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Simultaneous z‐shim method for reducing susceptibility artifacts with multiple transmitters
Author(s) -
Deng Weiran,
Yang Cungeng,
Alagappan Vijayanand,
Wald Lawrence L.,
Boada Fernando E.,
Stenger V. Andrew
Publication year - 2009
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.21870
Subject(s) - shim (computing) , specific absorption rate , computer science , artifact (error) , radio frequency , transmitter , parallel communication , signal (programming language) , gradient echo , transmission (telecommunications) , imaging phantom , acoustics , nuclear magnetic resonance , physics , optics , channel (broadcasting) , magnetic resonance imaging , telecommunications , artificial intelligence , medicine , erectile dysfunction , antenna (radio) , radiology , programming language
The signal loss susceptibility artifact is a major limitation in gradient‐echo MRI applications. Various methods, including z‐shim techniques and multidimensional tailored radio frequency (RF) pulses, have been proposed to mitigate the through‐plane signal loss artifact, which is dominant in axial slices above the sinus region. Unfortunately, z‐shim techniques require multiple steps and multidimensional RF methods are complex, with long pulse lengths. Parallel transmission methods were recently shown to be promising for improving B 1 inhomogeneity and reducing the specific absorption rate. In this work, a novel method using time‐shifted slice‐select RF pulses is presented for reducing the through‐plane signal loss artifact in parallel transmission applications. A simultaneous z‐shim is obtained by concurrently applying unique time‐shifted pulses on each transmitter. The method is shown to reduce the signal loss susceptibility artifact in gradient‐echo images using a four‐channel parallel transmission system at 3T. Magn Reson Med 61:255–259, 2009. © 2009 Wiley‐Liss, Inc.