IDEAL spiral CSI for dynamic metabolic MR imaging of hyperpolarized [1-13C]pyruvate.

Metabolic imaging with hyperpolarized [1-(13)C]pyruvate offers the unique opportunity for a minimally invasive detection of cellular metabolism. Efficient and robust acquisition and reconstruction techniques are required for capturing the wealth of information present for the limited duration of the hyperpolarized state (~1 min). In this study, the Dixon/IDEAL type of water-fat separation is expanded toward spectroscopic imaging of [1-(13) C]pyruvate and its down-stream metabolites. For this purpose, the spectral-spatial encoding is based on single-shot spiral image encoding and echo-time shifting in between excitations for the chemical-shift encoding. In addition, also a free-induction decay spectrum is acquired and the obtained chemical-shift prior knowledge is efficiently used in the reconstruction. The spectral-spatial reconstruction problem is found to efficiently separate into a chemical-shift inversion followed by a spatial reconstruction. The method is successfully demonstrated for dynamic, multislice [1-(13)C]pyruvate metabolic MR imaging in phantom and in vivo rat experiments.