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Andronesi OC, Bhattacharyya PK, Bogner W, Choi IY, Hess AT, Lee P, Meintjes E, Tisdall MD, Zaitzev M, van der Kouwe A. Motion correction methods for MRS: experts' consensus recommendations. NMR IN BIOMEDICINE 2021; 34:e4364. [PMID: 33089547 PMCID: PMC7855523 DOI: 10.1002/nbm.4364] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 06/07/2020] [Accepted: 06/08/2020] [Indexed: 05/07/2023]
Abstract
Long acquisition times due to intrinsically low signal-to-noise ratio and the need for highly homogeneous B0 field make MRS particularly susceptible to motion or scanner instability compared with MRI. Motion-induced changes in both localization and shimming (ie B0 homogeneity) degrade MRS data quality. To mitigate the effects of motion three approaches can be employed: (1) subject immobilization, (2) retrospective correction, and (3) prospective real-time correction using internal and/or external tracking methods. Prospective real-time correction methods can simultaneously update localization and the B0 field to improve MRS data quality. While localization errors can be corrected with both internal (navigators) and external (optical camera, NMR probes) tracking methods, the B0 field correction requires internal navigator methods to measure the B0 field inside the imaged volume and the possibility to update the scanner shim hardware in real time. Internal and external tracking can rapidly update the MRS localization with submillimeter and subdegree precision, while scanner frequency and first-order shims of scanner hardware can be updated by internal methods every sequence repetition. These approaches are most well developed for neuroimaging, for which rigid transformation is primarily applicable. Real-time correction greatly improves the stability of MRS acquisition and quantification, as shown in clinical studies on subjects prone to motion, including children and patients with movement disorders, enabling robust measurement of metabolite signals including those with low concentrations, such as gamma-aminobutyric acid and glutathione. Thus, motion correction is recommended for MRS users and calls for tighter integration and wider availability of such methods by MR scanner manufacturers.
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Affiliation(s)
- Ovidiu C. Andronesi
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
- Corresponding Author: Ovidiu C. Andronesi, MD, PhD, Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Thirteenth Street, Charlestown, MA 02129, USA;
| | | | - Wolfgang Bogner
- High Field MR Center, Department of Biomedical Imaging and Image-guided Therapy, Medical University Vienna, Vienna, Austria
| | - In-Young Choi
- Department of Neurology, Hoglund Biomedical Imaging Center, University of Kansas Medical Center, Kansas City, KS, USA
| | - Aaron T. Hess
- University of Oxford Centre for Clinical Magnetic Resonance Research, Division of Cardiovascular Medicine, University of Oxford
| | - Phil Lee
- Department of Radiology, Hoglund Biomedical Imaging Center, University of Kansas Medical Center, Kansas City, KS, USA
| | - Ernesta Meintjes
- UCT Medical Imaging Research Unit, Division of Biomedical Engineering, Department of Human Biology, University of Cape Town
| | - M. Dylan Tisdall
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania
| | - Maxim Zaitzev
- Department of Radiology, Medical Physics, Medical Center, University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- High Field Magnetic Resonance Center, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - André van der Kouwe
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
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2
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Marsman A, Lind A, Petersen ET, Andersen M, Boer VO. Prospective frequency and motion correction for edited 1H magnetic resonance spectroscopy. Neuroimage 2021; 233:117922. [PMID: 33662573 DOI: 10.1016/j.neuroimage.2021.117922] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 02/18/2021] [Accepted: 02/25/2021] [Indexed: 12/18/2022] Open
Abstract
The major inhibitory neurotransmitter gamma-aminobutyric acid (GABA) and the dominant antioxidant glutathione (GSH) both play a crucial role in brain functioning and are involved in several neurodegenerative and psychiatric diseases. Magnetic resonance spectroscopy (MRS) is a unique way to measure these neurometabolites non-invasively, but the measurement is highly sensitive to head movements, and especially in specific patient groups, motion stabilization in MRS could be valuable. Conventional MRS is acquired at relatively short echo times (TE), however, for unambiguous detection of GABA and GSH, spectral editing techniques are typically used. These depend on longer TEs and use frequency selective spectral editing pulses to separate the low-intensity peaks of GABA and GSH from overlapping resonances, but results in further increased motion sensitivity. Low-intensity metabolite peaks are usually edited one-by-one, however, simultaneous editing of multiple metabolites can be achieved using a Hadamard scheme, resulting in a substantial reduction in scan time. To investigate and correct for motion sensitivity in both conventional short-TE MRS (PRESS) and edited MRS (HERMES), we implemented a navigator-based prospective motion correction strategy including reacquisition of corrupted data. PRESS and HERMES spectra were acquired without motion, with motion with correction (repeated twice), and with motion without correction. Results indicate that when sufficient retrospective outlier removal is used, no significant differences in concentration and spectral quality were observed between motion conditions, even without prospective correction. HERMES spectral editing data showed to be more sensitive to motion, as significant differences in metabolite estimates and variability of spectral quality measures were observed for tCr, GABA+ and GSH when only retrospective outlier removal was applied. When using both prospective and retrospective correction, spectral quality was improved to almost the level of the no-motion acquisition. No differences in metabolite ratios for GABA and GSH could be observed when using motion correction. In conclusion, edited MRS showed to be more prone to motion artifacts, and prospective motion correction can restore most of the spectral quality in both conventional and edited MRS.
