title: SAR-reduced spin-echo-based Bloch-Siegert B(1)(+) mapping: BS-SE-BURST.
abstract: 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.
authors: Department of Experimental Physics 5, University of Würzburg, Würzburg, Germany. thomas.basse-luesebrink@physik.uni-wuerzburg.de
authors: Thomas Christian
authors: TC
authors: Basse-Lüsebrink
authors: Thomas
authors: T
authors: Kampf
authors: André
authors: A
authors: Fischer
authors: Volker Jörg Friedrich
authors: VJ
authors: Sturm
authors: Daniel
authors: D
authors: Neumann
authors: Herbert
authors: H
authors: Köstler
authors: Dietbert
authors: D
authors: Hahn
authors: Guido
authors: G
authors: Stoll
authors: Peter Michael
authors: PM
authors: Jakob
mesh_terms: D000465:Algorithms; D001921:Brain / Q000033:anatomy & histology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013113:Spin Labels
chemical_list: D013113:Spin Labels