The normal, absent, and abnormal corpus callosum: sonographic findings.

The normal corpus callosum can be identified on sonography as a hypoechoic band superior to the third ventricle on the midline sagittal scan and forming the roof of the lateral ventricles on the coronal scan. Absence of the corpus callosum may be partial or complete and may be developmental or acquired. The sonographic features and associated intracranial abnormalities in six patients are presented. The findings include separation of the lateral ventricles with increased angulation and concavity to the medial border due to the prominent bundles of Probst, and dilatation and elevation of the third ventricle with interposition between the lateral ventricles.