Jimin Ren1, Baolian Yang, A Dean Sherry, Craig R Malloy. 1. Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA; Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Abstract
PURPOSE: To develop an inversion pulse-based, chemical exchange saturation transfer-like method for detection of (31) P magnetization exchanges among all nuclear magnetic resonance visible metabolites suitable for providing an integrated kinetic analysis of phosphorus exchange reactions in vivo. METHODS: The exchange kinetics by inversion transfer (EKIT) sequence includes application of a frequency-selective inversion pulse arrayed over the range of relevant (31) P frequencies, followed by a constant delay and a hard readout pulse. A series of EKIT spectra, each given by a plot of Z-magnetization for each metabolite of interest versus frequency of the inversion pulse, can be generated from this single data set. RESULTS: EKIT spectra reflect chemical exchange due to known biochemical reactions, cross-relaxation effects, and relayed magnetization transfers due to both processes. The rate constants derived from EKIT data collected on resting human skeletal muscle were: ATP synthesis via ATP synthase (0.050 ± 0.016 s(-1) ), ATP synthesis via creatine kinase (0.264 ± 0.023 s(-1) ), and cross-relaxation between neighboring spin pairs within ATP (0.164 ± 0.022 s(-1) ). CONCLUSION: EKIT provides a simple, alternative method to detect chemical exchange, cross relaxation, and relayed magnetization transfer effects in human skeletal muscle at 7 T.
PURPOSE: To develop an inversion pulse-based, chemical exchange saturation transfer-like method for detection of (31) P magnetization exchanges among all nuclear magnetic resonance visible metabolites suitable for providing an integrated kinetic analysis of phosphorus exchange reactions in vivo. METHODS: The exchange kinetics by inversion transfer (EKIT) sequence includes application of a frequency-selective inversion pulse arrayed over the range of relevant (31) P frequencies, followed by a constant delay and a hard readout pulse. A series of EKIT spectra, each given by a plot of Z-magnetization for each metabolite of interest versus frequency of the inversion pulse, can be generated from this single data set. RESULTS: EKIT spectra reflect chemical exchange due to known biochemical reactions, cross-relaxation effects, and relayed magnetization transfers due to both processes. The rate constants derived from EKIT data collected on resting human skeletal muscle were: ATP synthesis via ATP synthase (0.050 ± 0.016 s(-1) ), ATP synthesis via creatine kinase (0.264 ± 0.023 s(-1) ), and cross-relaxation between neighboring spin pairs within ATP (0.164 ± 0.022 s(-1) ). CONCLUSION: EKIT provides a simple, alternative method to detect chemical exchange, cross relaxation, and relayed magnetization transfer effects in human skeletal muscle at 7 T.
Authors: Ladislav Valkovič; Marek Chmelík; Ivica Just Kukurova; Martin Krššák; Stephan Gruber; Ivan Frollo; Siegfried Trattnig; Wolfgang Bogner Journal: Eur J Radiol Date: 2011-12-10 Impact factor: 3.528
Authors: Peter C M van Zijl; Craig K Jones; Jimin Ren; Craig R Malloy; A Dean Sherry Journal: Proc Natl Acad Sci U S A Date: 2007-03-05 Impact factor: 11.205
Authors: Julia Szendroedi; Albrecht I Schmid; Marek Chmelik; Christian Toth; Attila Brehm; Martin Krssak; Peter Nowotny; Michael Wolzt; Werner Waldhausl; Michael Roden Journal: PLoS Med Date: 2007-05 Impact factor: 11.069