The CT scanner in posterior fossa tumours of childhood.

Eighty-five consecutive posterior fossa tumours occurring in children and detected by computed tomography (CT) were submitted to detailed analysis. There was only one false positive diagnosis, which would have been avoided with present knowledge, and no known false negative diagnoses during the same period. In most cases the histological type of the tumour could be reliably predicted. CT was less accurate for determining the anatomical extent of the lesions but tumours arising in the brainstem could always be distinguished from those predominantly affecting the fourth ventricle and cerebellum.