Williams, S. N. , Nielsen, J.-F., Fessler, J. A. and Noll, D. C. (2017) Design of spectral-spatial phase prewinding pulses and their use in small-tip fast recovery steady-state imaging. Magnetic Resonance in Medicine, 79, pp. 1377-1386. 26794. (doi: 10.1002/mrm.26794) (PMID:28671320) (PMCID:PMC5752636)
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Abstract
Purpose: Spectrally selective “prewinding” radiofrequency pulses can counteract B0 inhomogeneity in steady-state sequences, but can only prephase a limited range of offresonance. We propose spectral-spatial small-tip angle prewinding pulses that increase the off-resonance bandwidth that can be successfully prephased by incorporating spatially tailored excitation patterns. Theory and Methods: We present a feasibility study to compare spectral and spectral-spatial prewinding pulses. These pulses add a prephasing term to the target magnetization pattern that aims to recover an assigned off-resonance bandwidth at the echo time. For spectral-spatial pulses, the design bandwidth is centered at the off-resonance frequency for each spatial location in a field map. We use these pulses in the small-tip fast recovery steady-state sequence, which is similar to balanced steady-state free precession. We investigate improvement of spectral-spatial pulses over spectral pulses using simulations and small-tip fast recovery scans of a gel phantom and human brain. Results: In simulation, spectral-spatial pulses yielded lower normalized root mean squared excitation error than spectral pulses. For both experiments, the spectral-spatial pulse images are also qualitatively better (more uniform, less signal loss) than the spectral pulse images. Conclusion: Spectral-spatial prewinding pulses can prephase over a larger range of off-resonance than their purely spectral counterparts.
Item Type: | Articles |
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Keywords: | RF pulse design, field inhomogeneity, phase prewinding, spectral-spatial pulses. |
Status: | Published |
Refereed: | Yes |
Glasgow Author(s) Enlighten ID: | Williams, Dr Sydney |
Authors: | Williams, S. N., Nielsen, J.-F., Fessler, J. A., and Noll, D. C. |
Subjects: | Q Science > Q Science (General) Q Science > QC Physics R Medicine > R Medicine (General) T Technology > T Technology (General) |
College/School: | College of Medical Veterinary and Life Sciences > School of Psychology & Neuroscience |
Research Group: | fMRI Laboratory, University of Michigan |
Journal Name: | Magnetic Resonance in Medicine |
Publisher: | Wiley |
ISSN: | 1522-2594 |
ISSN (Online): | 1522-2594 |
Published Online: | 03 July 2017 |
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