Recognizing the empty sella by CT: the infundibulum sign.

Inaccuracy in recognizing the empty sella by conventional computed tomography (CT) techniques derives from diverse intrasellar cystic structures that are not distinguished from it. In 23 cases of presumed empty sella, it was observed that the pituitary stalk within the enlarged sella (infundibulum) was demonstrated by thin (1.5 mm) coronal CT sections. ALthough the diagnosis was not proven by conventional studies, the normal appearance of the infundibulum is believed to exclude an intrasellar cyst or tumor as the cause of sellar enlargement. Coronal CT sections with thin slices and intravenous contrast enhancement are recommended when empty sella is to be documented by CT. When the infundibulum is not demonstrated by this technique, CT with intrathecal enhancement may be warranted.