Effect of Normal Aging On the Intra-Cellular Sodium Volume Fraction in the Human Brain: A 7T MRI In-Vivo Study

Lazar Fleysher¹, Niels Oesingmann², Ryan Brown¹, Hina Jaggi¹, Graham Wiggins¹, Daniel Sodickson¹, Matilde Inglese^1,3

Many morphologic MRI-based studies reported age-associated volume loss of the cerebral gray and white matters in normal aging. In this work, we report age-related changes in the tissue sodium concentration (TSC) in the healthy human brain. We find that TSC increases in gray and white matter with age consistent with cellular loss or shrinkage. The measured rate of fractional intracellular sodium volume fraction (ISVF) loss is found to be significantly different from the rate of fractional tissue volume loss for both GM and WM measured by morphologic MRI. This difference can be explained by the micro-structural changes in GM and WM associated with normal aging.