5-year-old with juvenile pilocytic astrocytoma status post induction chemotherapy. Evaluate for interval change. There are postoperative findings related to occipital craniotomy and C1 laminectomy for partial resection of a posterior fossa mass with subjacent susceptibility effect compatible with chronic blood products. There is a right parietal approach ventriculostomy catheter that terminates near the foramen of Monro, which is unchanged in position. The ventricles have not significantly changed in size compared to prior exam. The tumor centered in the right cerebellar hemisphere and brainstem with encasement of the basilar artery and right 7th and 8th cranial nerves has decreased in size. Indeed, the tumor overall measures 24 x 36 mm, previously 29 x 40 mm. In particular, a T2 hyperintense portion involving the medulla and upper cervical cord measures 22 x 10 mm, previously 28 x 18 mm. There has also been interval decrease of the associated enhancement. There is interval decrease in the tumor extension along the cisternal portion of the right trigeminal nerve and into Meckel cave. Apparent high signal in the left cerebellopontine angle cistern on the FLAIR sequence without correlate on other sequences likely represents CSF flow artifact. There is no evidence of acute infarct. The major cerebral flow voids are intact. The skull and scalp soft tissues are unchanged.
Interval decrease in size and enhancement of the residual posterior fossa pilocytic astrocytoma is compatible with treatment response. I personally reviewed the Images and/or procedure with the Resident/Fellow and agree with this report.