title: Magnetic resonance imaging of (1)H long lived states derived from parahydrogen induced polarization in a clinical system.
abstract: Hyperpolarization is a powerful tool to overcome the low sensitivity of nuclear magnetic resonance (NMR). However, applications are limited due to the short lifetime of this non equilibrium spin state caused by relaxation processes. This issue can be addressed by storing hyperpolarization in slowly decaying singlet spin states which was so far mostly demonstrated for non-proton spin pairs, e.g. (13)C-(13)C. Protons hyperpolarized by parahydrogen induced polarization (PHIP) in symmetrical molecules, are very well suited for this strategy because they naturally exhibit a long-lived singlet state. The conversion of the NMR silent singlet spin state to observable magnetization can be achieved by making use of singlet-triplet level anticrossings. In this study, a low-power radiofrequency pulse sequence is used for this purpose, which allows multiple successive singlet-triplet conversions. The generated magnetization is used to record proton images in a clinical magnetic resonance imaging (MRI) system, after 3min waiting time. Our results may open unprecedented opportunities to use the standard MRI nucleus (1)H for e.g. metabolic imaging in the future.
authors.affiliation: Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany; Department of Radiology, Johannes Gutenberg University Medical Center, Langenbeckstr. 1, 55131 Mainz, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Graafen
authors.affiliation: Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany. Electronic address: franzoni@famaf.unc.edu.ar.
authors.forename: María Belén
authors.initials: MB
authors.lastname: Franzoni
authors.affiliation: Department of Radiology, Johannes Gutenberg University Medical Center, Langenbeckstr. 1, 55131 Mainz, Germany.
authors.forename: Laura M
authors.initials: LM
authors.lastname: Schreiber
authors.affiliation: Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
authors.forename: Hans W
authors.initials: HW
authors.lastname: Spiess
authors.affiliation: Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Münnemann
mesh_terms: D004574:Electromagnetic Fields; D006859:Hydrogen / Q000737:chemistry*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy; D011522:Protons; D011846:Radio Waves; D014753:Vinyl Compounds / Q000737:chemistry
chemical_list: D011522:Protons; D014753:Vinyl Compounds; D006859:Hydrogen
keywords: Hyperpolarization; Long lived state; PHIP; Parahydrogen; Pulse sequence