title: A continuous-flow, high-throughput, high-pressure parahydrogen converter for hyperpolarization in a clinical setting.
abstract: Pure parahydrogen (pH(2) ) is the prerequisite for optimal pH(2) -based hyperpolarization experiments, promising approaches to access the hidden orders of magnitude of MR signals. pH(2) production on-site in medical research centers is vital for the proliferation of these technologies in the life sciences. However, previously suggested designs do not meet our requirements for safety or production performance (flow rate, pressure or enrichment). In this article, we present the safety concept, design and installation of a pH(2) converter, operated in a clinical setting. The apparatus produces a continuous flow of four standard liters per minute of ≈98% enriched pH(2) at a pressure maximum of 50 bar. The entire production cycle, including cleaning and cooling to 25 K, takes less than 5 h, only ≈45 min of which are required for actual pH(2) conversion. A fast and simple quantification procedure is described. The lifetimes of pH(2) in a glass vial and aluminum storage cylinder are measured to be T(1C) (glass vial) =822 ± 29 min and T(1C) (Al cylinder) =129 ± 36 days, thus providing sufficiently long storage intervals and allowing the application of pH(2) on demand. A dependence of line width on pH(2) enrichment is observed. As examples, (1) H hyperpolarization of pyridine and (13) C hyperpolarization of hydroxyethylpropionate are presented.
authors: Medical Physics, Department of Radiology, University Medical Center Freiburg, Freiburg, Germany. jan.hoevener@uniklinik-freiburg.de
authors: Jan-Bernd
authors: JB
authors: Hövener
authors: Sébastien
authors: S
authors: Bär
authors: Jochen
authors: J
authors: Leupold
authors: Klaus
authors: K
authors: Jenne
authors: Dieter
authors: D
authors: Leibfritz
authors: Jürgen
authors: J
authors: Hennig
authors: Simon B
authors: SB
authors: Duckett
authors: Dominik
authors: D
authors: von Elverfeldt
mesh_terms: D002247:Carbon Isotopes / Q000737:chemistry*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006859:Hydrogen / Q000737:chemistry* / Q000302:isolation & purification*; D007553:Isotope Labeling / Q000295:instrumentation*; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation*; D011312:Pressure; D012034:Refrigeration / Q000295:instrumentation*; D012212:Rheology / Q000295:instrumentation*
chemical_list: D002247:Carbon Isotopes; D006859:Hydrogen