3 Tesla magnetic resonance imaging with and without corticotropin releasing hormone stimulation for the detection of microadenomas in Cushing's syndrome.
OBJECTIVE
We sought to determine if higher resolution 3 Tesla (T) magnetic resonance imaging (MRI) with or without ovine corticotropin releasing hormone (o-CRH) stimulation would increase the sensitivity for detection of pituitary microadenomas in ACTH-dependent Cushing's syndrome (CS).


METHODS
We prospectively identified 23 patients over a 2-year period with clinical and biochemical evidence of ACTH-dependent CS with no lesion (n = 11) or equivocal lesion (n = 10) on 1.5T MRI. Subsequently, two additional MRIs were performed in random order: 3T nonstimulated MRI or 3T MRI with o-CRH in all patients. Three neuroradiologists reviewed all examinations in a randomized blinded fashion. Patients were divided into four groups, depending on the outcome of their evaluation and treatment for CS. Two patients had to be excluded, and so we report on 21 subjects.


RESULTS
Both 3T MRI without (P < 0.016) and with o-CRH stimulation (P < 0.013) was significantly more sensitive for detection of pituitary microadenomas than 1.5T MRI for Group 1 (definitive proof of Cushing's disease, n = 10). Group 2 (those in group 1, plus three patients where dynamic/invasive testing suggested pituitary source) also showed a significant (P < 0.012) advantage for 3T. There was no difference between the 3T and the 3T o-CRH examinations for any of the pulse sequences. We did not observe a statistically significant difference in other patient groups [patients with recurrent CD (n = 6) and patients with ectopic CS (n = 2)].


CONCLUSIONS
The results of our prospective blinded studies suggest that 3T MRI of pituitary gland should be considered in evaluation of patients with ACTH-dependent CD when 1.5T imaging is negative or equivocal.
Erickson
Dana
D
Division of Endocrinology, Metabolism and Nutrition, Mayo College of Medicine, Rochester, MN 55905, USA.
Erickson
Bradley
B
Watson
Robert
R
Patton
Alice
A
Atkinson
John
J
Meyer
Fredric
F
Nippoldt
Todd
T
Carpenter
Paul
P
Natt
Neena
N
Vella
Adrian
A
Thapa
Prabin
P
D049913:ACTH-Secreting Pituitary Adenoma / Q000000981:diagnostic imaging* / Q000473:pathology; D000236:Adenoma / Q000000981:diagnostic imaging* / Q000473:pathology; D000328:Adult; D000368:Aged; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology / Q000627:therapeutic use*; D003480:Cushing Syndrome / Q000000981:diagnostic imaging*; D003940:Diagnostic Techniques, Endocrine; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011859:Radiography; D012680:Sensitivity and Specificity; D016037:Single-Blind Method; D013268:Stimulation, Chemical; D047368:Tumor Burden / Q000187:drug effects / Q000502:physiology; D055815:Young Adult
D003346:Corticotropin-Releasing Hormone