Signal enhancement of hyperpolarized 15N sites in solution—increase in solid‐state polarization at 3.35 T and prolongation of relaxation in deuterated water mixtures. (14th July 2022)

• Record Type: Journal Article
• Authors: Gamliel, Ayelet; Shaul, David; Gomori, J. Moshe; Katz‐Brull, Rachel
• Is Part Of: NMR in biomedicine. Volume 35:Number 11(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-07-14
• Subjects: ammonium -- carbon‐13 -- D2O -- dissolution dynamic nuclear polarization -- nitrogen‐15 -- urea; Nuclear magnetic resonance -- Periodicals; Magnetic Resonance Spectroscopy -- Periodicals; 574
• DOI: 10.1002/nbm.4787
• Languages: English
• ISSNs: 0952-3480

Abstract

Abstract : Hyperpolarized 15 N sites have been found to be promising for generating long‐lived hyperpolarized states in solution, and present a promising approach for utilizing dissolution‐dynamic nuclear polarization (dDNP)‐driven hyperpolarized MRI for imaging in biology and medicine. Specifically, 15 N sites with directly bound protons were shown to be useful when dissolved in D2 O. The purpose of the current study was to further characterize and increase the visibility of such 15 N sites in solutions that mimic an intravenous injection during the first cardiac pass in terms of their H2 O:D2 O composition. The T 1 values of hyperpolarized 15 N in [ 15 N2 ]urea and [ 15 N]NH4 Cl demonstrated similar dependences on the H2 O:D2 O composition of the solution, with a T 1 of about 140 s in 100% D2 O, about twofold shortening in 90% and 80% D2 O, and about threefold shortening in 50% D2 O. [ 13 C]urea was found to be a useful solid‐state 13 C marker for qualitative monitoring of the 15 N polarization process in a commercial pre‐clinical dDNP device. Adding trace amounts of Gd 3+ to the polarization formulation led to higher solid‐state polarization of [ 13 C]urea and to higher polarization levels of [ 15 N2 ]urea in solution. Abstract : The T 1 of hyperpolarized 15 N in [ 15 N2 ]urea and [ 15 N]NH4 Cl demonstrated similar dependences on the H2 O:D2 O composition of the solution, with a T 1 of about 140 s in 100% D2 O, about twofold shortening in 80–90% D2 O (mimicking conditions of first cardiac pass following intravenous injection), and about threefold shortening in 50% D2 O. [ 13 C]urea served as solid‐state 13 C marker for the 15 N polarization progress. Gd 3+ doping led to higher polarization of both [ 13 C]urea in the solid state and [ 15 N2 ]urea in solution.