A change in pituitary magnetic resonance imaging protocol detects ACTH-secreting tumours in patients with previously negative results.
OBJECTIVE
While detection of pituitary tumours with magnetic resonance imaging (MRI) may reduce diagnostic costs and improve surgical outcomes for patients with Cushing's disease, the optimal T1-weighted spin-echo (SE) MRI protocol remains unknown. We hypothesized that specific MR scanning parameters influence detection of corticotropinomas.


METHODS
Between December 1997 and November 2004, 21 of 84 consecutive patients with Cushing's disease had a falsely negative initial pituitary MRI study and a lesion identified subsequently at the National Institutes of Health Clinical Center. This study retrospectively reviewed and compared technical parameters used for the two pituitary T1-weighted SE MRIs in 18 patients with available scans.


METHODS
Repetition time (TR)/echo times (TE), field of view (FOV), matrix size, magnetic field strength, slice thickness, use of gadolinium contrast and the time interval between studies were recorded.


RESULTS
The MRI interscan interval was 5.4 +/- 1.1 months. All scans used gadolinium, matrix sizes were similar and nearly all had 3-mm thick slices. Parameters that differed between the NIH- and externally performed scans were: TR (400 ms vs. 492 +/- 19 ms, P = 0.0002); TE (10.3 +/- 0.5 vs. 17.2 +/- 1.2 ms, P = 0.0003); FOV (12 x 12 cm vs.17 +/- 0.6 x 18 +/- 0.7 cm, P < 0.0001). Immunohistochemistry of tumours resected at transsphenoidal surgery confirmed all to be corticotropinomas.


CONCLUSIONS
Not all 'T1-weighted SE' scans are equally accurate. MRI technique, particularly FOV and TR/TE value, influences results. We recommend that endocrinologists consider pituitary MRI parameters when interpreting the results.
Chowdhury
Iffat N
IN
Reproductive Biology and Medicine Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD, USA.
Sinaii
Ninet
N
Oldfield
Edward H
EH
Patronas
Nicholas
N
Nieman
Lynnette K
LK
D049913:ACTH-Secreting Pituitary Adenoma / Q000175:diagnosis* / Q000473:pathology; D000328:Adult; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D047748:Pituitary ACTH Hypersecretion / Q000473:pathology; D010902:Pituitary Gland / Q000473:pathology; D010911:Pituitary Neoplasms / Q000175:diagnosis* / Q000473:pathology; D012189:Retrospective Studies