Delivering Robust Proton-Only Sensing of Hyperpolarized [1,2-13C2]-Pyruvate Using Broad-Spectral-Range Nuclear Magnetic Resonance Pulse Sequences

Hyperpolarized [1-C-13]pyruvate is the leading hyperpolarized injectable contrast agent and is currently under evaluation in clinical trials for molecular imaging of metabolic diseases, including cardiovascular disease and cancer. One aspect limiting broad scalability of the technique is that hyperpolarized C-13 MRI requires specialized C-13 hardware and software that are not generally available on clinical MRI scanners, which employ proton-only detection. Here, we present an approach that uses pulse sequences to transfer C-13 hyperpolarization to methyl protons for detection of the C-13-C-13 pyruvate singlet, employing proton-only excitation and detection only. The new pulse sequences are robust to the B-1 and B-0 magnetic field inhomogeneities. The work focuses on singlet-to-magnetization (S2M) and rotor-synchronized (R) pulses, both relying on trains of hard pulses with broad spectral width coverage designed to effectively transform hyperpolarized C-13(2)-singlet hyperpolarization to H-1 polarization on the CH3 group of [1,2-C-13(2)]pyruvate. This approach may enable a broader adoption of hyperpolarized MRI as a molecular imaging technique.

Automated summary

This study presents a new pulse sequence approach that allows the use of hyperpolarized MRI for molecular imaging of metabolic diseases on clinical MRI scanners. The approach transfers C-13 hyperpolarization to methyl protons for detection and is robust to magnetic field inhomogeneities.