title: Differentiation between Cystic Pituitary Adenomas and Rathke Cleft Cysts: A Diagnostic Model Using MRI.
abstract: OBJECTIVE
  Cystic pituitary adenomas may mimic Rathke cleft cysts when there is no solid enhancing component found on MR imaging, and preoperative differentiation may enable a more appropriate selection of treatment strategies. We investigated the diagnostic potential of MR imaging features to differentiate cystic pituitary adenomas from Rathke cleft cysts and to develop a diagnostic model.
  
  
  METHODS
  This retrospective study included 54 patients with a cystic pituitary adenoma (40 women; mean age, 37.7 years) and 28 with a Rathke cleft cyst (18 women; mean age, 31.5 years) who underwent MR imaging followed by surgery. The following imaging features were assessed: the presence or absence of a fluid-fluid level, a hypointense rim on T2-weighted images, septation, an off-midline location, the presence or absence of an intracystic nodule, size change, and signal change. On the basis of the results of logistic regression analysis, a diagnostic tree model was developed to differentiate between cystic pituitary adenomas and Rathke cleft cysts. External validation was performed for an additional 16 patients with a cystic pituitary adenoma and 8 patients with a Rathke cleft cyst.
  
  
  RESULTS
  The presence of a fluid-fluid level, a hypointense rim on T2-weighted images, septation, and an off-midline location were more common with pituitary adenomas, whereas the presence of an intracystic nodule was more common with Rathke cleft cysts. Multiple logistic regression analysis showed that cystic pituitary adenomas and Rathke cleft cysts can be distinguished on the basis of the presence of a fluid-fluid level, septation, an off-midline location, and the presence of an intracystic nodule (P = .006, .032, .001, and .023, respectively). Among 24 patients in the external validation population, 22 were classified correctly on the basis of the diagnostic tree model used in this study.
  
  
  CONCLUSIONS
  A systematic approach using this diagnostic tree model can be helpful in distinguishing cystic pituitary adenomas from Rathke cleft cysts.
authors.affiliation: From the Department of Radiology, Research Institute of Radiological Science (M.P., S.-K.L., J.K., S.S.A.).
authors.forename: M
authors.initials: M
authors.lastname: Park
authors.affiliation: From the Department of Radiology, Research Institute of Radiological Science (M.P., S.-K.L., J.K., S.S.A.).
authors.forename: S-K
authors.initials: SK
authors.lastname: Lee
authors.affiliation: Biostatistics Collaboration Unit, Medical Research Center (J.C.).
authors.forename: J
authors.initials: J
authors.lastname: Choi
authors.affiliation: Departments of Neurosurgery (S.-H.K.).
authors.forename: S-H
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Pathology (S.H.K.), Yonsei University College of Medicine, Seoul, South Korea.
authors.forename: S H
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Department of Radiology (N.-Y.S.), Ewha Womans University School of Medicine, Seoul, South Korea.
authors.forename: N-Y
authors.initials: NY
authors.lastname: Shin
authors.affiliation: From the Department of Radiology, Research Institute of Radiological Science (M.P., S.-K.L., J.K., S.S.A.).
authors.forename: J
authors.initials: J
authors.lastname: Kim
authors.affiliation: From the Department of Radiology, Research Institute of Radiological Science (M.P., S.-K.L., J.K., S.S.A.) sungsoo@yuhs.ac.
authors.forename: S S
authors.initials: SS
authors.lastname: Ahn
mesh_terms: D000236:Adenoma / Q000175:diagnosis*; D000328:Adult; D020863:Central Nervous System Cysts / Q000175:diagnosis*; D003560:Cysts / Q000175:diagnosis*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010902:Pituitary Gland / Q000473:pathology; D010911:Pituitary Neoplasms / Q000175:diagnosis*; D012189:Retrospective Studies