CT
A well-defined, extra-axial low-density lesion of near CSF attenuation is noted in the right quadrigeminal cistern region. The lesion has a scalloped posterior aspect of the midbrain and right cerebellar hemisphere. The fourth ventricle is displaced towards the left, with convincing evidence of hydrocephalus. There is no solid component.
Periventricular low attenuation in keeping with trans-ependymal oedema also is noted.