title: Three-dimensional arbitrary voxel shapes in spectroscopy with submillisecond TEs.
abstract: A novel spectroscopic method for submillisecond TEs and three-dimensional arbitrarily shaped voxels was developed and applied to phantom and in vivo measurements, with additional parallel excitation (PEX) implementation. A segmented spherical shell excitation trajectory was used in combination with appropriate radiofrequency weights for target selection in three dimensions. Measurements in a two-compartment phantom realized a TE of 955 µs, excellent spectral quality and comparable signal-to-noise ratios between accelerated (R = 2) and nonaccelerated modes. The two-compartment model allowed a comparison of the spectral suppression qualities of the method and, although outer volume signals were suppressed by factors of 1434 and 2246 compared with the theoretical unsuppressed case for the clinical and PEX modes, respectively, incomplete suppression of the outer volume (935 cm(3) compared with a target volume of 5.86 cm(3) ) resulted in a spectral contamination of 10.2% and 6.5% compared with the total signal. The method was also demonstrated in vivo in human brain on a clinical system at TE = 935 µs with good signal-to-noise ratio and spatial and spectral selection, and included LCModel relative quantification analysis. Eight metabolites showed significant fitting accuracy, including aspartate, N-acetylaspartylglutamate, glutathione and glutamate.
authors.affiliation: Department of Radiology, Medical Physics, University Medical Center Freiburg, Freiburg, Germany. jeff.snyder@uniklinik-freiburg.de
authors.forename: Jeff
authors.initials: J
authors.lastname: Snyder
authors.forename: Martin
authors.initials: M
authors.lastname: Haas
authors.forename: Iulius
authors.initials: I
authors.lastname: Dragonu
authors.forename: Jürgen
authors.initials: J
authors.lastname: Hennig
authors.forename: Maxim
authors.initials: M
authors.lastname: Zaitsev
mesh_terms: D003198:Computer Simulation; D017352:Echo-Planar Imaging; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D019047:Phantoms, Imaging; D011846:Radio Waves; D013997:Time Factors