Enhanced hyperpolarized chemical shift imaging based on a priori segmented information

Purpose: The purpose of the study was to develop an approach for improving the resolution and sensitivity of hyperpolarized C-13 MRSI based on a priori anatomical information derived from featured, water-based H-1 images.

Methods: A reconstruction algorithm exploiting H-1 MRI for the redefinition of the C-13 MRSI anatomies was developed, based on a modification of the spectroscopy with linear algebraic modeling (SLAM) principle. To enhance C-13 spatial resolution and reduce spillover effects without compromising SNR, this model was extended by endowing it with a search allowing smooth variations in the C-13 MR intensity within the targeted regions of interest.

Results: Experiments were performed in vitro on enzymatic solutions and in vivo on rodents, based on the administration of C-13-enriched hyperpolarized pyruvate and urea. The spectral images reconstructed for these substrates and from metabolic products based on predefined H-1 anatomical compartments using the new algorithm, compared favorably with those arising from conventional Fourier-based analyses of the same data. The new approach also delivered reliable kinetic C-13 results, for the kind of processes and timescales usually targeted by hyperpolarized MRSI.

Conclusion: A simple, flexible strategy is introduced to boost the sensitivity and resolution provided by hyperpolarized C-13 MRSI, based on readily available H-1 MR information.