Lipid-targeted echo-planar spectroscopic imaging for in-vivo quantification of lipid composition

Motivation: Investigating lipid composition in different tissues in vivo is essential. Demand exists for rapid, high-resolution chemical-shift imaging to analyze lipids. Goal(s): We aimed to employ EPSI to simultaneously target lipid signals and suppress water, enabling precise in-vivo quantification of lipid composition in various tissues for the first time. Approach: We implemented EPSI incorporating chemical-shift-selective adiabatic-refocusing pulses for lipid refocusing, with a full-automated pipeline for data reconstruction and lipid composition calculation. Results: Phantom and in-vivo experiments validate the technique's effectiveness. The technique successfully differentiates various vegetable oils and lipid emulsions precisely and quantifies lipid composition with high spatial resolution in mice’s neck and abdomen. Impact: Lipid-targeted EPSI technology surpasses traditional single-voxel spectroscopy or multi-echo chemical-shift water-fat imaging by providing higher spatial and spectral resolution, empowering researchers with deeper insights into lipid metabolism for future investigations.