History of GBM brain tumor, on Avastin. Per technologist's note, patient had difficulty tolerating the study; several sequences are mildly degraded by motion.Again seen are postsurgical changes of suboccipital craniotomy for resection of posterior fossa tumor. Compared to the 6/16/2016 and 4/14/2016 examinations, there has been an interval decrease in the FLAIR hyperintensity in the cerebellar vermis and right greater than left cerebellar hemisphere surrounding the resection cavity. There is also a decrease in the heterogeneously enhancing tissue surrounding the resection cavity. Mass effect on the fourth ventricle has decreased. There is mild restricted diffusion along the resection cavity without restricted diffusion elsewhere to suggest acute ischemic infarction. No new enhancing lesions are identified within the brain. A nonspecific punctate focus of increased T2/FLAIR signal within the white matter adjacent to the frontal horn of the left lateral ventricle is unchanged. There is increased T2/FLAIR signal within the bilateral medullary olives which may be related to hypertrophic olivary degeneration. The lateral and third ventricles remain mildly prominent, likely related to volume loss, and not significantly changed. The basal cisterns remain patent. There is no midline shift. No extra-axial fluid collection is identified. Normal flow-voids are demonstrated in the major intracranial vascular structures. The midline structures and craniocervical junction are within normal limits. There is trace mucosal thickening within the paranasal sinuses.
Interval decrease in FLAIR hyperintensity and enhancement surrounding the cerebellar resection cavity is seen compatible with antiangiogenic effect.