Pilot Study of Hyperpolarized 13C Metabolic Imaging in Pediatric Patients with Diffuse Intrinsic Pontine Glioma and Other CNS Cancers.

Background and purpose Pediatric CNS tumors commonly present challenges for radiographic interpretation on conventional MR imaging. This study sought to investigate the safety and tolerability of hyperpolarized carbon-13 (HP-13C) metabolic imaging in pediatric patients with brain tumors. Materials and methods Pediatric patients 3 to 18 years of age who were previously diagnosed with a brain tumor and could undergo MR imaging without sedation were eligible to enroll in this safety study of HP [1-13C]pyruvate. Participants received a one-time injection of HP [1-13C]pyruvate and were imaged using dynamic HP-13C MR imaging. We assessed 2 dose levels: 0.34 mL/kg and the highest tolerated adult dose of 0.43 mL/kg. Participants were monitored throughout imaging and for 60 minutes postinjection, including pre- and postinjection electrocardiograms and vital sign measurements. Results Between February 2017 and July 2019, ten participants (9 males; median age, 14 years; range, 10-17 years) were enrolled, of whom 6 completed injection of HP [1-13C]pyruvate and dynamic HP-13C MR imaging. Four participants failed to undergo HP-13C MR imaging due to technical failures related to generating HP [1-13C]pyruvate or MR imaging operability. HP [1-13C]pyruvate was well-tolerated in all participants who completed the study, with no dose-limiting toxicities or adverse events observed at either 0.34 (n = 3) or 0.43 (n = 3) mL/kg. HP [1-13C]pyruvate demonstrated characteristic conversion to [1-13C]lactate and [13C]bicarbonate in the brain. Due to poor accrual, the study was closed after only 3 participants were enrolled at the highest dose level. Conclusions Dynamic HP-13C MR imaging was safely performed in 6 pediatric patients with CNS tumors and demonstrated HP [1-13C]pyruvate brain metabolism.