DCC must be diagnosed by viewing the brain, either with MRI, Computerized Axial Tomography (CT-scan or CAT scan), or pre/post-natal sonogram (ultrasound). Among these, MRI is clearly best to see DCC and any other brain abnormalities. Absence of the corpus callosum can be seen at any age after the critical period of prenatal development. A neurologist or other physician may request an MRI or CT scan of the brain. An obstetrician or neonatal specialist may request an extensive pre-natal or post-natal sonogram or MRI. The pictures typically will be examined by a neuroradiologist or pediatric neuroradiologist, who will write a report describing any unusual findings. A neurologist or other physician also may examine the scan and diagnose DCC. If that is the case, it is always wise to have a neuroradiologist re-examine the pictures to verify the diagnosis and carefully assess for any other possible abnormalities. DCC itself cannot be detected by amniocentesis.