MRI of the brain is an important aid in the diagnosis of CDI, however images do not always show a patognomonic pattern of this disease. In the present study we describe the heterogeneous images found in 14 patients with CDI (W=8,F=6) with ages from 1 to 14 years. The images were as follows:Idiopathic CDI(n=9): Seven patients on admission lacked the typical bright spot of the neurohypophysis. In the remaining 2 patients the bright spot dissapeared on follow-up after 7 and 12 months of diagnosis. In one of these patients on admission a thickening of the pituitary stalk was observed that was normalized 3 years later. The other patient one year after diagnosis showed a thickening of the stalk not shown previously.Tumoral(germinoma) (n=3): Two patients on admission lacked the bright spot, also a tumoral infiltration of the hypothalamus was observed, which was best defined with gadolinium. The third patient at diagnosis showed a widening of the pituitary stalk with an ectopic bright spot, however a year later a tumoral infiltration of the hypothalamus was observed with dissaperance of the bright spot. Histiocytosis(n=1): This patient on admission lacked the bright spot without any further finding on the MRI.

In summary the absence of the bright spot of the neurohypophysis was found in patients with neurohypophyseal disfunction. However it's presence does not exclude the diagnosis of CDI. A thickening of the pituitary stalk at diagnosis that normalizes on follow-up might be due to an inespecific inflamatory process. However the former finding has to be closely followed in order to discard an inflamatory or tumoral infiltration as seen in histiocytosis or germinoma respectively.