title: A new sequence for shaped voxel spectroscopy in the human brain using 2D spatially selective excitation and parallel transmission.
abstract: Spatially selective excitation in two dimensions (2D-SSE) utilizing parallel transmission was applied as a means to acquire signal from voxels adapted to the anatomy of interest for in vivo (1) H MR spectroscopy. A novel method to select spectroscopy voxels with arbitrary shapes in two dimensions was investigated. An on-off scheme with an adiabatic slice selective inversion pulse preceding a 2D-SSE pulse together with a segmented inward spiral excitation k-space trajectory enabled rapid free induction decay acquisitions. Performance of the sequence was evaluated in simulations, phantom experiments, and in vivo measurements at 3 T. High spatial fidelity of the excitation profile was achieved for different target shapes and with little off-resonance deterioration. Metabolite concentrations in human brain determined with the new sequence were quantified with Cramér-Rao lower bounds less than 20%. They were in the physiological range and did not deviate systematically from results acquired with a conventional SPECIAL sequence. In conclusion, a new approach for shaped voxel MRS in the human brain is presented, which complements existing sequences. Simulations show that 2D-SSE pulses yield reduced chemical shift artifact when compared with conventional localization methods. Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berlin, Germany.
authors.forename: Patrick
authors.initials: P
authors.lastname: Waxmann
authors.affiliation: Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berlin, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Mekle
authors.affiliation: Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berlin, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Schubert
authors.affiliation: Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berlin, Germany.
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Brühl
authors.affiliation: Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.|MR Center of Excellence, Medical University of Vienna, Vienna, Austria.
authors.forename: Andre
authors.initials: A
authors.lastname: Kuehne
authors.affiliation: Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berlin, Germany.
authors.forename: Tomasz D
authors.initials: TD
authors.lastname: Lindel
authors.affiliation: Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berlin, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Seifert
authors.affiliation: Department of Biomedical Magnetic Resonance, Institute for Experimental Physics, Otto-von-Guericke-University, Magdeburg, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Speck
authors.affiliation: Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berlin, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Ittermann
mesh_terms: D000465:Algorithms; D001921:Brain / Q000033:anatomy & histology / Q000378:metabolism*; D006801:Humans; D007089:Image Enhancement; D007090:Image Interpretation, Computer-Assisted; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging; D057054:Molecular Imaging / Q000379:methods*; D010363:Pattern Recognition, Automated / Q000379:methods*; D066244:Proton Magnetic Resonance Spectroscopy; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted
keywords: chemical shift artifact; parallel transmission; shaped voxel spectroscopy; spatially selective excitation