title: Dynamic contrast-enhanced MR imaging of the stimulated pituitary gland.
abstract: Apoplexy due to infarction and/or hemorrhage is a frequent complication of pituitary adenoma, occurring either spontaneously or precipitated by several factors, among them pituitary function test with hypothalamic releasing hormones. The mechanism by which releasing hormones cause pituitary apoplexy is unclear. It has been proposed that increase in pituitary size and/or alterations in blood flow could be responsible. The aim of this study was to explore the effects of intravenous administration of hypothalamic releasing hormones on pituitary size and hemodynamics in healthy subjects. Gadolinium-DTPA-enhanced dynamic magnetic resonance imaging (MRI) was performed in eight healthy volunteers under basal conditions and 20 min after injection of releasing hormones. Mean upslopes of Gadolinium-DTPA enhancement curves showed good correlation between basal and stimulated conditions (R = 0.89) and were significantly steeper after stimulation (P = 0.017). In contrast, pituitary height, width and length did not differ significantly between basal and stimulated conditions. In conclusion, the pituitary does not swell in healthy subjects in response to stimulation with hypothalamic releasing hormones, whereas transfer of contrast agent to tissue (blood flow and/or vessel permeability) is enhanced.
authors.affiliation: Department of Medicine III, Clinical Division of Endocrinology and Metabolism and Department of Radiology, University of Vienna, Waehringer Guertel 18-20, Vienna 1090, Austria. christina.maier@akh-wien.ac.at
authors.forename: Christina
authors.initials: C
authors.lastname: Maier
authors.forename: Michaela
authors.initials: M
authors.lastname: Riedl
authors.forename: Martin
authors.initials: M
authors.lastname: Clodi
authors.forename: Christian
authors.initials: C
authors.lastname: Bieglmayer
authors.forename: Vladimir
authors.initials: V
authors.lastname: Mlynarik
authors.forename: Siegfried
authors.initials: S
authors.lastname: Trattnig
authors.forename: Anton
authors.initials: A
authors.lastname: Luger
mesh_terms: D000236:Adenoma / Q000473:pathology; D000328:Adult; D000465:Algorithms; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007028:Hypothalamic Hormones / Q000494:pharmacology; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D008297:Male; D010902:Pituitary Gland / Q000033:anatomy & histology* / Q000502:physiology*; D010907:Pituitary Hormones / Q000097:blood; D010911:Pituitary Neoplasms / Q000473:pathology; D012016:Reference Values; D013268:Stimulation, Chemical
chemical_list: D003287:Contrast Media; D007028:Hypothalamic Hormones; D010907:Pituitary Hormones; D019786:Gadolinium DTPA