Preoperative Location of the Pituitary Bright Spot in Patients with Pituitary Macroadenomas

BACKGROUND AND PURPOSE: The purpose of this study was to determine the location of the pituitary bright spot in patients with pituitary macroadenomas before surgery. METHODS: A total of 54 patients with pituitary macroadenomas were retrospectively in-cluded in this study. Nonenhanced spin-echo T1-weighted MR images were reviewed to identify the location of the high-intensity-signal posterior pituitary lobe that indicates antidiuretic hormone (ADH) storage. Images were acquired with a 1.5-T machine by using 3-mm-thick contiguous sections in two or three orthogonal planes and a 300 512 matrix. RESULTS: The bright spot corresponding to ADH storage was identified in 44 (81%) patients. Two groups of patients were defined by the height of the macroadenoma: Group A patients (n 27) had pituitary macroadenomas less than 20 mm in height, and group B (n 27) had macroadenomas 20 mm or larger. In group A, the bright spot was identified in 25 patients (93%); it was located in the sella in 24 of these cases (96%). In group B, the bright spot was identified in 19 patients (70%); it was in an ectopic location in 14 of these cases (74%). CONCLUSION: MR imaging can be used to depict the pituitary bright spot in most patients with pituitary macroadenomas before surgery. The bright spot is usually identified at it