MR imaging features of thyrotropin-secreting pituitary adenomas at initial presentation.
OBJECTIVE
We report the MR imaging characteristics of thyrotropin-producing pituitary adenomas at their initial presentation and also report the role of MR imaging in predicting surgical outcome in these rare tumors.


METHODS
We reviewed the records and MR images of 21 patients with thyrotropin-producing pituitary adenomas from 1984 to 1999. The imaging features of these tumors were examined, including enhancing characteristics and tumor volumes. A staging system of tumor invasion was designed by grading cavernous and sphenoid sinus invasion and suprasellar extension. A cumulative invasion score was then used as a predictor of short-term surgical outcome.


RESULTS
Twenty patients had macroadenomas, and one patient had a microadenoma. In 17 of 21 patients, the thyrotropin-producing pituitary adenoma was clearly visualized as a hypoenhancing mass compressing the normal pituitary gland. Conversely, in four patients, the pituitary gland was not discernible because of complete distortion by the adenoma. Thyrotropin-producing pituitary adenomas were large and showed a tendency to invade surrounding structures. Tumor volume ranged from 0.42 to 94.2 cm(3) (mean +/- SD, 16.0 +/- 17.8 cm(3)). The mean score of tumor invasion was 4.77 +/- 2.06 of a maximal possible value of 9.0. A high staging score was found to be predictive of an unfavorable response to surgery.


CONCLUSIONS
Thyrotropin-producing pituitary adenomas are usually large tumors at initial presentation with hypoenhancing features compared with normal pituitary tissue; they tend to be invasive. Greater amounts of invasion correlate with incomplete surgical removal of the tumor and continued hormonal secretion.
Sarlis
Nicholas J
NJ
Clinical Endocrinology Branch, National Institutes of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Rm. 8D04, Bldg. 10, 10 Center Dr., Bethesda, MD 20892, USA.
Gourgiotis
Loukas
L
Koch
Christian A
CA
Skarulis
Monica C
MC
Brucker-Davis
Françoise
F
Doppman
John L
JL
Oldfield
Edward H
EH
Patronas
Nicholas J
NJ
D000236:Adenoma / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D010911:Pituitary Neoplasms / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D012189:Retrospective Studies; D013972:Thyrotropin / Q000378:metabolism*
D013972:Thyrotropin