title: Measurements of the persistent singlet state of N2O in blood and other solvents--potential as a magnetic tracer.
abstract: The development of hyperpolarized tracers has been limited by short nuclear polarization lifetimes. The dominant relaxation mechanism for many hyperpolarized agents in solution arises from intramolecular nuclear dipole-dipole coupling modulated by molecular motion. It has been previously demonstrated that nuclear spin relaxation due to this mechanism can be removed by storing the nuclear polarization in long-lived, singlet-like states. In the case of N(2)O, storing the polarization of the nitrogen nuclei has been shown to substantially increase the polarization lifetime. The feasibility of utilizing N(2)O as a tracer is investigated by measuring the singlet-state lifetime of the N(2)O when dissolved in a variety of solvents including whole blood. Comparison of the singlet lifetime to longitudinal relaxation and between protonated and deuterated solvents is consistent with the dominance of spin-rotation relaxation, except in the case of blood.
authors.affiliation: Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6056, USA. rajghosh@mail.med.upenn.edu
authors.forename: R K
authors.initials: RK
authors.lastname: Ghosh
authors.forename: S J
authors.initials: SJ
authors.lastname: Kadlecek
authors.forename: J H
authors.initials: JH
authors.lastname: Ardenkjaer-Larsen
authors.forename: B M
authors.initials: BM
authors.lastname: Pullinger
authors.forename: G
authors.initials: G
authors.lastname: Pileio
authors.forename: M H
authors.initials: MH
authors.lastname: Levitt
authors.forename: N N
authors.initials: NN
authors.lastname: Kuzma
authors.forename: R R
authors.initials: RR
authors.lastname: Rizi
mesh_terms: D000273:Adipose Tissue / Q000737:chemistry; D000818:Animals; D005777:Geese; D008280:Magnetics; D009609:Nitrous Oxide / Q000097:blood* / Q000737:chemistry*; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012996:Solutions; D012997:Solvents / Q000737:chemistry
chemical_list: D012996:Solutions; D012997:Solvents; D009609:Nitrous Oxide