On the usefulness of brain PET scanning to the paediatric neuro-oncologist.

Positron emission tomography (PET) scanning adds a functional dimension to brain scanning; levels of metabolic activity are imaged and this information may complement the more "anatomic" imaging of CT and MRI. In a series of 10 young patients the usefulness of PET scanning technique was investigated. The major areas of usefulness were the distinction of posttreatment sequelae from active tumour (both postsurgical MRI changes from tumour and postradiation MRI changes from tumour) and the localization of persisting tumour amenable to radiosurgical treatment. The technique was beneficial in assessing continuing activity in pineal tumours (residual pineal teratoma mass and residual pineocytoma mass) and in assessing activity in brainstem/cerebellar peduncle gliomas (three cases). In one unusual case of widespread leptomeningeal melanoma, the PET scan under-read the situation.