Increased main field (B0) strength in MRI leads to increased signal levels but also causes higher field inhomogeneity (delta-B0). This thesis presents the implementation and evaluation of Dynamic Shimming, an advanced field shimming (correction) technique, on a high field human 7 Tesla clinical scanner. In this technique, the shim settings are changed during the acquisition of data from individual sub-volumes leading to better optimized field homogeneity compared to conventional static global shimming. Phantom and invivo experiments have been performed comparing the two shimming techniques. Dynamic shimming was seen to produce lower residual delta- B0 , image distortion and signal losses that static global shimming. In addition, a novel software based prospective method of eddy field compensation applied to higher order shim induced eddy currents has been developed and implemented. The method is shown to significantly reduced eddy fields and related artifacts in dynamic shimming.
| Identifer | oai:union.ndltd.org:VANDERBILT/oai:VANDERBILTETD:etd-12012010-113404 |
| Date | 06 December 2010 |
| Creators | Sengupta, Saikat Tarun |
| Contributors | John C. Gore, Malcolm J Avison, Adam W. Anderson, Mark D. Does, Edward B. 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-12012010-113404/ |
| 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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