The Pituitary Stalk and the Infundibular Unidentified Object

The diagnosis of a thickened pituitary stalk may be missed if its diameter only is considered. Its precise morphology is more informative if changes of the pituitary stalk are limited. The normal PS displays a flared-up funnel appearance. Conversely, a tube-like PS, even in normal limits, constitutes a red flag and enforces a strict follow-up. An “infundibular unidentified object” (IUO) has been recently described and could help to decide if a pituitary stalk is normal or not. With this in mind, the T2W MR sequence has been proven more useful than the gadolinium-enhanced T1W one.