Spectral phase-corrected GRAPPA reconstruction of three-dimensional echo-planar spectroscopic imaging (3D-EPSI).
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.
Zhu
Xiaoping
X
Department of Radiology, University of California-San Francisco, San Francisco, California, USA. Xiaoping.Zhu@ucsf.edu
Ebel
Andreas
A
Ji
Jim X
JX
Schuff
Norbert
N
D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D002794:Choline / Q000378:metabolism; D003401:Creatine / Q000378:metabolism; D017352:Echo-Planar Imaging / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008875:Middle Aged
D001224:Aspartic Acid; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline