title: Design of flyback echo-planar readout gradients for magnetic resonance spectroscopic imaging.
abstract: The spatial resolution of conventional magnetic resonance spectroscopic imaging-(MRSI) is typically coarse, mainly due to SNR limitations. The increased signal available with higher field scanners and new array coils now permits higher spatial resolution, but conventional chemical shift imaging (phase encoding) limits the spatial coverage possible in a patient-acceptable acquisition time. The "flyback" echo-planar trajectory is particularly insensitive to errors and provides data that are simple to process. In this study, high-efficiency gradient waveforms for flyback echo-planar MRSI were designed and implemented. Normal volunteer studies at 3 T showed the feasibility of acquiring high spatial resolution with large coverage in a short scan time (2048 voxels in 2.3 min and 4096 voxels in 8.5 min). The trajectories were insensitive to errors in timing and require only a modest (10 to 30%) penalty in SNR relative to conventional phase encoding using the same acquisition time.
authors.affiliation: Department of Electrical Engineering, Stanford University, Stanford, California, USA. chuck.cunningham@stanford.edu
authors.forename: Charles H
authors.initials: CH
authors.lastname: Cunningham
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Vigneron
authors.forename: Albert P
authors.initials: AP
authors.lastname: Chen
authors.forename: Duan
authors.initials: D
authors.lastname: Xu
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Nelson
authors.forename: Ralph E
authors.initials: RE
authors.lastname: Hurd
authors.forename: Douglas A
authors.initials: DA
authors.lastname: Kelley
authors.forename: John M
authors.initials: JM
authors.lastname: Pauly
mesh_terms: D000465:Algorithms; D017352:Echo-Planar Imaging / Q000379:methods*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods; D016247:Information Storage and Retrieval / Q000379:methods; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity