Optimization and validation of methods for mapping of the radiofrequency transmit field at 3T.

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Serval ID
serval:BIB_93C85C29EB9F
Type
Article: article from journal or magazin.
Collection
Publications
Title
Optimization and validation of methods for mapping of the radiofrequency transmit field at 3T.
Journal
Magnetic Resonance in Medicine
Author(s)
Lutti A., Hutton C., Finsterbusch J., Helms G., Weiskopf N.
ISSN
1522-2594 (Electronic)
ISSN-L
0740-3194
Publication state
Published
Issued date
2010
Volume
64
Number
1
Pages
229-238
Language
english
Notes
Publication types: Comparative Study ; Journal Article ; Research Support, Non-U.S. Gov't ; Validation StudiesPublication Status: ppublish
Abstract
MRI techniques such as quantitative imaging and parallel transmit require precise knowledge of the radio-frequency transmit field (B(1) (+)). Three published methods were optimized for robust B(1) (+) mapping at 3T in the human brain: three-dimensional (3D) actual flip angle imaging (AFI), 3D echo-planar imaging (EPI), and two-dimensional (2D) stimulated echo acquisition mode (STEAM). We performed a comprehensive comparison of the methods, focusing on artifacts, reproducibility, and accuracy compared to a reference 2D double angle method. For the 3D AFI method, the addition of flow-compensated gradients for diffusion damping reduced the level of physiological artifacts and improved spoiling of transverse coherences. Correction of susceptibility-induced artifacts alleviated image distortions and improved the accuracy of the 3D EPI imaging method. For the 2D STEAM method, averaging over multiple acquisitions reduced the impact of physiological noise and a new calibration method enhanced the accuracy of the B(1) (+) maps. After optimization, all methods yielded low noise B(1) (+) maps (below 2 percentage units), of the nominal flip angle value (p.u.) with a systematic bias less than 5 p.u. units. Full brain coverage was obtained in less than 5 min. The 3D AFI method required minimal postprocessing and showed little sensitivity to off-resonance and physiological effects. The 3D EPI method showed the highest level of reproducibility. The 2D STEAM method was the most time-efficient technique.
Keywords
Adult, Artifacts, Brain Mapping, Female, Head/radiography, Humans, Magnetic Resonance Imaging/methods, Male
Pubmed
Web of science
Open Access
Yes
Create date
08/07/2013 9:22
Last modification date
20/08/2019 14:56
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