T 1 nuclear magnetic relaxation dispersion of hyperpolarized sodium and cesium hydrogencarbonate- 13 C.

Autor: Martínez-Santiesteban FM; Department of Medical Biophysics, Western University, London, Ontario, Canada., Dang TP; Department of Medical Biophysics, Western University, London, Ontario, Canada., Lim H; Department of Medical Biophysics, Western University, London, Ontario, Canada., Chen AP; GE Healthcare, Toronto, Ontario, Canada., Scholl TJ; Department of Medical Biophysics, Western University, London, Ontario, Canada.; Robarts Research Institute, Western University, London, Ontario, Canada.
Jazyk: angličtina
Zdroj: NMR in biomedicine [NMR Biomed] 2017 Sep; Vol. 30 (9). Date of Electronic Publication: 2017 Jun 27.
DOI: 10.1002/nbm.3749
Abstrakt: In vivo pH mapping in tissue using hyperpolarized hydrogencarbonate- 13 C has been proposed as a method to study tumor growth and treatment and other pathological conditions related to pH changes. The finite spin-lattice relaxation times (T 1 ) of hyperpolarized media are a significant limiting factor for in vivo imaging. Relaxation times can be measured at standard magnetic fields (1.5 T, 3.0 T etc.), but no such data are available at low fields, where T 1 values can be significantly shorter. This information is required to determine the potential loss of polarization as the agent is dispensed and transported from the polarizer to the MRI scanner. The purpose of this study is to measure T 1 dispersion from low to clinical magnetic fields (0.4 mT to 3.0 T) of different hyperpolarized hydrogencarbonate formulations previously proposed in the literature for in vivo pH measurements. 13 C-enriched cesium and sodium hydrogencarbonate preparations were hyperpolarized using dynamic nuclear polarization, and the T 1 values of different samples were measured at different magnetic field strengths using a fast field-cycling relaxometer and a 3.0 T clinical MRI system. The effects of deuterium oxide as a dissolution medium for sodium hydrogencarbonate were also analyzed. This study finds that the cesium formulation has slightly shorter T 1 values compared with the sodium preparation. However, the higher solubility of cesium hydrogencarbonate- 13 C means it can be polarized at greater concentration, using less trityl radical than sodium hydrogencarbonate- 13 C. This study also establishes that the preparation and handling of sodium hydrogencarbonate formulations in relation to cesium hydrogencarbonate is more difficult, due to the higher viscosity and lower achievable concentrations, and that deuterium oxide significantly increases the T 1 of sodium hydrogencarbonate solutions. Finally, this work also investigates the influence of pH on the spin-lattice relaxation of cesium hydrogencarbonate- 13 C measured over a pH range of 7 to 9 at 0.47 T.
(Copyright © 2017 John Wiley & Sons, Ltd.)
Databáze: MEDLINE
Externí odkaz: