Wavelet-encoded MR spectroscopic imaging incorporating parallel imaging to further reduce acquisition time: in-vitro results

Introduction: It has been shown that wavelet encoding spectroscopic imaging (WE-SI) reduces both acquisition time and voxel bleed in magnetic resonance spectroscopic imaging (MRSI) as compared to chemical shift imaging (CSI) for equal number of encodes, with an associated loss of signal-to-noise ratio (SNR) [1, 2]. It has also been shown, from simulation results, that wavelet encoding (WE) combined with parallel imaging (PI, WE-PI) reduces further the acquisition time by approximately the well known acceleration factor R, and preserves the spatial metabolite distribution with minimal loss of the signal-to-noise ratio (SNR) of the WE-SI technique [3]. Here we report phantom results confirming simulation results and demonstrating that WE-PI decreases the acquisition time of the standard WE-SI technique, while preserving its metabolite spatial distribution, and an associated SNR decrease, which is given by ( ) SI WE PI WE SNR R N N g SNR − − + + = . ) 2 /( ) 2 ( 1 2 2 2 . In wavelet encoding, shaped RF pulses with profiles resembling