Michael A Antonacci1,2, Le Zhang2,3, Alex Burant1,2, Drew McCallister1,2, Rosa T Branca1,2. 1. Department of Physics and Astronomy, University of North Carolina at Chapel Hill, North Carolina, USA. 2. Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, North Carolina, USA. 3. Department of Applied Physical Sciences, University of North Carolina at Chapel Hill, North Carolina, USA.
Abstract
PURPOSE: To assess the effect of macroscopic susceptibility gradients on the gas-phase referenced dissolved-phase 129 Xe (DPXe) chemical shift (CS) and to establish the robustness of a water-based referencing system for in vivo DPXe spectra. METHODS: Frequency shifts induced by spatially varying magnetic susceptibility are calculated by finite-element analysis for the human head and chest. Their effect on traditional gas-phase referenced DPXe CS is then assessed theoretically and experimentally. A water-based referencing system for the DPXe resonances that uses the local water protons as reference is proposed and demonstrated in vivo in rats. RESULTS: Across the human brain, macroscopic susceptibility gradients can induce an apparent variation in the DPXe CS of up to 2.5 ppm. An additional frequency shift as large as 6.5 ppm can exist between DPXe and gas-phase resonances. By using nearby water protons as reference for the DPXe CS, the effect of macroscopic susceptibility gradients is eliminated and consistent CS values are obtained in vivo, regardless of shimming conditions, region of interest analyzed, animal orientation, or lung inflation. Combining in vitro and in vivo spectroscopic measurements finally enables confident assignment of some of the DPXe peaks observed in vivo. CONCLUSION: To use hyperpolarized xenon as a biological probe in tissues, the DPXe CS in specific organs/tissues must be reliably measured. When the gas-phase is used as reference, variable CS values are obtained for DPXe resonances. Reliable peak assignments in DPXe spectra can be obtained by using local water protons as reference. Magn Reson Med 80:431-441, 2018.
PURPOSE: To assess the effect of macroscopic susceptibility gradients on the gas-phase referenced dissolved-phase 129 Xe (DPXe) chemical shift (CS) and to establish the robustness of a water-based referencing system for in vivo DPXe spectra. METHODS: Frequency shifts induced by spatially varying magnetic susceptibility are calculated by finite-element analysis for the human head and chest. Their effect on traditional gas-phase referenced DPXeCS is then assessed theoretically and experimentally. A water-based referencing system for the DPXe resonances that uses the local water protons as reference is proposed and demonstrated in vivo in rats. RESULTS: Across the human brain, macroscopic susceptibility gradients can induce an apparent variation in the DPXeCS of up to 2.5 ppm. An additional frequency shift as large as 6.5 ppm can exist between DPXe and gas-phase resonances. By using nearby water protons as reference for the DPXeCS, the effect of macroscopic susceptibility gradients is eliminated and consistent CS values are obtained in vivo, regardless of shimming conditions, region of interest analyzed, animal orientation, or lung inflation. Combining in vitro and in vivo spectroscopic measurements finally enables confident assignment of some of the DPXe peaks observed in vivo. CONCLUSION: To use hyperpolarized xenon as a biological probe in tissues, the DPXeCS in specific organs/tissues must be reliably measured. When the gas-phase is used as reference, variable CS values are obtained for DPXe resonances. Reliable peak assignments in DPXe spectra can be obtained by using local water protons as reference. Magn Reson Med 80:431-441, 2018.
Authors: John P Mugler; Talissa A Altes; Iulian C Ruset; Isabel M Dregely; Jaime F Mata; G Wilson Miller; Stephen Ketel; Jeffrey Ketel; F William Hersman; Kai Ruppert Journal: Proc Natl Acad Sci U S A Date: 2010-11-22 Impact factor: 11.205
Authors: Rosa Tamara Branca; Ting He; Le Zhang; Carlos S Floyd; Matthew Freeman; Christian White; Alex Burant Journal: Proc Natl Acad Sci U S A Date: 2014-12-01 Impact factor: 11.205
Authors: Mary L Mazzanti; Ronn P Walvick; Xin Zhou; Yanping Sun; Niral Shah; Joey Mansour; Jessica Gereige; Mitchell S Albert Journal: PLoS One Date: 2011-07-15 Impact factor: 3.240
Authors: Michael A Antonacci; Christian McHugh; Michele Kelley; Andrew McCallister; Simone Degan; Rosa T Branca Journal: Sci Rep Date: 2019-10-16 Impact factor: 4.379
Authors: Jorge Chacon-Caldera; Adam Maunder; Madhwesha Rao; Graham Norquay; Oliver I Rodgers; Matthew Clemence; Claudio Puddu; Lothar R Schad; Jim M Wild Journal: Magn Reson Med Date: 2019-08-09 Impact factor: 4.668
Authors: Yurii Shepelytskyi; Vira Grynko; Madhwesha R Rao; Tao Li; Martina Agostino; Jim M Wild; Mitchell S Albert Journal: Magn Reson Med Date: 2022-03-07 Impact factor: 3.737