FIG 1. Dandy-Walker malformation with cerebellar dysplasia in a 4-month-old infant.

A, Coronal fast spin-echo (3000/102 [TR/TE]) image shows that the vermis is hypoplastic and the posterior fossa large, with the cerebellar hemispheres widely separated. The cerebellar hemispheres have an abnormal folial pattern, compatible with dysplasia. The cerebral hemispheres are abnormal with marked thinned white matter, enlarged ventricles, and shallow sulci.

B, Axial fast spin-echo (3500/112) image shows, in addition to the large posterior fossa fluid collection and dysplastic cerebellar hemispheres, an abnormality of the pons, which is small and has a ventral cleft.