Grade 3 oligodendroglioma. Status post surgery, TMZ and RT/PCV Initiated Avastin treatment since the prior MRI. There are changes of prior tumor resection from right anterior right frontal lobe with associated dural thickening and volume loss as well as susceptibility effect. However, the periventricular contrast-enhancing tissue anterolateral and superior to the frontal horn and anterior body of the left lateral ventricle has increased in size. Transaxially, it measures 3.0 cm x 1.5 cm compared to 1.2 cm x 0.5 cm previously and is associated with mild mass-effect. It is mildly, heterogeneously T2 hypointense relative to the surrounding white-matter T2-hyperintensity and shows diffusion restriction. On the other hand, contrast enhancement is less pronounced compared to the previous examination. On dynamic susceptibility-weighted contrast-enhanced MR perfusion shows the abnormality to be hypoperfused compared to the adjacent parenchyma. This may reflect evolving posttreatment change though the overall picture is confounded also by recent treatment by Avastin. Otherwise, focal T2-hyperintensity in the posterior-inferior right temporal lobe with associated foreign loss, encephalomalacia, is unchanged. There are tiny foci of encephalomalacia in the right cerebellar hemisphere, likely chronic infarcts.The orbits are unremarkable. There is no destructive skull lesion.
The ependymal/subependymal abnormalities left frontal lobe has progressed since the previous examination from March 2016, being larger and more diffusion-restricted. However, contrast enhancement and perfusion characteristics have decreased since the previous examination but this may reflect the patient being on antiangiogenic treatment. Therefore, this progressing abnormality may reflect evolving posttreatment change or progressive tumor recurrence. Other posttreatment findings remain unchanged.