A reproducible dynamic phantom for sequence testing in hyperpolarised 13 C-magnetic resonance.

Objective: To develop a phantom system which can be integrated with an automated injection system, eliminating the experimental variability that arises with manual injection; for the purposes of pulse sequence testing and metric derivation in hyperpolarised ¹³ C-MR.
Methods: The custom dynamic phantom was machined from Ultem and filled with a nicotinamide adenine dinucleotide and lactate dehydrogenase mixture dissolved in phosphate buffered saline. Hyperpolarised [1- ¹³ C]-pyruvate was then injected into the phantom ( n = 8) via an automated syringe pump and the conversion of pyruvate to lactate monitored through a ¹³ C imaging sequence.
Results: The phantom showed low coefficient of variation for the lactate to pyruvate peak signal heights (11.6%) and dynamic area-under curve ratios (11.0%). The variance for the lactate dehydrogenase enzyme rate constant (kP) was also seen to be low at 15.6%.
Conclusion: The dynamic phantom demonstrates high reproducibility for quantification of ¹³ C-hyperpolarised MR-derived metrics. Establishing such a phantom is needed to facilitate development of hyperpolarsed ¹³ C-MR pulse sequenced; and moreover, to enable multisite hyperpolarised ¹³ C-MR clinical trials where assessment of metric variability across sites is critical.
Advances in Knowledge: The dynamic phantom developed during the course of this study will be a useful tool in testing new pulse sequences and standardisation in future hyperpolarised work.