Over four minutes relaxation of pyruvate using chemically and physically induced deceleration of relaxation

Abstract

[1-13C]pyruvate is the most widely used tracer for hyperpolarized metabolic magnetic resonance imaging, with profound applications in tumor and inflammation diagnosis as well as treatment monitoring. The most fundamental hurdle to broader application, however, remains the rapid polarization relaxation and the associated signal loss. Here, we report a method to address this challenge. Studying the nuclear spin relaxation dispersion of [1-13C]pyruvate across magnetic fields from 8 {\mu}T to 9.4 T, as a function of additives, solvents, and preparation methods, allowed us to achieve relaxation times of up to four minutes. Such a long time could enable reliable quality control and nearly polarization loss-free transport, further boosting the power of hyperpolarized metabolic MRI.