In addition to the inherent chemical phase shift between different proton species, fat-water
MRI k-space raw data are corrupted by several sources such as magnetic field
inhomogeneity; chemical shift phase accumulated during the data readout window and
trajectory shifts due to non-ideal gradient performance. NMR signal can be modeled within a
single voxel as the mixture of different type protons with all corrupting factors clearly defined.
If multiecho data are acquired, the evolving fat-water signal can be described as a linear
system which can be unmixed. A reversed readout-based method is investigated in this work
to correct the field inhomogeneity for radial fat-water MRI data. In the Cartesian case, the field
map can be estimated using an iterative approach when other corrupting factors are precisely
modeled. In addition, accurate fat-water signal modeling includes the use of a multipeak fat
spectrum, and precise sampling time information. Multipeak fat spectrum information is
obtained from nuclear magnetic spectroscopy, and the precise sampling time information is
based on the employed pulse sequence. On the other hand, fat-water image reconstruction
from radial trajectory data requires non-uniform Fourier transformation including regridding,
density correction and interpolation. All these procedures are inserted as a part of radial
fat-water separation. The artifact caused by imperfect gradients for radial MRI is also
discussed and corrected in this work. Reconstruction results for both Cartesian and radial
data with all corrections applied are displayed and compared.
| Identifer | oai:union.ndltd.org:VANDERBILT/oai:VANDERBILTETD:etd-12022011-201052 |
| Date | 13 December 2011 |
| Creators | Cui, Xuelin (Nick) |
| Contributors | William Grissom, Mark Dose, Edward Brian Welch |
| Publisher | VANDERBILT |
| Source Sets | Vanderbilt University Theses |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.vanderbilt.edu/available/etd-12022011-201052/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to Vanderbilt University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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