TSPO and neurodegenerative disease: Increased brain binding of Positron-Emission Tomography (PET) ligands with affinity for Translator protein (TSPO) has been proposed as a biomarker of microglial activation and neuroinflammation after it was shown that TSPO is mainly expressed in microglia and that TSPO binding is increased after traumatic brain injury and in neurodegenerative diseases [89,90].