Neuroinflammation, characterized in particular by microglia activation, is an essential component of Amyotrophic Lateral Sclerosis (ALS) pathogenesis. Translocator Protein (TSPO) is recognized as a specific and sensitive biomarker of neuroinflammation, reflecting disease activity. An experimental radiopharmaceutical specific of TSPO expression, namely \[18F\]DPA714, allow to quantify this microglial activation using Positon Emission Tomography (PET) imaging.

The purpose of this study is to longitudinally correlate the spatial distribution of neuroinflammation with the pro- or anti-inflammatory state of activated microglia cells in ALS, in order to evaluate neurotoxic or neuroprotective microglia activity, by complementary approaches in 20 ALS patients:

in vitro: measuring concentrations of several pro- and anti-inflammatory cytokines secreted by microglial cells in the cerebrospinal fluid (CSF).

in vivo: \[18F\]DPA714 PET imaging. These assays will be performed in the framework of the clinical follow-up of ALS patients, at the diagnosis of ALS disease and 6 months latter.