Chemical shift displacement and within-voxel saturation of water signals on MRS data: prospective & retrospective corrections

Motivation: Chemical shift displacement error (CSDE) and within-voxel saturation (WVS) lead to significant spatial displacement of the MRS voxel from the prescribed region and to overestimation of metabolite concentrations. Goal(s): To compare prospective and retrospective corrections for severe CSDE+WVS observed in standard 3T GE PRESS data. Approach: Prospective corrections utilize (a) removal of OVS saturation bands and (b) over-prescription of the shifted water voxel at data acquisition. Retrospective correction relies on Gasparovic’s equation and re-scaling of metabolite concentrations by the water vs. metabolite volume ratio. Results: Corrected concentrations agree with literature. Both corrections are applicable in multi-centre studies and laboratories with limited technical support. Impact: Chemical shift displacement error (CSDE) and within-voxel saturation (WVS) observed in standard 3T GE PRESS data can be corrected prospectively and retrospectively relative to data acquisition. These solutions are relevant to multi-centre studies and laboratories with limited pulse-sequence technical support.