Volume interpolated 3D-spoiled gradient echo sequence is better than dynamic contrast spin echo sequence for MRI detection of corticotropin secreting pituitary microadenomas.

BACKGROUND

Various techniques have been attempted to increase the yield of magnetic resonance imaging (MRI) for localization of pituitary microadenomas in corticotropin (ACTH)-dependent Cushing's syndrome (CS).

OBJECTIVE

To compare the performance of dynamic contrast spin echo (DC-SE) and volume interpolated 3D-spoiled gradient echo (VI-SGE) MR sequences in the diagnostic evaluation of ACTH-dependent CS.

DESIGN

Data was analysed retrospectively from a series of ACTH-dependent CS patients treated over 2-year period at a tertiary care referral centre (2009-2011).

PATIENTS

Thirty-six patients (24 female and 12 male) were diagnosed to have ACTH-dependent CS during the study period. All patients underwent MRI by both sequences during a single examination. Cases with negative and equivocal pituitary MR imaging underwent corticotropin-releasing hormone (CRH) stimulated bilateral inferior petrosal sinus sampling (BIPSS) to confirm pituitary origin of ACTH excess state. Thirty patients were finally diagnosed to have Cushing's disease (CD) [based on histopathology proof of adenoma and/or remission (partial/complete) of hypercortisolism postsurgery]. Six patients were diagnosed to have histopathologically proven ectopic CS.

RESULTS

Of 30 patients with CD, 24 patients had microadenomas and 6 patients had macroadenomas. DC-SE MRI sequence was able to identify microadenomas in 16 of 24 patients, whereas postcontrast VI-SGE sequence was able to identify microadenomas in 21 of 24 patients. All six patients of ectopic CS had negative pituitary MR imaging by both techniques (specificity: 100%).

CONCLUSION

VI-SGE MR sequence was better for localization of pituitary microadenomas particularly when DC-SE MR sequence is negative or equivocal and should be used in addition to DC-SE MR sequence for the evaluation of ACTH-dependent CS.