Simultaneous T and T mapping of hyperpolarized C compounds using the bSSFP sequence.

As in conventional H MRI, T and T relaxation times of hyperpolarized (HP) C nuclei can provide important biomedical information. Two new approaches were developed for simultaneous T and T mapping of HP C probes based on balanced steady state free precession (bSSFP) acquisitions: a method based on sequential T and T mapping modules, and a model-based joint T/T approach analogous to MR fingerprinting. These new methods were tested in simulations, HP C phantoms, and in vivo in normal Sprague-Dawley rats. Non-localized T values, low flip angle EPI T maps, bSSFP T maps, and Bloch-Siegert B maps were also acquired for comparison. T and T maps acquired using both approaches were in good agreement with both literature values and data from comparative acquisitions. Multiple HP C compounds were successfully mapped, with their relaxation time parameters measured within heart, liver, kidneys, and vasculature in one acquisition for the first time.