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Hennig J, Barghoorn A, Zhang S, Zaitsev M. Single shot spiral
TSE
with annulated segmentation. Magn Reson Med 2022; 88:651-662. [DOI: 10.1002/mrm.29224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 02/11/2022] [Accepted: 02/20/2022] [Indexed: 11/11/2022]
Affiliation(s)
- Juergen Hennig
- University Medical Center FREIBURG, Dept.of Radiology, Medical Physics Freiburg Germany
- Center for Basics in NeuroModulation (NeuroModulBasics) Faculty of Medicine, University of Freiburg Freiburg Germany
| | - Antonia Barghoorn
- University Medical Center FREIBURG, Dept.of Radiology, Medical Physics Freiburg Germany
| | - Shuoyue Zhang
- University Medical Center FREIBURG, Dept.of Radiology, Medical Physics Freiburg Germany
| | - Maxim Zaitsev
- University Medical Center FREIBURG, Dept.of Radiology, Medical Physics Freiburg Germany
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Kolbitsch C, Bastkowski R, Schäffter T, Prieto Vasquez C, Weiss K, Maintz D, Giese D. Respiratory motion corrected 4D flow using golden radial phase encoding. Magn Reson Med 2019; 83:635-644. [DOI: 10.1002/mrm.27918] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 06/26/2019] [Accepted: 07/04/2019] [Indexed: 01/14/2023]
Affiliation(s)
- Christoph Kolbitsch
- Physikalisch‐Technische Bundesanstalt (PTB) Braunschweig and Berlin Germany
- King's College London School of Biomedical Engineering and Imaging Sciences London United Kingdom
| | - Rene Bastkowski
- Department of Radiology University Hospital of Cologne Cologne Germany
| | - Tobias Schäffter
- Physikalisch‐Technische Bundesanstalt (PTB) Braunschweig and Berlin Germany
- King's College London School of Biomedical Engineering and Imaging Sciences London United Kingdom
| | - Claudia Prieto Vasquez
- King's College London School of Biomedical Engineering and Imaging Sciences London United Kingdom
| | - Kilian Weiss
- Department of Radiology University Hospital of Cologne Cologne Germany
- Philips GmbH Healthcare Hamburg Germany
| | - David Maintz
- Department of Radiology University Hospital of Cologne Cologne Germany
| | - Daniel Giese
- Department of Radiology University Hospital of Cologne Cologne Germany
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Doganay O, Wade T, Hegarty E, McKenzie C, Schulte RF, Santyr GE. Hyperpolarized (129) Xe imaging of the rat lung using spiral IDEAL. Magn Reson Med 2015; 76:566-76. [PMID: 26332385 DOI: 10.1002/mrm.25911] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 08/03/2015] [Accepted: 08/06/2015] [Indexed: 12/22/2022]
Abstract
PURPOSE To implement and optimize a single-shot spiral encoding strategy for rapid 2D IDEAL projection imaging of hyperpolarized (Hp) (129) Xe in the gas phase, and in the pulmonary tissue (PT) and red blood cells (RBCs) compartments of the rat lung, respectively. THEORY AND METHODS A theoretical and experimental point spread function analysis was used to optimize the spiral k-space read-out time in a phantom. Hp (129) Xe IDEAL images from five healthy rats were used to: (i) optimize flip angles by a Bloch equation analysis using measured kinetics of gas exchange and (ii) investigate the feasibility of the approach to characterize the exchange of Hp (129) Xe. RESULTS A read-out time equal to approximately 1.8 × T2* was found to provide the best trade-off between spatial resolution and signal-to-noise ratio (SNR). Spiral IDEAL approaches that use the entire dissolved phase magnetization should give an SNR improvement of a factor of approximately three compared with Cartesian approaches with similar spatial resolution. The IDEAL strategy allowed imaging of gas, PT, and RBC compartments with sufficient SNR and temporal resolution to permit regional gas exchange measurements in healthy rats. CONCLUSION Single-shot spiral IDEAL imaging of gas, PT and RBC compartments and gas exchange is feasible in rat lung using Hp (129) Xe. Magn Reson Med 76:566-576, 2016. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- Ozkan Doganay
- Department of Medical Biophysics, Western University, London, ON, Canada.,Imaging Research Laboratories, Robarts Research Institute, London, ON, Canada
| | - Trevor Wade
- Department of Medical Biophysics, Western University, London, ON, Canada.,Imaging Research Laboratories, Robarts Research Institute, London, ON, Canada
| | - Elaine Hegarty
- Imaging Research Laboratories, Robarts Research Institute, London, ON, Canada
| | - Charles McKenzie
