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Shamaei A, Starcukova J, Rizzo R, Starcuk Z. Water removal in MR spectroscopic imaging with Casorati singular value decomposition. Magn Reson Med 2024; 91:1694-1706. [PMID: 38181180 DOI: 10.1002/mrm.29959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 11/04/2023] [Accepted: 11/17/2023] [Indexed: 01/07/2024]
Abstract
PURPOSE Water removal is one of the computational bottlenecks in the processing of high-resolution MRSI data. The purpose of this work is to propose an approach to reduce the computing time required for water removal in large MRS data. METHODS In this work, we describe a singular value decomposition-based approach that uses the partial position-time separability and the time-domain linear predictability of MRSI data to reduce the computational time required for water removal. Our approach arranges MRS signals in a Casorati matrix form, applies low-rank approximations utilizing singular value decomposition, removes residual water from the most prominent left-singular vectors, and finally reconstructs the water-free matrix using the processed left-singular vectors. RESULTS We have demonstrated the effectiveness of our proposed algorithm for water removal using both simulated and in vivo data. The proposed algorithm encompasses a pip-installable tool ( https://pypi.org/project/CSVD/), available on GitHub ( https://github.com/amirshamaei/CSVD), empowering researchers to use it in future studies. Additionally, to further promote transparency and reproducibility, we provide comprehensive code for result replication. CONCLUSIONS The findings of this study suggest that the proposed method is a promising alternative to existing water removal methods due to its low processing time and good performance in removing water signals.
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Affiliation(s)
- Amirmohammad Shamaei
- Institute of Scientific Instruments of the Czech Academy of Sciences, Brno, Czech Republic
- Department of Electrical and Software Engineering, Schulich School of Engineering, University of Calgary, Calgary, Alberta, Canada
| | - Jana Starcukova
- Institute of Scientific Instruments of the Czech Academy of Sciences, Brno, Czech Republic
| | - Rudy Rizzo
- MR Methodology, Department of Interventional Neuroradiology, University of Bern, Bern, Switzerland
- Department of Biomedical Research, University of Bern, Bern, Switzerland
- Translational Imaging Center (TIC), Swiss Institute of Translational Entrepreneurial Medicine, Bern, Switzerland
| | - Zenon Starcuk
- Institute of Scientific Instruments of the Czech Academy of Sciences, Brno, Czech Republic
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2
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Farley N, Susnjar A, Chiew M, Emir UE. Test-Retest Reproducibility of Reduced-Field-of-View Density-Weighted CRT MRSI at 3T. Tomography 2024; 10:493-503. [PMID: 38668396 PMCID: PMC11055142 DOI: 10.3390/tomography10040038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 03/25/2024] [Accepted: 03/26/2024] [Indexed: 04/29/2024] Open
Abstract
Quantifying an imaging modality's ability to reproduce results is important for establishing its utility. In magnetic resonance spectroscopic imaging (MRSI), new acquisition protocols are regularly introduced which improve upon their precursors with respect to signal-to-noise ratio (SNR), total acquisition duration, and nominal voxel resolution. This study has quantified the within-subject and between-subject reproducibility of one such new protocol (reduced-field-of-view density-weighted concentric ring trajectory (rFOV-DW-CRT) MRSI) by calculating the coefficient of variance of data acquired from a test-retest experiment. The posterior cingulate cortex (PCC) and the right superior corona radiata (SCR) were selected as the regions of interest (ROIs) for grey matter (GM) and white matter (WM), respectively. CVs for between-subject and within-subject were consistently around or below 15% for Glx, tCho, and Myo-Ins, and below 5% for tNAA and tCr.
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Affiliation(s)
- Nicholas Farley
- School of Health Sciences, Purdue University, West Lafayette, IN 47907, USA;
| | - Antonia Susnjar
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA;
| | - Mark Chiew
- Department of Medical Biophysics, University of Toronto, Toronto, ON M5G 1L7, Canada;
| | - Uzay E. Emir
- School of Health Sciences, Purdue University, West Lafayette, IN 47907, USA;
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA;
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3
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Andrushko JW, Levenstein JM, Zich C, Edmond EC, Campbell J, Clarke WT, Emir U, Farthing JP, Stagg CJ. Repeated unilateral handgrip contractions alter functional connectivity and improve contralateral limb response times. Sci Rep 2023; 13:6437. [PMID: 37081073 PMCID: PMC10119116 DOI: 10.1038/s41598-023-33106-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 04/07/2023] [Indexed: 04/22/2023] Open
Abstract
In humans, motor learning is underpinned by changes in sensorimotor network functional connectivity (FC). Unilateral contractions increase FC in the ipsilateral primary motor cortex (M1) and supplementary motor area (SMA); areas involved in motor planning and execution of the contralateral hand. Therefore, unilateral contractions are a promising approach to augment motor performance in the contralateral hand. In a within-participant, randomized, cross-over design, 15 right-handed adults had two magnetic resonance imaging (MRI) sessions, where functional-MRI and MR-Spectroscopic Imaging were acquired before and after repeated right-hand contractions at either 5% or 50% maximum voluntary contraction (MVC). Before and after scanning, response times (RTs) were determined in both hands. Nine minutes of 50% MVC contractions resulted in decreased handgrip force in the contracting hand, and decreased RTs and increased handgrip force in the contralateral hand. This improved motor performance in the contralateral hand was supported by significant neural changes: increased FC between SMA-SMA and increased FC between right M1 and right Orbitofrontal Cortex. At a neurochemical level, the degree of GABA decline in left M1, left and right SMA correlated with subsequent behavioural improvements in the left-hand. These results support the use of repeated handgrip contractions as a potential modality for improving motor performance in the contralateral hand.
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Affiliation(s)
- Justin W Andrushko
- College of Kinesiology, University of Saskatchewan, Saskatoon, Canada.
- FMRIB, Nuffield Department of Clinical Neurosciences, Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, UK.
| | - Jacob M Levenstein
- FMRIB, Nuffield Department of Clinical Neurosciences, Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, UK
- Section on Functional Imaging Methods, National Institutes of Mental Health, National Institutes of Health, Bethesda, MD, USA
- Thompson Institute, University of the Sunshine Coast, Sippy Downs, Australia
| | - Catharina Zich
- FMRIB, Nuffield Department of Clinical Neurosciences, Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, UK
- Department of Clinical and Movement Neurosciences, University College London, London, UK
| | - Evan C Edmond
- FMRIB, Nuffield Department of Clinical Neurosciences, Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, UK
| | - Jon Campbell
- FMRIB, Nuffield Department of Clinical Neurosciences, Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, UK
| | - William T Clarke
- FMRIB, Nuffield Department of Clinical Neurosciences, Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, UK
| | - Uzay Emir
- School of Health Sciences, College of Health and Human Sciences, Purdue University, West Lafayette, USA
| | | | - Charlotte J Stagg
- FMRIB, Nuffield Department of Clinical Neurosciences, Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, UK
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Nettekoven C, Mitchell L, Clarke WT, Emir U, Campbell J, Johansen-Berg H, Jenkinson N, Stagg CJ. Cerebellar GABA Change during Visuomotor Adaptation Relates to Adaptation Performance and Cerebellar Network Connectivity: A Magnetic Resonance Spectroscopic Imaging Study. J Neurosci 2022; 42:7721-7732. [PMID: 36414012 PMCID: PMC9581563 DOI: 10.1523/jneurosci.0096-22.2022] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 06/09/2022] [Accepted: 06/16/2022] [Indexed: 12/15/2022] Open
Abstract
Motor adaptation is crucial for performing accurate movements in a changing environment and relies on the cerebellum. Although cerebellar involvement has been well characterized, the neurochemical changes in the cerebellum underpinning human motor adaptation remain unknown. We used a novel magnetic resonance spectroscopic imaging (MRSI) technique to measure changes in the inhibitory neurotransmitter GABA in the human cerebellum during visuomotor adaptation. Participants (n = 17, six female) used their right hand to adapt to a rotated cursor in the scanner, compared with a control task requiring no adaptation. We spatially resolved adaptation-driven GABA changes at the cerebellar nuclei and cerebellar cortex in the left and the right cerebellar hemisphere independently and found that simple right-hand movements increase GABA in the right cerebellar nuclei and decreases GABA in the left. When isolating adaptation-driven GABA changes, we found that GABA in the left cerebellar nuclei and the right cerebellar nuclei diverged, although GABA change from baseline at the right cerebellar nuclei was not different from zero at the group level. Early adaptation-driven GABA fluctuations in the right cerebellar nuclei correlated with adaptation performance. Participants showing greater GABA decrease adapted better, suggesting early GABA change is behaviorally relevant. Early GABA change also correlated with functional connectivity change in a cerebellar network. Participants showing greater decreases in GABA showed greater strength increases in cerebellar network connectivity. Results were specific to GABA, to adaptation, and to the cerebellar network. This study provides first evidence for plastic changes in cerebellar neurochemistry during motor adaptation. Characterizing these naturally occurring neurochemical changes may provide a basis for developing therapeutic interventions to facilitate human motor adaptation.SIGNIFICANCE STATEMENT Despite motor adaptation being fundamental to maintaining accurate movements, its neurochemical basis remains poorly understood, perhaps because measuring neurochemicals in the human cerebellum is technically challenging. Using a novel magnetic resonance spectroscopic imaging method, this study provides evidence for GABA changes in the left compared with the right cerebellar nuclei driven by both simple movement and motor adaptation. Although right cerebellar GABA changes were not significantly different from zero at the group level, the adaptation-driven GABA fluctuations in the right cerebellar nuclei correlated with adaptation performance and with functional connectivity change in a cerebellar network. These results show the first evidence for plastic changes in cerebellar neurochemistry during a cerebellar learning task. This provides the basis for developing therapeutic interventions that facilitate these naturally occurring changes to amplify cerebellar-dependent learning.
