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Title page for ETD etd-12022011-201052


Type of Document Master's Thesis
Author Cui, Xuelin (Nick)
Author's Email Address xuelin.cui@vanderbilt.edu
URN etd-12022011-201052
Title An Investigation of Raw Data Corrections for Radial Fat-Water Magnetic Resonance Imaging
Degree Master of Science
Department Biomedical Engineering
Advisory Committee
Advisor Name Title
Edward Brian Welch Committee Chair
Mark Dose Committee Member
William Grissom Committee Member
Keywords
  • mri
  • radial reconstruction
  • fat-water imaging
Date of Defense 2011-12-02
Availability unrestricted
Abstract
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.

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