Purpose: In this MRS study, we aimed to demonstrate the feasibility of visualizing pyruvate metabolism in isolated viable xenograft breast tumor tissue using hyperpolarized [1-13C]pyruvate.
Materials and Methods: Xenograft MCF-7 tumors were grown in immunosuppressed mice. Tumors were harvested after they reached sufficient size (about 1 cm), and cut into precision slices. Each study used cumulative tissue from three mice. Slices were kept viable in an NMR tube in an NMR spectrometer using a perfusion system. Hyperpolarized [1-13C]pyruvate was injected into the NMR tube containing and metabolism of the slices was monitored. This was performed on 3 different occasions with consecutive injections. Lactate production was observed via 13C spectroscopy and the ATP level was monitored via 31P spectroscopy.
Results: Lactate signal was observed using tissues weighing between 587-983 mg per study. The ATP level was preserved for up to 10 hours within the spectrometer, and following consecutive injections. Lactate production was observed following repeated and consecutive injections of hyperpolarized [1-13C]pyruvate.
Conclusions: This study proves the feasibility of observing real time metabolism in viable xenograft tumor tissue. This study warrants future studies focusing on other metabolic tracers of specific enzymatic reactions, characterization of breast lesions, and monitoring the response to treatment.
