Computed tomography of sellar and parasellar lesions: indications for metrizamide cisternography.

Sixty-four patients with intrasellar and suprasellar lesions on conventional computed tomography (CT) have been studied retrospectively to determine the indications for metrizamide CT cisternography (MCTC). Enhancing or calcified lesions, like a craniopharyngioma, pituitary adenoma, meningioma or aneurysm are adequately evaluated by conventional CT and MCTC is usually not needed. Determination of the exact suprasellar extent of an enhancing pituitary adenoma is best accomplished with coronal thin-section conventional CT alone. However, for isodense or hypodense suprasellar and intrasellar lesions, MCTC is indicated if conventional CT does not define their extent accurately. Differentiation of an empty sella from the occasional entirely lucent pituitary adenoma or other low density intrasellar lesions remains difficult by conventional CT at times, especially when the infundibulum is not identified. Then MCTC will also be indicated.