Fig. 4.

STE signal decay for 5 healthy subjects (mean and standard deviation in each ROI), in ROIS in the mWM (red), oWM (orange), cWM (green), dGM (cyan), and cGM (blue); examples of the ROIs are shown for Subject 1. The left column shows the signal before Rician-bias correction plotted with a logarithmic y-scale, to better visualise deviations from mono-exponential behaviour, with a close-up at high b-values. The right column shows the signal after Rician-bias correction plotted with a linear y-scale to be able to visualise negative values. b is given in ${\text{s}/\text{mm}}^2$. The dotted line represents the mean of the estimated noise floor in each ROI (Koay et al., 2009b); the lines of each ROI visually overlap.