Project on multiple sclerosis

In addition to the presence of focal lesions (plaques) in the white matter (WM), multiple sclerosis (MS) is also characterized by gray matter (GM) involvement, which is less well understood because it cannot be detected by conventional imaging techniques. GM involvement, however, is present from the onset of the disease. It is responsible for progressive neuronoaxonal loss, resulting in insidious and irreversible clinical deterioration. Postmortem studies suggest that this neurodegeneration is preceded by a reduction in cortical synaptic density, which cannot yet be quantified in vivo.

Our cross-sectional case-control study uses new imaging techniques—multiparametric quantitative MRI at 7 Tesla (T) and PET scans—to explore the pathology of GM. First, based on current histopathological knowledge, we divide the cerebral cortex into three theoretical zones, each behaving distinctly from a pathophysiological perspective but indistinguishable by conventional imaging: focal cortical lesions, cortical areas whose axonal projections may be damaged within MS lesions, and the apparently normal SG. 7 T MRI will allow us to analyze the microstructure of these three zones and compare their quantitative parameters in MS patients and controls.

Second, we use PET scanning with [18F] UCB-H tracer to quantify synaptic density in each of the three cortical zones.
This tracer has a high affinity for the SV2A protein expressed synaptically. It has already been used for the same purpose in other neurodegenerative diseases.

Finally, this study will include a clinical dimension: the results obtained by imaging are correlated with the patient's age, the duration of the disease and the clinical and neuropsychological assessment.