Pituitary deformity examples in three crewmembers before spaceflight and after spaceflight (day 1). (a) Only the first crewmember shown in a had no previous exposure to spaceflight. Reconstructed orthogonal sagittal three-dimensional T1-weighted images in the pituitary gland centered at the pituitary stalk are shown for each crewmember. (a) Before flight there is normal upward convexity of the pituitary gland dome (black arrowhead) and a straight pituitary stalk (white arrowhead). In this astronaut, there is no change in the morphologic structure of the pituitary gland or stalk after spaceflight (pituitary deformity score, 0). The anterior pituitary gland (indicated by the a in a) and posterior pituitary gland (p) are indicated. (b) Before spaceflight there is normal upward convexity of the pituitary gland dome. After spaceflight there is flattening of the pituitary gland dome (pituitary deformity score, 1). Note the cerebrospinal fluid (CSF) within the suprasellar cistern immediately above the dome of the pituitary gland. (c) Before spaceflight there is mild concavity of the pituitary gland dome. After spaceflight there is moderate concavity of the pituitary gland dome with loss of volume and new subtle posterior deviation with slight curvature of the pituitary stalk (arrows; pituitary deformity score, 1). *Increased congestion of the sphenoid sinus after spaceflight is shown.