Recently I encountered a case of CDI, in which MR imaging shows absence of normal hyperintensity of post pitutary. What is the specificity of this finding?
The posterior pituitary bright spot is absent in most if not all patients with CDI, irrespective of the cause. However, it is not completely specific for CDI because the bright spot is also absent in 10% to 30% of normal healthy adults and in about the same fraction of patients with other types of DI (nephrogenic, dipsogenic, psychogenic). Therefore, it supports but does not completely prove the diagnosis of CDI.
