title: MR of corticotropin-secreting pituitary microadenomas.
abstract: OBJECTIVE
  To assess the accuracy of MR in the preoperative identification of corticotropin-secreting pituitary microadenomas.
  
  
  METHODS
  Twenty-six patients with clinical and biochemical evidence of pituitary-driven Cushing disease in whom MR of the seller region was performed were selected for this study. The MR examinations were retrospectively evaluated by a neuroradiologist who was aware of the presence of an adenoma at surgery but not of location and size of the lesion.
  
  
  RESULTS
  Considering the whole group of MR examinations performed either without (n = 26) or without and with intravenous injection of gadopentetate dimeglumine (n = 16), overall 20 MR studies were judged to show disease. Seventeen of 26 microadenomas were adequately shown and located by MR (true-positive, 65.4%). In three cases the sides of the microadenomas were misjudged (false-positive, 11.5%). Six patients had negative MR studies (false-negative, 23%). Twelve of the 16 patients studied after gadopentetate dimeglumine injection had true-positive MR findings (75%).
  
  
  CONCLUSIONS
  In our experience the accuracy of MR in detecting corticotropin-secreting microadenomas as small as 2 to 3 mm is 65% to 75%. Although precontrast images provide diagnostic information, the microadenoma can be better seen with administration of contrast material.
authors.affiliation: Department of Neuroradiology, Niguarda Hospital, Milan, Italy.
authors.forename: N
authors.initials: N
authors.lastname: Colombo
authors.forename: P
authors.initials: P
authors.lastname: Loli
authors.forename: F
authors.initials: F
authors.lastname: Vignati
authors.forename: G
authors.initials: G
authors.lastname: Scialfa
mesh_terms: D000236:Adenoma / Q000175:diagnosis* / Q000378:metabolism*; D000293:Adolescent; D000324:Adrenocorticotropic Hormone / Q000378:metabolism*; D000328:Adult; D003287:Contrast Media / Q000008:administration & dosage; D003480:Cushing Syndrome / Q000175:diagnosis; D004338:Drug Combinations; D005260:Female; D005682:Gadolinium / Q000008:administration & dosage; D019786:Gadolinium DTPA; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007275:Injections, Intravenous; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008536:Meglumine / Q000008:administration & dosage; D008875:Middle Aged; D009942:Organometallic Compounds / Q000008:administration & dosage; D004369:Pentetic Acid / Q000008:administration & dosage / Q000031:analogs & derivatives; D010902:Pituitary Gland / Q000473:pathology; D010911:Pituitary Neoplasms / Q000175:diagnosis* / Q000378:metabolism*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D004338:Drug Combinations; D009942:Organometallic Compounds; D008536:Meglumine; D004369:Pentetic Acid; D000324:Adrenocorticotropic Hormone; D005682:Gadolinium; D019786:Gadolinium DTPA