- a lobulated rather rounded intraventricular mass lesion is noted filling and expanding the 4th ventricle is seen related to the superior medullary velum (roof of the 4th ventricle), measuring about 4 X 4.5 X 7 cm in its maximal dimensions. The mass elicits heterogenous low T1 with few high signal foci (likely met-Hb signal of subacute blood) and intermediate to high T2 signal with multiple necrotic foci. It shows heterogenous post-contrast enhancement as well as restricted diffusion.
- the mass is compressing the posterior aspect of the brain stem as well as the related cerebellar peduncles and significantly compressing and obstructing the cerebral aqueduct with resultant moderate to marked supra-tentorial hydrocephalic changes as well as mild transependymal CSF permeation seen as mild periventricular T2/FLAIR hyperintensity.
- MRS of the lesion shows depressed N-acetyl aspartate (NAA) and creatine (Cr) with increased choline (Cho) as well as increased lipid/lactate.