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Affiliation(s)
- Anouk Marsman
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Amager and Hvidovre, Hvidovre, Denmark.
| | - Anna Lind
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Amager and Hvidovre, Hvidovre, Denmark
| | - Esben Thade Petersen
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Amager and Hvidovre, Hvidovre, Denmark; Center for Magnetic Resonance, Department of Electrical Engineering, Technical University of Denmark, Lyngby, Denmark
| | | | - Vincent Oltman Boer
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Amager and Hvidovre, Hvidovre, Denmark
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3
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Okada T, Kuribayashi H, Kaiser LG, Urushibata Y, Salibi N, Seethamraju RT, Ahn S, Thuy DHD, Fujimoto K, Isa T. Repeatability of proton magnetic resonance spectroscopy of the brain at 7 T: effect of scan time on semi-localized by adiabatic selective refocusing and short-echo time stimulated echo acquisition mode scans and their comparison. Quant Imaging Med Surg 2021; 11:9-20. [PMID: 33392007 DOI: 10.21037/qims-20-517] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Background Proton magnetic resonance spectroscopy (MRS) provides a unique opportunity for in vivo measurements of the brain's metabolic profile. Two methods of mainstream data acquisition are compared at 7 T, which provides certain advantages as well as challenges. The two representative methods have seldom been compared in terms of measured metabolite concentrations and different scan times. The current study investigated proton MRS of the posterior cingulate cortex using a semi-localized by adiabatic selective refocusing (sLASER) sequence and a short echo time (TE) stimulated echo acquisition mode (sSTEAM) sequence, and it compared their reliability and repeatability at 7 T using a 32-channel head coil. Methods Sixteen healthy subjects were prospectively enrolled and scanned twice with an off-bed interval between scans. The scan parameters for sLASER were a TR/TE of 6.5 s/32 ms and 32 and 48 averages (sLASER×32 and sLASER×48, respectively). The scan parameters for sSTEAM were a TR/TE of 4 s/5 ms and 32, 48, and 64 averages (sSTEAM4×32, sSTEAM4×48, and sSTEAM4×64, respectively) in addition to that with a TR/TE of 8 s/5 ms and 32 averages (sSTEAM8×32). Data were analyzed using LCModel. Metabolites quantified with Cramér-Rao lower bounds (CRLBs) >50% were classified as not detected, and metabolites quantified with mean or median CRLBs ≤20% were included for further analysis. The SNR, CRLBs, coefficient of variation (CV), and metabolite concentrations were statistically compared using the Shapiro-Wilk test, one-way ANOVA, or the Friedman test. Results The sLASER spectra for N-acetylaspartate + N-acetylaspartylglutamate (tNAA) and glutamate (Glu) had a comparable or higher SNR than sSTEAM spectra. Ten metabolites had lower CRLBs than prefixed thresholds: aspartate (Asp), γ-aminobutyric acid (GABA), glutamine (Gln), Glu, glutathione (GSH), myo-inositol (Ins), taurine (Tau), the total amount of phosphocholine + glycerophosphocholine (tCho), creatine + phosphocreatine (tCr), and tNAA. Performance of the two sequences was satisfactory except for GABA, for which sLASER yielded higher CRLBs (≥18%) than sSTEAM. Some significant differences in CRLBs were noted, but they were ≤2% except for GABA and Gln. Signal averaging significantly lowered CRLBs for some metabolites but only by a small amount. Measurement repeatability as indicated by median CVs was ≤10% for Gln, Glu, Ins, tCho, tCr, and tNAA in all scans, and that for Asp, GABA, GSH, and Tau was ≥10% under some scanning conditions. The CV for GABA according to sLASER was significantly higher than that according to sSTEAM, whereas the CV for Ins was higher according to sSTEAM. An increase in signal averaging contribute little to lower CVs except for Ins. Conclusions Both sequences quantified brain metabolites with a high degree of precision and repeatability. They are comparable except for GABA, for which sSTEAM would be a better choice.
