title: Simultaneous estimation of T₁ and the flip angle in hyperpolarized NMR experiments using acquisition at non-regular time intervals.
abstract: In NMR spectroscopy of the liquid state T(1) is typically measured using an inversion recovery pulse sequence; but with hyperpolarized spins use is made of a sequence of multiple small radiofrequency (RF) induced nutations, α. Depending on the values of α and τ, the time interval between the pulses, the estimate of T(1) can be artifactually smaller than the real value; so without knowing the value of α the estimate of T(1) can be incorrect. Thus, we propose a method that involves a series of pulses with timing governed by a geometric sequence (or in general, any mathematically specified non-uniformly spaced sequence). This approach enables the simultaneous estimation of both the intrinsic T(1) value and α. The method was successfully applied to obtain T(1)=(44.9 ± 0.3)s and α=(4.0 ± 0.2)° (n=3) for a sample of hyperpolarized (13)C-urea in solution, matching with the inversion recovery pulse sequence estimate of T(1)=44 ± 2s using non-hyperpolarized (13)C-urea in solution.
authors: School of Molecular Bioscience, G08, University of Sydney, New South Wales 2006, Australia.
authors: Max
authors: M
authors: Puckeridge
authors: Guilhem
authors: G
authors: Pagès
authors: Philip W
authors: PW
authors: Kuchel
mesh_terms: D000465:Algorithms; D004574:Electromagnetic Fields; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008660:Metabolism; D017711:Nonlinear Dynamics; D011846:Radio Waves; D013816:Thermodynamics; D014508:Urea / Q000737:chemistry
chemical_list: D014508:Urea