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

Lutti, A., Hutton, C., Finsterbusch, J., Helms, G., & Weiskopf, N. (2010). Optimization and validation of methods for mapping of the radiofrequency transmit field at 3T. Magnetic Resonance in Medicine, 64(1), 229-238. doi:10.1002/mrm.22421.

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Lutti, Antoine1, Autor
Hutton, Chloe1, Autor
Finsterbusch, Jürgen2, Autor
Helms, Gunther3, Autor
Weiskopf, Nikolaus1, Autor           
Affiliations:
1Wellcome Trust Centre for Neuroimaging, University College London, United Kingdom, ou_persistent22              
2Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany, ou_persistent22              
3MR Research in Neurology and Psychiatry, Department of Cognitive Neurology, University Medical Center, Göttingen, Germany, ou_persistent22              

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Schlagwörter: RF mapping; Quantitative MRI; Flip-angle correction; Bmath image; B1
 Zusammenfassung: 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.

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Sprache(n): eng - English
 Datum: 2010-05-202010-07-01
 Publikationsstatus: Erschienen
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 Art der Begutachtung: -
 Identifikatoren: DOI: 10.1002/mrm.22421
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Titel: Magnetic Resonance in Medicine
Genre der Quelle: Zeitschrift
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Ort, Verlag, Ausgabe: -
Seiten: - Band / Heft: 64 (1) Artikelnummer: - Start- / Endseite: 229 - 238 Identifikator: ISSN: 0740-3194
CoNE: https://pure.mpg.de/cone/journals/resource/954925538149