title: Spectroscopic imaging using concentrically circular echo-planar trajectories in vivo.
abstract: An alternative to the standard echo-planar spectroscopic imaging technique is presented, spectroscopic imaging using concentrically circular echo-planar trajectories (SI-CONCEPT). In contrast to the conventional chemical shift imaging data, the sampled data from each set of concentric rings were regridded into Cartesian space. Usage of concentric k-space trajectories has the advantage of requiring significantly reduced slew rates than echo-planar spectroscopic imaging, allowing for the collection of higher spectral bandwidths and opening the door for high-bandwidth echo-planar styled spectroscopic imaging at higher magnetic fields. Before two-dimensional spatial and one-dimensional spectral encoding, the volume of interest was localized using the standard point-resolved spectroscopy sequence. The feasibility of using concentric k-space trajectories is demonstrated, and the spatial profiles and representative spectra are compared with the standard echo-planar spectroscopic imaging technique in a gray matter phantom containing metabolites at physiological concentrations and healthy human brain in vivo. The symmetric nature of the concentric circles also reduces the number of required excitations for a given resolution by a factor of two. Possible artifacts and limitations are discussed.
authors: Department of Radiological Sciences, University of California, Los Angeles, California 90095, USA.
authors: Jon K
authors: JK
authors: Furuyama
authors: Neil E
authors: NE
authors: Wilson
authors: M Albert
authors: MA
authors: Thomas
mesh_terms: D000328:Adult; D000465:Algorithms; D001921:Brain / Q000033:anatomy & histology* / Q000378:metabolism*; D017352:Echo-Planar Imaging / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity