Transection of the pituitary stalk caused by a fall in a 17-year-old male. The signs and symptoms of DI developed two months after trauma. Sagittal T1-weighted MR image (600/15) reveals diffuse atrophy of the pituitary gland (arrows). The high signal intensity normally seen in the posterior lobe is absent, and the normal pituitary stalk is not seen. Two foci of high signal intensity anterior and posterior to the pituitary fossa represent the fat marrow of the sella turcica.