A novel parallel sparse MRSI reconstruction scheme

INTRODUCTION Low SNR of proton magnetic resonance spectroscopic imaging (MRSI) in vivo data for a small voxel size (e.g., 0.4cc) necessitates multiple-average acquisition that leads to a long scan time. This issue is even more pronounced when one attempts to acquire J-resolved spectroscopic data using multi-echo acquisition [3] in order to resolve metabolite concentrations such as glutamate and glutamine. Recently, we proposed an efficient MRSI sparse reconstruction technique where we modeled the system using priors such as inhomogeneity, and brain and lipid masks estimated from a companion MR scan for the EPSI sequence using a single channel coil [1]. Here, we propose a fast parallel MRSI acquisition scheme designed on a spiral trajectory. Using a 12-channel head coil, we acquire the in vivo MRSI data at spatial resolution of 44 44 with a single average. We extend our sparse reconstruction scheme to parallel MRSI data on the spiral trajectory. This way, we efficiently reduce measurement noise and other artifacts such as field inhomogeneity and spectral leakage in our proposed reconstruction while we have a fast MRSI acquisition (~1min for a slice). We show that the proposed scheme could recover the spectral data and outperforms Tikhonov-regularized SENSE reconstruction. We also demonstrate a two-fold acceleration of the acquisition that leads to a comparable reconstruction. This indicates the potential of the proposed scheme for multi-echo MRSI scans.