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Four‐dimensional spectral‐spatial RF pulses for simultaneous correction of B 1 + inhomogeneity and susceptibility artifacts in T 2 *‐weighted MRI
Author(s) -
Yang Cungeng,
Deng Weiran,
Alagappan Vijayanand,
Wald Lawrence L.,
Stenger V. Andrew
Publication year - 2010
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.22471
Subject(s) - parallel communication , transmission (telecommunications) , artifact (error) , homogeneity (statistics) , signal (programming language) , excitation , offset (computer science) , pulse (music) , physics , optics , computer science , nuclear magnetic resonance , telecommunications , artificial intelligence , quantum mechanics , machine learning , detector , programming language
Abstract Susceptibility artifacts and excitation radiofrequency field B 1 + inhomogeneity are major limitations in high‐field MRI. Parallel transmission methods are promising for reducing artifacts in high‐field applications. In particular, three‐dimensional RF pulses have been shown to be useful for reducing B 1 + inhomogeneity using multiple transmitters due to their ability to spatially shape the slice profile. Recently, two‐dimensional spectral‐spatial pulses have been demonstrated to be effective for reducing the signal loss susceptibility artifact by incorporating a frequency‐dependent through‐plane phase correction. We present the use of four‐dimensional spectral‐spatial RF pulses for simultaneous B 1 + and through‐plane signal loss susceptibility artifact compensation. The method is demonstrated with simulations and in T 2 *‐weighted human brain images at 3 T, using a four‐channel parallel transmission system. Parallel transmission was used to reduce the in‐plane excitation resolution to improve the slice‐selection resolution between two different pulse designs. Both pulses were observed to improve B 1 + homogeneity and reduce the signal loss artifact in multiple slice locations and several human volunteers. Magn Reson Med 64:1–8, 2010. © 2010 Wiley‐Liss, Inc.