Parallel radiofrequency transmission for 3 Tesla and 7 Tesla magnetic resonance imaging
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2017.
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| Format: | Thesis |
| Language: | eng |
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Massachusetts Institute of Technology
2018
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| Online Access: | http://hdl.handle.net/1721.1/113982 |
| _version_ | 1811080855090626560 |
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| author | Yetişir, Filiz |
| author2 | Elfar Adalsteinsson. |
| author_facet | Elfar Adalsteinsson. Yetişir, Filiz |
| author_sort | Yetişir, Filiz |
| collection | MIT |
| description | Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2017. |
| first_indexed | 2024-09-23T11:37:58Z |
| format | Thesis |
| id | mit-1721.1/113982 |
| institution | Massachusetts Institute of Technology |
| language | eng |
| last_indexed | 2024-09-23T11:37:58Z |
| publishDate | 2018 |
| publisher | Massachusetts Institute of Technology |
| record_format | dspace |
| spelling | mit-1721.1/1139822019-04-11T05:20:08Z Parallel radiofrequency transmission for 3 Tesla and 7 Tesla magnetic resonance imaging Yetişir, Filiz Elfar Adalsteinsson. Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science. Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science. Electrical Engineering and Computer Science. Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2017. Cataloged from PDF version of thesis. Includes bibliographical references (pages 141-146). Magnetic resonance imaging (MRI) is a noninvasive imaging technique with high soft tissue contrast. MR scanners are characterized by their main magnetic field strength. Commercially available clinical MR scanners commonly have main field strengths of 1.5 and 3 Tesla. Researchers increasingly explore clinical benefits of higher field strength scanners as they provide higher signal to noise ratio and higher resolution images. On the other hand, higher field strength imaging comes with increased image shading leading to non-uniform image contrast. Moreover, the tissue heating rate due to radiofrequency (RF) energy deposition (also called specific absorption rate or SAR) increases, limiting the imaging speed. Parallel RF transmission (pTx) was proposed to address both of these challenges by optimization of RF pulses transmitted from multiple independent channels simultaneously. However, both the RF pulse design and RF safety management become more complicated with pTx. In this work, a framework to apply pTx to 3T fetal and 7T brain imaging is developed to address the image shading and high SAR issues. Fetal imaging where a large pregnant torso is imaged rapidly to avoid fetal motion artifacts, suffers from similar levels of image shading and imaging limitations by SAR to 7T brain MRI. Hence the same techniques benefit both application domains. First, a SAR constrained pTx RF pulse design technique is developed for slice selective high flip angle imaging which is clinically the most common imaging technique. Next, the performance of the developed technique in reducing SAR and the image contrast non-uniformity is demonstrated through simulations and in phantom experiments for 7T brain imaging. Then, a comprehensive RF safety workflow for an 8 channel pTx system at 7T is developed. Finally, the potential of pTx for fetal imaging at 3T is demonstrated with simulation studies and a protected fetus mode of pTx was created using additional constraints in the RF pulse design. By addressing the two main RF transmission challenges associated with high and ultrahigh field MRI, this work aims to help bring the benefits of 7T brain imaging into routine clinical use and significantly improve the clinical experience for 3T fetal imaging. by Filiz Yetişir. Ph. D. 2018-03-02T22:21:38Z 2018-03-02T22:21:38Z 2017 2017 Thesis http://hdl.handle.net/1721.1/113982 1023628556 eng MIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission. http://dspace.mit.edu/handle/1721.1/7582 156 pages application/pdf Massachusetts Institute of Technology |
| spellingShingle | Electrical Engineering and Computer Science. Yetişir, Filiz Parallel radiofrequency transmission for 3 Tesla and 7 Tesla magnetic resonance imaging |
| title | Parallel radiofrequency transmission for 3 Tesla and 7 Tesla magnetic resonance imaging |
| title_full | Parallel radiofrequency transmission for 3 Tesla and 7 Tesla magnetic resonance imaging |
| title_fullStr | Parallel radiofrequency transmission for 3 Tesla and 7 Tesla magnetic resonance imaging |
| title_full_unstemmed | Parallel radiofrequency transmission for 3 Tesla and 7 Tesla magnetic resonance imaging |
| title_short | Parallel radiofrequency transmission for 3 Tesla and 7 Tesla magnetic resonance imaging |
| title_sort | parallel radiofrequency transmission for 3 tesla and 7 tesla magnetic resonance imaging |
| topic | Electrical Engineering and Computer Science. |
| url | http://hdl.handle.net/1721.1/113982 |
| work_keys_str_mv | AT yetisirfiliz parallelradiofrequencytransmissionfor3teslaand7teslamagneticresonanceimaging |