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Affiliation(s)
- Caroline Nettekoven
- Wellcome Centre for Integrative Neuroimaging, Functional MRI of the Brain, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU UK
- Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, Department of Psychiatry, University of Oxford, Oxford OX3 7JX, UK
- Medical Research Council Brain Network Dynamics Unit, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX1 3TH UK
- Department of Psychiatry, University of Oxford, Oxford OX3 7JX UK
| | - Leah Mitchell
- Wellcome Centre for Integrative Neuroimaging, Functional MRI of the Brain, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU UK
| | - William T Clarke
- Wellcome Centre for Integrative Neuroimaging, Functional MRI of the Brain, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU UK
- Medical Research Council Brain Network Dynamics Unit, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX1 3TH UK
| | - Uzay Emir
- School of Health Sciences, Purdue University, Purdue, Indiana 47907
| | - Jon Campbell
- Wellcome Centre for Integrative Neuroimaging, Functional MRI of the Brain, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU UK
| | - Heidi Johansen-Berg
- Wellcome Centre for Integrative Neuroimaging, Functional MRI of the Brain, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU UK
- Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, Department of Psychiatry, University of Oxford, Oxford OX3 7JX, UK
| | - Ned Jenkinson
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham B15 2TT UK
| | - Charlotte J Stagg
- Wellcome Centre for Integrative Neuroimaging, Functional MRI of the Brain, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU UK
- Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, Department of Psychiatry, University of Oxford, Oxford OX3 7JX, UK
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Peereboom SM, Kozerke S. Metabolite-cycled echo-planar spectroscopic imaging of the human heart. Magn Reson Med 2022; 88:1516-1527. [PMID: 35666820 PMCID: PMC9544353 DOI: 10.1002/mrm.29333] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 04/30/2022] [Accepted: 05/13/2022] [Indexed: 11/12/2022]
Abstract
Purpose Spectroscopic imaging could provide insights into regional cardiac triglyceride variations, but is hampered by relatively long scan times. It is proposed to synergistically combine echo‐planar spectroscopic imaging (EPSI) with motion‐adapted gating, weighted acquisition and metabolite cycling to reduce scan times to less than 10 min while preserving spatial‐spectral quality. The method is compared to single‐voxel measurements and to metabolite‐cycled EPSI with conventional acquisition for assessing triglyceride‐to‐water (TG/W) ratios in the human heart. Methods Measurements were performed on 10 healthy volunteers using a clinical 1.5T system. EPSI data was acquired both without and with motion‐adapted gating in combination with weighted acquisition to assess TG/W ratios and relative Cramér‐Rao lower bounds (CRLB) of TG. For comparison, single‐voxel (PRESS) spectra were acquired in the interventricular septum. Results Bland–Altman analyses did not show a significant bias in TG/W when comparing both metabolite‐cycled EPSI methods to PRESS for any of the cardiac segments. Scan time was 8.05 ± 2.06 min and 17.91 ± 3.93 min for metabolite‐cycled EPSI with and without motion‐adapted gating and weighted acquisition, respectively, while relative CRLB of TG did not differ significantly between the two methods for any of the cardiac segments. Conclusions Metabolite‐cycled EPSI with motion‐adapted gating and weighted acquisition allows detecting TG/W ratios in different regions of the in vivo human heart. Scan time is reduced by more than 2‐fold to less than 10 min as compared to conventional acquisition, while keeping the quality of TG fitting constant. Click here for author‐reader discussions
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Affiliation(s)
- Sophie M Peereboom
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - Sebastian Kozerke
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
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In Vivo Renal Lipid Quantification by Accelerated Magnetic Resonance Spectroscopic Imaging at 3T: Feasibility and Reliability Study. Metabolites 2022; 12:metabo12050386. [PMID: 35629890 PMCID: PMC9146867 DOI: 10.3390/metabo12050386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 04/15/2022] [Accepted: 04/19/2022] [Indexed: 11/17/2022] Open
Abstract
A reliable and practical renal-lipid quantification and imaging method is needed. Here, the feasibility of an accelerated MRSI method to map renal fat fractions (FF) at 3T and its repeatability were investigated. A 2D density-weighted concentric-ring-trajectory MRSI was used for accelerating the acquisition of 48 × 48 voxels (each of 0.25 mL spatial resolution) without respiratory navigation implementations. The data were collected over 512 complex-FID timepoints with a 1250 Hz spectral bandwidth. The MRSI sequence was designed with a metabolite-cycling technique for lipid–water separation. The in vivo repeatability performance of the sequence was assessed by conducting a test–reposition–retest study within healthy subjects. The coefficient of variation (CV) in the estimated FF from the test–retest measurements showed a high degree of repeatability of MRSI-FF (CV = 4.3 ± 2.5%). Additionally, the matching level of the spectral signature within the same anatomical region was also investigated, and their intrasubject repeatability was also high, with a small standard deviation (8.1 ± 6.4%). The MRSI acquisition duration was ~3 min only. The proposed MRSI technique can be a reliable technique to quantify and map renal metabolites within a clinically acceptable scan time at 3T that supports the future application of this technique for the non-invasive characterization of heterogeneous renal diseases and tumors.
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7
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Hangel G, Spurny-Dworak B, Lazen P, Cadrien C, Sharma S, Hingerl L, Hečková E, Strasser B, Motyka S, Lipka A, Gruber S, Brandner C, Lanzenberger R, Rössler K, Trattnig S, Bogner W. Inter-subject stability and regional concentration estimates of 3D-FID-MRSI in the human brain at 7 T. NMR IN BIOMEDICINE 2021; 34:e4596. [PMID: 34382280 DOI: 10.1002/nbm.4596] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 07/14/2021] [Accepted: 07/14/2021] [Indexed: 05/13/2023]
Abstract
PURPOSE Recently, a 3D-concentric ring trajectory (CRT)-based free induction decay (FID)-MRSI sequence was introduced for fast high-resolution metabolic imaging at 7 T. This technique provides metabolic ratio maps of almost the entire brain within clinically feasible scan times, but its robustness has not yet been thoroughly investigated. Therefore, we have assessed quantitative concentration estimates and their variability in healthy volunteers using this approach. METHODS We acquired whole-brain 3D-CRT-FID-MRSI at 7 T in 15 min with 3.4 mm nominal isometric resolution in 24 volunteers (12 male, 12 female, mean age 27 ± 6 years). Concentration estimate maps were calculated for 15 metabolites using internal water referencing and evaluated in 55 different regions of interest (ROIs) in the brain. Data quality, mean metabolite concentrations, and their inter-subject coefficients of variation (CVs) were compared for all ROIs. RESULTS Of 24 datasets, one was excluded due to motion artifacts. The concentrations of total choline, total creatine, glutamate, myo-inositol, and N-acetylaspartate in 44 regions were estimated within quality thresholds. Inter-subject CVs (mean over 44 ROIs/minimum/maximum) were 9%/5%/19% for total choline, 10%/6%/20% for total creatine, 11%/7%/24% for glutamate, 10%/6%/19% for myo-inositol, and 9%/6%/19% for N-acetylaspartate. DISCUSSION We defined the performance of 3D-CRT-based FID-MRSI for metabolite concentration estimate mapping, showing which metabolites could be robustly quantified in which ROIs with which inter-subject CVs expected. However, the basal brain regions and lesser-signal metabolites in particular remain as a challenge due susceptibility effects from the proximity to nasal and auditory cavities. Further improvement in quantification and the mitigation of B0 /B1 -field inhomogeneities will be necessary to achieve reliable whole-brain coverage.
