Reconstruction methods from hyperpolarized 13C chemical shift imaging spiral 3D data: Comparison between direct summation and gridding method

Hyperpolarized ¹³C chemical shift imaging (CSI) is a spectroscopy technique for magnetic resonance imaging. Due to the fast decay of the hyperpolarized tracer, acquisition speed represents a key issue. Spiral trajectories are usually exploited to fast fill the K-space. Several strategies have been proposed for CSI image reconstruction form spiral trajectories, but the performances in hyperpolarized ¹³C CSI of these strategies have not been investigated. In hyperpolarized ¹³C 3D CSI, some of the imaged metabolites may appear with very low signal, so reconstruction methods should keep SNR high to allow better viewing of metabolites´ locations. In this study we compared the performances of Direct Summation (DS) and Gridding (GR) reconstruction methods. Methods were compared evaluating SNR on reconstructed images and reconstruction time. In vivo experimental data were obtained from medium-sized animals injected with hyperpolarized ¹³C. DS obtained higher SNR for all metabolites of interest. On the other hand, GR was much faster. The study results may provide a useful indication on how to choose the appropriate reconstruction method for hyperpolarized ¹³C in vivo data acquisition.