Inclusion Criteria:

• - Patients over 18 and under 55 years of age.

• - Patients with Relapsing-remitting MS without relapse for at least 6 months.

• - EDSS<6 at time of inclusion.

Exclusion Criteria:

• - Secondary progressive MS or Primary progressive MS at time of inclusion.

• - Evidence of disease progression (clinical or radiological) - Change in treatment in the year prior to inclusion.

• - Subject with a contraindication to MRI (claustrophobia, pacemaker, etc.) - Inability to follow the follow-up planned by the study.

• - Pregnant or breastfeeding women.

• - Patient not affiliated to the social security system or not benefiting from such a system.

• - Adult protected by law or patient under guardianship or curatorship.

Several prospective monocentric cohorts of between 250 and 1000 patients have been set up in order to characterize more precisely the evolution of the disease. Nevertheless, due to an initial recruitment carried out in the years 2000-2010, they do not constitute a faithful representation of the patients followed in clinical routine, in particular in terms of distribution of treatments. Indeed, the introduction, about 10 years ago, of high efficacy treatments (HET : Natalizumab, Fingolimod, Ocrelizumab, Rituximab, Ofatumumab, Cladribine) has changed the management of the disease and a significant proportion of patients not controlled by medium efficacy treatments (MET : Beta interferons, glatiramer acetate, teriflunomide, dimethyl fumarate, monomethyl fumarate) of the disease are now stable on HET. Nevertheless, if their short-term efficacy has been clearly demonstrated, it remains important to be able to confirm the superiority of HET over MET with the help of prospective cohorts (thus ensuring a retention of patients > 90% over the long term) analyzing all clinical and imaging biomarkers, imaging and biological data. The measurement of cerebral atrophy and its progression is probably one of the most interesting and most easily used biomarkers that can be used clinically to assess this silent progression in these groups of patients. The progression of brain atrophy is also dependent on many other non-modifiable but also modifiable factors outside of MS that need to be better evaluated and eventually managed. Nevertheless, the existence of various neurological comorbidities (sleep disorders, headaches) on this atrophy has not been specifically analyzed to date. The functional assessments used in routine follow-up are most often performed in a care facility and have many limitations: lack of reproducibility, inter/intra operator variability, poor correlation with functional and quality of life scales, etc. It is therefore extremely important to be able to identify new clinical biomarkers of disease progression of the disease by evaluating the physical capacities of the patients as precisely as possible. This study is a single-center, prospective cohort study of a population of 400 patients with relapsing remitting MS (RRMS). The main objective of this study is to compare, on morphological imaging criteria (T1 volumetry), the progression of brain atrophy (biomarker of disease progression) at 3 years in RRMS patients according to treatment line (MET vs.#46;HET). 3 groups of interest will be studied and included in the study: - Group 1: RRMS with medium efficacy treatment (interferon beta, glatiramer acetate, Teriflunomide, dimethyl fumarate, monomethyl fumarate) of the disease (n=175 patients) - Group 2: RRMS with high efficacy treatment (Natalizumab, Ocrelizumab, Rituximab, Ofatumumab, Fingolimod, Cladribine: n=175 patients) - Group 3: Untreated RRMS (n=50 patients)

Arms

Interventions