The diaphragma sellae, diaphragm opening, and subdiaphragmatic cistern: an anatomical study using magnetic resonance imaging.

PURPOSE: Few studies have explored the detailed morphology of the diaphragma sellae (DS), diaphragm opening (DO) or stoma, and subdiaphragmatic cistern (SDC) using neuroimages. The aim of the present study was to characterize these structures using magnetic resonance imaging. METHODS: Thin-sliced, sagittal and coronal T2-weighted imaging was performed for a total of 84 outpatients. RESULTS: The DS, DO, SDC, and relevant structures were consistently delineated in all patients. In 66% of patients, all three structures appeared to be highly variable, and were classifiable as six distinct morphological types. In 4% of patients, the DS presented as a complete sheet lacking a discernible DO. In addition, 30% of the patients presented with undiscernible SDCs. In the coronal sections of 11% of patients, the pituitary glands extended laterally, reaching or extending beyond the center line on the sectional image of the cavernous internal carotid artery. CONCLUSIONS: Thin-sliced, sagittal, and coronal T2-weighted sequences are useful for delineating the DS, DO, and SDC. Morphological variation of these structures among individuals may considerably influence the direction of pituitary tumor expansion.