Fig 1. Intracranial semiautomated segmentation was based on axial T2 (A) and proton attenuation–weighted images. The outer contour of the subarachnoid space was manually delineated on each section (B). This was followed by an automated segmentation procedure that assigned brain tissue and CSF within this region. We determined TICV, ventricular volume (C), brain volume, and pericerebral CSF volume (D).