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Affiliation(s)
- Tomohisa Okada
- Human Brain Research Center, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | | | - Lana G Kaiser
- Henry H. Wheeler Brain Imaging Center, University of California, Berkeley, CA, USA
| | | | - Nouha Salibi
- Siemens Medical Solutions USA, Inc., Malvern, PA/Boston, MA/Berkeley, CA, USA
| | | | - Sinyeob Ahn
- Siemens Medical Solutions USA, Inc., Malvern, PA/Boston, MA/Berkeley, CA, USA
| | - Dinh Ha Duy Thuy
- Human Brain Research Center, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Koji Fujimoto
- Human Brain Research Center, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Tadashi Isa
- Human Brain Research Center, Graduate School of Medicine, Kyoto University, Kyoto, Japan
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Topfer R, Foias A, Stikov N, Cohen-Adad J. Real-time correction of respiration-induced distortions in the human spinal cord using a 24-channel shim array. Magn Reson Med 2018; 80:935-946. [DOI: 10.1002/mrm.27089] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 12/22/2017] [Accepted: 12/24/2017] [Indexed: 12/25/2022]
Affiliation(s)
- Ryan Topfer
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montreal; Montreal Quebec Canada
| | - Alexandru Foias
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montreal; Montreal Quebec Canada
| | - Nikola Stikov
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montreal; Montreal Quebec Canada
- Montreal Heart Institute, Université de Montréal; Montreal Quebec Canada
| | - Julien Cohen-Adad
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montreal; Montreal Quebec Canada
- Functional Neuroimaging Unit, CRIUGM, Université de Montréal; Montreal Quebec Canada
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5
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Spatiotemporal characterization of breathing-induced B 0 field fluctuations in the cervical spinal cord at 7T. Neuroimage 2017; 167:191-202. [PMID: 29175497 PMCID: PMC5854299 DOI: 10.1016/j.neuroimage.2017.11.031] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 10/09/2017] [Accepted: 11/15/2017] [Indexed: 01/31/2023] Open
Abstract
Magnetic resonance imaging and spectroscopy of the spinal cord stand to benefit greatly from the increased signal-to-noise ratio of ultra-high field. However, ultra-high field also poses considerable technical challenges, especially related to static and dynamic B0 fields. Breathing causes the field to fluctuate with the respiratory cycle, giving rise to artifacts such as ghosting and apparent motion in images. We here investigated the spatial and temporal characteristics of breathing-induced B0 fields in the cervical spinal cord at 7T. We analyzed the magnitude and spatial profile of breathing-induced fields during breath-holds in an expired and inspired breathing state. We also measured the temporal field evolution during free breathing by acquiring a time series of fast phase images, and a principal component analysis was performed on the measured field evolution. In all subjects, the field shift was largest around the vertebral level of C7 and lowest at the top of the spinal cord. At C7, we measured peak-to-peak field fluctuations of 36 Hz on average during normal free breathing; increasing to on average 113 Hz during deep breathing. The first principal component could explain more than 90% of the field variations along the foot-head axis inside the spinal cord in all subjects. We further implemented a proof-of-principle shim correction, demonstrating the feasibility of using the shim system to compensate for the breathing-induced fields inside the spinal cord. Effective correction strategies will be crucial to unlock the full potential of ultra-high field for spinal cord imaging. The B0 field in the spinal cord fluctuates with the breathing cycle. Average peak-to-peak ΔB0 of 36/113 Hz at C7 during normal/deep breathing at 7T. The first principal component explains more than 90% of the field variance. Respiratory trace correlates well with field fluctuations during normal breathing. Proof-of-principle correction using 2nd-order shims was demonstrated.
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6
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Chang P, Nassirpour S, Eschelbach M, Scheffler K, Henning A. Constrained optimization for position calibration of an NMR field camera. Magn Reson Med 2017; 80:380-390. [PMID: 29159823 DOI: 10.1002/mrm.27010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 10/23/2017] [Accepted: 10/25/2017] [Indexed: 11/07/2022]
Abstract
PURPOSE Knowledge of the positions of field probes in an NMR field camera is necessary for monitoring the B0 field. The typical method of estimating these positions is by switching the gradients with known strengths and calculating the positions using the phases of the FIDs. We investigated improving the accuracy of estimating the probe positions and analyzed the effect of inaccurate estimations on field monitoring. METHODS The field probe positions were estimated by 1) assuming ideal gradient fields, 2) using measured gradient fields (including nonlinearities), and 3) using measured gradient fields with relative position constraints. The fields measured with the NMR field camera were compared to fields acquired using a dual-echo gradient recalled echo B0 mapping sequence. Comparisons were done for shim fields from second- to fourth-order shim terms. RESULTS The position estimation was the most accurate when relative position constraints were used in conjunction with measured (nonlinear) gradient fields. The effect of more accurate position estimates was seen when compared to fields measured using a B0 mapping sequence (up to 10%-15% more accurate for some shim fields). The models acquired from the field camera are sensitive to noise due to the low number of spatial sample points. CONCLUSION Position estimation of field probes in an NMR camera can be improved using relative position constraints and nonlinear gradient fields. Magn Reson Med 80:380-390, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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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
