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) has changed the management of the disease and a significant proportion of patients not controlled by medium efficacy treatments (MET) 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 HET).