T‐Hex: Tilted hexagonal grids for rapid 3D imaging. Issue 5 (3rd December 2020)
- Record Type:
- Journal Article
- Title:
- T‐Hex: Tilted hexagonal grids for rapid 3D imaging. Issue 5 (3rd December 2020)
- Main Title:
- T‐Hex: Tilted hexagonal grids for rapid 3D imaging
- Authors:
- Engel, Maria
Kasper, Lars
Wilm, Bertram
Dietrich, Benjamin
Vionnet, Laetitia
Hennel, Franciszek
Reber, Jonas
Pruessmann, Klaas P. - Abstract:
- Abstract : Purpose: The purpose of this work is to devise and demonstrate an encoding strategy for 3D MRI that reconciles high speed with flexible segmentation, uniform k‐space density, and benign T 2 ∗ effects. Methods: Fast sampling of a 3D k‐space is typically accomplished by 2D readouts per shot using EPI trains or spiral readouts. Tilted hexagonal (T‐Hex) sampling is a way of acquiring more k‐space volume per excitation while maintaining uniform sampling density and a smooth T 2 ∗ filter. The k‐space volume covered per shot is controlled by the tilting angle. Image reconstruction is performed with a 3D extension of the iterative SENSE approach, incorporating actual field dynamics and static off‐resonance. T‐Hex imaging is compared with established 3D schemes in terms of speed and noise performance. Results: Tilted hexagonal acquisition is found to achieve greater imaging speed than known alternatives, particularly in combination with spiral trajectories. The interplay of the proposed 3D trajectories, array detection, and off‐resonance is successfully addressed by iterative inversion of the full signal model. Enhanced coverage per shot is of greatest utility for high speed in an intermediate resolution regime of 1 to 4 mm. T‐Hex EPI combines the benefits of extended coverage per shot with increased robustness against off‐resonance effects. Conclusion: Sampling of tilted hexagonal grids is a feasible means of gaining 3D imaging speed with near‐optimal SNR efficiency andAbstract : Purpose: The purpose of this work is to devise and demonstrate an encoding strategy for 3D MRI that reconciles high speed with flexible segmentation, uniform k‐space density, and benign T 2 ∗ effects. Methods: Fast sampling of a 3D k‐space is typically accomplished by 2D readouts per shot using EPI trains or spiral readouts. Tilted hexagonal (T‐Hex) sampling is a way of acquiring more k‐space volume per excitation while maintaining uniform sampling density and a smooth T 2 ∗ filter. The k‐space volume covered per shot is controlled by the tilting angle. Image reconstruction is performed with a 3D extension of the iterative SENSE approach, incorporating actual field dynamics and static off‐resonance. T‐Hex imaging is compared with established 3D schemes in terms of speed and noise performance. Results: Tilted hexagonal acquisition is found to achieve greater imaging speed than known alternatives, particularly in combination with spiral trajectories. The interplay of the proposed 3D trajectories, array detection, and off‐resonance is successfully addressed by iterative inversion of the full signal model. Enhanced coverage per shot is of greatest utility for high speed in an intermediate resolution regime of 1 to 4 mm. T‐Hex EPI combines the benefits of extended coverage per shot with increased robustness against off‐resonance effects. Conclusion: Sampling of tilted hexagonal grids is a feasible means of gaining 3D imaging speed with near‐optimal SNR efficiency and benign depiction properties. It is a particularly promising technique for time‐resolved applications such as fMRI. … (more)
- Is Part Of:
- Magnetic resonance in medicine. Volume 85:Issue 5(2021)
- Journal:
- Magnetic resonance in medicine
- Issue:
- Volume 85:Issue 5(2021)
- Issue Display:
- Volume 85, Issue 5 (2021)
- Year:
- 2021
- Volume:
- 85
- Issue:
- 5
- Issue Sort Value:
- 2021-0085-0005-0000
- Page Start:
- 2507
- Page End:
- 2523
- Publication Date:
- 2020-12-03
- Subjects:
- 3D encoding -- algebraic image reconstruction -- magnetic field monitoring -- spiral imaging
Nuclear magnetic resonance -- Periodicals
Electron paramagnetic resonance -- Periodicals
616.07548 - Journal URLs:
- http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1522-2594 ↗
http://onlinelibrary.wiley.com/ ↗ - DOI:
- 10.1002/mrm.28600 ↗
- Languages:
- English
- ISSNs:
- 0740-3194
- Deposit Type:
- Legaldeposit
- View Content:
- Available online (eLD content is only available in our Reading Rooms) ↗
- Physical Locations:
- British Library DSC - 5337.798000
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British Library HMNTS - ELD Digital store - Ingest File:
- 21832.xml