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Affiliation(s)
- Gilbert Hangel
- High-field MR Center, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria
- Department of Neurosurgery, Medical University of Vienna, Vienna, Austria
| | - Benjamin Spurny-Dworak
- Division of General Psychiatry, Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
| | - Philipp Lazen
- High-field MR Center, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Cornelius Cadrien
- High-field MR Center, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria
- Department of Neurosurgery, Medical University of Vienna, Vienna, Austria
| | - Sukrit Sharma
- High-field MR Center, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Lukas Hingerl
- High-field MR Center, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Eva Hečková
- High-field MR Center, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Bernhard Strasser
- High-field MR Center, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Stanislav Motyka
- High-field MR Center, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Alexandra Lipka
- High-field MR Center, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria
- Institute for Clinical Molecular MRI, Karl Landsteiner Society, St. Pölten, Austria
| | - Stephan Gruber
- High-field MR Center, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Christoph Brandner
- High-field MR Center, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Rupert Lanzenberger
- Division of General Psychiatry, Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
| | - Karl Rössler
- Department of Neurosurgery, Medical University of Vienna, Vienna, Austria
| | - Siegfried Trattnig
- High-field MR Center, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria
- Institute for Clinical Molecular MRI, Karl Landsteiner Society, St. Pölten, Austria
| | - Wolfgang Bogner
- High-field MR Center, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria
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Tal A, Zhao T, Schirda C, Hetherington HP, Pan JW, Gonen O. Fast, regional three-dimensional hybrid (1D-Hadamard 2D-rosette) proton MR spectroscopic imaging in the human temporal lobes. NMR IN BIOMEDICINE 2021; 34:e4507. [PMID: 33754420 PMCID: PMC8122085 DOI: 10.1002/nbm.4507] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 02/03/2021] [Accepted: 02/25/2021] [Indexed: 05/05/2023]
Abstract
1 H-MRSI is commonly performed with gradient phase encoding, due to its simplicity and minimal radio frequency (RF) heating (specific absorption rate). Its two well-known main problems-(i) "voxel bleed" due to the intrinsic point-spread function, and (ii) chemical shift displacement error (CSDE) when slice-selective RF pulses are used, which worsens with increasing volume of interest (VOI) size-have long become accepted as unavoidable. Both problems can be mitigated with Hadamard multislice RF encoding. This is demonstrated and quantified with numerical simulations, in a multislice phantom and in five healthy young adult volunteers at 3 T, targeting a 2-cm thick temporal lobe VOI through the bilateral hippocampus. This frequently targeted region (e.g. in epilepsy and Alzheimer's disease) is subject to strong, 1-2 ppm.cm-1 regional B0, susceptibility gradients that can dramatically reduce the signal-to-noise ratio (SNR) and water suppression effectiveness. The chemical shift imaging (CSI) sequence used a 3-ms Shinnar-Le Roux (SLR) 90° RF pulse, acquiring eight steps in the slice direction. The Hadamard sequence acquired two overlapping slices using the same SLR 90° pulses, under twofold stronger gradients that proportionally halved the CSDE. Both sequences used 2D 20 × 20 rosette spectroscopic imaging (RSI) for in-plane spatial localization and both used RF and gradient performance characteristics that are easily met by all modern MRI instruments. The results show that Hadamard spectroscopic imaging (HSI) suffered dramatically less signal bleed within the VOI compared with CSI (<1% vs. approximately 26% in simulations; and 5%-8% vs. >50%) in a phantom specifically designed to test these effects. The voxels' SNR per unit volume per unit time was also 40% higher for HSI. In a group of five healthy volunteers, we show that HSI with in-plane 2D-RSI facilitates fast, 3D multivoxel encoding at submilliliter spatial resolution, over the bilateral human hippocampus, in under 10 min, with negligible CSDE, spectral and spatial contamination and more than 6% improved SNR per unit time per unit volume.
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Affiliation(s)
- Assaf Tal
- Department of Chemical and Biological Physics, The Weizmann Institute of Science, Rehovot, Israel
| | - Tiejun Zhao
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University Grossman School of Medicine, New York, New York, USA
- Siemens Medical Solutions USA Inc., Malvern, Pennsylvania, USA
| | - Claudiu Schirda
- Departments of Radiology and Neurology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Hoby P. Hetherington
- Departments of Radiology and Neurology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Jullie W. Pan
- Departments of Radiology and Neurology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Oded Gonen
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University Grossman School of Medicine, New York, New York, USA
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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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Near J, Harris AD, Juchem C, Kreis R, Marjańska M, Öz G, Slotboom J, Wilson M, Gasparovic C. Preprocessing, analysis and quantification in single-voxel magnetic resonance spectroscopy: experts' consensus recommendations. NMR IN BIOMEDICINE 2021; 34:e4257. [PMID: 32084297 PMCID: PMC7442593 DOI: 10.1002/nbm.4257] [Citation(s) in RCA: 153] [Impact Index Per Article: 51.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 12/21/2019] [Accepted: 12/22/2019] [Indexed: 05/05/2023]
Abstract
Once an MRS dataset has been acquired, several important steps must be taken to obtain the desired metabolite concentration measures. First, the data must be preprocessed to prepare them for analysis. Next, the intensity of the metabolite signal(s) of interest must be estimated. Finally, the measured metabolite signal intensities must be converted into scaled concentration units employing a quantitative reference signal to allow meaningful interpretation. In this paper, we review these three main steps in the post-acquisition workflow of a single-voxel MRS experiment (preprocessing, analysis and quantification) and provide recommendations for best practices at each step.
