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Adiabatic turbo spin echo in human applications at 7 T
Author(s) -
van Kalleveen Irene M. L.,
Koning Wouter,
Boer Vincent O.,
Luijten Peter R.,
Zwanenburg Jaco J. M.,
Klomp Dennis W. J.
Publication year - 2012
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.23264
Subject(s) - adiabatic process , radio frequency , imaging phantom , rf power amplifier , physics , signal (programming language) , image quality , nuclear magnetic resonance , turbo , computational physics , acoustics , optics , computer science , image (mathematics) , telecommunications , optoelectronics , artificial intelligence , quantum mechanics , amplifier , cmos , programming language , automotive engineering , engineering
Nonuniform B 1 fields in ultrahigh‐field MR imaging cause severe image artifacts, when conventional radiofrequency (RF) pulses are used. Particularly in MR sequences that encompass multiple RF pulses, e.g., turbo spin echo (TSE) sequences, complete signal loss may occur in certain areas. When using a surface coil for transmitting the RF pulses, these problems become even more challenging, as the spatial B 1 field variance is substantial. As an alternative to conventional TSE sequences, adiabatic TSE sequences can be applied, which have the benefit that these sequences are insensitive to B 1 nonuniformity. In this study, we investigate the potential of using adiabatic TSE at 7 T with surface coil transceivers in human applications. The adiabatic RF pulses were tuned to deal with the constraints in B 1 strength and RF power deposition, but remained in the superadiabatic regime. As a consequence, the dynamic range in B 1 is compromised, and signal modulation is obtained over the echo train. Multidimensional Bloch simulations over the echo train and phantom measurements were obtained to assess these limitations. Still, using proper k ‐space sampling, we demonstrate improved image quality of the adiabatic TSE versus conventional TSE in the brain, the neck (carotid artery) and in the pelvis (prostate) at 7 T. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.