Rapid Monitoring of Glycogen Dynamics: MRS-based T1 and T2 Water Relaxation Times as potential surrogates for 13C-MRS

Motivation: The limited temporal resolution and accessibility of 13C-MRS restrict studying rapid glycogen changes. Since glycogen influences water relaxation times by binding water, water relaxation measurements by 1H-MRS may offer a faster alternative to monitor glycogen content dynamically. Goal(s): This study assesses water relaxation time measurements using 1H-MRS as a surrogate for glycogen. Approach: Water T1 and T2 relaxation times were measured with 1H-MRS in phantoms and in vivo. Glycogen was quantified using 13C-MRS. Measurements were performed before and after ingestion of 75g of glucose. Results: Water T1 correlated better with glycogen levels and detected post-glucose dynamic changes in liver and muscle tissue. Impact: We demonstrate that water T1 relaxation time measured by 1H-MRS could provide a faster, accessible alternative to 13C-MRS for glycogen detection, enabling real-time, simultaneous measurement of glycogen dynamics across multiple organs.