- Department of Medical Biophysics, Western University, London, ON, Canada.,Imaging Research Laboratories, Robarts Research Institute, London, ON, Canada.,Department of Medical Imaging, Western University, London, ON, Canada
| | | | - Giles E Santyr
- Department of Medical Biophysics, Western University, London, ON, Canada.,Imaging Research Laboratories, Robarts Research Institute, London, ON, Canada.,Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, ON, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
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Vannesjo SJ, Dietrich BE, Pavan M, Brunner DO, Wilm BJ, Barmet C, Pruessmann KP. Field camera measurements of gradient and shim impulse responses using frequency sweeps. Magn Reson Med 2013; 72:570-83. [PMID: 24105800 DOI: 10.1002/mrm.24934] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Revised: 07/19/2013] [Accepted: 08/01/2013] [Indexed: 11/09/2022]
Abstract
PURPOSE Applications of dynamic shimming require high field fidelity, and characterizing the shim field dynamics is therefore necessary. Modeling the system as linear and time-invariant, the purpose of this work was to measure the impulse response function with optimal sensitivity. THEORY AND METHODS Frequency-swept pulses as inputs are analyzed theoretically, showing that the sweep speed is a key factor for the measurement sensitivity. By adjusting the sweep speed it is possible to achieve any prescribed noise profile in the measured system response. Impulse response functions were obtained for the third-order shim system of a 7 Tesla whole-body MR scanner. Measurements of the shim fields were done with a dynamic field camera, yielding also cross-term responses. RESULTS The measured shim impulse response functions revealed system characteristics such as response bandwidth, eddy currents and specific resonances, possibly of mechanical origin. Field predictions based on the shim characterization were shown to agree well with directly measured fields, also in the cross-terms. CONCLUSION Frequency sweeps provide a flexible tool for shim or gradient system characterization. This may prove useful for applications involving dynamic shimming by yielding accurate estimates of the shim fields and a basis for setting shim pre-emphasis.
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Affiliation(s)
- S Johanna Vannesjo
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
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Yang J, Feng C, Zhao D. A CUDA-based reverse gridding algorithm for MR reconstruction. Magn Reson Imaging 2013; 31:313-23. [DOI: 10.1016/j.mri.2012.06.038] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Revised: 06/29/2012] [Accepted: 06/29/2012] [Indexed: 11/30/2022]
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Giese D, Haeberlin M, Barmet C, Pruessmann KP, Schaeffter T, Kozerke S. Analysis and correction of background velocity offsets in phase-contrast flow measurements using magnetic field monitoring. Magn Reson Med 2011; 67:1294-302. [PMID: 21826731 DOI: 10.1002/mrm.23111] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Revised: 06/06/2011] [Accepted: 06/27/2011] [Indexed: 11/11/2022]
Abstract
The value of phase-contrast magnetic resonance imaging for quantifying tissue motion and blood flow has been long recognized. However, the sensitivity of the method to system imperfections can lead to inaccuracies limiting its clinical acceptance. A key source of error relates to eddy current-induced phase fluctuations, which can offset the measured object velocity significantly. A higher-order dynamic field camera was used to study the spatiotemporal evolution of background phases in cine phase-contrast measurements. It is demonstrated that eddy current-induced offsets in phase-difference data are present up to the second spatial order. Oscillatory temporal behaviors of offsets in the kHz range suggest mechanical resonances of the MR system to be non-negligible in phase-contrast imaging. By careful selection of the echo time, their impact can be significantly reduced. When applying field monitoring data for correcting eddy current and mechanically induced velocity offsets, errors decrease to less than 0.5% of the maximum velocity for various sequence settings proving the robustness of the correction approach. In vivo feasibility is demonstrated for aortic and pulmonary flow measurements in five healthy subjects. Using field monitoring data, mean error in stroke volume was reduced from 10% to below 3%.
