with complete agenesis, the corpus callosum is totally absent
with partial agenesis (hypoplasia), the anterior portion (posterior genu and anterior body) is formed, but the posterior portion (posterior body and splenium) is not. The rostrum and the anterior/inferior genu are also not formed
It is important to be aware of the features of agenesis of the corpus callosum. First, to distinguish it from hydrocephalus and second to instigate a search for further, more serious, anomalies with which it may be associated.
MRI is currently the imaging modality of choice in infants and children with agenesis/dysgenesis of the corpus callosum, even in patients who have previously undergone CT and US examinations.