19 years, Male, evaluate for abscess or meningitis. Examination is limited to post contrast sequences and demonstrates postoperative changes related to resection of recurrent tumor in the posterior fossa. There is minimal enhancement along the resection cavity margin include foci of nodularity, some of which appeared increased since prior postoperative MRI from 1/13/2016 particularly on the left lateral margin of the resection cavity. Restricted diffusion was evident within this region and therefore this is likely representative of evolution of postsurgical changes. There is a approximately 6 mm nodule with T1 hyperintensity and susceptibility indicative of blood products along the right dorsal margin of the fourth ventricle which was present on prior; there is questionable associated enhancement. There is no definite evidence of residual tumor on this current studyElsewhere in the brain there is no abnormal parenchymal or meningeal enhancement to suggest infection. No evidence of intracranial abscess or empyema. Air is an extra-axial fluid collection in the posterior fossa. There is also a larger fluid collection with surrounding enhancement in the suboccipital soft tissues which extends below the field-of-view at the C1 level, larger than prior study from 1/13/2016. Collection measures approximately 8 cm in the craniocaudal dimension. There is surrounding enhancement without restricted diffusion centrally and favored to be a pseudomeningocele. In the left frontotemporal scalp there is a focus of peripheral enhancement with restricted diffusion measuring approximately 3 cm in the AP dimension and 4 mm in thickness.
1. Examination limited to postcontrast sequences demonstrate no evidence of intracranial abscess or empyema. There is enhancement at the cerebellar resection cavity margins which may represent postsurgical change. No definite MR evidence of meningitis, although assessment is limited due to recent surgery. Suggest correlation with CSF sampling for meningitis. 2. Postoperative changes of resection of recurrent tumor in the posterior fossa without definitive evidence of residual tumor. There is mild residual enhancement in the surgical bed as described above and can be further assessed on follow-up studies.3. Suboccipital fluid collection is compatible with a pseudomeningocele and larger than prior MRI from 1/13/2016. Fluid collection is seen extending to the skin surface. There is surrounding enhancement which may be postsurgical. No associated restricted diffusion is seen to definitively suggest pus however superimposed infection cannot be excluded.4. Thin fluid collection involving the left frontal temporal scalp measuring up to 4 mm in thickness and 3 cm in the AP dimension, which is suspicious for a superficial abscess by imaging.5. Please refer to recent noncontrast MRI report from 1/27/2016 for additional findings.