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Affiliation(s)
- Daniel Giese
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland.
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Schneider JT, Haas M, Ruhm W, Hennig J, Ullmann P. Robust spatially selective excitation using radiofrequency pulses adapted to the effective spatially encoding magnetic fields. Magn Reson Med 2010; 65:409-21. [PMID: 20872857 DOI: 10.1002/mrm.22635] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2010] [Revised: 07/21/2010] [Accepted: 08/16/2010] [Indexed: 11/06/2022]
Abstract
Multidimensional spatially selective excitation (SSE) has stimulated a variety of useful applications in magnetic resonance imaging and magnetic resonance spectroscopy, which have regained considerable interest after the recent introduction of parallel excitation. For SSE, radiofrequency pulses are designed specifically for certain time-courses of spatially encoding magnetic fields (SEM) which are applied simultaneously with the radiofrequency pulses. However, experimental imperfections of gradient-systems and undesired SEM field contributions often prevent the correct co-action of radiofrequency pulses and gradient-waveforms and therefore degrade the fidelity of excitation patterns, especially for parallel excitation. To cope with such imperfections, a classical measurement of k-space-trajectories can be performed followed by an adaptation of the SSE-pulses. However, this method is limited to linear SEM field distributions, which are describable in the k-space-formalism. Hence, this work presents a more sophisticated method consisting in a spatially resolved measurement of the temporal phase evolution of the transverse magnetization. This exhaustive phase information can be incorporated into pulse-design algorithms to compensate even for undesired spatially nonlinear, dynamic SEM field contributions. Both approaches are assessed in various experimental scenarios and individual benefits and limitations are discussed. The adaptation of SSE-pulses to experimentally achieved calibration data turned out to be very beneficial, and especially the novel spatially resolved method exhibited high potential for robust SSE even in adverse experimental setups.
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Affiliation(s)
- Johannes T Schneider
- Bruker BioSpin MRI GmbH, Ettlingen, Germany; Department of Radiology, Medical Physics, University Hospital Freiburg, Freiburg, Germany.
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Delattre BMA, Heidemann RM, Crowe LA, Vallée JP, Hyacinthe JN. Spiral demystified. Magn Reson Imaging 2010; 28:862-81. [PMID: 20409660 DOI: 10.1016/j.mri.2010.03.036] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2009] [Revised: 02/24/2010] [Accepted: 03/05/2010] [Indexed: 10/19/2022]
Abstract
Spiral acquisition schemes offer unique advantages such as flow compensation, efficient k-space sampling and robustness against motion that make this option a viable choice among other non-Cartesian sampling schemes. For this reason, the main applications of spiral imaging lie in dynamic magnetic resonance imaging such as cardiac imaging and functional brain imaging. However, these advantages are counterbalanced by practical difficulties that render spiral imaging quite challenging. Firstly, the design of gradient waveforms and its hardware requires specific attention. Secondly, the reconstruction of such data is no longer straightforward because k-space samples are no longer aligned on a Cartesian grid. Thirdly, to take advantage of parallel imaging techniques, the common generalized autocalibrating partially parallel acquisitions (GRAPPA) or sensitivity encoding (SENSE) algorithms need to be extended. Finally, and most notably, spiral images are prone to particular artifacts such as blurring due to gradient deviations and off-resonance effects caused by B(0) inhomogeneity and concomitant gradient fields. In this article, various difficulties that spiral imaging brings along, and the solutions, which have been developed and proposed in literature, will be reviewed in detail.
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Affiliation(s)
- Bénédicte M A Delattre
- Radiology Clinic, Geneva University Hospital and Faculty of Medicine, University of Geneva, 1211 Geneva 14, Switzerland.
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