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Accelerated 3D echo‐planar spectroscopic imaging at 4 Tesla using modified blipped phase‐encoding
Author(s) -
Ebel Andreas,
Schuff Norbert
Publication year - 2007
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.21305
Subject(s) - ghosting , nuclear magnetic resonance , echo planar imaging , k space , physics , imaging phantom , signal (programming language) , magnetic resonance spectroscopic imaging , phase (matter) , magnetic resonance imaging , planar , echo time , computer science , optics , fourier transform , medicine , radiology , computer graphics (images) , quantum mechanics , programming language
Whole‐brain echo‐planar spectroscopic imaging (EPSI) often substantially lengthens MRI/MRSI (magnetic resonance spectroscopic imaging) protocols. To halve acquisition time, application of a blipped phase‐encoding (PE) gradient during the EPSI readout (RO) was previously suggested by PE of the even RO echoes in k ‐space at an interstitial location along k PE , separated from the odd RO echoes, effectively reducing the number of PEs by a factor of 2. However, the approach is very susceptible to phase inconsistencies between even and odd RO echoes in the presence of B 0 inhomogeneities and gradient imbalance, leading to ghosting in the PE direction. In this work, the blipped PE gradient is placed in between pairs of even/odd RO gradient lobes to avoid these problems. This approach is demonstrated in a phantom and in normal human brain in vivo at 4T. While the proposed method allows substantial reduction in metabolite ghosting, it may be limited by the presence of a relatively large spurious signal at the Nyquist frequency. Magn Reson Med 58:1061–1066, 2007. © 2007 Wiley‐Liss, Inc.