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Spectral phase‐corrected GRAPPA reconstruction of three‐dimensional echo‐planar spectroscopic imaging (3D‐EPSI)
Author(s) -
Zhu Xiaoping,
Ebel Andreas,
Ji Jim X.,
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.21217
Subject(s) - voxel , computer science , echo planar imaging , nuclear magnetic resonance , artificial intelligence , magnetic resonance imaging , physics , radiology , medicine
MR spectroscopic (MRS) images from a large volume of brain can be obtained using a 3D echo‐planar spectroscopic imaging (3D‐EPSI) sequence. However, routine applications of 3D‐EPSI are still limited by a long scan time. In this communication, a new approach termed “spectral phase‐corrected generalized autocalibrating partially parallel acquisitions” (SPC‐GRAPPA) is introduced for the reconstruction of 3D‐EPSI data to accelerate data acquisition while preserving the accuracy of quantitation of brain metabolites. In SPC‐GRAPPA, voxel‐by‐voxel spectral phase alignment between metabolite 3D‐EPSI from individual coil elements is performed in the frequency domain, utilizing the whole spectrum from interleaved water reference 3D‐EPSI for robust estimation of the zero‐order phase correction. The performance of SPC‐GRAPPA was compared with that of fully encoded 3D‐EPSI and conventional GRAPPA. Analysis of whole‐brain 3D‐EPSI data reconstructed by SPC‐GRAPPA demonstrates that SPC‐GRAPPA with an acceleration factor of 1.5 yields results very similar to those obtained by fully encoded 3D‐EPSI, and is more accurate than conventional GRAPPA. Magn Reson Med 57:815–820, 2007. © 2007 Wiley‐Liss, Inc.