In:
Magnetic Resonance in Medicine, Wiley, Vol. 77, No. 2 ( 2017-02), p. 571-580
Abstract:
Together with the development of MRI contrasts that are inherently small in their magnitude, increased magnetic field accuracy is also required. Hence, mapping of the static magnetic field (B 0 ) and the excitation field (B 1 ) is not only important to feedback shim algorithms, but also for postprocess contrast‐correction procedures. Methods A novel field‐inhomogeneity mapping method is presented that allows simultaneous mapping of the water shift and B 1 (WASABI) using an off‐resonant rectangular preparation pulse. The induced Rabi oscillations lead to a sinc‐like spectrum in the frequency‐offset dimension and allow for determination of B 0 by its symmetry axis and of B 1 by its oscillation frequency. Results Stability of the WASABI method with regard to the influences of T 1 , T 2 , magnetization transfer, and repetition time was investigated and its convergence interval was verified. B 0 and B 1 maps obtained simultaneously by means of WASABI in the human brain at 3 T and 7 T can compete well with maps obtained by standard methods. Finally, the method was applied successfully for B 0 and B 1 correction of chemical exchange saturation transfer MRI (CEST‐MRI) data of the human brain. Conclusion The proposed WASABI method yields a novel simultaneous B 0 and B 1 mapping within 1 min that is robust and easy to implement. Magn Reson Med 77:571–580, 2017. © 2016 International Society for Magnetic Resonance in Medicine
Type of Medium:
Online Resource
ISSN:
0740-3194
,
1522-2594
Language:
English
Publisher:
Wiley
Publication Date:
2017
detail.hit.zdb_id:
1493786-4
