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Fast CPMG‐based Bloch‐Siegert B 1 + mapping
Author(s) -
BasseLüsebrink T. C.,
Sturm V. J. F.,
Kampf T.,
Stoll G.,
Jakob P. M.
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.23013
Subject(s) - fast spin echo , spin echo , specific absorption rate , nuclear magnetic resonance , physics , signal (programming language) , echo (communications protocol) , spin (aerodynamics) , chemistry , atomic physics , magnetic resonance imaging , computer science , telecommunications , medicine , computer network , antenna (radio) , radiology , programming language , thermodynamics
A novel method for B 1 +mapping based on the Bloch‐Siegert (BS) shift was recently presented. This method applies off‐resonant pulses before signal acquisition to encode B 1 information into the signal phase. BS‐based methods possess significant advantages in measurement time and accuracy compared to magnitude‐based B 1 +methods. This study extends the idea of BS B 1 +mapping to Carr, Purcell, Meiboom, Gill (CPMG)‐based multi‐spin‐echo (BS‐CPMG‐MSE) and turbo‐spin‐echo (BS‐CPMG‐TSE) imaging. Compared to BS‐based spin echo imaging (BS‐SE), faster acquisition of the B 1 +information was possible using the BS‐CPMG‐TSE sequence. Furthermore, signal loss by T 2 * effects could be minimized using these spin echo‐based techniques. These effects are critical for gradient echo‐based BS methods at high field strengths. However, multi‐spin‐echo‐based BS B 1 methods inherently possess high specific absorption rates. Thus, the relative specific absorption rate of BS‐CPMG‐TSE sequences was estimated and compared with the specific absorption rate produced by BS‐SE sequences. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.