Volumetric multishot echo-planar spectroscopic imaging.
Rapid volumetric magnetic resonance spectroscopic imaging (MRSI) is potentially of great relevance to the diagnosis and treatment of focal cerebral diseases such as cancer and epilepsy. A strategy for volumetric multishot echo-planar spectroscopic imaging (MEPSI) is described which allows whole-brain metabolite mapping in approximately 20 min. A multishot trajectory is used in both the spatial and temporal domains which reduces the accumulated phase during each echo train and tolerates conventional Fourier reconstruction without regridding. Also described is a generalized correction for phase discontinuities arising from the multishot acquisition of the time domain, which is independent of the spatial k-space trajectory and is therefore also applicable to multishot spiral MRSI. Whole-brain, lipid-suppressed MEPSI data were acquired from five normal subjects. The mean signal-to-noise ratios (SNRs) (+/-SE) for the n-acetylaspartate (NAA), choline (Cho), and creatine (Cr) maps across all subjects were 21.3 +/- 1.8, 11.7 +/- 0.6, and 9.2 +/- 0.6, respectively, with a computed voxel size of 2.33 ml.
Tyszka
J M
JM
Division of Molecular Medicine, Beckman Research Institute of the City of Hope, Duarte, California 91010, USA. mtyszka@coh.org
Mamelak
A N
AN
D000465:Algorithms; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D001931:Brain Mapping / Q000379:methods*; D002794:Choline / Q000378:metabolism; D003401:Creatine / Q000378:metabolism; D017352:Echo-Planar Imaging / Q000379:methods*; D005240:Feasibility Studies; D019047:Phantoms, Imaging; D012815:Signal Processing, Computer-Assisted
D001224:Aspartic Acid; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline