Accelerated high-bandwidth MR spectroscopic imaging using compressed sensing.

Purpose: To develop a compressed sensing (CS) acceleration method with a high spectral bandwidth exploiting the spatial-spectral sparsity of MR spectroscopic imaging (MRSI). Methods: Accelerations were achieved using blip gradients during the readout to perform nonoverlapped and stochastically delayed random walks in k(x)-k(y)-t space, combined with block-Hankel matrix completion for efficient reconstruction. Both retrospective and prospective CS accelerations were applied to C-13 MRSI experiments, including in vivo rodent brain and liver studies with administrations of hyperpolarized [1-C-13] pyruvate at 7.0 Tesla (T) and [2-C-13] dihydroxyacetone at 3.0 T, respectively. Results: In retrospective undersampling experiments using in vivo 7.0 T data, the proposed method preserved spectral, spatial, and dynamic fidelities with R-2 >= 0.96 and >= 0.87 for pyruvate and lactate signals, respectively, 750-Hz spectral separation, and up to 6.6-fold accelerations. In prospective in vivo experiments, with 3.8-fold acceleration, the proposed method exhibited excellent spatial localization of metabolites and peak recovery for pyruvate and lactate at 7.0 T as well as for dihydroxyacetone and its metabolic products with a 4.5-kHz spectral span (140 ppm at 3.0 T). Conclusions: This study demonstrated the feasibility of a new CS approach to accelerate high spectral bandwidth MRSI experiments. (C) 2016 Wiley Periodicals, Inc.