Computed tomographic demonstration of the posterior pituitary.

From a series of 700 thin, axial, contrast-enhanced CT scans of the sellar region, the posterior lobe of the pituitary was studied. Empty sellae and pituitary lesions larger than 8 mm in diameter were excluded from the study. Of the 320 remaining axial contrast-enhanced CT scans, the posterior lobe of the pituitary was apparent in 124 (39%) as an oval lucency 3-4 mm thick, located medially or paramedially just in front of the dorsum sellae. Normally, the anterior limit of the posterior lobe is always regularly convex forward, but in the presence of a microadenoma of the anterior lobe it may be compressed. The lesser enhancement of the posterior lobe probably correlates with the different volumes of the interstitial spaces in the anterior and in the posterior lobes. The normal picture of the posterior lobe of the pituitary must not be confused with a posteriorly located microadenoma.