title: Correlation of high signal intensity of the pituitary stalk in macroadenoma and postoperative diabetes insipidus.
abstract: OBJECTIVE
  High signal intensity (HSI) at the pituitary stalk is reported in pituitary adenomas. Our purpose was to clarify how and when this HSI formed, its long-term fate, and its relation to the function of infundibuloneurohypophyseal (INH) system.
  
  
  METHODS
  Twenty-two patients with pituitary adenoma and supradiaphragmatic extension underwent 1.5-T MR imaging. Patients were assigned to two groups A (n = 18; those with stalk tip HSI) and B (n = 4; those without HSI) on postoperative T1-weighted images. Endocrine status was postoperatively evaluated and compared in both groups.
  
  
  RESULTS
  Group A patients did not have postoperative permanent diabetes insipidus (DI). Preoperative images in 17 patients revealed linear or ovoid HSI on the adenoma surface immediately above the diaphragma sellae. Of these, two with a poorly developed diaphragma sellae had HSI near the median eminence and inside the sella turcica. HSI was not apparent in the remaining patient with a giant, irregularly shaped adenoma. In group B, three patients had permanent DI. No patient had HSI on preoperative images.
  
  
  CONCLUSIONS
  Postoperative pituitary stalk HSI is derived from preoperative supradiaphragmatic HSI on the adenoma surface. The suspected mechanism is blockage of the hypophyseal-pituitary axis, with an accumulation of neurosecretory granules at the diaphragmatic level. Diaphragmatic shape may influence the location of HSI. The shape and location of HSI are essentially stable for years after surgery. No patients with permanent DI had HSI before or after surgery. HIS at the pituitary stalk tip is a useful landmark for predicting functional integrity of the INH system in patients with a large pituitary adenoma.
authors: Department of Neurosurgery, Chiba University School of Medicine, Chiba-city, Japan.
authors: Naokatsu
authors: N
authors: Saeki
authors: Seiichiro
authors: S
authors: Hoshi
authors: Souichi
authors: S
authors: Sunada
authors: Kenro
authors: K
authors: Sunami
authors: Hisayuki
authors: H
authors: Murai
authors: Motoo
authors: M
authors: Kubota
authors: Ichiro
authors: I
authors: Tatsuno
authors: Toshihiko
authors: T
authors: Iuchi
authors: Akira
authors: A
authors: Yamaura
mesh_terms: D000236:Adenoma / Q000175:diagnosis* / Q000601:surgery; D000293:Adolescent; D000328:Adult; D000368:Aged; D003919:Diabetes Insipidus / Q000209:etiology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008473:Median Eminence / Q000473:pathology; D008875:Middle Aged; D019635:Neurosurgical Procedures; D010911:Pituitary Neoplasms / Q000175:diagnosis* / Q000601:surgery; D011183:Postoperative Complications; D012189:Retrospective Studies; D012658:Sella Turcica / Q000473:pathology