Tracer transport and metabolism in a patient with juvenile pilocytic astrocytoma. A PET study.

We studied a patient with juvenile pilocytic astrocytoma (JPA) using positron emission tomography (PET), 18F-fluorodeoxyglucose (FDG), 11C-methionine (MET), and 82Rubidium (RUB). Non-linear fitting and multiple time graphical plotting of the dynamic PET data revealed values for tumor plasma volume, blood-brain barrier transport rate constants and tracer distribution volume in the range of glioblastomas and meningiomas, or higher. Likewise, the steady-state accumulation of MET and FDG was increased. With regard to the known vascular composition of JPA, our data suggest that increased transport and distribution considerably contribute to the high net tracer uptake observed in this tumor.