SAR-reduced spin-echo-based Bloch-Siegert B(1)(+) mapping: BS-SE-BURST.

Autor: Basse-Lüsebrink TC; Department of Experimental Physics 5, University of Würzburg, Würzburg, Germany. thomas.basse-luesebrink@physik.uni-wuerzburg.de, Kampf T, Fischer A, Sturm VJ, Neumann D, Köstler H, Hahn D, Stoll G, Jakob PM
Jazyk: angličtina
Zdroj: Magnetic resonance in medicine [Magn Reson Med] 2012 Aug; Vol. 68 (2), pp. 529-36. Date of Electronic Publication: 2011 Nov 30.
DOI: 10.1002/mrm.23259
Abstrakt: Fast and accurate B(1)(+) mapping is possible using phase-based Bloch-Siegert (BS) methods. Importantly, the off-resonant pulses needed for BS B(1)(+) mapping methods can easily be implemented in multiple MR sequences. BS-based B(1)(+) mapping has thus been introduced for gradient echo (BS-FLASH), spin-echo (BS-SE), and Carr, Purcell, Meiboom, Gill (CPMG)-based multi-SE and turbo-SE sequences. When using SE and multi-SE/turbo-SE-based BS sequences, however, the high intrinsic specific absorption rates must be considered in clinical situations. This study introduces a fast BS B(1)(+) mapping method based on a SE-BURST sequence (BS-SE-BURST). With SE-BURST sequences, multiple low-magnitude excitation pulses are applied prior to the refocusing pulse. Thus, multiple and different phase-encoded echoes can be acquired per excitation cycle. Compared with a SE sequence, this excitation strategy results in a similar signal-to-noise ratio (SNR) per unit time but with reduced specific absorption rate. The proposed BS-SE-BURST sequence was implemented on a conventional 3 T whole body MRI scanner and applied successfully.
(Copyright © 2011 Wiley Periodicals, Inc.)
Databáze: MEDLINE
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