Reconstructed sagittal 5-mm orthogonal midline images in the brain using the sagittal three-dimensional T1weighted data set. (a) Preflight baseline image and (b) matching postflight image (postflight day 1) in the same astronaut. The black arrowheads show upward expansion of the anterior, middle, and posterior superior margins of the lateral ventricle with associated narrowing of the marginal sulcus of the cingulate sulcus (white arrowhead). There is subtle expansion of the third ventricle (indicated by a 3), which has displaced the thalamus (T) from midline, making it less visible. There is thickening of the intermediate signal scalp soft tissues (arrows).