Real-Time Metabolic Magnetic Resonance Spectroscopy of Pancreatic and Colon Cancer Tumor-Xenografts with Parahydrogen...

Parahydrogen-induced polarization (PHIP) is an emerging technique to enhance the signal of stable isotope metabolic contrast agents for Magnetic Resonance (MR). The objective of this study is to continue establishing 1-¹³C-pyruvate-d₃, signal-enhanced via PHIP, as a hyperpolarized contrast agent, obtained in seconds, to monitor metabolism in human cancer. Our focus was on human pancreatic and colon tumor xenografts. 1-¹³C-vinylpyruvate-d₆ was hydrogenated using parahydrogen. Thereafter, the polarization of the protons was transferred to ¹³C. Following a workup procedure, the free hyperpolarized 1-¹³C-pyruvate-d₃ was obtained in clean aqueous solution. After injection into animals bearing either pancreatic or colon cancer xenografts, slice-selective MR spectra were acquired and analyzed to determine rate constants of metabolic conversion into lactate and alanine. 1-¹³C-pyruvate-d₃ proved to follow the increased metabolic rate to lactate and alanine in the tumor xenografts.