1. An MRI apparatus comprising: a magnetic resonance imaging (MRI) assembly having a plurality of gradient coils positioned about a bore of a magnet to impress a polarizing magnetic field and an RF transceiver system and an RF switch controlled by a pulse module to transmit RF signals to an RF coil assembly to acquire MR images; and a system controller coupled to the MRI assembly, the system controller configured to: cause the RF coil assembly to excite a single metabolic species of a hyperpolarized agent injected into a subject of interest, wherein in causing the RF coil assembly to excite the single metabolic species, the system controller is configured to apply a true fast imaging with steady precession (trueFISP) pulse sequence having a low flip angle RF pulse train to the single metabolic species; cause the RF transceiver system to acquire MR signals from the excited single metabolic species; and reconstruct an image from the acquired MR signals.