What does the hyperdensity on non-contrast CT imply about the tumour?
It suggests the tumour is highly / densely cellular.
Given its location (intra / peri-ventricular) what two entities should be at the top of your list, taking into account homogeneous contrast enhancement.
Intraventricular meningioma and CNS lymphoma both typically demonstrate hyperdensity and vivid homogeneous contrast enhancement. In the setting of a known malignancy, a hemorrhagic metastasis cannot entirely be discounted.
Within the trigone of the left lateral ventricle, and involving or bulging into the adjacent brain is a lobulated mass which is slightly hypderdense pre-contrast and demonstrates vivid homogeneous contrast enhancement.