Comparison of magnetic resonance imaging and computed tomography in the preoperative evaluation of pituitary adenomas.

Twenty surgically verified pituitary adenomas were imaged in a systematic comparative fashion with high field strength magnetic resonance imaging (MRI) and computed tomography (CT) before operation. The study group included 11 microadenomas, 4 macroadenomas, 2 recurrent microadenomas, and 3 recurrent macroadenomas. The MRI and CT examinations were evaluated for lesion detection, pituitary stalk displacement, cavernous sinus displacement or invasion, hemorrhage, cystic degeneration within the adenoma, bony erosion, detection of suprasellar extension, and displacement of suprasellar structures. T1 and T2 relaxation characteristics of the adenomas were evaluated on MRI examinations, and contrast enhancement characteristics were evaluated on CT examinations. MRI was superior to CT for detecting the extrasellar extent of tumor. Within the sella turcica, MRI and CT were equivalent with regard to lesion detection, except for 1 patient in whom CT was able to detect a surgically confirmed 3-mm microadenoma that was not visualized on the MRI examination.