MRI
- A right thalamic mass lesion is seen with intermixed signal intensity; predominantly hyperintense T1 with isointense core as well as mild heterogeneously hyperintense T2 signal. The lesion shows restricted diffusion of its rim (met Hb signal). The lesion measures 4 X 3.5 X 3.5 cm in its maximal AP, CC and TS diameters respectively. The lesion is seen surrounded by mild vasogenic brain edema with mild compression of the 3rd ventricle and moderate supratentorial as well as infratentorial hydrocephalus with peri-ventricular T2/FLAIR hyperintensities.
- Small intra-ventricular blood sedimentations are seen within the occipital horns of the lateral ventricles as well as within the 4th ventricle (best appreciated in the GRE sequence).
- MR CSF flowmetry shows Hyper-dynamic CSF flow across the cerebral aqueduct with opposed flow in the systole and diastole as well as type IV signal void across the cerebral aqueduct in the axial and sagittal T2 images.