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 kx-ky-t space, combined with block-Hankel matrix completion for efficient reconstruction. Both retrospective and prospective CS accelerations were applied to 13C MRSI experiments, including in vivo rodent brain and liver studies with administrations of hyperpolarized [1-13C] pyruvate at 7.0 Tesla (T) and [2-13C] 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 R2 ≥ 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. Magn Reson Med, 2016. © 2016 Wiley Periodicals, Inc.