Fig. 4

Prone hydrated (top) vs. Supine dehydrated (bottom) scan positions for common (left) and external (right) iliac veins in a healthy subject. Common iliac veins (white arrows) are larger in the hydrated/prone position (right, top image) when compared to dehydrated/supine position (right, bottom image). External iliac veins (right images, white arrows) are larger in the hydrated and prone position (top right) when compared to dehydrated and supine position (bottom right)