Hyperpolarized 13C 3D MRSI using Radial Multi-echo bSSFP and k-Space-based IDEAL

Motivation: 3D Metabolic imaging of hyperpolarized (HP) 13C agents demands specialized signal excitation and acquisition strategies. Goal(s): This study introduces the combination of multi-echo bSSFP and radial readout with a spiral phyllotaxis pattern to rapidly image 13C-labeled contrast agents. Approach: We implemented the novel sequence in a rodent in vivo experiment using HP [1-13C]pyruvate. Results: Employing iterative signal decomposition and radial data reconstruction, we successfully captured the global signal dynamics with an unprecedented temporal resolution of 16 ms. Besides, we generated concentration maps for pyruvate, lactate, alanine, and calculated area-under-the-curve (AUC) metabolite ratio maps for Lac/Pyr and Ala/Pyr. Impact: Hyperpolarized 13C 3D metabolic MRI is challenging due to the short-living magnetization. With 3D spiral phyllotaxis radial multi-echo bSSFP MRI and post-scan metabolite separation, large areas of interest can be acquired and reconstructed into signal time-curves and 3D metabolite maps.