Fig. 2. Brain volume aging trajectories derived from clinical data using SynthSR combined with FreeSurfer.

Clinical scans were processed with SynthSR and then segmented with FreeSurfer to obtain ROI volumes as well as an estimate of the intracranial volume (ICV). The ROI volumes were corrected by ICV and sex and regressed against age using a Laplace distribution with location and scale modeled with a spline with six knots. The Laplace distribution provides a more robust fit than a Gaussian. The median trajectory is overlaid on the individual (ICV- and gender-corrected) volumes; the 95% confidence interval is shaded. The volumes are computed at the scan level; trajectories computed at the subject level are shown in fig. S1.