Measuring Tissue-Specific Relaxation Times of Deuterium (2H) Labeled Resonances in the Human Brain at 7T

Motivation: Deuterium metabolic imaging (DMI) is an emerging Magnetic Resonance technique to non-invasively map the cellular glucose uptake and downstream metabolism. For a reliable concentration estimation, tissue-specific relaxation times are essential, yet only unlocalized relaxation time constants of deuterium labeled resonances are reported. Goal(s): Measure tissue-specific relaxation times of deuterated resonances (glucose, glutamate+glutamine). Approach: Inversion recovery and Hahn spin-echo acquisition schemes were implemented into 3D FID 2H-MRSI using concentric ring trajectory readout. Results: Measured T1 and T2 relaxation time constants of Glc (T1GM=56±14ms; T1WM=60±19ms; T2GM=37±1ms; T2WM=36±2ms) and Glx (T1WM=167±22ms; T1GM=173±12ms; T2GM=36±1ms; T2WM=34±1ms) were not significantly different between GM and WM. Impact: Many severe brain pathologies feature regional differences in brain glucose metabolism, therefore tissue-specific (grey and white matter) relaxation times (T1 and T2) of deuterium labeled resonances are needed for accurate concentration estimation of the kinetics of energy metabolites (Glc,Glx).