Peripheral benzodiazepine binding sites in human gliomas evaluated with positron emission tomography.

A specific ligand for peripheral type benzodiazepine receptors, Ro5-4864, was synthesised and labelled with 11C for use in positron emission tomography (PET). Four patients with suspected glioma, two patients with high grade astrocytoma and two with low grade astrocytoma, as well as one patient with meningioma were examined with PET after the administration of 200 MBq 11C-Ro5-4864. The images as well as kinetic analyses revealed lower uptake of the ligand in tumor as compared with cortical tissue. Markedly elevated uptake in the thalamus suggests a functional role of the ligand.