| | - Martin Eschelbach
- Max Planck Institute for Biological Cybernetics, Tuebingen, Germany
- Department of Physics, Eberhard-Karls University of Tuebingen, Germany
| | - Klaus Scheffler
- Max Planck Institute for Biological Cybernetics, Tuebingen, Germany
- Department of Biomedical Magnetic Resonance, Eberhard-Karls University of Tuebingen, Germany
| | - Anke Henning
- Max Planck Institute for Biological Cybernetics, Tuebingen, Germany
- Department of Physics, University of Greifswald, Greifswald, Germany
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7
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Wyss M, Duerst Y, Nanz D, Kasper L, Wilm BJ, Dietrich BE, Gross S, Schmid T, Brunner DO, Pruessmann KP. Feedback field control improves the precision of T 2 * quantification at 7 T. NMR IN BIOMEDICINE 2017; 30:e3753. [PMID: 28678353 DOI: 10.1002/nbm.3753] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 04/10/2017] [Accepted: 05/04/2017] [Indexed: 06/07/2023]
Abstract
T2 * mapping offers access to a number of important structural and physiological tissue parameters. It is robust against RF field variations and overall signal scaling. However, T2 * measurement is highly sensitive to magnetic field errors, including perturbations caused by breathing motion at high baseline field. The goal of this work is to assess this issue in T2 * mapping of the brain and to study the benefit of field stabilization by feedback field control. T2 * quantification in the brain was investigated by phantom and in vivo measurements at 7 T. Repeated measurements were made with and without feedback field control using NMR field sensing and dynamic third-order shim actuation. The precision and reliability of T2 * quantification was assessed by studying variation across repeated measurements as well as fitting errors. Breathing effects were found to introduce significant error in T2 * mapping results. Field control mitigates this problem substantially. In a phantom it virtually eliminates the effects of emulated breathing fluctuations in the head. In vivo it enhances the structural fidelity of T2 * maps and reduces fitting residuals along with standard deviation. In conclusion, feedback field control improves the fidelity of T2 * mapping in the presence of field perturbations. It is an effective means of countering bulk susceptibility effects of breathing and hence holds particular promise for efforts to leverage high field for T2 * studies in vivo.
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Affiliation(s)
- Michael Wyss
- University of Zurich and ETH Zurich Institute for Biomedical Engineering, Zurich, Switzerland
| | - Yolanda Duerst
- University of Zurich and ETH Zurich Institute for Biomedical Engineering, Zurich, Switzerland
| | - Daniel Nanz
- University Hospital Zurich Institute of Diagnostic and Interventional Radiology, Zurich, Switzerland
| | - Lars Kasper
- University of Zurich and ETH Zurich Institute for Biomedical Engineering, Zurich, Switzerland
- University of Zurich and ETH Zurich Translational Neuromodeling Unit, Zurich, Switzerland
| | - Bertram Jakob Wilm
- University of Zurich and ETH Zurich Institute for Biomedical Engineering, Zurich, Switzerland
| | | | - Simon Gross
- University of Zurich and ETH Zurich Institute for Biomedical Engineering, Zurich, Switzerland
| | - Thomas Schmid
- University of Zurich and ETH Zurich Institute for Biomedical Engineering, Zurich, Switzerland
| | - David Otto Brunner
- University of Zurich and ETH Zurich Institute for Biomedical Engineering, Zurich, Switzerland
| | - Klaas Paul Pruessmann
- University of Zurich and ETH Zurich Institute for Biomedical Engineering, Zurich, Switzerland
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8
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Giapitzakis I, Shao T, Avdievich N, Mekle R, Kreis R, Henning A. Metabolite‐cycled STEAM and semi‐LASER localization for MR spectroscopy of the human brain at 9.4T. Magn Reson Med 2017; 79:1841-1850. [DOI: 10.1002/mrm.26873] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 07/25/2017] [Accepted: 07/25/2017] [Indexed: 12/24/2022]
Affiliation(s)
- Ioannis‐Angelos Giapitzakis
- High‐Field Magnetic Resonance, Max Planck Institute for Biological CyberneticsTübingen Germany
- IMPRS for Cognitive & Systems NeuroscienceTübingen Germany
| | - Tingting Shao
- High‐Field Magnetic Resonance, Max Planck Institute for Biological CyberneticsTübingen Germany
| | - Nikolai Avdievich
- High‐Field Magnetic Resonance, Max Planck Institute for Biological CyberneticsTübingen Germany
| | - Ralf Mekle
- Center for Stroke Research Berlin (CSB), Charité Universitätsmedizin BerlinBerlin Germany
| | - Roland Kreis
- Departments of Radiology and Clinical ResearchUniversity BernBern Switzerland
| | - Anke Henning
- High‐Field Magnetic Resonance, Max Planck Institute for Biological CyberneticsTübingen Germany
- Institute of PhysicsUniversity of GreifswaldGreifswald Germany
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9
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Henning A. Proton and multinuclear magnetic resonance spectroscopy in the human brain at ultra-high field strength: A review. Neuroimage 2017; 168:181-198. [PMID: 28712992 DOI: 10.1016/j.neuroimage.2017.07.017] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 06/27/2017] [Accepted: 07/10/2017] [Indexed: 12/11/2022] Open
Abstract
Magnetic Resonance Spectroscopy (MRS) allows for a non-invasive and non-ionizing determination of in vivo tissue concentrations and metabolic turn-over rates of more than 20 metabolites and compounds in the central nervous system of humans. The aim of this review is to give a comprehensive overview about the advantages, challenges and advances of ultra-high field MRS with regard to methodological development, discoveries and applications from its beginnings around 15 years ago up to the current state. The review is limited to human brain and spinal cord application at field strength of 7T and 9.4T and includes all relevant nuclei (1H, 31P, 13C).
