title: Temperature-ramped (129)Xe spin-exchange optical pumping.
abstract: We describe temperature-ramped spin-exchange optical pumping (TR-SEOP) in an automated high-throughput batch-mode (129)Xe hyperpolarizer utilizing three key temperature regimes: (i) "hot"-where the (129)Xe hyperpolarization rate is maximal, (ii) "warm"-where the (129)Xe hyperpolarization approaches unity, and (iii) "cool"-where hyperpolarized (129)Xe gas is transferred into a Tedlar bag with low Rb content (<5 ng per ∼1 L dose) suitable for human imaging applications. Unlike with the conventional approach of batch-mode SEOP, here all three temperature regimes may be operated under continuous high-power (170 W) laser irradiation, and hyperpolarized (129)Xe gas is delivered without the need for a cryocollection step. The variable-temperature approach increased the SEOP rate by more than 2-fold compared to the constant-temperature polarization rate (e.g., giving effective values for the exponential buildup constant γSEOP of 62.5 ± 3.7 × 10(-3) min(-1) vs 29.9 ± 1.2 × 10(-3) min(-1)) while achieving nearly the same maximum %PXe value (88.0 ± 0.8% vs 90.1% ± 0.8%, for a 500 Torr (67 kPa) Xe cell loading-corresponding to nuclear magnetic resonance/magnetic resonance imaging (NMR/MRI) enhancements of ∼3.1 × 10(5) and ∼2.32 × 10(8) at the relevant fields for clinical imaging and HP (129)Xe production of 3 T and 4 mT, respectively); moreover, the intercycle "dead" time was also significantly decreased. The higher-throughput TR-SEOP approach can be implemented without sacrificing the level of (129)Xe hyperpolarization or the experimental stability for automation-making this approach beneficial for improving the overall (129)Xe production rate in clinical settings.
authors.affiliation: Department of Radiology, Vanderbilt University Institute of Imaging Science, Vanderbilt University , Nashville, Tennessee 37232, United States.
authors.forename: Panayiotis
authors.initials: P
authors.lastname: Nikolaou
authors.forename: Aaron M
authors.initials: AM
authors.lastname: Coffey
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Barlow
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Rosen
authors.forename: Boyd M
authors.initials: BM
authors.lastname: Goodson
authors.forename: Eduard Y
authors.initials: EY
authors.lastname: Chekmenev
mesh_terms: D004867:Equipment Design; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation*; D013696:Temperature; D014978:Xenon / Q000737:chemistry*
chemical_list: D014978:Xenon