The Physics of Hyperpolarized Gas MRI

High Xe density, high photon flux, stopped-flow spin-exchange optical pumping: Simulations versus experiments

“…[33,34] Each of these applications take advantage of various properties of 129 Xe including its moderate tissue solubility, exquisite chemical shift sensitivity, avidity for binding to proteins and other molecular hosts, its lipophilic tendencies, non-toxic nature, and sufficiently 15 long in vivo T 1 relaxation times that permit delivery to distal tissues-all of which have been discussed previously in a number of reviews. [35,36,37,38,39,40] Production of HP 129 Xe by SEOP begins with the optical pumping of alkali metal (typically Rb) valence electrons using circularly polarised light resonant at the D 1 transition. This process quickly leads to a highly polarised 20 Rb electronic ground state that subsequently polarises the 129 Xe nuclear spins through a combination of binary and molecular van der Waals (vdW) collisions wherein spin-exchange occurs, mediated by the Fermi contact hyperfine interaction.…”

2D Mapping of NMR Signal Enhancement and Relaxation for Heterogeneously Hyperpolarized Propane Gas

“…Biomedical applications of hyperpolarization are the main driving forces for the fundamental and applied scientific development of hyperpolarization methods. ,− Hyperpolarized (HP) compounds are prepared exogenously, and once administered in vivo (via intravenous injection or inhalation), they act as contrast agents for probing metabolism and organ function. Historically, hyperpolarization of noble gases (i.e., 129 Xe and 3 He) ,, has been developed first, and they have been readily applied for functional pulmonary imaging. ,− Numerous clinical trials have been completed and are ongoing or pending …”