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Design and use of tailored hard‐pulse trains for uniformed saturation of myocardium at 3 Tesla
Author(s) -
Sung Kyunghyun,
Nayak Krishna S.
Publication year - 2008
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.21765
Subject(s) - pulse (music) , saturation (graph theory) , nuclear magnetic resonance , adiabatic process , train , residual , materials science , rotation (mathematics) , pulsed radiofrequency , physics , biomedical engineering , computer science , optics , mathematics , medicine , surgery , cartography , algorithm , combinatorics , artificial intelligence , detector , thermodynamics , geography , pain relief
Complete and uniform saturation of myocardium is essential for quantitative myocardial perfusion imaging using the first pass of a contrast agent. At 3 T, inhomogeneities of both the static ( B 0 ) and radiofrequency ( B 1 ) magnetic fields have led to the use of adiabatic B 1 ‐insensitive rotation type 4 (BIR‐4) pulses, which in practice are constrained by radiofrequency (RF) heating. In this study, we propose the use of trains of weighted hard pulses that are optimized for the measured variation of B 0 and B 1 fields in the myocardium. These pulses are simple to design, and require substantially lower RF power when compared with BIR‐4 pulses. In volunteers, at 3 T, we demonstrated that the proposed saturation pulse with three subpulses results in lower peak and lower average residual longitudinal magnetization over the heart, as compared with 8‐msec BIR‐4 pulses and conventional hard pulse trains ( P < 0.05). Magn Reson Med 60:997–1002, 2008. © 2008 Wiley‐Liss, Inc.