What can cause the pituitary gland to show up bright white on mri with out contrast?

Posterior Pituitary: The posterior pituitary has intrinsic high t1 signal. It's thought to reflect the high concentration of neurosecretory granules in the neurohypophysis (posterior pituitary which stores/releases oxytocin ; vasopressin produced in hypothalamus). Absence of the normal posterior pituitary bright spot should prompt a search for an ectopic posterior pituitary that has failed to migrate from hypothalamus.