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Affiliation(s)
- Anke Henning
- Max Plank Institute for Biological Cybernetics, Tübingen, Germany; Institute of Physics, Ernst-Moritz-Arndt University, Greifswald, Germany.
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10
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Wezel J, Boer VO, van der Velden TA, Webb AG, Klomp DWJ, Versluis MJ, van Osch MJP, Garpebring A. A comparison of navigators, snap-shot field monitoring, and probe-based field model training for correcting B 0 -induced artifacts in T2*-weighted images at 7 T. Magn Reson Med 2016; 78:1373-1382. [PMID: 27859614 DOI: 10.1002/mrm.26524] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 09/27/2016] [Accepted: 10/02/2016] [Indexed: 11/06/2022]
Abstract
PURPOSE To compare methods for estimating B0 maps used in retrospective correction of high-resolution anatomical images at ultra-high field strength. The B0 maps were obtained using three methods: (1) 1D navigators and coil sensitivities, (2) field probe (FP) data and a low-order spherical harmonics model, and (3) FP data and a training-based model. METHODS Data from nine subjects were acquired while they performed activities inducing B0 field fluctuations. Estimated B0 fields were compared with reference data, and the reductions of artifacts were compared in corrected T2* images. RESULTS Reduction of sum-of-squares difference relative to a reference image was evaluated, and Method 1 yielded the largest artifact reduction: 27 ± 15%, 20 ± 18% (mean ± 1 standard deviation) for deep breathing and combined deep breathing and hand motion activities. Method 3 performed almost as well (24 ± 18%, 15 ± 17%), provided that adequate training data were used, and Method 2 gave a similar result (21 ± 16%, 19 ± 17%). CONCLUSION This study confirms that all of the investigated methods can be used in retrospective image correction. In terms of image quality, Method 1 had a small advantage, whereas the FP-based methods measured the B0 field slightly more accurately. The specific strengths and weaknesses of FPs and navigators should therefore be considered when determining which B0 -estimation method to use. Magn Reson Med 78:1373-1382, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Joep Wezel
- C.J. Gorter Center for high field MRI, Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Vincent O Boer
- Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Tijl A van der Velden
- Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Andrew G Webb
- C.J. Gorter Center for high field MRI, Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Dennis W J Klomp
- Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | | | - Matthias J P van Osch
- C.J. Gorter Center for high field MRI, Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Anders Garpebring
- C.J. Gorter Center for high field MRI, Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands.,Department of Radiation Sciences, Umeå University, Umeå, Sweden
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11
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Henning A, Koning W, Fuchs A, Raaijmakers A, Bluemink JJ, van den Berg CAT, Boer VO, Klomp DWJ. (1) H MRS in the human spinal cord at 7 T using a dielectric waveguide transmitter, RF shimming and a high density receive array. NMR IN BIOMEDICINE 2016; 29:1231-1239. [PMID: 27191947 DOI: 10.1002/nbm.3541] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 03/22/2016] [Accepted: 03/23/2016] [Indexed: 06/05/2023]
Abstract
Multimodal MRI is the state of the art method for clinical diagnostics and therapy monitoring of the spinal cord, with MRS being an emerging modality that has the potential to detect relevant changes of the spinal cord tissue at an earlier stage and to enhance specificity. Methodological challenges related to the small dimensions and deep location of the human spinal cord inside the human body, field fluctuations due to respiratory motion, susceptibility differences to adjacent tissue such as vertebras and pulsatile flow of the cerebrospinal fluid hinder the clinical application of (1) H MRS to the human spinal cord. Complementary to previous studies that partly addressed these problems, this work aims at enhancing the signal-to-noise ratio (SNR) of (1) H MRS in the human spinal