Fig. 3

Bland–Altman (B-A) plots for three measurements (M1, M2, M3) for tissue sodium concentration (TSC) in three lower leg muscles: gastrocnemius medialis (GM); tibialis anterior (TA); and soleus (S) determined for healthy participants (n = 10). Bland–Altman plot was used to describe the agreement between two quantitative measurements. The horizontal axis of the plot represents the average of the two measurements and the vertical axis represents the difference between the two measurements. The mean value and lower and upper limits of the 95% confidence interval for the average difference are also present in the plot. Three B-A plots for each combination of measurements (M1 and M2, M1 and M2, M2 and M3) were constructed separately for each of the three muscles (gastrocnemius, tibialis anterior, and soleus). Each point represents one volunteer. In our case measurements are coded as follows: M1 – first MRI scan, M2 – MRI scan during the same session as M1 after a 5-min break and M3 – MRI scan performed 7–8 days after M1 and M2