Neuroinflammation PET imaging: Current opinion and future directions.

Neuroinflammation is a pathological hallmark of numerous neurologic diseases. Positron emission tomography (PET) imaging enables a non-invasive means to investigate, quantify, and track the spatiotemporal dynamics of various immune cells in living subjects. Translocator protein 18 kDa (TSPO)-PET is a technique for detecting glial activation that has yielded valuable clinical data linking neuroinflammation to cognitive decline in neurodegenerative diseases and has also been used preliminarily as a therapy monitoring tool. However, considerable limitations of TSPO-PET have prompted identification of other more cell-specific and functionally relevant biomarkers. This review analyzes the clinical potential of available and emerging PET biomarkers of innate and adaptive immune responses, with mention of exciting future directions for the field.