Abstract
Magnetic resonance (MR) imaging was performed
in 15 normal healthy individuals and 6 patients, 4
with complete central type idiopathic diabetes insipidus
(DI) and 2 with partial central idiopathic DI.
Two cases of complete idiopathic DI were associated
with empty sella. Characteristic high intensity of
the posterior pituitary lobe on T1-weighted image
was seen in all 15 normal pituitary glands; however,
it was undetectable in all 6 cases of DI. In dynamic
study, the posterior lobe was well enhanced within
30 seconds after injection of gadopentetate dimeglumine
in healthy subjects and in one of mild partial
DI. In contrast, no or faint early enhancement of
the posterior pituitary lobe was observed in 4 cases
of complete and 1 case of partial DI. Regardless of
whether sella were empty or not, the early enhanced
area of posterior pituitary was not seen in
complete central idiopathic DI. The posterior pituitary
high intensity on MR T1-weighted images
probably reflects the stored antidiuretic hormone
(ADH) granules in the posterior lobe, and the posterior
pituitary vascularity may be decreased in neurohypophysial
hypofunctioning states such as
central idiopathic DI. These findings were clearly
demonstrable by MR dynamic imaging of pituitary
glands after intravenous injection of contrast materials,
using an anteroposterior orientation of frequency
encoding gradient.
