Secretory and nonsecretory pituitary adenomas are distinguishable by 1/T1 magnetic relaxation rates at very low magnetic fields in vitro.
OBJECTIVE
The authors investigated whether hormonally active and inactive pituitary adenomas can be discriminated in vitro by magnetic resonance (MR) imaging-related data.


METHODS
1/T1 nuclear magnetic relaxation dispersion profiles were measured for 39 fresh surgical specimens of secreting and nonsecreting adenomas, classified using clinical criteria or preoperative serum hormone levels. Nonsecreting adenomas were subdivided into hormone-producing and nonhormone-producing by immunostains. At five fields (0.00024 to 1.2 tesla [T]), mean 1/T1 was analyzed for statistically significant differences among these three tumor categories.


RESULTS
Mean 1/T1 was significantly higher (P < 0.02) for hormone-secreting than for nonsecreting adenomas at fields below 0.24 T; no significant difference existed at typical MR imaging fields (0.5 to 1.5 T). Mean 1/T1 for hormone-producing and nonhormone-producing, nonsecreting adenomas were not significantly different at any field.


CONCLUSIONS
Because 1/T1 at low fields is related to 1/T2 at imaging fields, it may be possible to detect hormone secretion of pituitary adenomas noninvasively by MR imaging.
Spiller
M
M
Department of Radiology, New York Medical College, Valhalla 10595, USA.
Childress
S M
SM
Koenig
S H
SH
Duffy
K R
KR
Valsamis
M P
MP
Tenner
M S
MS
Kasoff
S S
SS
D000236:Adenoma / Q000175:diagnosis* / Q000378:metabolism; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D010907:Pituitary Hormones / Q000378:metabolism*; D010911:Pituitary Neoplasms / Q000175:diagnosis* / Q000378:metabolism; D015175:Prolactinoma / Q000175:diagnosis / Q000378:metabolism
D010907:Pituitary Hormones