Normal and abnormal pituitary glands: gadopentetate dimeglumine-enhanced MR imaging.

Dynamic magnetic resonance (MR) imaging with a 1.5-T superconductive unit was used in the evaluation of nine normal pituitary glands and 10 pituitary adenomas, including four microadenomas and six macroadenomas. Seven to 10 images were obtained every 20-30 seconds with use of the spin-echo technique after rapid injection of gadopentetate dimeglumine. The earliest contrast material enhancement of normal structures was seen in the infundibulum and posterior lobe of the pituitary gland at 20 seconds, followed by gradual contrast material enhancement of the anterior lobe of the pituitary gland from the junction of the infundibulum to the peripheral portion of the anterior lobe of the pituitary gland within 80 seconds after gadopentetate dimeglumine injection. The peak enhancement of pituitary adenomas occurred at 60-200 seconds, usually after the most marked enhancement of the normal pituitary gland. Microadenomas are best visualized at earlier phases of gadopentetate dimeglumine-enhanced dynamic imaging, with signal intensity lower than that seen on images of normal pituitary glands.