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Affiliation(s)
- Jamie Near
- Douglas Mental Health University Institute and Department of Psychiatry, McGill University, Montreal, Canada
- McConnell Brain Imaging Centre, Montreal Neurological Institute, Montreal, Canada
| | - Ashley D. Harris
- Department of Radiology, University of Calgary, Calgary, Canada
- Alberta Children’s Hospital Research Institute, Calgary, Canada
- Hotchkiss Brain Institute, Calgary, Canada
| | - Christoph Juchem
- Department of Biomedical Engineering, Columbia University, New York NY, USA
| | - Roland Kreis
- Departments of Radiology and Biomedical Research, University Bern, Switzerland
| | - Małgorzata Marjańska
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis MN, USA
| | - Gülin Öz
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis MN, USA
| | - Johannes Slotboom
- Support Center for Advanced Neuroimaging (SCAN), Neuroradiology, University Hospital Inselspital, Bern, Switzerland
| | - Martin Wilson
- Centre for Human Brain Health and School of Psychology, University of Birmingham, Birmingham, England
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11
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Posse S, Sa De La Rocque Guimaraes B, Hutchins-Delgado T, Vakamudi K, Fotso Tagne K, Moeller S, Dager SR. On the acquisition of the water signal during water suppression: High-speed MR spectroscopic imaging with water referencing and concurrent functional MRI. NMR IN BIOMEDICINE 2021; 34:e4261. [PMID: 31999397 PMCID: PMC7390701 DOI: 10.1002/nbm.4261] [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: 05/10/2019] [Revised: 12/09/2019] [Accepted: 01/03/2020] [Indexed: 06/10/2023]
Abstract
This study evaluated the utility of concurrent water signal acquisition as part of the water suppression in MR spectroscopic imaging (MRSI), to allow simultaneous water referencing for metabolite quantification, and to concurrently acquire functional MRI (fMRI) data. We integrated a spatial-spectral binomial water excitation RF pulse and a short spatial-spectral echo-planar readout into the water suppression module of 2D and 3D proton-echo-planar-spectroscopic-imaging (PEPSI) with a voxel size as small as 4 x 4 x 6 mm3 . Metabolite quantification in reference to tissue water was validated in healthy controls for different prelocalization methods (spin-echo, PRESS and semi-LASER) and the clinical feasibility of a 3-minute 3D semi-Laser PEPSI scan (TR/TE: 1250/32 ms) with water referencing in patients with brain tumors was demonstrated. Spectral quality, SNR, Cramer-Rao-lower-bounds and water suppression efficiency were comparable with conventional PEPSI. Metabolite concentration values in reference to tissue water, using custom LCModel-based spectral fitting with relaxation correction, were in the range of previous studies and independent of the prelocalization method used. Next, we added a phase-encoding undersampled echo-volumar imaging (EVI) module during water suppression to concurrently acquire metabolite maps with water referencing and fMRI data during task execution and resting state in healthy controls. Integration of multimodal signal acquisition prolongated minimum TR by less than 50 ms on average. Visual and motor activation in concurrent fMRI/MRSI (TR: 1250-1500 ms, voxel size: 4 x 4 x 6 mm3 ) was readily detectable in single-task blocks with percent signal change comparable with conventional fMRI. Resting-state connectivity in sensory and motor networks was detectable in 4 minutes. This hybrid water suppression approach for multimodal imaging has the potential to significantly reduce scan time and extend neuroscience research and clinical applications through concurrent quantitative MRSI and fMRI acquisitions.
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Affiliation(s)
- Stefan Posse
- Department of Neurology, University of New Mexico, Albuquerque, NM, United States
- Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM, United States
| | - Bruno Sa De La Rocque Guimaraes
- Department of Neurology, University of New Mexico, Albuquerque, NM, United States
- Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM, United States
| | | | - Kishore Vakamudi
- Department of Neurology, University of New Mexico, Albuquerque, NM, United States
| | - Kevin Fotso Tagne
- Department of Neurology, University of New Mexico, Albuquerque, NM, United States
| | - Steen Moeller
- Center for Magnetic Resonance Research, Radiology, University of Minnesota, Minneapolis, MN, United States
| | - Stephen R Dager
- Departments of Radiology and Bioengineering, University of Washington, Seattle, WA, USA
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12
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Tkáč I, Deelchand D, Dreher W, Hetherington H, Kreis R, Kumaragamage C, Považan M, Spielman DM, Strasser B, de Graaf RA. Water and lipid suppression techniques for advanced 1 H MRS and MRSI of the human brain: Experts' consensus recommendations. NMR IN BIOMEDICINE 2021; 34:e4459. [PMID: 33327042 PMCID: PMC8569948 DOI: 10.1002/nbm.4459] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 11/23/2020] [Indexed: 05/09/2023]
Abstract
The neurochemical information provided by proton magnetic resonance spectroscopy (MRS) or MR spectroscopic imaging (MRSI) can be severely compromised if strong signals originating from brain water and extracranial lipids are not properly suppressed. The authors of this paper present an overview of advanced water/lipid-suppression techniques and describe their advantages and disadvantages. Moreover, they provide recommendations for choosing the most appropriate techniques for proper use. Methods of water signal handling are primarily focused on the VAPOR technique and on MRS without water suppression (metabolite cycling). The section on lipid-suppression methods in MRSI is divided into three parts. First, lipid-suppression techniques that can be implemented on most clinical MR scanners (volume preselection, outer-volume suppression, selective lipid suppression) are described. Second, lipid-suppression techniques utilizing the combination of k-space filtering, high spatial resolutions and lipid regularization are presented. Finally, three promising new lipid-suppression techniques, which require special hardware (a multi-channel transmit system for dynamic B1+ shimming, a dedicated second-order gradient system or an outer volume crusher coil) are introduced.
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Affiliation(s)
- Ivan Tkáč
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA
| | - Dinesh Deelchand
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA
| | - Wolfgang Dreher
- Department of Chemistry, In vivo-MR Group, University Bremen, Bremen, Germany
| | - Hoby Hetherington
- Department of Radiology Magnetic Resonance Research Center, University of Pittsburgh, Pittsburgh, PA, USA
| | - Roland Kreis
- Departments of Radiology and Biomedical Research, University Bern, Bern, Switzerland
| | - Chathura Kumaragamage
- Department of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, CT, USA
| | - Michal Považan
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Daniel M. Spielman
- Department of Radiology, Stanford University, Stanford, California, CA, USA
| | - Bernhard Strasser
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Department of Radiology, Boston, MA, USA
| | - Robin A. de Graaf
- Department of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, CT, USA
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13
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Saucedo A, Macey PM, Thomas MA. Accelerated radial echo-planar spectroscopic imaging using golden angle view-ordering and compressed-sensing reconstruction with total variation regularization. Magn Reson Med 2021; 86:46-61. [PMID: 33604944 DOI: 10.1002/mrm.28728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 12/30/2020] [Accepted: 01/20/2021] [Indexed: 11/11/2022]
Abstract
PURPOSE To implement a novel, accelerated, 2D radial echo-planar spectroscopic imaging (REPSI) sequence using undersampled radial k-space trajectories and compressed-sensing reconstruction, and to compare results with those from an undersampled Cartesian spectroscopic sequence. METHODS The REPSI sequence was implemented using golden-angle view-ordering on a 3T MRI scanner. Radial and Cartesian echo-planar spectroscopic imaging (EPSI) data were acquired at six acceleration factors, each with time-equivalent scan durations, and reconstructed using compressed sensing with total variation regularization. Results from prospectively and retrospectively undersampled phantom and in vivo brain data were compared over estimated concentrations and Cramer-Rao lower-bound values, normalized RMS errors of reconstructed metabolite maps, and percent absolute differences between fully sampled and reconstructed spectroscopic images. RESULTS The REPSI method with compressed sensing is able to tolerate greater reductions in scan time compared with EPSI. The reconstruction and quantitation metrics (i.e., spectral normalized RMS error maps, metabolite map normalized RMS error values [e.g., for total N-acetyl asparate, REPSI = 9.4% vs EPSI = 16.3%; acceleration factor = 2.5], percent absolute difference maps, and concentration and Cramer-Rao lower-bound estimates) showed that accelerated REPSI can reduce the scan time by a factor of 2.5 while retaining image and quantitation quality. CONCLUSION Accelerated MRSI using undersampled radial echo-planar acquisitions provides greater reconstruction accuracy and more reliable quantitation for a range of acceleration factors compared with time-equivalent compressed-sensing reconstructions of undersampled Cartesian EPSI. Compared to the Cartesian approach, radial undersampling with compressed sensing could help reduce 2D spectroscopic imaging acquisition time, and offers a better trade-off between imaging speed and quality.
