Nicholas N. Kuzma1, Mehrdad Pourfathi1, Hoora Shaghaghi1, Rajat Kumar Ghosh1, Stephen J. Kadlecek1, Rahim Rizi1
1Radiology, University of Pennsylvania, Philadelphia, PA, United States
We describe a new general approach for producing highly spin-polarized frozen gases, such as 129Xe, 13CO2, and 15N2O, for magnetic resonance imaging. Each gas is liquefied and mechanically mixed with a free radical (trityl) dissolved in a liquid glassing agent (1-propanol) at a specific temperature and pressure. Molecular diffusion both in the liquid and in the solid state can cause self-segregation of these mixtures into pure frozen-gas clusters surrounded by the well-mixed matrix. We report the effects of the annealing temperature during the sample preparation on the subsequent T1 relaxation times and on the efficiency of the DNP process in the 15N2O system and contrast these new findings with our earlier 129Xe results.