T1 Signal Intensity and Height of the Anterior Pituitary in Neonates: Correlation with Postnatal Time

Abstract

BACKGROUND AND PURPOSE:The anterior pituitary of a term neonate is usually hyperintense on T1-weighted MR images, which may represent histologic changes of the gland due to the effect of high estrogen levels during the fetal period; however, MR findings of a preterm neonate have not been fully evaluated. The purpose of this study was to investigate whether intensity and size of the neonatal anterior pituitary on MR images obtained near term of corrected age correlates with the gestational age at birth or postnatal time.

MR Imaging of the Pituitary Gland and Postsphenoid Ossification in Fetal Specimens

“…Such effects mean that our results might differ from those of in vivo fetal MR imaging, but several MR imaging studies have covered formalin-fixed fetal specimens, 16,30 and we have demonstrated the similar appearance of fetal pituitary hyperintensity reported from in vivo studies. 1,31 Further in vivo fetal MR imaging studies may be expected for validation of our results. Another limitation was the small number of cases included in this study, and a larger number of cases might have more precisely clarified the relationship between gestational age and the size of the pituitary gland or postsphenoid ossification.…”

“…24,25 A weak correlation between the pituitary/ pons signal ratio and gestational weeks was shown in this study; these findings were contradictory to those in previous studies targeting prematurely born neonates. 1,26 The population of fetuses in this study was approximately 11-12 gestational weeks, younger than the ages in previous reports; this difference may be the cause of the discrepancy in the relationship between the pituitary signal and gestational weeks. The pituitary gland did not show any increase in size with gestational age in our study population, probably because an increase in pituitary size may not be evident during a period of weeks or the pituitary may remain nonfunctional, with the fetus relying solely on maternal hormones.…”

“…1 The pituitary gland plays an essential role in the maintenance of homeostasis, metabolism, reproduction, growth, and lactation and comprises 2 different parts in terms of function and embryologic origin: the adenohypophysis and the neurohypophysis. During embryologic development, the adenohypophysis is formed by the Rathke pouch, which is derived from oral ectoderm from the roof of the stomodeum.…”

Transient Hyperintensity in the Subthalamic Nucleus and Globus Pallidus of Newborns on T1-Weighted Images

“…Normal signal intensity changes also are seen in other parts of the brain such as anterior pituitary lobe that also depends on postnatal age. Kitamura et al 19 reported that signal intensity pattern changes in the anterior lobe of the pituitary gland depend on postnatal age at examination rather than gestational age. In their report, the anterior lobe of the pituitary gland showed a high signal intensity immediately after birth that gradually decreased as postnatal age increased.…”

‘Double Bright Spot’ in T1 Weighted Non-contrast MRI of Pituitary in Multiple Pituitary Hormone Deficiency

“…In newborns, anterior pituitary typically shows hyperintensity on T1 MRI, particularly in the first 2 mo of life [2]. Other rare causes of similar MRI appearance include normal pregnancy and lactation [3].…”