Encoding methods for B 1 + mapping in parallel transmit systems at ultra high field

Tse, Desmond H. Y., Poole, Michael S., Magill, Arthur W., Felder, Joerg, Brenner, Daniel and Shah, N. Jon (2014) Encoding methods for B 1 + mapping in parallel transmit systems at ultra high field. Journal of Magnetic Resonance, 245 125-132. doi:10.1016/j.jmr.2014.06.006


Author Tse, Desmond H. Y.
Poole, Michael S.
Magill, Arthur W.
Felder, Joerg
Brenner, Daniel
Shah, N. Jon
Title Encoding methods for B 1 + mapping in parallel transmit systems at ultra high field
Journal name Journal of Magnetic Resonance   Check publisher's open access policy
ISSN 1096-0856
1090-7807
Publication date 2014-08-01
Year available 2014
Sub-type Article (original research)
DOI 10.1016/j.jmr.2014.06.006
Open Access Status Not yet assessed
Volume 245
Start page 125
End page 132
Total pages 8
Place of publication Maryland Heights, MO, United States
Publisher Academic Press
Language eng
Formatted abstract
Parallel radiofrequency (RF) transmission, either in the form of RF shimming or pulse design, has been proposed as a solution to the B1+ inhomogeneity problem in ultra high field magnetic resonance imaging. As a prerequisite, accurate B1+ maps from each of the available transmit channels are required. In this work, four different encoding methods for B1+ mapping, namely 1-channel-on, all-channels-on-except-1, all-channels-on-1-inverted and Fourier phase encoding, were evaluated using dual refocusing acquisition mode (DREAM) at 9.4 T. Fourier phase encoding was demonstrated in both phantom and in vivo to be the least susceptible to artefacts caused by destructive RF interference at 9.4 T. Unlike the other two interferometric encoding schemes, Fourier phase encoding showed negligible dependency on the initial RF phase setting and therefore no prior B1+ knowledge is required. Fourier phase encoding also provides a flexible way to increase the number of measurements to increase SNR, and to allow further reduction of artefacts by weighted decoding. These advantages of Fourier phase encoding suggest that it is a good choice for B1+ mapping in parallel transmit systems at ultra high field.
Keyword High-field MRI
Parallel transmit
Phase-rotation
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: Centre for Advanced Imaging Publications
 
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