• Patrick Waxmann, Ralf Mekle, Florian Schubert, Rüdiger Brühl, Andre Kuehne, Tomasz D Lindel, Frank Seifert, Oliver Speck, and Bernd Ittermann.
• Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berlin, Germany.
• NMR Biomed. 2016 Aug 1; 29 (8): 1028-37.

AbstractSpatially 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.Copyright © 2016 John Wiley & Sons, Ltd.

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