Detection of pituitary microadenomas: comparison of dynamic keyhole fast spin-echo, unenhanced, and conventional contrast-enhanced MR imaging.

OBJECTIVE: Pituitary microadenomas may not be detected on conventional MR images. We supplemented conventional unenhanced and contrast-enhanced MR imaging with a dynamic keyhole fast spin-echo (kFSE) method in order to compare how frequently a microadenoma could be detected with the three different methods. SUBJECTS AND METHODS: Eighteen consecutive patients with clinical and laboratory evidence of pituitary microadenomas had unenhanced, dynamic kFSE, and conventional contrast-enhanced MR imaging of the pituitary gland. A control group of 13 subjects without pituitary disease also had dynamic kFSE MR imaging. Hard copies of all the studies were obtained in an identical fashion, and then the MR images of the patients and control subjects were randomly mixed. The studies were reviewed by a neuroradiologist who had no knowledge of the clinical status of the subjects. The presence or absence of any pituitary focal hypointensity consistent with the appearance of a microadenoma was noted.
RESULTS: A pituitary lesion consistent in appearance with a microadenoma was detected on dynamic kFSE images in 13 of the 18 patients, on unenhanced images in nine patients, and on conventional contrast-enhanced images in 10 patients. In four patients, a microadenoma was detected on dynamic kFSE images only. Dynamic kFSE images showed a lesion in four of the 13 control subjects.
CONCLUSION: Dynamic kFSE MR imaging is a useful supplemental sequence in patients undergoing MR imaging because of pituitary endocrinopathy. It may show lesions that would otherwise escape detection.