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| Item Type: | Article |
|---|---|
| Title: | Characterization of phase-based methods used for transmission field uniformity mapping: a magnetic resonance study at 3.0 T and 7.0 T |
| Creators Name: | Carinci, F., Santoro, D., von Samson-Himmelstjerna, F., Lindel, T.D., Dieringer, M.A. and Niendorf, T. |
| Abstract: | Knowledge of the transmission field (B1(+)) of radio-frequency coils is crucial for high field (B0 = 3.0 T) and ultrahigh field (B0 >/=7.0 T) magnetic resonance applications to overcome constraints dictated by electrodynamics in the short wavelength regime with the ultimate goal to improve the image quality. For this purpose B1(+) mapping methods are used, which are commonly magnitude-based. In this study an analysis of five phase-based methods for three-dimensional mapping of the B1(+) field is presented. The five methods are implemented in a 3D gradient-echo technique. Each method makes use of different RF-pulses (composite or off-resonance pulses) to encode the effective intensity of the B1(+) field into the phase of the magnetization. The different RF-pulses result in different trajectories of the magnetization, different use of the transverse magnetization and different sensitivities to B1(+) inhomogeneities and frequency offsets, as demonstrated by numerical simulations. The characterization of the five methods also includes phantom experiments and in vivo studies of the human brain at 3.0 T and at 7.0 T. It is shown how the characteristics of each method affect the quality of the B1(+) maps. Implications for in vivo B1(+) mapping at 3.0 T and 7.0 T are discussed. |
| Keywords: | Algorithms, Brain, Brain Mapping, Computer Simulation, Computer-Assisted Image Processing, Imaging Phantoms, Magnetic Resonance Imaging, Theoretical Models, Three-Dimensional Imaging |
| Source: | PLoS ONE |
| ISSN: | 1932-6203 |
| Publisher: | Public Library of Science |
| Volume: | 8 |
| Number: | 3 |
| Page Range: | e57982 |
| Date: | 5 March 2013 |
| Official Publication: | https://doi.org/10.1371/journal.pone.0057982 |
| PubMed: | View item in PubMed |
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