Osteoarthritis (OA) is a degenerative disease of articular cartilage that may be associated with a loss of glycosaminoglycans (GAG). Quantitative sodium MRI is highly specific to GAG content and could be used to assess the biochemical degradation of cartilage in early OA. However, the reproducibility and repeatability of this technique are not well documented. The aim of this study is to test the repeatability and reproducibility of sodium quantification in cartilage in vivo using intra- and inter-day acquisitions at 3T and 7T, with a 3D radial sequence, with and without fluid suppression. Fluid suppression was obtained by adiabatic inversion recovery (IR WURST), and is expected to improve the sensitivity of the method to GAG content. The root mean square of coefficients of variation (CV) are all in the range of 7.5-13.6%. No significant inter-magnet, inter-sequence, intra-day and inter-day differences in the CV were observed. Sodium quantification using IR WURST gave values closer to those reported in the literature for healthy cartilage (220-310 mM) than 3D radial. In conclusion, IR WURST was more accurate in context of sodium measurement, with a reproducibility and repeatability comparable to other compositional MRI techniques of cartilage.