Table 2:

Automated measures of distance and area

Measure	How to Measure
Biparietal width	Identify most lateral sagittal slices of parietal GM (regionprops3) For each GM voxel, calculate distance to voxels in opposite hemisphere Calculate maximum distance
Interhemispheric distance	Calculate distance from each voxel of superior frontal gyrus label in left hemisphere to each voxel label in right hemisphere (bwmorph3, bwdist) Derive minimum distance
Callosal thickness	Combine 2D corpus callosum segmentation of the 11 most medial slices Increase resolution (imresize) and improve mask (bwmorph3, bwmorph) Derive skeleton (bwskel); for every voxel, calculate normal vector, identify intersection with borders of segmentation (points2contour, polyfit) Derive distance between upper/lower segmentation borders for every voxel Apply smoothing (nanfastsmooth), make 3 divisions Obtain 97th percentile for each division (prctile)
Transcerebellar diameter	Model cerebellum segmentation as 3D ellipsoid (bwmorph3, regionprops3) Calculate length of principal axis (regionprops3)
Lateral ventricular dilation	Identify coronal slice at level of ventricular atrium (regionprops3): find maximum surface area using ventricle label (bwmorph, regionprops) Model 2D ventricle as ellipse, calculate length of minor axes (regionprops)
Deep grey matter area	Identify axial slice: centroid of caudate, thalamus, and lentiform nucleus (bwmorph, regionprops) Combine labels to calculate area (regionprops)