PET imaging of translocator protein expression in neurological disorders

Abstract

Microglia provide the intrinsic immune defence of the brain and are activated by any injurious process. As such they provide a non-specific marker of disease activity. Their function can be both detrimental and beneficial as they release cytokines which drive disease progression but also release restorative growth factors, help clear cellular debris and abnormal protein aggregations and can remodel connections as an adaptive response to brain damage. Activated microglia express translocator protein (TSPO), and this allows them to be imaged in vivo with positron emission tomography (PET) radioligands which are substrates. In this review the role of TSPO imaging with PET is discussed in neurodegenerative and inflammatory brain diseases and in focal brain injury due to trauma or stroke.