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Affiliation(s)
- Andres Saucedo
- Department of Radiological Sciences, University of California Los Angeles, Los Angeles, California, USA.,Physics and Biology in Medicine Interdepartmental Graduate Program, University of California Los Angeles, Los Angeles, California, USA
| | - Paul M Macey
- School of Nursing, University of California, Los Angeles, Los Angeles, California, USA
| | - M Albert Thomas
- Department of Radiological Sciences, University of California Los Angeles, Los Angeles, California, USA.,Physics and Biology in Medicine Interdepartmental Graduate Program, University of California Los Angeles, Los Angeles, California, USA
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14
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Emir UE, Sood J, Chiew M, Thomas MA, Lane SP. High-resolution metabolic mapping of the cerebellum using 2D zoom magnetic resonance spectroscopic imaging. Magn Reson Med 2020; 85:2349-2358. [PMID: 33283917 DOI: 10.1002/mrm.28614] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 10/03/2020] [Accepted: 11/04/2020] [Indexed: 12/20/2022]
Abstract
PURPOSE The human cerebellum plays an important role in the functional activity of the cerebrum, ranging from motor to cognitive systems given its relaying role between the spinal cord and cerebrum. The cerebellum poses many challenges to Magnetic Resonance Spectroscopic Imaging (MRSI) due to its caudal location, susceptibility to physiological artifacts, and partial volume artifacts resulting from its complex anatomical structure. Thus, in the present study, we propose a high-resolution MRSI acquisition scheme for the cerebellum. METHODS A zoom or reduced field of view (rFOV) metabolite-cycled MRSI acquisition at 3 Tesla, with a grid of 48 × 48, was developed to achieve a nominal resolution of 62.5 μL. Single-slice rFOV MRSI data were acquired from the cerebellum of 5 healthy subjects with a nominal resolution of 2.5 × 2.5 × 10 mm3 in 9.6 min. Spectra were quantified using the LCModel package. A spatially unbiased atlas template of the cerebellum was used to analyze metabolite distributions in the cerebellum. RESULTS The superior quality of the achieved spectra-enabled generation of high-resolution metabolic maps of total N-acetylaspartate, total Creatine (tCr), total Choline (tCho), glutamate+glutamine, and myo-inositol, with Cramér-Rao lower bounds below 50%. A template-based regions of interest (ROI) analysis resulted in spatially dependent metabolite distributions in 9 ROIs. The group-averaged high-resolution metabolite maps across subjects increased the contrast-to-noise ratio between cerebellum regions. CONCLUSION These findings indicate that very high-resolution metabolite probing of the cerebellum is feasible using rFOV or zoomed MRSI at 3 Tesla.
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Affiliation(s)
- Uzay E Emir
- School of Health Sciences, Purdue University, West Lafayette, Indiana, USA.,Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, USA
| | - Jaiyta Sood
- School of Health Sciences, Purdue University, West Lafayette, Indiana, USA
| | - Mark Chiew
- Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, United Kingdom
| | - Micheal Albert Thomas
- Department of Radiology, University of California Los Angeles, Los Angeles, California, USA
| | - Sean P Lane
- Department of Psychological Sciences, Purdue University, West Lafayette, Indiana, USA
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15
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Hoefemann M, Döring A, Fichtner ND, Kreis R. Combining chemical exchange saturation transfer and 1 H magnetic resonance spectroscopy for simultaneous determination of metabolite concentrations and effects of magnetization exchange. Magn Reson Med 2020; 85:1766-1782. [PMID: 33151011 PMCID: PMC7821128 DOI: 10.1002/mrm.28574] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 10/06/2020] [Accepted: 10/07/2020] [Indexed: 12/21/2022]
Abstract
Purpose A new sequence combining chemical‐exchange saturation‐transfer (CEST) with traditional MRS is used to simultaneously determine metabolite content and effects of magnetization exchange. Methods A CEST saturation block consisting of a train of RF‐pulses is placed before a metabolite‐cycled semi‐LASER single‐voxel spectroscopy sequence. The saturation parameters are adjustable to allow optimization of the saturation for a specific target. Data were collected in brain from 20 subjects in experiments with different B1‐settings (0.4‐2.0 µT) on a 3T MR scanner. CEST Z‐spectra were calculated from water intensities and fitted with a multi‐pool Lorentzian model. Interrelated metabolite spectra were fitted in fitting tool for arrays of interrelated datasets (FiTAID). Results Evaluation of traditional Z‐spectra from water revealed exchange effects from amides, amines, and hydroxyls as well as an upfield nuclear Overhauser effect. The magnetization transfer effect was evaluated on metabolites and macromolecules for the whole spectral range and for the different B1 levels. A correction scheme for direct saturation on metabolites is proposed. Both magnetization‐transfer and direct saturation proved to differ for individual metabolites. Conclusion Using non‐water‐suppressed spectroscopy offers time‐saving simultaneous recording of the traditional CEST Z‐spectrum from water and the metabolite spectrum under frequency‐selective saturation. In addition, exchange and magnetization‐transfer effects on metabolites and macromolecules can be detected, which might offer additional possibilities for quantification or give further insight into the composition of the traditional CEST Z‐spectrum. Apparent magnetization‐transfer effects on macromolecular signals in the 1H‐MR spectrum have been found. Detailed knowledge of magnetization‐transfer effects is also relevant for judging the influence of water‐suppression on the quantification of metabolite signals.
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Affiliation(s)
- Maike Hoefemann
- Departments of Radiology and Biomedical Research, University of Bern, Bern, Switzerland.,Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - André Döring
- Departments of Radiology and Biomedical Research, University of Bern, Bern, Switzerland.,Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland.,Cardiff University Brain Research Imaging Centre (CUBRIC), Cardiff University, Cardiff, UK
| | - Nicole Damara Fichtner
- Departments of Radiology and Biomedical Research, University of Bern, Bern, Switzerland.,Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland.,University of British Columbia, Vancouver, Canada
| | - Roland Kreis
- Departments of Radiology and Biomedical Research, University of Bern, Bern, Switzerland
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16
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Dziadosz M, Bogner W, Kreis R. Non-water-excitation MR spectroscopy techniques to explore exchanging protons in human brain at 3 T. Magn Reson Med 2020; 84:2352-2363. [PMID: 32602971 DOI: 10.1002/mrm.28322] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 04/23/2020] [Accepted: 04/23/2020] [Indexed: 12/13/2022]
Abstract
PURPOSE To develop localization sequences for in vivo MR spectroscopy (MRS) on clinical scanners of 3 T to record spectra that are not influenced by magnetization transfer from water. METHODS Image-selected in vivo spectroscopy (ISIS) localization and chemical-shift-selective excitation (termed I-CSE) was combined in two ways: first, full ISIS localization plus a frequency-selective spin-echo and second, two-dimensional (2D) ISIS plus a frequency-selective excitation and slice-selective refocusing. The techniques were evaluated at 3 T in phantoms and human subjects in comparison to standard techniques with water presaturation or metabolite-cycling. ISIS included gradient-modulated offset-independent adiabatic (GOIA)-type adiabatic inversion pulses; echo times were 8-10 ms. RESULTS The novel 2D and 3D I-CSE methods yield upfield spectra that are comparable to those from standard MRS, except for shorter echo times and a limited frequency range. On the downfield/high-frequency side, they yield much more signal for exchangeable protons when compared to MRS with water presaturation or metabolite-cycling and longer echo times. CONCLUSION Novel non-water-excitation MRS sequences offer substantial benefits for the detection of metabolite signals that are otherwise suppressed by saturation transfer from water. Avoiding water saturation and using very short echo times allows direct observation of faster exchanging moieties than was previously possible at 3 T and additionally makes the methods less susceptible to fast T2 relaxation.
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Affiliation(s)
- Martyna Dziadosz
- Departments of Radiology and Biomedical Research, University of Bern, Bern, Switzerland.,Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Wolfgang Bogner
- High-field MR Center, Department of Biomedical Imaging and Image-guided Therapy, Medical University Vienna, Vienna, Austria
| | - Roland Kreis
- Departments of Radiology and Biomedical Research, University of Bern, Bern, Switzerland
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17
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Alhulail AA, Patterson DA, Xia P, Zhou X, Lin C, Thomas MA, Dydak U, Emir UE. Fat-water separation by fast metabolite cycling magnetic resonance spectroscopic imaging at 3 T: A method to generate separate quantitative distribution maps of musculoskeletal lipid components. Magn Reson Med 2020; 84:1126-1139. [PMID: 32103549 DOI: 10.1002/mrm.28228] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2019] [Revised: 01/03/2020] [Accepted: 02/03/2020] [Indexed: 12/29/2022]
Abstract
PURPOSE To provide a rapid, noninvasive fat-water separation technique that allows producing quantitative maps of particular lipid components. METHODS The calf muscles in 5 healthy adolescents (age 12-16 years; body mass index = 20 ± 3 kg/m2 ) were scanned by two different fat fraction measurement methods. A density-weighted concentric-ring trajectory metabolite-cycling MRSI technique was implemented to collect data with a nominal resolution of 0.25 mL within 3 minutes and 16 seconds. For comparative purposes, the standard Dixon technique was performed. The two techniques were compared using structural similarity analysis. Additionally, the difference in the distribution of each lipid over the adolescent calf muscles was assessed based on the MRSI data. RESULTS The proposed MRSI technique provided individual fat fraction maps for eight musculoskeletal lipid components identified by LCModel analysis (IMC/L [CH3 ], EMCL [CH3 ], IMC/L [CH2 ]n , EMC/L [CH2 ]n , IMC/L [CH2 -CH], EMC/L [CH2 -CH], IMC/L [-CH=CH-], and EMC/L [-CH=CH-]) with mean structural similarity indices of 0.19, 0.04, 0.03, 0.50, 0.45, 0.04, 0.07, and 0.12, respectively, compared with the maps generated by the used Dixon method. Further analysis of voxels with zero structural similarity demonstrated an increased sensitivity of fat fraction lipid maps from the data acquired using this MRSI technique over the standard Dixon technique. The lipid spatial distribution over calf muscles was consistent with previously published findings in adults. CONCLUSION This MRSI technique can be a useful tool when individual lipid fat fraction maps are desired within a clinically acceptable time and with a nominal spatial resolution of 0.25 mL.
