Methods: In twelve adult, male Wistar rats, sequential (R)-[C]PK11195 PET scans were performed 24 h before (baseline), and one and ten days after TBI using controlled cortical impact or sham procedure. Scans were acquired using a High Resolution Research Tomograph (HRRT). ECF glutamate concentrations were measured using cerebral microdialysis at a flow rate of 1.0 ml min−1. At autopsy, brains were processed for histopathology and (immuno)histochemistry to assess both the degree of injury and various biomarkers involved in TBI. Haemotoxylin eosine and Perl's staining were used for morphological detection of injury, haemorrhage and inflammation. Fluoro-Jade B was applied as an effective marker of neuronal injury. Antibodies ED-1, OX-6 (MHC class II) and GFAP were used for detection of activated microglia and/or astrocytes.