Quality assurance of PASADENA hyperpolarization for ^(13)C biomolecules

Object Define MR quality assurance procedures for maximal PASADENA hyperpolarization of a biological ^(13)C molecular imaging reagent. Materials and methods An automated PASADENA polarizer and a parahydrogen generator were installed. ^(13)C enriched hydroxyethyl acrylate, 1^(-13)C, 2,3,3-d_3 (HEA), was converted to hyperpolarized hydroxyethyl propionate, 1^(-13)C, 2,3,3-d_3 (HEP) and fumaric acid, 1^(-13)C, 2,3-d_2 (FUM) to hyperpolarized succinic acid, 1^(-13)C, 2,3-d_2 (SUC), by reaction with parahydrogen and norbornadiene rhodium catalyst. Incremental optimization of successive steps in PASADENA was implemented. MR spectra and in vivo images of hyperpolarized ^(13)C imaging agents were acquired at 1.5 and 4.7 T. Results Application of quality assurance (QA) criteria resulted in incremental optimization of the individual steps in PASADENA implementation. Optimal hyperpolarization of HEP of P = 20% was achieved by calibration of the NMR unit of the polarizer (B_0 field strength ± 0.002 mT). Mean hyperpolarization of SUC, P = [15.3 ± 1.9]% (N = 16) in D _2O, and P = [12.8 ± 3.1]% (N = 12) in H_2O, was achieved every 5–8 min (range 13–20%). An in vivo ^(13)C succinate image of a rat was produced. Conclusion PASADENA spin hyperpolarization of SUC to 15.3% in average was demonstrated (37,400 fold signal enhancement at 4.7 T). The biological fate of 13C succinate, a normally occurring cellular intermediate, might be monitored with enhanced sensitivity.