Image quality is mildly degraded by motion artefact.
Extensive abnormality consisting of a homogeneously enhancing mass centred in the right thalamus extending into the right cerebral peduncle, with a small area of nodular enhancement located just anterior ( genu of internal capsule ), and abnormal FLAIR hyperintensity and expansion extending inferiorly to involve the entire midbrain, the right lateral and dorsal pons, extending to the right superior cerebellar peduncle. Abnormal signal extends across the posterior limb and genu of the right internal capsule and into the right medial temporal lobe. Confluent bilateral periventricular T2 hyperintensities probably in the main due to background chronic small vessel ischaemia, although there is hyperintensity of the genu of the corpus callosum.
The main enhancing component has dimensions of 2.8 x 2.5 x 2.6 cm, and the more anterior regularly nodular enhancing region measures 1.3 x 1 x 0.9 cm. This region demonstrates diffusion restriction and cerebral blood volume increase. The non-enhancing portion is similar in T2 intensity to grey matter.
There is mass effect upon the 3rd ventricle which is partially effaced. No convincing evidence of obstructive hydrocephalus.
MRV is unremarkable with a dominant right transverse sinus.
No aneurysm or vascular stenosis. The right ACA is dominant.
The extracranial structures are unremarkable.
Conclusion: Findings are most consistent with a primary CNS lymphoma rather than GBM in view of the enhancement and T2 signal characteristics (and precontrast density on CT).