Challenges of field inhomogeneities and a method for compensation
2011-11
Loading...
View/Download File
Persistent link to this item
Statistics
View StatisticsJournal Title
Journal ISSN
Volume Title
Title
Challenges of field inhomogeneities and a method for compensation
Authors
Published Date
2011-11
Publisher
Type
Thesis or Dissertation
Abstract
MRI of the body at 7 T has become possible only very recently. High fields bring the advantages of increased signal to noise ratio, resolution gains, faster image acquisition through better parallel imaging, improved and novel types of contrast, and greater spectral dispersion. There are many obstacles to be faced in the advancement to 7 T including field inhomogeneities, transmit inhomogeneities, and increased RF-absorption risk. Inhomogeneous B1+ is possibly the most significant obstacle currently facing 7 T body imaging in consistently producing clinical-quality images. In this work, the first demonstrations of MR imaging and spectroscopy (MRS) of the liver at 7 T are presented and evaluated with special attention given to parallel imaging. Also presented here is the first demonstration of imaging of the uterus at 7 T with particular emphasis on contrast between uterine layers. A comparison was done between 3 T and 7 T, and relaxation rates were mapped including higher rotating frame relaxations.SWIRLY (spatiotemporal-encoding with incremental refocusing along a trajectory) is a novel pulse sequence that employs a frequency and amplitude modulated excitation pulse in the presence of sinusoidal gradients to move a region of resonance through space along a spiral trajectory. The signal can be sequentially refocused and acquired in an entirely spatiotemporal manner such that no Fourier Transform is needed for reconstruction. Because each resonance region can be treated entirely independently, this sequence has incredible potential for addressing problems that are inherently spatial in nature, such as B1+ and B0 inhomogeneities.
Keywords
Description
University of Minnesota Ph.D dissertation. Ph.D. November 2011. Major: Biomedical Engineering. Advisor: Michael Garwood. 1 computer file (PDF); vi, 96 pages.
Related to
Replaces
License
Collections
Series/Report Number
Funding information
Isbn identifier
Doi identifier
Previously Published Citation
Suggested citation
Styczynski Snyder, Angela Lynn. (2011). Challenges of field inhomogeneities and a method for compensation. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/162262.
Content distributed via the University Digital Conservancy may be subject to additional license and use restrictions applied by the depositor. By using these files, users agree to the Terms of Use. Materials in the UDC may contain content that is disturbing and/or harmful. For more information, please see our statement on harmful content in digital repositories.