In vivo imaging of 15N-Betaine: A long-lived, endogenous molecular contrast agent for hyperpolarized MRI

Motivation: Hyperpolarized-MRI enables real-time molecular imaging, but short signal-lifetimes limit its use for observing delayed dynamics and uptake in vivo, motivating the development of longer-lived molecular contrast-agents. Goal(s): We aim to demonstrate a long T1 and feasibility of in vivo MRI of 15N-Betaine and explore potential for multiple imaging sessions from a single dose. Approach: 15N-Betaine was hyperpolarized by dDNP, and T1-values assessed. Dynamic 2D imaging of 15N-Betaine distribution in rodent kidneys was conducted at 3T. Results: At 3T, T1 was >7 minutes in buffer and blood and 5.5 minutes in vivo. Imaging captured early rapid dynamics and later distribution from a single dose. Impact: We introduce 15N-Betaine, a long-lived endogenous molecular contrast agent for hyperpolarized MRI, demonstrating feasibility for in vivo imaging. Its extended signal-lifetime supports prolonged acquisitions and enables flexible protocols with adaptable timing and resolution, offering a new tool for molecular imaging.