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

Hyperpolarized [1-¹³C]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 ¹³C MRI requires specialized ¹³C 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 ¹³C hyperpolarization to methyl protons for detection of the ¹³C-¹³C pyruvate singlet, employing proton-only excitation and detection only. The new pulse sequences are robust to the B₁ and B₀ 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 ¹³C₂-singlet hyperpolarization to ¹H polarization on the CH₃ group of [1,2-¹³C₂]pyruvate. This approach may enable a broader adoption of hyperpolarized MRI as a molecular imaging technique.