cord. To this end a flexible tight fit high density receiver array and ultra-high field strength (7 T) were combined. A dielectric waveguide and dipole antenna transmission coil allowed for dual channel RF shimming, focusing the RF field in the spinal cord, and an inner-volume saturated semi-LASER sequence was used for robust localization in the presence of B1 (+) inhomogeneity. Herein we report the first 7 T spinal cord (1) H MR spectra, which were obtained in seven independent measurements of 128 averages each in three healthy volunteers. The spectra exhibit high quality (full width at half maximum 0.09 ppm, SNR 7.6) and absence of artifacts and allow for reliable quantification of N-acetyl aspartate (NAA) (NAA/Cr (creatine) 1.31 ± 0.20; Cramér-Rao lower bound (CRLB) 5), total choline containing compounds (Cho) (Cho/Cr 0.32 ± 0.07; CRLB 7), Cr (CRLB 5) and myo-inositol (mI) (mI/Cr 1.08 ± 0.22; CRLB 6) in 7.5 min in the human cervical spinal cord. Thus metabolic information from the spinal cord can be obtained in clinically feasible scan times at 7 T, and its benefit for clinical decision making in spinal cord disorders will be investigated in the future using the presented methodology. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- A Henning
- Max Plank Institute for Biological Cybernetics, Tübingen, Germany
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - W Koning
- University Medical Center Utrecht, Utrecht, The Netherlands
| | - A Fuchs
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - A Raaijmakers
- University Medical Center Utrecht, Utrecht, The Netherlands
| | - J J Bluemink
- University Medical Center Utrecht, Utrecht, The Netherlands
| | | | - V O Boer
- University Medical Center Utrecht, Utrecht, The Netherlands
| | - D W J Klomp
- University Medical Center Utrecht, Utrecht, The Netherlands
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12
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Brunner DO, Dietrich BE, Çavuşoğlu M, Wilm BJ, Schmid T, Gross S, Barmet C, Pruessmann KP. Concurrent recording of RF pulses and gradient fields - comprehensive field monitoring for MRI. NMR IN BIOMEDICINE 2016; 29:1162-1172. [PMID: 26269210 DOI: 10.1002/nbm.3359] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 05/26/2015] [Accepted: 06/18/2015] [Indexed: 06/04/2023]
Abstract
Reconstruction of MRI data is based on exact knowledge of all magnetic field dynamics, since the interplay of RF and gradient pulses generates the signal, defines the contrast and forms the basis of resolution in spatial and spectral dimensions. Deviations caused by various sources, such as system imperfections, delays, eddy currents, drifts or externally induced fields, can therefore critically limit the accuracy of MRI examinations. This is true especially at ultra-high fields, because many error terms scale with the main field strength, and higher available SNR renders even smaller errors relevant. Higher baseline field also often requires higher acquisition bandwidths and faster signal encoding, increasing hardware demands and the severity of many types of hardware imperfection. To address field imperfections comprehensively, in this work we propose to expand the concept of magnetic field monitoring to also encompass the recording of RF fields. In this way, all dynamic magnetic fields relevant for spin evolution are covered, including low- to audio-frequency magnetic fields as produced by main magnets, gradients and shim systems, as well as RF pulses generated with single- and multiple-channel transmission systems. The proposed approach permits field measurements concurrently with actual MRI procedures on a strict common time base. The combined measurement is achieved with an array of miniaturized field probes that measure low- to audio-frequency fields via (19) F NMR and simultaneously pick up RF pulses in the MRI system's (1) H transmit band. Field recordings can form the basis of system calibration, retrospective correction of imaging data or closed-loop feedback correction, all of which hold potential to render MRI more robust and relax hardware requirements. The proposed approach is demonstrated for a range of imaging methods performed on a 7 T human MRI system, including accelerated multiple-channel RF pulses. Copyright © 2015 John Wiley & Sons, Ltd.
