Simultaneous 3D CEST imaging of phosphocreatine and glycogen in skeletal muscle at 5T

Motivation: The metabolic heterogeneities in human are high, it is crucial to improve the slice-encoding coverage in phosphocreatine and glycogen mapping. Goal(s): To develop a 3D-CEST sequence for simultaneous mapping of phosphocreatine and glycogen within the acceptable time. Approach: The optimal sequence using stack-of-star readouts was applied. The patch-based low-rank reconstruction was introduced to accelerate the scan. The concentrations were quantified with ex-vivo and in-vivo experiments. Results: The coverage in slice-encoding dimension was improved to 140 mm. The scan time was reduced from 41.8 to 11.2 minutes. The concentrations of PCr and glycogen were 36.8 ± 14.4 mM and 80.4 ± 12.5 mM, respectively. Impact: This study demonstrates the feasibility of a 3D-CEST imaging method that simultaneously quantifies phosphocreatine and glycogen in skeletal muscle at 5T. It can be accomplished within 11.2 minutes using patch-based low-rank reconstruction. It shows great potential in evaluateing metabolic heterogeneities.