title: The pituitary gland: changes on MR images during the 1st year after delivery.
abstract: OBJECTIVE
  To longitudinally and prospectively investigate changes in the volume and signal intensity on T1-weighted magnetic resonance (MR) images of the pituitary gland up to 1 year after delivery and evaluate whether termination of lactation has an effect on these parameters.
  
  
  METHODS
  All participants provided informed consent for participation in the study, which was approved by the institutional review board. Thirteen volunteers (mean age, 28 years; age range, 26-32 years) underwent MR imaging 2 and 4 weeks after delivery and then at intervals of 0.5-2.0 months until 1 year after delivery. Eight participants terminated lactation during the study period. Sagittal and coronal T1-weighted images were obtained. Signal intensities of the anterior and posterior lobes of the pituitary were calculated relative to that of the pons. The volume of the pituitary was also calculated. Two-tailed paired Student t tests and separate simple linear regression analyses were used to test for statistically significant differences.
  
  
  RESULTS
  The mean pituitary volume was 544 mm3 at 2 weeks, 523 mm3 at 4 months, 512 mm3 at 8 months, and 511 mm3 at 12 months after delivery, with significant differences between 2 weeks and 4 months (P = .002) and between 4 and 8 months (P = .003) after delivery. The mean ratio of the signal intensity of the anterior lobe of the pituitary to the signal intensity of the pons was 1.11 at 2 weeks, 1.07 at 4 months, 1.03 at 8 months, and 1.00 at 12 months after delivery, with significant differences between 2 weeks and 4 months (P = .004) and between 4 and 8 months (P = .0001) after delivery. Termination of lactation had no statistically significant effect on pituitary volume or the ratio of the signal intensity of the anterior or posterior lobe of the pituitary to the signal intensity of the pons.
  
  
  CONCLUSIONS
  The volume of the pituitary gland decreases up to 8 months after delivery, and the T1-weighted signal intensity of the anterior lobe of the pituitary decreases; termination of lactation has no statistically significant effect on these parameters.
authors.affiliation: Department of Nuclear Medicine and Diagnostic Imaging, Kyoto University Hospital, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan. mikiy@kuhp.kyoto-u.ac.jp
authors.forename: Yukio
authors.initials: Y
authors.lastname: Miki
authors.forename: Milliam L
authors.initials: ML
authors.lastname: Kataoka
authors.forename: Toshiya
authors.initials: T
authors.lastname: Shibata
authors.forename: Tabassum L
authors.initials: TL
authors.lastname: Haque
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Kanagaki
authors.forename: Taro
authors.initials: T
authors.lastname: Shimono
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Okada
authors.forename: Akira
authors.initials: A
authors.lastname: Hiraga
authors.forename: Sadahiko
authors.initials: S
authors.lastname: Nishizawa
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ueda
authors.forename: Mahbubur
authors.initials: M
authors.lastname: Rahman
authors.forename: Junji
authors.initials: J
authors.lastname: Konishi
mesh_terms: D000328:Adult; D036861:Delivery, Obstetric; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D010902:Pituitary Gland / Q000033:anatomy & histology*; D011446:Prospective Studies; D013997:Time Factors