisition speed, artifact suppression, number of detectable metabolites and quantification precision. Acceleration not only has been the enabling factor in high-resolution whole-brain 1 H-MRSI, but today is also common in non-proton MRSI (31 P, 2 H and 13 C) and applied in many different organs. In this process, MRSI techniques had to constantly adapt, but have also benefitted from the significant increase of magnetic field strength boosting the signal-to-noise ratio along with high gradient fidelity and high-density receive arrays. In combination with recent trends in image reconstruction and much improved computation power, these advances led to a number of novel developments with respect to MRSI acceleration. Today MRSI allows for non-invasive and non-ionizing mapping of the spatial distribution of various metabolites' tissue concentrations in animals or humans, is applied for clinical diagnostics and has been established as an important tool for neuro-scientific and metabolism research. This review highlights the developments of the last five years and puts them into the context of earlier MRSI acceleration techniques. In addition to 1 H-MRSI it also includes other relevant nuclei and is not limited to certain body regions or specific applications.
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Affiliation(s)
- Wolfgang Bogner
- High‐Field MR Center, Department of Biomedical Imaging and Image‐Guided TherapyMedical University of ViennaViennaAustria
| | - Ricardo Otazo
- Department of Medical PhysicsMemorial Sloan Kettering Cancer CenterNew York, New YorkUSA
| | - Anke Henning
- Max Planck Institute for Biological CyberneticsTübingenGermany
- Advanced Imaging Research Center, UT Southwestern Medical CenterDallasTexasUSA
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Diffusion-weighted magnetic resonance spectroscopy enables cell-specific monitoring of astrocyte reactivity in vivo. Neuroimage 2019; 191:457-469. [PMID: 30818026 DOI: 10.1016/j.neuroimage.2019.02.046] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 01/21/2019] [Accepted: 02/19/2019] [Indexed: 01/08/2023] Open
Abstract
Reactive astrocytes exhibit hypertrophic morphology and altered metabolism. Deciphering astrocytic status would be of great importance to understand their role and dysregulation in pathologies, but most analytical methods remain highly invasive or destructive. The diffusion of brain metabolites, as non-invasively measured using diffusion-weighted magnetic resonance spectroscopy (DW-MRS) in vivo, depends on the structure of their micro-environment. Here we perform advanced DW-MRS in a mouse model of reactive astrocytes to determine how cellular compartments confining metabolite diffusion are changing. This reveals myo-inositol as a specific intra-astrocytic marker whose diffusion closely reflects astrocytic morphology, enabling non-invasive detection of astrocyte hypertrophy (subsequently confirmed by confocal microscopy ex vivo). Furthermore, we measure massive variations of lactate diffusion properties, suggesting that intracellular lactate is predominantly astrocytic under control conditions, but predominantly neuronal in case of astrocyte reactivity. This indicates massive remodeling of lactate metabolism, as lactate compartmentation is tightly linked to the astrocyte-to-neuron lactate shuttle mechanism.
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Palombo M, Shemesh N, Ronen I, Valette J. Insights into brain microstructure from in vivo DW-MRS. Neuroimage 2018; 182:97-116. [DOI: 10.1016/j.neuroimage.2017.11.028] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2017] [Revised: 10/09/2017] [Accepted: 11/15/2017] [Indexed: 12/27/2022] Open
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Fotso K, Dager SR, Landow A, Ackley E, Myers O, Dixon M, Shaw D, Corrigan NM, Posse S. Diffusion tensor spectroscopic imaging of the human brain in children and adults. Magn Reson Med 2016; 78:1246-1256. [PMID: 27791287 DOI: 10.1002/mrm.26518] [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: 04/28/2016] [Revised: 08/26/2016] [Accepted: 09/28/2016] [Indexed: 12/27/2022]
Abstract
PURPOSE We developed diffusion tensor spectroscopic imaging (DTSI), based on proton-echo-planar-spectroscopic imaging (PEPSI), and evaluated the feasibility of mapping brain metabolite diffusion in adults and children. METHODS PRESS prelocalized DTSI at 3 Tesla (T) was performed using navigator-based correction of movement-related phase errors and cardiac gating with compensation for repetition time (TR) related variability in T1 saturation. Mean diffusivity (MD) and fractional anisotropy (FA) of total N-acetyl-aspartate (tNAA), total creatine (tCr), and total choline (tCho) were measured in eight adults (17-60 years) and 10 children (3-24 months) using bmax = 1734 s/mm2 , 1 cc and 4.5 cc voxel sizes, with nominal scan times of 17 min and 8:24 min. Residual movement-related phase encoding ghosting (PEG) was used as a regressor across scans to correct overestimation of MD. RESULTS After correction for PEG, metabolite slice-averaged MD estimated at 20% PEG were lower (P < 0.042) for adults (0.17/0.20/0.18 × 10-3 mm2 /s) than for children (0.26/0.27/0.24 × 10-3 mm2 /s). Extrapolated to 0% PEG, the MD estimates decreased further (0.09/0.11/0.11 × 10-3 mm2 /s versus 0.15/0.16/0.15 × 10-3 mm2 /s). Slice-averaged FA of tNAA (P = 0.049), tCr (P = 0.067), and tCho (P = 0.003) were higher in children. CONCLUSION This high-speed DTSI approach with PEG regression allows for estimation of metabolite MD and FA with improved tolerance to movement. Our preliminary data suggesting age-related changes support DTSI as a sensitive technique for investigating intracellular markers of biological processes. Magn Reson Med 78:1246-1256, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Kevin Fotso
- Department of Neurology, University of New Mexico, Albuquerque, New Mexico, USA.,Department of Biomedical Engineering, University of New Mexico, Albuquerque, New Mexico, USA
| | - Stephen R Dager
- Department of Radiology, University of Washington, Seattle, Washington, USA
| | - Alec Landow
- Department of Neurology, University of New Mexico, Albuquerque, New Mexico, USA.,Department of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico, USA
| | - Elena Ackley
- Department of Neurology, University of New Mexico, Albuquerque, New Mexico, USA
| | - Orrin Myers
- Department of Internal Medicine, University of New Mexico, Albuquerque, New Mexico, USA
| | - Mindy Dixon
- Seattle Children's Hospital, Seattle, Washington, USA
| | - Dennis Shaw
- Department of Radiology, University of Washington, Seattle, Washington, USA.,Seattle Children's Hospital, Seattle, Washington, USA
| | - Neva M Corrigan
- Department of Radiology, University of Washington, Seattle, Washington, USA
| | - Stefan Posse
- Department of Neurology, University of New Mexico, Albuquerque, New Mexico, USA.,Department of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico, USA.,Department of Electrical and Computer Engineering, University of New Mexico, Albuquerque, New Mexico, USA
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