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Fast 3D radiofrequency field mapping using echo‐planar imaging
Author(s) -
Jiru F.,
Klose U.
Publication year - 2006
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.21083
Subject(s) - flip angle , echo (communications protocol) , nuclear magnetic resonance , radio frequency , signal (programming language) , echo planar imaging , physics , echo time , spin echo , planar , radiofrequency coil , magnetic resonance imaging , computer science , magnetic field , medicine , computer network , telecommunications , computer graphics (images) , quantum mechanics , radiology , programming language
An inhomogeneous radiofrequency (RF) magnetic field is an essential source of error for the quantification of MRI and MRS parameters. To correct for effects of RF inhomogeneities in 3D data sets, it is necessary to have knowledge of the 3D RF distribution in the sample. In this paper a method for fast 3D RF mapping is presented. The method is based on the simultaneous acquisition of a spin echo (SE) and a stimulated echo (STE) using echo‐planar imaging (EPI). The acquisition of the 3D RF map using 64 partitions and TR = 500 ms requires 1.5 min. The use of the sequence in vivo is demonstrated by the calculation of the RF maps in the human brain at 3T. The comparison of calculated flip angles with the flip angles obtained by fitting signal behavior in the 3D stimulated‐echo acquisition mode (STEAM)‐EPI sequence and the analysis of errors due to spatially dependent T 1 values in the brain show that the accuracy of the calculated flip angles in the human brain is about 2°. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.