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  Rapid radiofrequency field mapping in vivo using single-shot STEAM MRI

Helms, G., Finsterbusch, J., Weiskopf, N., & Dechent, P. (2008). Rapid radiofrequency field mapping in vivo using single-shot STEAM MRI. Magnetic Resonance in Medicine, 60(3), 739-743. doi:10.1002/mrm.21676.

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 Creators:
Helms, Gunter1, Author
Finsterbusch, Jürgen2, Author
Weiskopf, Nikolaus3, Author           
Dechent, Peter1, Author
Affiliations:
1MR-Research in Neurology and Psychiatry, Georg August University, Göttingen, Germany, ou_persistent22              
2Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Germany, ou_persistent22              
3Wellcome Trust Centre for Neuroimaging, University College London, United Kingdom, ou_persistent22              

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Free keywords: Radiofrequency mapping; Stimulated echo; Human brain
 Abstract: Higher field strengths entail less homogeneous RF fields. This may influence quantitative MRI and MRS. A method for rapidly mapping the RF field in the human head with minimal distortion was developed on the basis of a single-shot stimulated echo acquisition mode (STEAM) sequence. The flip angle of the second RF pulse in the STEAM preparation was set to 60 degrees and 100 degrees instead of 90 degrees , inducing a flip angle-dependent signal change. A quadratic approximation of this trigonometric signal dependence together with a calibration accounting for slice excitation-related bias allowed for directly determining the RF field from the two measurements only. RF maps down to the level of the medulla could be obtained in less than 1 min and registered to anatomical volumes by means of the T(2)-weighted STEAM images. Flip angles between 75% and 125% of the nominal value were measured in line with other methods.

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Language(s): eng - English
 Dates: 2008-08-252008-09-01
 Publication Status: Issued
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Type: -
 Identifiers: DOI: 10.1002/mrm.21676
 Degree: -

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Title: Magnetic Resonance in Medicine
Source Genre: Journal
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Publ. Info: -
Pages: - Volume / Issue: 60 (3) Sequence Number: - Start / End Page: 739 - 743 Identifier: ISSN: 0740-3194
CoNE: https://pure.mpg.de/cone/journals/resource/954925538149