 There are post-treatment findings in the posterior fossa with cerebellar volume loss and distortion, confluent T2 hyperintensity in the cerebellar treatment zone and smaller areas of T2 hyperintensity in the brainstem that may include olivary degeneration, and persistent susceptibility effects and intrinsic T1 hyperintensity in the surgical cavity. However, there is an area of nodular enhancement that has developed in the left aspect of the cerebellar resection cavity, measuring up to 15 mm. There are unchanged punctate foci of susceptibility effect in the right basal ganglia and left precentral gyrus, which may represent chronic microhemorrhages or cavernous malformations. There is no evidence of acute cerebral infarct. There is a posterior left ventricular catheter that terminates in the right lateral ventricle with persistent confluent high T2 signal in the brain parenchyma along the catheter path. There is unchanged T2 hyperintensity along the previous right ventriculostomy tract in the right frontal lobe. The third and lateral ventricles remain collapsed.
1. Post-treatment findings in the posterior fossa with developing nodular enhancement, which may represent tumor progression.2. Unchanged appearance of the stunted ventricular system.