Accelerated Proton Echo-Planar Spectroscopic Imaging Using Parallel Imaging and Compressed Sensing

INTRODUCTION: Proton Echo-Planar Spectroscopic Imaging (PEPSI) provides fast spatial-spectral encoding and has been demonstrated to map a variety of metabolites in the human brain [1,2]. Further acceleration in PEPSI can be accomplished by using parallel imaging along the phaseencoding dimension(s) [3,4]. However, the acceleration is limited by the relatively low SNR of the metabolites and g-factor related noise amplification. Compressed sensing was recently introduced as a powerful method to accelerate the MRI encoding process by exploiting the sparsity of the images in a known transform domain (e.g. wavelets) to reconstruct randomly undersampled k-space data [5]. Two-fold accelerated echo-planar spectroscopic imaging has been demonstrated with a compressed sensing technique using wavelets along the spectral dimension to sparsify the image and k-t random undersampling [6]. In this work, a joint reconstruction approach, named Parallel-Sparse PEPSI, is developed to combine compressed sensing and parallel imaging to further accelerate PEPSI encoding.