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Affiliation(s)
- David O Brunner
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Benjamin E Dietrich
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Mustafa Çavuşoğlu
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Bertram J Wilm
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
- Skope Magnetic Resonance Technologies, Zurich, Switzerland
| | - Thomas Schmid
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Simon Gross
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Christoph Barmet
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
- Skope Magnetic Resonance Technologies, Zurich, Switzerland
| | - Klaas P Pruessmann
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
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13
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Wezel J, Garpebring A, Webb AG, van Osch MJ, Beenakker JWM. Automated eye blink detection and correction method for clinical MR eye imaging. Magn Reson Med 2016; 78:165-171. [DOI: 10.1002/mrm.26355] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 06/14/2016] [Accepted: 07/05/2016] [Indexed: 12/13/2022]
Affiliation(s)
- Joep Wezel
- C.J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center; Leiden The Netherlands
| | - Anders Garpebring
- C.J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center; Leiden The Netherlands
- Radiation Sciences; Umeå University; Umeå Sweden
| | - Andrew G. Webb
- C.J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center; Leiden The Netherlands
| | - Matthias J.P. van Osch
- C.J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center; Leiden The Netherlands
| | - Jan-Willem M. Beenakker
- C.J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center; Leiden The Netherlands
- Department of Ophthalmology; Leiden University Medical Center; Leiden The Netherlands
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14
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Edden RAE, Oeltzschner G, Harris AD, Puts NAJ, Chan KL, Boer VO, Schär M, Barker PB. Prospective frequency correction for macromolecule-suppressed GABA editing at 3T. J Magn Reson Imaging 2016; 44:1474-1482. [PMID: 27239903 DOI: 10.1002/jmri.25304] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 04/25/2016] [Indexed: 11/08/2022] Open
Abstract
PURPOSE To investigate the effects of B0 field offsets and drift on macromolecule (MM)-suppressed GABA-editing experiments, and to implement and test a prospective correction scheme. "Symmetric" editing schemes are proposed to suppress unwanted coedited MM signals in GABA editing. MATERIALS AND METHODS Full density-matrix simulations of both conventional (nonsymmetric) and symmetric MM-suppressed editing schemes were performed for the GABA spin system to evaluate their offset-dependence. Phantom and in vivo (15 subjects at 3T) GABA-edited experiments with symmetrical suppression of MM signals were performed to quantify the effects of field offsets on the total GABA+MM signal (designated GABA+). A prospective frequency correction method based on interleaved water referencing (IWR) acquisitions was implemented and its experimental performance evaluated during positive and negative drift. RESULTS Simulations show that the signal from MM-suppressed symmetrical editing schemes is an order of magnitude more susceptible to field offsets than the signal from nonsymmetric editing schemes. The MM-suppressed GABA signal changes by 8.6% per Hz for small field offsets. IWR significantly reduces variance in the field offset and measured GABA levels (both P < 0.001 by F-tests), maintaining symmetric suppression of MM signal. CONCLUSION Symmetrical editing schemes substantially increase the dependence of measurements on B0 field offsets, which can arise due to patient movement and/or scanner instability. It is recommended that symmetrical editing should be used in combination with effective B0 stabilization, such as that provided by IWR. J. Magn. Reson. Imaging 2016;44:1474-1482.
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Affiliation(s)
- Richard A E Edden
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - Georg Oeltzschner
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - Ashley D Harris
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA.,CAIR Program, Alberta Children's Hospital Research Institute, University of Calgary, AB, Canada.,Department of Radiology, University of Calgary, AB, Canada.,Hotchkiss Brain Institute and Alberta Children's Hospital Research Institute, Calgary, AB, Canada
| | - Nicolaas A J Puts
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - Kimberly L Chan
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA.,Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Vincent O Boer
- Hvidovre Hospital, Danish Research Center for Magnetic Resonance, Hvidovre, Denmark
| | - Michael Schär
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Peter B Barker
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
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15
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Andersen M, Hanson LG, Madsen KH, Wezel J, Boer V, van der Velden T, van Osch MJP, Klomp D, Webb AG, Versluis MJ. Measuring motion-induced B0 -fluctuations in the brain using field probes. Magn Reson Med 2015; 75:2020-30. [PMID: 26073175 DOI: 10.1002/mrm.25802] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 05/04/2015] [Accepted: 05/24/2015] [Indexed: 12/13/2022]
Abstract
PURPOSE Fluctuations of the background magnetic field (B0 ) due to body and breathing motion can lead to significant artifacts in brain imaging at ultrahigh field. Corrections based on real-time sensing using external field probes show great potential. This study evaluates different aspects of field interpolation from these probes into the brain which is implicit in such methods. Measurements and simulations were performed to quantify how well B0 -fluctuations in the brain due to body and breathing motion are reflected in external field probe measurements. METHODS Field probe measurements were compared with scanner acquired B0 -maps from experiments with breathing and shoulder movements. A realistic simulation of B0 -fluctuations caused by breathing was performed, and used for testing different sets of field probe positions. RESULTS The B0 -fluctuations were well reflected in the field probe measurements in the shoulder experiments, while the breathing experiments showed only moderate correspondence. The simulations showed the importance of the probe positions, and that performing full 3(rd) order corrections based on 16 field probes is not recommended. CONCLUSION Methods for quantitative assessment of the field interpolation problem were developed and demonstrated. Field corrections based on external field measurements show great potential, although potential pitfalls were identified.