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Affiliation(s)
- Ahmad A Alhulail
- School of Health Sciences, Purdue University, West Lafayette, Indiana.,Department of Radiology and Medical Imaging, Prince Sattam bin Abdulaziz University, Al Kharj, Saudi Arabia
| | - Debra A Patterson
- School of Health Sciences, Purdue University, West Lafayette, Indiana.,Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, Indiana
| | - Pingyu Xia
- School of Health Sciences, Purdue University, West Lafayette, Indiana
| | - Xiaopeng Zhou
- School of Health Sciences, Purdue University, West Lafayette, Indiana
| | - Chen Lin
- Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, Indiana
| | - M Albert Thomas
- Department of Radiology, University of California Los Angeles, Los Angeles, California
| | - Ulrike Dydak
- School of Health Sciences, Purdue University, West Lafayette, Indiana.,Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, Indiana
| | - Uzay E Emir
- School of Health Sciences, Purdue University, West Lafayette, Indiana.,Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana
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18
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Kumaragamage C, De Feyter HM, Brown P, McIntyre S, Nixon TW, de Graaf RA. Robust outer volume suppression utilizing elliptical pulsed second order fields (ECLIPSE) for human brain proton MRSI. Magn Reson Med 2019; 83:1539-1552. [PMID: 31742799 DOI: 10.1002/mrm.28047] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 09/23/2019] [Accepted: 10/01/2019] [Indexed: 02/06/2023]
Abstract
PURPOSE The robust and reliable utilization of proton magnetic resonance spectroscopic imaging (MRSI) at high fields is hampered by several key technical difficulties, including contamination from extracranial lipids. To that end, this work presents novel lipid suppression sequences for proton MRSI in the human brain utilizing elliptical localization with pulsed second-order fields (ECLIPSE). METHODS Two lipid suppression methods were implemented with the ECLIPSE gradient insert. One method is a variable power, 4-pulse sequence optimized to achieve outer volume suppression (OVS) and compared against a standard, 8-slice OVS method. The second ECLIPSE method is implemented as an inversion recovery (IR) sequence with elliptical inner volume selection (IVS) and compared against a global IR method. RESULTS The ECLIPSE-OVS sequence provided a 116-fold mean lipid suppression (range, 104-134), whereas an optimized 8-slice OVS sequence achieved 15-fold suppression (range, 13-18). Furthermore, the superior ECLIPSE-OVS suppression was achieved at 30% of the radiofrequency (RF) power required by 8-slice OVS. The ECLIPSE-based IR sequence suppressed skull lipids by 155-fold (range, 122-257), compared to 16-fold suppression (range, 14-19) achieved with IR. CONCLUSION OVS and IVS executed with ECLIPSE provide robust and effective lipid suppression at reduced RF power with high immunity to variations in B1 and T1 .
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Affiliation(s)
- Chathura Kumaragamage
- Department of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut
| | - Henk M De Feyter
- Department of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut
| | - Peter Brown
- Department of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut
| | - Scott McIntyre
- Department of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut
| | - Terence W Nixon
- Department of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut
| | - Robin A de Graaf
- Department of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut.,Department of Biomedical Engineering, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut
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19
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Moser P, Bogner W, Hingerl L, Heckova E, Hangel G, Motyka S, Trattnig S, Strasser B. Non-Cartesian GRAPPA and coil combination using interleaved calibration data - application to concentric-ring MRSI of the human brain at 7T. Magn Reson Med 2019; 82:1587-1603. [PMID: 31183893 PMCID: PMC6772100 DOI: 10.1002/mrm.27822] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 04/29/2019] [Accepted: 05/01/2019] [Indexed: 12/12/2022]
Abstract
PURPOSE Proton MR spectroscopic imaging (MRSI) benefits from B0 ≥ 7T and multichannel receive coils, promising substantial resolution improvements. However, MRSI acquisition with high spatial resolution requires efficient acceleration and coil combination. To speed up the already-fast sampling via concentric rings, we implemented additional, non-Cartesian, hybrid through-time/through-k-space (tt/tk)-generalized autocalibrating partially parallel acquisition (GRAPPA). A new multipurpose interleaved calibration scan (interleaved MUSICAL) acquires reference data for both coil combination and PI. This renders the reconstruction process (especially PI) less sensitive to instabilities. METHODS Six healthy volunteers were scanned at 7T. Three calibration datasets for coil combination and PI were recorded: a) iMUSICAL, b) static MUSICAL as prescan, c) moved MUSICAL as prescan with misaligned head position. The coil combination performance, including motion sensitivity, of iMUSICAL was compared to MUSICAL for single-slice free induction decay (FID)-MRSI. Through-time/through-k-space-GRAPPA with constant/variable-density undersampling was evaluated on the same data, comparing the three calibration datasets. Additionally, the proposed method was successfully applied to 3D whole-brain FID-MRSI. RESULTS Using iMUSICAL for coil combination yielded the highest signal-to-noise ratio (SNR) (+9%) and lowest Cramer-Rao lower bounds (CRLBs) (-6%) compared to both MUSICAL approaches, with similar metabolic map quality. Also, excellent mean g-factors of 1.07 and low residual lipid aliasing were obtained when using iMUSICAL as calibration data for two-fold, variable-density undersampling, while significantly degraded metabolic maps were obtained using the misaligned MUSICAL calibration data. CONCLUSION Through-time/through-k-space-GRAPPA can accelerate already time-efficient non-Cartesian spatial-spectral 2D/3D-MRSI encoding even further. Particularly promising results have been achieved using iMUSICAL as a robust, interleaved multipurpose calibration for MRSI reconstruction, without extra calibration prescan.
