In vivo hyperpolarization transfer in a clinical MRI scanner.

Abstract

The purpose of this study was to investigate the feasibility of in vivo 13 C->1 H hyperpolarization transfer, which has significant potential advantages for detecting the distribution and metabolism of hyperpolarized 13 C probes in a clinical MRI scanner. A standalone pulsed 13 C RF transmit channel was developed for operation in conjunction with the standard 1 H channel of a clinical 3T MRI scanner. Pulse sequences for 13 C power calibration and polarization transfer were programmed on the external hardware and integrated with a customized water-suppressed 1 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 1 JCH -coupled systems: phantom experiments in thermally polarized and hyperpolarized [2-13 C]glycerol, and 1 H detection of [2-13 C]lactate generated from hyperpolarized [2-13 C]pyruvate in rat liver in vivo. Operation of the custom pulsed 13 C RF channel resulted in effective 13 C->1 H hyperpolarization transfer, as confirmed by the characteristic antiphase appearance of 1 H-detected, 1 JCH -coupled doublets. In conjunction with a pulse sequence providing 190-fold water suppression in vivo, 1 H detection of hyperpolarized [2-13 C]lactate generated in vivo was achieved in a rat liver slice. The results show clear feasibility for effective 13 C->1 H hyperpolarization transfer in a clinical MRI scanner with customized heteronuclear RF system.