In vivo hyperpolarization transfer in a clinical MRI scanner.

Purpose: The purpose of this study was to investigate the feasibility of in vivo C-> H hyperpolarization transfer, which has significant potential advantages for detecting the distribution and metabolism of hyperpolarized C probes in a clinical MRI scanner.

Methods: A standalone pulsed C RF transmit channel was developed for operation in conjunction with the standard H channel of a clinical 3T MRI scanner. Pulse sequences for C power calibration and polarization transfer were programmed on the external hardware and integrated with a customized water-suppressed H MRS acquisition running in parallel on the scanner. The newly developed RF system was tested in both phantom and in vivo polarization transfer experiments in J -coupled systems: phantom experiments in thermally polarized and hyperpolarized [2- C]glycerol, and H detection of [2- C]lactate generated from hyperpolarized [2- C]pyruvate in rat liver in vivo.

Results: Operation of the custom pulsed C RF channel resulted in effective C-> H hyperpolarization transfer, as confirmed by the characteristic antiphase appearance of H-detected, J -coupled doublets. In conjunction with a pulse sequence providing 190-fold water suppression in vivo, H detection of hyperpolarized [2- C]lactate generated in vivo was achieved in a rat liver slice.

Conclusion: The results show clear feasibility for effective C-> H hyperpolarization transfer in a clinical MRI scanner with customized heteronuclear RF system.