In this study we plan to image the compartmentalized inflammation in MS using molecular
imaging by positron emission tomography (PET) with a very highly resolutive camera. Two
tracers will be studied and compared: i) [18F]DPA-714, which bind to the peripheral
benzodiazepine receptor (PBR), a target mainly expressed by activated microglial cells. This
new ligand for PBR displays several advantages compared to the existing reference compound
PK11195 in term of brain entrance, signal to noise ratio, and radiolabelling possibility with
[18F] ii) [18F]-fluoro-desoxy-glucose ([18F]FDG), which should reflect glucose metabolism in
activated immune cells in the white matter. Progressive MS patients (secondary progressive
and primary progressive) will be compared to relapsing-remitting patients and to healthy
volunteers. All subjects will pass a complete neurological evaluation and a multimodal MRI to
document clinical disability and tissue injury. A clinical and radiological follow up will
then be performed for a 2-year period. This study should help to understand the contribution
of the intracerebral inflammation on the progression of disability and could provide a
surrogate marker for further therapeutic trials in chronic progressive MS.