R1ρ dispersion and sodium imaging in human calf muscle

ΔR1ρ reports on the contribution of labile protons such as hydroxyls which may be associated with macromolecule accumulation in the extracellular matrix (ECM). An increase of sodium signal suggests an enlarged ECM volume fraction and/or an increase in sodium concentration, which occurs during normal aging. The strong correlation between ΔR1ρ and sodium is likely the consequence of increased ECM and density of total charged sites within the matrix from molecules such as collagens and proteoglycans. The results from this study show the potential use of R1ρ dispersion and sodium imaging in the assessment of pathological changes in muscle such as fibrosis.