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Wilm BJ, Nagy Z, Barmet C, Vannesjo SJ, Kasper L, Haeberlin M, Gross S, Dietrich BE, Brunner DO, Schmid T, Pruessmann KP. Diffusion MRI with concurrent magnetic field monitoring. Magn Reson Med 2015; 74:925-33. [DOI: 10.1002/mrm.25827] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 06/08/2015] [Accepted: 06/09/2015] [Indexed: 11/10/2022]
Affiliation(s)
- Bertram J. Wilm
- Institute for Biomedical Engineering; University of Zurich and ETH Zurich; Switzerland
| | - Zoltan Nagy
- Laboratory for Social and Neural Systems Research; University of Zurich; Switzerland
| | - Christoph Barmet
- Institute for Biomedical Engineering; University of Zurich and ETH Zurich; Switzerland
- Skope Magnetic Resonance Technologies LCC; Zurich Switzerland
| | - S. Johanna Vannesjo
- Institute for Biomedical Engineering; University of Zurich and ETH Zurich; Switzerland
| | - Lars Kasper
- Institute for Biomedical Engineering; University of Zurich and ETH Zurich; Switzerland
- Translational Neuromodeling Unit; Institute for Biomedical Engineering, University of Zurich and ETH Zurich; Switzerland
| | - Max Haeberlin
- Institute for Biomedical Engineering; University of Zurich and ETH Zurich; Switzerland
| | - Simon Gross
- Institute for Biomedical Engineering; University of Zurich and ETH Zurich; Switzerland
| | - Benjamin E. Dietrich
- Institute for Biomedical Engineering; University of Zurich and ETH Zurich; Switzerland
| | - David O. Brunner
- Institute for Biomedical Engineering; University of Zurich and ETH Zurich; Switzerland
| | - Thomas Schmid
- Institute for Biomedical Engineering; University of Zurich and ETH Zurich; Switzerland
| | - Klaas P. Pruessmann
- Institute for Biomedical Engineering; University of Zurich and ETH Zurich; Switzerland
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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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53
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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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54
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Haeberlin M, Kasper L, Barmet C, Brunner DO, Dietrich BE, Gross S, Wilm BJ, Kozerke S, Pruessmann KP. Real-time motion correction using gradient tones and head-mounted NMR field probes. Magn Reson Med 2014; 74:647-60. [PMID: 25219482 DOI: 10.1002/mrm.25432] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 07/30/2014] [Accepted: 08/07/2014] [Indexed: 11/10/2022]
Abstract
PURPOSE Sinusoidal gradient oscillations in the kilohertz range are proposed for position tracking of NMR probes and prospective motion correction for arbitrary imaging sequences without any alteration of sequence timing. The method is combined with concurrent field monitoring to robustly perform image reconstruction in the presence of potential dynamic field deviations. METHODS Benchmarking experiments were done to assess the accuracy and precision of the method and to compare it with theoretical predictions based on the field probe's time-dependent signal-to-noise ratio. An array of four field probes was used to perform real-time prospective motion correction in vivo. Images were reconstructed based on both predetermined and concurrently measured k-space trajectories. RESULTS For observation windows of 4.8 ms, the precision of probe position determination was found to be 35 to 62 µm, and the maximal measurement error was 595 µm root-mean-square on a single axis. Sequence update per repetition time on this basis yielded images free of conspicuous artifacts despite substantial head motion. Predetermined and concurrently observed k-space trajectories yielded equivalent image quality. CONCLUSION NMR field probes in conjunction with gradient tones permit the tracking and prospective correction of rigid-body motion. Relying on gradient oscillations in the kilohertz range, the method allows for concurrent motion detection and image encoding.
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Affiliation(s)
- Maximilian Haeberlin
- 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
| | - Christoph Barmet
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland.,Skope Magnetic Resonance Technologies, Zurich, Switzerland
| | - 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
| | - Simon Gross
- 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
| | - Sebastian Kozerke
- 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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55
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Kasper L, Bollmann S, Vannesjo SJ, Gross S, Haeberlin M, Dietrich BE, Pruessmann KP. Monitoring, analysis, and correction of magnetic field fluctuations in echo planar imaging time series. Magn Reson Med 2014; 74:396-409. [PMID: 25123595 DOI: 10.1002/mrm.25407] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 07/21/2014] [Accepted: 07/22/2014] [Indexed: 12/14/2022]
Abstract
PURPOSE To assess the utility of concurrent magnetic field monitoring for observing and correcting for variations in k-space trajectories and global background fields that occur in single-shot echo planar imaging (EPI) time series as typically used in functional MRI (fMRI). METHODS Field monitoring was performed using an array of NMR field probes operated concurrently with series of single-shot EPI acquisitions from a static phantom. The observed fluctuations in field evolution were analyzed in terms of their temporal and spatial behavior at the field level as well as at the level of reconstructed image series. The potential to correct for such fluctuations was assessed by accounting for them upon image reconstruction. An indication of the number and relative magnitude of underlying effects was obtained via principal component analysis. RESULTS Trajectory and global field variations were found to induce substantial image fluctuations. Global field fluctuations induced standard deviations in image intensity up to 31%. Fluctuations in the trajectory induced ghosting artifacts with standard deviations up to 2%. Concurrent magnetic field monitoring reduced the fluctuations in the EPI time series to a maximum of 1.2%. CONCLUSION Concurrent magnetic field monitoring holds the potential to improve the net sensitivity of fMRI by reducing signal fluctuations unrelated to brain activity.
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Affiliation(s)
- Lars Kasper
- Institute of 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
| | - Saskia Bollmann
- Institute of Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - S Johanna Vannesjo
- Institute of Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Simon Gross
- Institute of Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Maximilian Haeberlin
- Institute of Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Benjamin E Dietrich
- Institute of Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Klaas P Pruessmann
- Institute of Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
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