Paul Chang1,2, Sahar Nassirpour1,2, Nikolai Avdievitch1,3, Anke Henning1,3. 1. Max Planck Institute for Biological Cybernetics, Tuebingen, Germany. 2. IMPRS for Cognitive and Systems Neuroscience, Eberhard-Karls University of Tuebingen, Germany. 3. Department of Physics, University of Greifswald, Germany.
Abstract
PURPOSE: This study investigates metabolite concentrations using metabolite-cycled 1 H free induction decay (FID) magnetic resonance spectroscopic imaging (MRSI) at ultra-high fields. METHODS: A non-lipid-suppressed and slice-selective ultra-short echo time (TE) 1 H FID MRSI sequence was combined with a low-specific absorption rate (SAR) asymmetric inversion adiabatic pulse to enable non-water-suppressed metabolite mapping using metabolite-cycling at 9.4T. The results were compared to a water-suppressed FID MRSI sequence, and the same study was performed at 3T for comparison. The scan times for performing single-slice metabolite mapping with a nominal voxel size of 0.4 mL were 14 and 17.5 min on 3T and 9.4T, respectively. RESULTS: The low-SAR asymmetric inversion adiabatic pulse enabled reliable non-water-suppressed metabolite mapping using metabolite cycling at both 3T and 9.4T. The spectra and maps showed good agreement with the water-suppressed FID MRSI ones at both field strengths. A quantitative analysis of metabolite ratios with respect to N-acetyl aspartate (NAA) was performed. The difference in Cre/NAA was statistically significant, ∼0.1 higher for the non-water-suppressed case than for water suppression (from 0.73 to 0.64 at 3T and from 0.69 to 0.59 at 9.4T). The difference is likely because of chemical exchange effects of the water suppression pulses. Small differences in mI/NAA were also statistically significant, however, are they are less reliable because the metabolite peaks are close to the water peak that may be affected by the water suppression pulses or metabolite-cycling inversion pulse. CONCLUSION: We showed the first implementation of non-water-suppressed metabolite-cycled 1 H FID MRSI at ultra-high fields. An increase in Cre/NAA was seen for the metabolite-cycled case. The same methodology was further applied at 3T and similar results were observed. Magn Reson Med 80:442-451, 2018.
PURPOSE: This study investigates metabolite concentrations using metabolite-cycled 1 H free induction decay (FID) magnetic resonance spectroscopic imaging (MRSI) at ultra-high fields. METHODS: A non-lipid-suppressed and slice-selective ultra-short echo time (TE) 1 H FID MRSI sequence was combined with a low-specific absorption rate (SAR) asymmetric inversion adiabatic pulse to enable non-water-suppressed metabolite mapping using metabolite-cycling at 9.4T. The results were compared to a water-suppressed FID MRSI sequence, and the same study was performed at 3T for comparison. The scan times for performing single-slice metabolite mapping with a nominal voxel size of 0.4 mL were 14 and 17.5 min on 3T and 9.4T, respectively. RESULTS: The low-SAR asymmetric inversion adiabatic pulse enabled reliable non-water-suppressed metabolite mapping using metabolite cycling at both 3T and 9.4T. The spectra and maps showed good agreement with the water-suppressed FID MRSI ones at both field strengths. A quantitative analysis of metabolite ratios with respect to N-acetyl aspartate (NAA) was performed. The difference in Cre/NAA was statistically significant, ∼0.1 higher for the non-water-suppressed case than for water suppression (from 0.73 to 0.64 at 3T and from 0.69 to 0.59 at 9.4T). The difference is likely because of chemical exchange effects of the water suppression pulses. Small differences in mI/NAA were also statistically significant, however, are they are less reliable because the metabolite peaks are close to the water peak that may be affected by the water suppression pulses or metabolite-cycling inversion pulse. CONCLUSION: We showed the first implementation of non-water-suppressed metabolite-cycled 1 H FID MRSI at ultra-high fields. An increase in Cre/NAA was seen for the metabolite-cycled case. The same methodology was further applied at 3T and similar results were observed. Magn Reson Med 80:442-451, 2018.
Authors: Stefan Posse; Bruno Sa De La Rocque Guimaraes; Troy Hutchins-Delgado; Kishore Vakamudi; Kevin Fotso Tagne; Steen Moeller; Stephen R Dager Journal: NMR Biomed Date: 2020-01-30 Impact factor: 4.044
Authors: Ivan Tkáč; Dinesh Deelchand; Wolfgang Dreher; Hoby Hetherington; Roland Kreis; Chathura Kumaragamage; Michal Považan; Daniel M Spielman; Bernhard Strasser; Robin A de Graaf Journal: NMR Biomed Date: 2020-12-16 Impact factor: 4.478
Authors: Philipp Moser; Korbinian Eckstein; Lukas Hingerl; Michael Weber; Stanislav Motyka; Bernhard Strasser; Andre van der Kouwe; Simon Robinson; Siegfried Trattnig; Wolfgang Bogner Journal: Magn Reson Med Date: 2019-11-13 Impact factor: 4.668
Authors: Andrew A Maudsley; Ovidiu C Andronesi; Peter B Barker; Alberto Bizzi; Wolfgang Bogner; Anke Henning; Sarah J Nelson; Stefan Posse; Dikoma C Shungu; Brian J Soher Journal: NMR Biomed Date: 2020-04-29 Impact factor: 4.044