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Affiliation(s)
- Philipp Moser
- High Field MR Center, Department of Biomedical Imaging and Image-Guided Therapy, Medical University Vienna, Vienna, Austria
| | - Wolfgang Bogner
- High Field MR Center, Department of Biomedical Imaging and Image-Guided Therapy, Medical University Vienna, Vienna, Austria
| | - Lukas Hingerl
- High Field MR Center, Department of Biomedical Imaging and Image-Guided Therapy, Medical University Vienna, Vienna, Austria
| | - Eva Heckova
- High Field MR Center, Department of Biomedical Imaging and Image-Guided Therapy, Medical University Vienna, Vienna, Austria
| | - Gilbert Hangel
- High Field MR Center, Department of Biomedical Imaging and Image-Guided Therapy, Medical University Vienna, Vienna, Austria
| | - Stanislav Motyka
- High Field MR Center, Department of Biomedical Imaging and Image-Guided Therapy, Medical University Vienna, Vienna, Austria
| | - Siegfried Trattnig
- High Field MR Center, Department of Biomedical Imaging and Image-Guided Therapy, Medical University Vienna, Vienna, Austria.,Christian Doppler Laboratory for Clinical Molecular MR Imaging, Vienna, Austria
| | - Bernhard Strasser
- High Field MR Center, Department of Biomedical Imaging and Image-Guided Therapy, Medical University Vienna, Vienna, Austria.,Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
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20
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Peereboom SM, Gastl M, Fuetterer M, Kozerke S. Navigator-free metabolite-cycled proton spectroscopy of the heart. Magn Reson Med 2019; 83:795-805. [PMID: 31448841 DOI: 10.1002/mrm.27961] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 07/04/2019] [Accepted: 07/31/2019] [Indexed: 11/07/2022]
Abstract
PURPOSE Respiratory gating in cardiac water-suppressed (WS) proton spectroscopy leads to long and unpredictable scan times. Metabolite cycling allows to perform frequency and phase correction on the water signal and, hence, offers an approach to navigator-free cardiac spectroscopy with fixed scan time. The objective of the present study was to develop and implement navigator-free metabolite-cycled cardiac proton spectroscopy (MC nonav) and compare it with standard navigator-gated WS (WS nav) and navigator-free WS (WS nonav) measurements for the assessment of triglyceride-to-water ratios (TG/W) and creatine-to-water ratios (CR/W) in the intraventricular septum of the in vivo heart. METHODS Navigator-free metabolite-cycled spectroscopy was implemented on a clinical 1.5T system. In vivo measurements were performed on 10 young and 5 older healthy volunteers to assess signal-to-noise ratio efficiency as well as TG/W and CR/W and the relative Cramér-Rao lower bounds for CR. The performance of the metabolite-cycled sequence was verified using simulations. RESULTS On average, scan times of MC nonav were 3.4 times shorter compared with WS nav, while no significant bias for TG/W was observed (coefficient of variation = 14.0%). signal-to-noise ratio efficiency of both TG and CR increased for MC nonav compared with WS nav. Relative Cramér-Rao lower bounds of CR decreased for MC nonav. Overall spectral quality was found comparable between MC nonav and WS nav, while it was inferior for WS nonav. CONCLUSION Navigator-free metabolite-cycled cardiac proton spectroscopy offers 3.4-fold accelerated assessment of TG/W and CR/W in the heart with preserved spectral quality when compared with navigator-gated WS scans.
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Affiliation(s)
- Sophie M Peereboom
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - Mareike Gastl
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - Maximilian Fuetterer
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - Sebastian Kozerke
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
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21
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Lin L, Považan M, Berrington A, Chen Z, Barker PB. Water removal in MR spectroscopic imaging with L2 regularization. Magn Reson Med 2019; 82:1278-1287. [PMID: 31148254 DOI: 10.1002/mrm.27824] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Revised: 04/03/2019] [Accepted: 05/01/2019] [Indexed: 12/31/2022]
Abstract
PURPOSE An L2-regularization based postprocessing method is proposed and tested for removal of residual or unsuppressed water signals in proton MR spectroscopic imaging (MRSI) data recorded from the human brain at 3T. METHODS Water signals are removed by implementation of the L2 regularization using a synthesized water-basis matrix that is orthogonal to metabolite signals of interest in the spectral dimension. Simulated spectra with variable water amplitude and in vivo brain MRSI datasets were used to demonstrate the proposed method. Results were compared with two commonly-used postprocessing methods for removing water signals. RESULTS The L2 method yielded metabolite signals that were close to true values for the simulated spectra. Residual/unsuppressed water signals in human brain short- and long-echo time MRSI datasets were efficiently removed by the proposed method allowing good quality metabolite maps to be reconstructed with minimized contamination from water signals. Significant differences of the creatine signal were observed between brain long-echo time MRSI without and with water saturation, attributable to the previously described magnetization transfer effect. CONCLUSIONS With usage of a synthesized water matrix generated based on reasonable prior knowledge about water and metabolite resonances, the L2 method is shown to be an effective way to remove water signals from MRSI of the human brain.
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Affiliation(s)
- Liangjie Lin
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland.,Department of Electronic Science, Xiamen University, Xiamen, China
| | - Michal Považan
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Adam Berrington
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Zhong Chen
- Department of Electronic Science, Xiamen University, Xiamen, China
| | - Peter B Barker
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland
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22
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Hingerl L, Bogner W, Moser P, Považan M, Hangel G, Heckova E, Gruber S, Trattnig S, Strasser B. Density-weighted concentric circle trajectories for high resolution brain magnetic resonance spectroscopic imaging at 7T. Magn Reson Med 2018; 79:2874-2885. [PMID: 29106742 PMCID: PMC5873433 DOI: 10.1002/mrm.26987] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 09/09/2017] [Accepted: 10/07/2017] [Indexed: 12/18/2022]
Abstract
PURPOSE Full-slice magnetic resonance spectroscopic imaging at ≥7 T is especially vulnerable to lipid contaminations arising from regions close to the skull. This contamination can be mitigated by improving the point spread function via higher spatial resolution sampling and k-space filtering, but this prolongs scan times and reduces the signal-to-noise ratio (SNR) efficiency. Currently applied parallel imaging methods accelerate magnetic resonance spectroscopic imaging scans at 7T, but increase lipid artifacts and lower SNR-efficiency further. In this study, we propose an SNR-efficient spatial-spectral sampling scheme using concentric circle echo planar trajectories (CONCEPT), which was adapted to intrinsically acquire a Hamming-weighted k-space, thus termed density-weighted-CONCEPT. This minimizes voxel bleeding, while preserving an optimal SNR. THEORY AND METHODS Trajectories were theoretically derived and verified in phantoms as well as in the human brain via measurements of five volunteers (single-slice, field-of-view 220 × 220 mm2 , matrix 64 × 64, scan time 6 min) with free induction decay magnetic resonance spectroscopic imaging. Density-weighted-CONCEPT was compared to (a) the originally proposed CONCEPT with equidistant circles (here termed e-CONCEPT), (b) elliptical phase-encoding, and (c) 5-fold Controlled Aliasing In Parallel Imaging Results IN Higher Acceleration accelerated elliptical phase-encoding. RESULTS By intrinsically sampling a Hamming-weighted k-space, density-weighted-CONCEPT removed Gibbs-ringing artifacts and had in vivo +9.5%, +24.4%, and +39.7% higher SNR than e-CONCEPT, elliptical phase-encoding, and the Controlled Aliasing In Parallel Imaging Results IN Higher Acceleration accelerated elliptical phase-encoding (all P < 0.05), respectively, which lead to improved metabolic maps. CONCLUSION Density-weighted-CONCEPT provides clinically attractive full-slice high-resolution magnetic resonance spectroscopic imaging with optimal SNR at 7T. Magn Reson Med 79:2874-2885, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
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Affiliation(s)
- Lukas Hingerl
- High Field MR Centre, Department of Biomedical Imaging and Image‐guided TherapyMedical University of ViennaViennaAustria
| | - Wolfgang Bogner
- High Field MR Centre, Department of Biomedical Imaging and Image‐guided TherapyMedical University of ViennaViennaAustria
- Christian Doppler Laboratory for Clinical Molecular MR ImagingMedical University of ViennaViennaAustria
| | - Philipp Moser
- High Field MR Centre, Department of Biomedical Imaging and Image‐guided TherapyMedical University of ViennaViennaAustria
| | - Michal Považan
- High Field MR Centre, Department of Biomedical Imaging and Image‐guided TherapyMedical University of ViennaViennaAustria
| | - Gilbert Hangel
- High Field MR Centre, Department of Biomedical Imaging and Image‐guided TherapyMedical University of ViennaViennaAustria
| | - Eva Heckova
- High Field MR Centre, Department of Biomedical Imaging and Image‐guided TherapyMedical University of ViennaViennaAustria
| | - Stephan Gruber
- High Field MR Centre, Department of Biomedical Imaging and Image‐guided TherapyMedical University of ViennaViennaAustria
| | - Siegfried Trattnig
- High Field MR Centre, Department of Biomedical Imaging and Image‐guided TherapyMedical University of ViennaViennaAustria
- Christian Doppler Laboratory for Clinical Molecular MR ImagingMedical University of ViennaViennaAustria
| | - Bernhard Strasser
- High Field MR Centre, Department of Biomedical Imaging and Image‐guided TherapyMedical University of ViennaViennaAustria
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23
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Steel A, Chiew M, Jezzard P, Voets NL, Plaha P, Thomas MA, Stagg CJ, Emir UE. Metabolite-cycled density-weighted concentric rings k-space trajectory (DW-CRT) enables high-resolution 1 H magnetic resonance spectroscopic imaging at 3-Tesla. Sci Rep 2018; 8:7792. [PMID: 29773892 PMCID: PMC5958083 DOI: 10.1038/s41598-018-26096-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 05/02/2018] [Indexed: 11/10/2022] Open
Abstract
Magnetic resonance spectroscopic imaging (MRSI) is a promising technique in both experimental and clinical settings. However, to date, MRSI has been hampered by prohibitively long acquisition times and artifacts caused by subject motion and hardware-related frequency drift. In the present study, we demonstrate that density weighted concentric ring trajectory (DW-CRT) k-space sampling in combination with semi-LASER excitation and metabolite-cycling enables high-resolution MRSI data to be rapidly acquired at 3 Tesla. Single-slice full-intensity MRSI data (short echo time (TE) semi-LASER TE = 32 ms) were acquired from 6 healthy volunteers with an in-plane resolution of 5 × 5 mm in 13 min 30 sec using this approach. Using LCModel analysis, we found that the acquired spectra allowed for the mapping of total N-acetylaspartate (median Cramer-Rao Lower Bound [CRLB] = 3%), glutamate+glutamine (8%), and glutathione (13%). In addition, we demonstrate potential clinical utility of this technique by optimizing the TE to detect 2-hydroxyglutarate (long TE semi-LASER, TE = 110 ms), to produce relevant high-resolution metabolite maps of grade III IDH-mutant oligodendroglioma in a single patient. This study demonstrates the potential utility of MRSI in the clinical setting at 3 Tesla.
