title: Magnetic resonance imaging of the brain in dogs with recently diagnosed but untreated pituitary-dependent hyperadrenocorticism.
abstract: Magnetic resonance imaging was used to determine the prevalence of visible pituitary masses in 21 dogs with recently diagnosed and untreated pituitary-dependent hyperadrenocorticism. All dogs had clinical signs and routine database values (CBC, serum biochemical panel, and urinalysis) consistent with a diagnosis of hyperadrenocorticism, and none had clinical signs suggestive of an intracranial mass. Each dog had plasma cortisol concentrations after adrenocorticotropic hormone administration or low-dose dexamethasone administration consistent with hyperadrenocorticism. Pituitary-dependent hyperadrenocorticism was confirmed by the finding of 2 equal-size adrenal glands on abdominal ultrasonography and by results of plasma endogenous adrenocorticotropic hormone concentration and high-dose dexamethasone suppression testing. Sagittal and transverse T1-weighted magnetic resonance images of the brain were obtained before and after IV administration of gadopentenate dimeglumine. Eleven dogs had visible masses, ranging in size from 4 to 12 mm at greatest vertical height. Mean age and body weight of dogs with a visible pituitary mass was not significantly different from dogs without a visible mass. There was no significant difference in endocrine test results when comparing dogs with a visible pituitary mass to dogs without. The prevalence of visible pituitary masses in dogs with pituitary-dependent hyperadrenocorticism was greater than suggested by the prevalence of clinical neurologic signs.
authors.affiliation: Veterinary Medical Teaching Hospital, Davis, CA, USA.
authors.forename: E H
authors.initials: EH
authors.lastname: Bertoy
authors.forename: E C
authors.initials: EC
authors.lastname: Feldman
authors.forename: R W
authors.initials: RW
authors.lastname: Nelson
authors.forename: C A
authors.initials: CA
authors.lastname: Duesberg
authors.forename: P H
authors.initials: PH
authors.lastname: Kass
authors.forename: M H
authors.initials: MH
authors.lastname: Reid
authors.forename: A B
authors.initials: AB
authors.lastname: Dublin
mesh_terms: D000303:Adrenal Cortex Diseases / Q000209:etiology / Q000662:veterinary*; D000324:Adrenocorticotropic Hormone / Q000378:metabolism; D000818:Animals; D004283:Dog Diseases / Q000175:diagnosis* / Q000453:epidemiology*; D004285:Dogs; D008279:Magnetic Resonance Imaging / Q000662:veterinary*; D010911:Pituitary Neoplasms / Q000150:complications / Q000175:diagnosis / Q000453:epidemiology / Q000662:veterinary*; D015995:Prevalence; D013223:Statistics as Topic
chemical_list: D000324:Adrenocorticotropic Hormone