Newborn with a brain cyst on prenatal ultrasound

MRI of Dandy Walker malformation
Coronal (above right) and axial (below) T1 MRI without contrast of the brain show hypoplasia of the inferior cerebellar vermis. Sagittal T1 MRI (above left) shows dilation of the fourth ventricle, expansion of the posterior fossa and elevation of the tentorium and torcula.

The diagnosis was Dandy Walker malformation.