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Affiliation(s)
- Adam Steel
- Wellcome Centre for Integrative Neuroimaging, FMRIB Division, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, OX3 9DU, UK
- Laboratory of Brain and Cognition, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, 20814, USA
| | - Mark Chiew
- Wellcome Centre for Integrative Neuroimaging, FMRIB Division, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, OX3 9DU, UK
| | - Peter Jezzard
- Wellcome Centre for Integrative Neuroimaging, FMRIB Division, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, OX3 9DU, UK
| | - Natalie L Voets
- Wellcome Centre for Integrative Neuroimaging, FMRIB Division, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, OX3 9DU, UK
- Department of Neurosurgery, John Radcliffe Hospital, Oxford, United Kingdom
| | - Puneet Plaha
- Wellcome Centre for Integrative Neuroimaging, FMRIB Division, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, OX3 9DU, UK
- Department of Neurosurgery, John Radcliffe Hospital, Oxford, United Kingdom
| | - Michael Albert Thomas
- Department of Radiological Sciences, University of California, Los Angeles, California, USA
| | - Charlotte J Stagg
- Wellcome Centre for Integrative Neuroimaging, FMRIB Division, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, OX3 9DU, UK
- Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, Department of Psychiatry, University of Oxford, Oxford, OX3 7JX, UK
| | - Uzay E Emir
- Wellcome Centre for Integrative Neuroimaging, FMRIB Division, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, OX3 9DU, UK.
- Purdue University, School of Health Sciences, West Lafayette, IN, 47907, USA.
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24
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Chiew M, Jiang W, Burns B, Larson P, Steel A, Jezzard P, Albert Thomas M, Emir UE. Density-weighted concentric rings k-space trajectory for 1 H magnetic resonance spectroscopic imaging at 7 T. NMR IN BIOMEDICINE 2018; 31:e3838. [PMID: 29044762 PMCID: PMC5969060 DOI: 10.1002/nbm.3838] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 08/31/2017] [Accepted: 09/05/2017] [Indexed: 05/21/2023]
Abstract
It has been shown that density-weighted (DW) k-space sampling with spiral and conventional phase encoding trajectories reduces spatial side lobes in magnetic resonance spectroscopic imaging (MRSI). In this study, we propose a new concentric ring trajectory (CRT) for DW-MRSI that samples k-space with a density that is proportional to a spatial, isotropic Hanning window. The properties of two different DW-CRTs were compared against a radially equidistant (RE) CRT and an echo-planar spectroscopic imaging (EPSI) trajectory in simulations, phantoms and in vivo experiments. These experiments, conducted at 7 T with a fixed nominal voxel size and matched acquisition times, revealed that the two DW-CRT designs improved the shape of the spatial response function by suppressing side lobes, also resulting in improved signal-to-noise ratio (SNR). High-quality spectra were acquired for all trajectories from a specific region of interest in the motor cortex with an in-plane resolution of 7.5 × 7.5 mm2 in 8 min 3 s. Due to hardware limitations, high-spatial-resolution spectra with an in-plane resolution of 5 × 5 mm2 and an acquisition time of 12 min 48 s were acquired only for the RE and one of the DW-CRT trajectories and not for EPSI. For all phantom and in vivo experiments, DW-CRTs resulted in the highest SNR. The achieved in vivo spectral quality of the DW-CRT method allowed for reliable metabolic mapping of eight metabolites including N-acetylaspartylglutamate, γ-aminobutyric acid and glutathione with Cramér-Rao lower bounds below 50%, using an LCModel analysis. Finally, high-quality metabolic mapping of a whole brain slice using DW-CRT was achieved with a high in-plane resolution of 5 × 5 mm2 in a healthy subject. These findings demonstrate that our DW-CRT MRSI technique can perform robustly on MRI systems and within a clinically feasible acquisition time.
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Affiliation(s)
- Mark Chiew
- Wellcome Centre for Integrative Neuroimaging, FMRIB Division, Nuffield Department of Clinical NeurosciencesUniversity of OxfordJohn Radcliffe HospitalOxfordUK
| | - Wenwen Jiang
- Department of Radiology and Biomedical ImagingUniversity of CaliforniaSan FranciscoCAUSA
| | - Brian Burns
- Department of OncologyUniversity of OxfordOxfordUK
| | - Peder Larson
- Department of Radiology and Biomedical ImagingUniversity of CaliforniaSan FranciscoCAUSA
| | - Adam Steel
- Wellcome Centre for Integrative Neuroimaging, FMRIB Division, Nuffield Department of Clinical NeurosciencesUniversity of OxfordJohn Radcliffe HospitalOxfordUK
- Laboratory of Brain and Cognition, National Institute of Mental HealthNational Institutes of HealthBethesdaMDUSA
| | - Peter Jezzard
- Wellcome Centre for Integrative Neuroimaging, FMRIB Division, Nuffield Department of Clinical NeurosciencesUniversity of OxfordJohn Radcliffe HospitalOxfordUK
| | - M. Albert Thomas
- Department of Radiological SciencesUniversity of CaliforniaLos AngelesCAUSA
| | - Uzay E. Emir
- Wellcome Centre for Integrative Neuroimaging, FMRIB Division, Nuffield Department of Clinical NeurosciencesUniversity of OxfordJohn Radcliffe HospitalOxfordUK
- School of Health SciencesPurdue UniversityWest LafayetteINUSA
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25
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Chang P, Nassirpour S, Avdievitch N, Henning A. Non-water-suppressed1H FID-MRSI at 3T and 9.4T. Magn Reson Med 2017; 80:442-451. [DOI: 10.1002/mrm.27049] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 11/21/2017] [Accepted: 11/27/2017] [Indexed: 02/04/2023]
Affiliation(s)
- Paul Chang
- Max Planck Institute for Biological Cybernetics; Tuebingen Germany
- IMPRS for Cognitive and Systems Neuroscience, Eberhard-Karls University of Tuebingen; Germany
| | - Sahar Nassirpour
- Max Planck Institute for Biological Cybernetics; Tuebingen Germany
- IMPRS for Cognitive and Systems Neuroscience, Eberhard-Karls University of Tuebingen; Germany
| | - Nikolai Avdievitch
- Max Planck Institute for Biological Cybernetics; Tuebingen Germany
- Department of Physics; University of Greifswald; Germany
| | - Anke Henning
- Max Planck Institute for Biological Cybernetics; Tuebingen Germany
- Department of Physics; University of Greifswald; Germany
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