Multi-Echo based Correlated Spectroscopic Imaging

Introduction – Despite the many advantages of Chemical Shift Imaging (CSI) [1] over ordinary single voxel spectroscopy, its onedimensional (1D) spectra are still limited by severe spectral overlap, which can complicate quantification of metabolites. Twodimensional Magnetic Resonance Spectroscopy (2D MRS) aims to alleviate the quantification problems due to spectral overlap by pushing resonances into a second spectral dimension. Despite the improvement in metabolite identification, widespread usage of 2D MRS is hindered by limited spatial coverage. Recently an Echo-Planar Correlated Spectroscopic Imaging (EPCOSI) technique was shown to produce multiple spatially resolved 2D MRS spectra in the human calf muscle in a clinically feasible scan time of 20 minutes [2]. In light of the feasibility, there is still a need to reduce the scan time for further clinical applicability. We propose the use of a MultiEcho based Echo-Planar Spectroscopic Imaging (ME-EPCOSI) technique, which makes use of spin echoes to collect multiple EchoPlanar Spectroscopic Imaging (EPSI) readouts in a single TR. As a proof of principle, we made use of two different echoes to reduce the scan time to 10 minutes without significant loss of spectral quality from T2 effects.