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Affiliation(s)
- Mads Andersen
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Denmark.,Biomedical Engineering Group, DTU Elektro, Technical University of Denmark, Kgs Lyngby, Denmark
| | - Lars G Hanson
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Denmark.,Biomedical Engineering Group, DTU Elektro, Technical University of Denmark, Kgs Lyngby, Denmark
| | - Kristoffer H Madsen
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Denmark
| | - Joep Wezel
- C.J. Gorter Center, Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Vincent Boer
- Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Tijl van der Velden
- Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Matthias J P van Osch
- C.J. Gorter Center, Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Dennis Klomp
- Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Andrew G Webb
- C.J. Gorter Center, Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Maarten J Versluis
- C.J. Gorter Center, Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands.,Philips Healthcare, Best, The Netherlands
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16
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Dietrich BE, Brunner DO, Wilm BJ, Barmet C, Gross S, Kasper L, Haeberlin M, Schmid T, Vannesjo SJ, Pruessmann KP. A field camera for MR sequence monitoring and system analysis. Magn Reson Med 2015; 75:1831-40. [DOI: 10.1002/mrm.25770] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 03/18/2015] [Accepted: 04/20/2015] [Indexed: 11/09/2022]
Affiliation(s)
- Benjamin E. Dietrich
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich; Zurich Switzerland
| | - David O. Brunner
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich; Zurich Switzerland
- Skope Magnetic Resonance Technologies; Zurich Switzerland
| | - Bertram J. Wilm
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich; Zurich Switzerland
- Skope Magnetic Resonance Technologies; Zurich Switzerland
| | - Christoph Barmet
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich; Zurich Switzerland
- Skope Magnetic Resonance Technologies; Zurich Switzerland
| | - Simon Gross
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich; Zurich Switzerland
| | - Lars Kasper
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich; Zurich Switzerland
- Translational Neuromodeling Unit, Institute for Biomedical Engineering, University of Zurich and ETH Zurich; Zurich Switzerland
| | - Maximilian Haeberlin
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich; Zurich Switzerland
| | - Thomas Schmid
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich; Zurich Switzerland
| | - S. Johanna Vannesjo
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich; Zurich Switzerland
| | - Klaas P. Pruessmann
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich; Zurich Switzerland
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17
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Vannesjo SJ, Wilm BJ, Duerst Y, Gross S, Brunner DO, Dietrich BE, Schmid T, Barmet C, Pruessmann KP. Retrospective correction of physiological field fluctuations in high-field brain MRI using concurrent field monitoring. Magn Reson Med 2014; 73:1833-43. [DOI: 10.1002/mrm.25303] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 04/08/2014] [Accepted: 05/08/2014] [Indexed: 12/12/2022]
Affiliation(s)
- S. Johanna Vannesjo
- Institute for Biomedical Engineering, University and ETH Zurich; Zurich Switzerland
| | - Bertram J. Wilm
- Institute for Biomedical Engineering, University and ETH Zurich; Zurich Switzerland
| | - Yolanda Duerst
- Institute for Biomedical Engineering, University and ETH Zurich; Zurich Switzerland
| | - Simon Gross
- Institute for Biomedical Engineering, University and ETH Zurich; Zurich Switzerland
| | - David O. Brunner
- Institute for Biomedical Engineering, University and ETH Zurich; Zurich Switzerland
| | - Benjamin E. Dietrich
- Institute for Biomedical Engineering, University and ETH Zurich; Zurich Switzerland
| | | | - Christoph Barmet
- Institute for Biomedical Engineering, University and ETH Zurich; Zurich Switzerland
- Skope Magnetic Resonance Technologies; Zurich Switzerland
| | - Klaas P. Pruessmann
- Institute for Biomedical Engineering, University and ETH Zurich; Zurich Switzerland
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18
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Duerst Y, Wilm BJ, Dietrich BE, Vannesjo SJ, Barmet C, Schmid T, Brunner DO, Pruessmann KP. Real-time feedback for spatiotemporal field stabilization in MR systems. Magn Reson Med 2014; 73:884-93. [PMID: 24634192 DOI: 10.1002/mrm.25167] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Revised: 12/21/2013] [Accepted: 01/14/2014] [Indexed: 11/10/2022]
Abstract
PURPOSE MR imaging and spectroscopy require a highly stable, uniform background field. The field stability is typically limited by hardware imperfections, external perturbations, or field fluctuations of physiological origin. The purpose of the present work is to address these issues by introducing spatiotemporal field stabilization based on real-time sensing and feedback control. METHODS An array of NMR field probes is used to sense the field evolution in a whole-body MR system concurrently with regular system operation. The field observations serve as inputs to a proportional-integral controller that governs correction currents in gradient and higher-order shim coils such as to keep the field stable in a volume of interest. RESULTS The feedback system was successfully set up, currently reaching a minimum latency of 20 ms. Its utility is first demonstrated by countering thermal field drift during an EPI protocol. It is then used to address respiratory field fluctuations in a T2 *-weighted brain exam, resulting in substantially improved image quality. CONCLUSION Feedback field control is an effective means of eliminating dynamic field distortions in MR systems. Third-order spatial control at an update time of 100 ms has proven sufficient to largely eliminate thermal and breathing effects in brain imaging at 7 Tesla.
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Affiliation(s)
- Yolanda Duerst
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Switzerland
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