Measuring Lactate Levels in Gray and White Matter of the healthy Human Brain using semi-LASER MRSI with Concentric Ring Trajectory Encoding at 3T

Motivation: Lactate is an important metabolite in the healthy human brain and serves as a marker for various pathologies. A non-invasive detection of lactate levels could enhance our understanding of brain metabolism, but low baseline concentrations and overlapping lipid and macromolecule resonances complicate reliable lactate quantification and limit detection to single-voxel approaches with decreased specificity. Goal(s): Quantify regional Lac levels in healthy human brain using MRSI selectively in GM/WM dominated regions. Approach: 1H-semi-LASER localization module was combined with 3D-concentric-ring-trajectory readout. Results: Similar Lac levels were observed in GM/WM dominated regions (cLacGM/WM=1.28±0.37/1.34±0.19mM), with a negative correlation with time in GM regions for repeated scans. Impact: Capturing time-resolved regional Lac-levels could improve understanding of various pathologies characterized by abnormal levels. The proposed versatile sLASER-CRT-MRSI-sequence allows spectral averaging over specific brain regions and could help detect metabolic changes associated with pathologies and improve diagnostic and therapeutic approaches.