MRI
On the MRI, the intradiploic lesion elicits a low signal on T1, heterogeneous signal on FLAIR and high signal on T2 with restricted diffusion and no enhancement seen on the postcontrast sequence. It extends along the left cerebellar hemisphere and vermis, compressing the brainstem and cerebellar parenchyma with tonsillar herniation and mild to moderate dilatation of the 3rd and lateral ventricles (obstructive hydrocephalus).
Small vessel ischaemic changes are noted.