Tissue Water Referencing with Proton Density in MRSI for Metabolic Mapping at 7T

Motivation: In MRSI, obtaining concentration estimates is desirable to using metabolite ratios. We were limited due to segmentation. PD-based water maps can address this issue. Goal(s): To compare and validate metabolic imaging using PD-based approach, and compared against literature-driven strategy. Approach: Quantitative proton density maps are used to arrive at the water content for metabolic imaging at 7T, allowing concentration estimation based on internal water mapping with PDs. Results: A PD-based tissue referencing was successfully implemented and compared against a literature-driven approach in 13 volunteers and one tumor patient. Regional comparisons showed ~4% difference between, with values aligning with the previously established ranges Impact: Using quantitative proton density maps as an internal reference for MRSI enables to get concentration estimates from not only healthy brains, but also in pathological ones like brains with glioma.