Extended Data Fig. 6: Regional S0 images from T2 fitting of multi-echo data maps are unaltered after marathon running.

To assess further the lack of post-run dehydration as a confounding factor in MWF values, we analyzed images as described below: 1) We carried out a bi-exponential decay analysis on acquired T2 multi-echo sets of images to obtain (a) 2 sets of T2 maps (low and high mobility protons) and (b) 2 sets of S0 images (Signal extrapolated at TE=0 ms). (c) Total S0 maps were obtained by adding the two individual S0 components. 2) CSF regions were segmented out, registering pre- (c) and post-run images (d). 3) Percentage of change of S0 images were determined pixel by pixel for each subject using the following image operation 100*(pre-post)/pre (e). Notice that maps reflect % changes. Subjects were scanned with identical acquisition sequence in the same scanner, with equal repetition time and flip angle. At fixed T1 weighting changes on water content should be reflected as change in S0 maps between pre- and post-run.